LINER LTC2205CUK-TR 16-bit, 65msps/40msp Datasheet

LTC2205/LTC2204
16-Bit, 65Msps/40Msps
ADCs
DESCRIPTIO
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FEATURES
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Sample Rate: 65Msps/40Msps
79dB SNR and 100dB SFDR (2.25VP-P Range)
SFDR >92dB at 140MHz (1.5VP-P Input Range)
PGA Front End (2.25VP-P or 1.5VP-P Input Range)
700MHz Full Power Bandwidth S/H
Optional Internal Dither
Optional Data Output Randomizer
Single 3.3V Supply
Power Dissipation: 610mW/480mW
Optional Clock Duty Cycle Stabilizer
Out-of-Range Indicator
Pin Compatible Family
105Msps: LTC2207 (16-Bit), LTC2207-14 (14-Bit)
80Msps: LTC2206 (16-Bit), LTC2206-14 (14-Bit)
65Msps: LTC2205 (16-Bit), LTC2205-14 (14-Bit)
40Msps: LTC2204 (16-Bit)
48-Pin (7mm × 7mm) QFN Package
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APPLICATIO S
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The LTC®2205/LTC2204 are sampling 16-bit A/D converters
designed for digitizing high frequency, wide dynamic range
signals up to input frequencies of 700MHz. The input range
of the ADC can be optimized with the PGA front end.
The LTC2205/LTC2204 are perfect for demanding communications applications, with AC performance that includes 79dB SNR and 100dB spurious free dynamic range
(SFDR). Ultralow jitter of 90fsRMS allows undersampling of
high input frequencies with excellent noise performance.
Maximum DC specs include ±4LSB INL, ±1LSB DNL (no
missing codes).
A separate output power supply allows the CMOS output
swing to range from 0.5V to 3.6V.
The ENC+ and ENC– inputs may be driven differentially
or single-ended with a sine wave, PECL, LVDS, TTL or
CMOS inputs. An optional clock duty cycle stabilizer allows high performance at full speed with a wide range of
clock duty cycles.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
Telecommunications
Receivers
Cellular Base Stations
Spectrum Analysis
Imaging Systems
ATE
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TYPICAL APPLICATIO
3.3V
LTC2205: 64K Point FFT,
fIN = 5.1MHz, –1dBFS,
PGA = 0, DITH = 0
SENSE
2.2µF
AIN+
1.25V
COMMON MODE
BIAS VOLTAGE
+
ANALOG
INPUT
AIN–
16-BIT
PIPELINED
ADC CORE
S/H
AMP
–
OVDD
INTERNAL ADC
REFERENCE
GENERATOR
OUTPUT
DRIVERS
CORRECTION
LOGIC AND
SHIFT REGISTER
0.5V TO 3.6V
0.1µF
0
OF
CLKOUT
D15
•
•
•
D0
–20
AMPLITUDE (dBFS)
VCM
OGND
CLOCK/DUTY
CYCLE
CONTROL
–60
–80
–100
3.3V
VDD
GND
–40
0.1µF
0.1µF
0.1µF
22076 TA01
–120
–140
0
ENC
ENC
PGA
SHDN
DITH
MODE
OE
ADC CONTROL INPUTS
RAND
5
20
15
25
10
FREQUENCY (MHz)
30
22054 TA01b
22054fb
1
LTC2205/LTC2204
ABSOLUTE MAXIMUM RATINGS
PIN CONFIGURATION
OVDD = VDD (Notes 1 and 2)
48 GND
47 PGA
46 RAND
45 MODE
44 OE
43 OF
42 D15
41 D14
40 D13
39 D12
38 OGND
37 OVDD
TOP VIEW
SENSE 1
VCM 2
VDD 3
VDD 4
GND 5
AIN+ 6
AIN– 7
GND 8
ENC+ 9
ENC– 10
GND 11
VDD 12
36 OVDD
35 D11
34 D10
33 D9
32 D8
31 OGND
30 CLKOUT+
29 CLKOUT–
28 D7
27 D6
26 D5
25 OVDD
49
VDD 13
VDD 14
GND 15
SHDN 16
DITH 17
D0 18
D1 19
D2 20
D3 21
D4 22
OGND 23
OVDD 24
Supply Voltage (VDD) ................................... –0.3V to 4V
Digital Output Ground Voltage (OGND)........ –0.3V to 1V
Analog Input Voltage (Note 3) ......–0.3V to (VDD + 0.3V)
Digital Input Voltage .....................–0.3V to (VDD + 0.3V)
Digital Output Voltage ................ –0.3V to (OVDD + 0.3V)
Power Dissipation.............................................2000mW
Operating Temperature Range
LTC2205C/LTC2204C ............................... 0°C to 70°C
LTC2205I/LTC2204I.............................. –40°C to 85°C
Storage Temperature Range .................. –65°C to 150°C
Digital Output Supply Voltage (OVDD) .......... –0.3V to 4V
UK PACKAGE
48-LEAD (7mm × 7mm) PLASTIC QFN
EXPOSED PAD IS GND (PIN 49) MUST BE SOLDERED TO PCB BOARD
TJMAX = 150°C, θJA = 29°C/W
ORDER INFORMATION
LEAD FREE FINISH
TAPE AND REEL
PART MARKING*
PACKAGE DESCRIPTION
TEMPERATURE RANGE
LTC2205CUK#PBF
LTC2205CUK#TRPBF
LTC2205UK
48-Lead (7mm x 7mm) Plastic DFN
0°C to 70°C
LTC2204CUK#PBF
LTC2204CUK#TRPBF
LTC2204UK
48-Lead (7mm x 7mm) Plastic DFN
0°C to 70°C
LTC2205IUK#PBF
LTC2205IUK#TRPBF
LTC2205UK
48-Lead (7mm x 7mm) Plastic DFN
–40°C to 85°C
LTC2204IUK#PBF
LTC2204IUK#TRPBF
LTC2204UK
48-Lead (7mm x 7mm) Plastic DFN
–40°C to 85°C
LEAD BASED FINISH
TAPE AND REEL
PART MARKING*
PACKAGE DESCRIPTION
TEMPERATURE RANGE
LTC2205CUK
LTC2205CUK#TR
LTC2205UK
48-Lead (7mm x 7mm) Plastic DFN
0°C to 70°C
LTC2204CUK
LTC2204CUK#TR
LTC2204UK
48-Lead (7mm x 7mm) Plastic DFN
0°C to 70°C
LTC2205IUK
LTC2205IUK#TR
LTC2205UK
48-Lead (7mm x 7mm) Plastic DFN
–40°C to 85°C
LTC2204IUK
LTC2204IUK#TR
LTC2204UK
48-Lead (7mm x 7mm) Plastic DFN
–40°C to 85°C
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
For more information on lead free part marking, go to: http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/
CONVERTER CHARACTERISTICS
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. (Note 4)
PARAMETER
Resolution (No Missing Codes)
Integral Linearity Error
Integral Linearity Error
Differential Linearity Error
Offset Error
Offset Drift
Gain Error
Full-Scale Drift
Transition Noise
CONDITIONS
l
Differential Analog Input (Note 5)
Differential Analog Input (Note 5), TA = 25°C
Differential Analog Input
(Note 6)
l
External Reference
Internal Reference
External Reference
l
l
l
MIN
16
TYP
MAX
±0.7
±0.7
±0.3
±1
±10
±0.2
±30
±10
2.5
±4.5
±4
±1
±8.5
±1.9
UNITS
Bits
LSB
LSB
LSB
mV
µV/°C
%FS
ppm/°C
ppm/°C
LSBRMS
22054fb
2
LTC2205/LTC2204
ANALOG INPUT
The l denotes the specifications which apply over the full operating temperature range, otherwise
specifications are at TA = 25°C. (Note 4)
SYMBOL
VIN
VIN, CM
IIN
ISENSE
IMODE
CIN
PARAMETER
Analog Input Range (AIN+ – AIN–)
Analog Input Common Mode
Analog Input Leakage Current
SENSE Input Leakage Current
MODE Pin Pull-Down Current to GND
Analog Input Capacitance
tAP
Sample-and-Hold
Aperture Delay Time
Sample-and-Hold
Aperture Delay Time Jitter
Analog Input
Common Mode Rejection Ratio
Full Power Bandwidth
tJITTER
CMRR
BW-3dB
CONDITIONS
3.135V ≤ VDD ≤ 3.465V
Differential Input (Note 7)
0V ≤ AIN+, AIN– ≤ VDD
0V ≤ SENSE ≤ VDD
MIN
l
l
l
l
1
–1
–3
Sample Mode ENC+ < ENC–
Hold Mode ENC+ > ENC–
1V < (AIN+ = AIN–) <1.5V
TYP
1.5 to 2.25
1.25
MAX
10
6.5
1.8
0.7
UNITS
VP-P
V
µA
µA
µA
pF
pF
ns
90
fsRMS
60
dB
700
MHz
1.5
1
3
DYNAMIC ACCURACY
The l denotes the specifications which apply over the full operating temperature range,
otherwise specifications are at TA = 25°C. AIN = –1dBFS. (Note 4)
SYMBOL PARAMETER
CONDITIONS
SNR
5MHz Input (2.25V Range, PGA = 0)
5MHz Input (1.5V Range, PGA = 1)
Signal-to-Noise Ratio
15MHz Input (2.25V Range, PGA = 0)
15MHz Input (2.25V Range, PGA = 0)
15MHz Input (1.5V Range, PGA = 1)
70MHz Input (2.25V Range, PGA = 0)
70MHz Input (1.5V Range, PGA = 1)
70MHz Input (1.5V Range, PGA = 1)
SFDR
Spurious Free
Dynamic Range
2nd or 3rd
Harmonic
MIN
LTC2204
TYP
MAX
MIN
79.1
76.5
l
77.6
78
l
74.6
75
79.0
79.0
76.5
78.5
76.3
77.5
77.9
74.6
75
LTC2205
TYP
MAX
UNITS
79.0
76.4
dBFS
dBFS
78.9
78.9
76.4
dBFS
dBFS
dBFS
78.4
76.2
dBFS
dBFS
dBFS
140MHz Input (2.25V Range, PGA = 0)
140MHz Input (1.5V Range, PGA = 1)
77.4
75.5
77.3
75.4
dBFS
dBFS
170MHz Input (2.25V Range, PGA = 0)
170MHz Input (1.5V Range, PGA = 1)
76.5
74.9
76.5
74.8
dBFS
dBFS
5MHz Input (2.25V Range, PGA = 0)
5MHz Input (1.5V Range, PGA = 1)
100
100
100
100
dB
dB
100
100
100
dB
dB
dB
92
94
94
dB
dB
dB
15MHz Input (2.25V Range, PGA = 0)
15MHz Input (2.25V Range, PGA = 0
15MHz Input (1.5V Range, PGA = 1)
70MHz Input (2.25V Range, PGA = 0)
70MHz Input (1.5V Range, PGA = 1)
70MHz Input (1.5V Range, PGA = 1)
l
87
88
l
84.5
86
100
100
100
92
94
94
87
88
84.5
86
140MHz Input (2.25V Range, PGA = 0)
140MHz Input (1.5V Range, PGA = 1)
89
92
89
92
dB
dB
170MHz Input (2.25V Range, PGA = 0)
170MHz Input (1.5V Range, PGA = 1)
82
84
82
84
dB
dB
22054fb
3
LTC2205/LTC2204
DYNAMIC ACCURACY
The l denotes the specifications which apply over the full operating temperature range,
otherwise specifications are at TA = 25°C. AIN = –1dBFS unless otherwise noted. (Note 4)
SYMBOL PARAMETER
CONDITIONS
SFDR
5MHz Input (2.25V Range, PGA = 0)
5MHz Input (1.5V Range, PGA = 1)
Spurious Free
Dynamic Range
4th Harmonic
or Higher
15MHz Input (2.25V Range, PGA = 0)
15MHz Input (1.5V Range, PGA = 1)
70MHz Input (2.25V Range, PGA = 0)
70MHz Input (1.5V Range, PGA = 1)
S/(N+D)
Signal-to-Noise
Plus Distortion Ratio
SFDR
Spurious Free
Dynamic Range
at –25dBFS
Dither “ON”
MAX
MIN
105
105
l
90
l
88.5
100
100
100
100
90
88.5
LTC2205
TYP
MAX
UNITS
105
105
dB
dB
100
100
dB
dB
100
100
dB
dB
97
97
97
97
dB
dB
170MHz Input (2.25V Range, PGA = 0)
170MHz Input (1.5V Range, PGA = 1)
95
95
95
95
dB
dB
79.1
76.5
79.0
76.4
dBFS
dBFS
78.9
78.9
76.4
dBFS
dBFS
dBFS
78.4
76.2
76.2
dBFS
dBFS
dBFS
5MHz Input (2.25V Range, PGA = 0)
5MHz Input (1.5V Range, PGA = 1)
70MHz Input (2.25V Range, PGA = 0)
70MHz Input (1.5V Range, PGA = 1)
70MHz Input (1.5V Range, PGA = 1)
Spurious Free
Dynamic Range
at –25dBFS
Dither “OFF”
LTC2204
TYP
140MHz Input (2.25V Range, PGA = 0)
140MHz Input (1.5V Range, PGA = 1)
15MHz Input (2.25V Range, PGA = 0)
15MHz Input (2.25V Range, PGA = 0)
15MHz Input (1.5V Range, PGA = 1)
SFDR
MIN
l
77.5
77.7
l
73.8
74.2
79.0
79.0
76.5
78.5
76.2
76.2
77.4
77.6
73.8
74.2
140MHz Input (2.25V Range, PGA = 0)
140MHz Input (1.5V Range, PGA = 1)
77.3
75.4
77.0
75.3
dBFS
dBFS
170MHz Input (2.25V Range, PGA = 0)
170MHz Input (1.5V Range, PGA = 1)
76.5
75.4
76.0
75.2
dBFS
dBFS
5MHz Input (2.25V Range, PGA = 0)
5MHz Input (1.5V Range, PGA = 1)
105
105
105
105
dBFS
dBFS
15MHz Input (2.25V Range, PGA = 0)
15MHz Input (1.5V Range, PGA = 1)
105
105
105
105
dBFS
dBFS
70MHz Input (2.25V Range, PGA = 0)
70MHz Input (1.5V Range, PGA = 1)
105
105
105
105
dBFS
dBFS
140MHz Input (2.25V Range, PGA = 0)
140MHz Input (1.5V Range, PGA = 1)
100
100
100
100
dBFS
dBFS
170MHz Input (2.25V Range, PGA = 0)
170MHz Input (1.5V Range, PGA = 1)
100
100
100
100
dBFS
dBFS
5MHz Input (2.25V Range, PGA = 0)
5MHz Input (1.5V Range, PGA = 1)
115
115
115
115
dBFS
dBFS
115
115
dBFS
dBFS
15MHz Input (2.25V Range, PGA = 0)
15MHz Input (1.5V Range, PGA = 1)
l
98
115
115
98
70MHz Input (2.25V Range, PGA = 0)
70MHz Input (1.5V Range, PGA = 1)
115
115
115
115
dBFS
dBFS
140MHz Input (2.25V Range, PGA = 0)
140MHz Input (1.5V Range, PGA = 1)
115
115
115
115
dBFS
dBFS
170MHz Input (2.25V Range, PGA = 0)
170MHz Input (1.5V Range, PGA = 1)
105
105
105
105
dBFS
dBFS
22054fb
4
LTC2205/LTC2204
COMMON MODE BIAS CHARACTERISTICS
The l denotes the specifications which apply over
the full operating temperature range, otherwise specifications are at TA = 25°C. (Note 4)
PARAMETER
VCM Output Voltage
VCM Output Tempco
VCM Line Regulation
VCM Output Resistance
CONDITIONS
IOUT = 0
IOUT = 0
3.135V ≤ VDD ≤ 3.465V
1mA ≤ | IOUT | ≤ 1mA
MIN
1.15
TYP
1.25
±40
1
1
MAX
1.35
UNITS
V
ppm/°C
mV/ V
Ω
DIGITAL INPUTS AND DIGITAL OUTPUTS
The l denotes the specifications which apply over the
full operating temperature range, otherwise specifications are at TA = 25°C. (Note 4)
SYMBOL
PARAMETER
ENCODE INPUTS (ENC+, ENC–)
VID
Differential Input Voltage (Note 7)
VICM
Common Mode Input Voltage
RIN
Input Resistance
CIN
Input Capacitance
LOGIC INPUTS (DITH, PGA, SHDN, RAND)
VIH
High Level Input Voltage
VIL
Low Level Input Voltage
IIN
Digital Input Current
CIN
Digital Input Capacitance
LOGIC OUTPUTS
OVDD = 3.3V
VOH
High Level Output Voltage
CONDITIONS
MIN
l
Internally Set
Externally Set (Note 7)
TYP
MAX
0.2
V
1.6
1.2
(See Figure 2)
(Note 7)
3.0
6
3
l
VDD = 3.3V
VDD = 3.3V
VIN = 0V to VDD
(Note 7)
0.8
±10
1.5
V
V
µA
pF
3.299
3.29
0.01
0.10
–50
50
0.4
V
V
V
V
mA
mA
l
IO = –10µA
IO = –200µA
l
IO = 160µA
IO = 1.6mA
l
3.1
V
V
kΩ
pF
2
l
VDD = 3.3V
UNITS
VOL
Low Level Output Voltage
VDD = 3.3V
ISOURCE
ISINK
OVDD = 2.5V
VOH
VOL
OVDD = 1.8V
VOH
VOL
Output Source Current
Output Sink Current
VOUT = 0V
VOUT = 3.3V
High Level Output Voltage
Low Level Output Voltage
VDD = 3.3V
VDD = 3.3V
IO = –200µA
IO = 1.60mA
2.49
0.1
V
V
High Level Output Voltage
Low Level Output Voltage
VDD = 3.3V
VDD = 3.3V
IO = –200µA
IO = 1.60mA
1.79
0.1
V
V
POWER REQUIREMENTS
The l denotes the specifications which apply over the full operating temperature
range, otherwise specifications are at TA = 25°C.
SYMBOL PARAMETER
CONDITIONS
MIN
LTC2204
TYP
MAX
MIN
LTC2205
TYP
MAX
UNITS
3.135
3.3
3.465
3.315
3.3
3.465
V
3.6
0.5V
3.3
3.6
V
VDD
Analog Supply Voltage
PSHDN
Shutdown Power
OVDD
Output Supply Voltage
l
IVDD
Analog Supply Current
l
145
200
185
235
mA
PDIS
Power Dissipation
l
480
660
610
776
mW
SHDN = VDD
0.2
0.5V
0.2
mW
22054fb
5
LTC2205/LTC2204
TIMING CHARACTERISTICS
The l denotes the specifications which apply over the full operating temperature
range, otherwise specifications are at TA = 25°C. (Note 4)
SYMBOL PARAMETER
CONDITIONS
MIN
LTC2204
TYP
MAX
MIN
40
1
l
1
Duty Cycle Stabilizer Off (Note 7)
Duty Cycle Stabilizer On (Note 7)
l
l
10.4
2.7
12.5
12.5
500
500
6.40
2.70
Duty Cycle Stabilizer Off (Note 7)
Duty Cycle Stabilizer On (Note 7)
l
10.4
2.7
12.5
12.5
500
500
6.40
2.70
LTC2205
TYP
MAX
UNITS
fS
Sampling Frequency
tL
ENC Low Time
tH
ENC High Time
tAP
Sample-and-Hold
Aperture Delay
tD
ENC to DATA Delay
(Note 7)
l
1.3
2.7
4.0
1.3
2.7
4.0
ns
tC
ENC to CLKOUT Delay
(Note 7)
l
1.3
2.7
4.0
1.3
2.7
4.0
ns
tSKEW
DATA to CLKOUT Skew
(tD – tC) (Note 7)
l
–0.6
0
0.6
–0.6
0
0.6
ns
tOE
DATA Access Time
Bus Relinquish Time
CL = 5pf (Note 7)
(Note 7)
l
l
5
5
15
15
5
5
15
15
ns
ns
0.7
Pipeline
Latency
MHz
7.69
7.69
500
500
ns
ns
7.69
7.69
500
500
ns
ns
0.7
7
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: All voltage values are with respect to GND, with GND and OGND
shorted (unless otherwise noted).
Note 3: When these pin voltages are taken below GND or above VDD, they
will be clamped by internal diodes. This product can handle input currents
of greater than 100mA below GND or above VDD without latchup.
Note 4: VDD = 3.3V, fSAMPLE = 65MHz (LTC2205), 40MHz (LTC2204)
differential ENC+/ENC– = 2VP-P sine wave with 1.6V common mode,
65
7
ns
Cycles
input range = 2.25VP-P with differential drive (PGA = 0), unless otherwise
specified.
Note 5: Integral nonlinearity is defined as the deviation of a code from
a “best fit straight line” to the transfer curve. The deviation is measured
from the center of the quantization band.
Note 6: Offset error is the offset voltage measured from –1/2LSB when the
output code flickers between 0000 0000 0000 0000 and 1111 1111 1111
1111 in 2’s complement output mode.
Note 7: Guaranteed by design, not subject to test.
Note 8: Recommended operating conditions.
TIMING DIAGRAM
tAP
ANALOG
INPUT
N+1
N+4
N
N+3
N+2
tH
tL
–
ENC
ENC+
tD
N–7
D0-D15, OF
CLKOUT+
CLKOUT –
N–6
N–5
N–4
N–3
tC
22054 TD01
22054fb
6
LTC2205/LTC2204
TYPICAL PERFORMANCE CHARACTERISTICS
LTC2205: DNL (Differential NonLinearity) vs Code
160,000
1.5
0.75
140,000
1.0
0.50
120,000
0.5
0.25
100,000
0
COUNT
1.00
0
–0.25
60,000
–1.0
–0.50
40,000
–1.5
–0.75
20,000
0
0
–1.00
8192 16384 24576 32768 40960 49152 57344 65536
0
CODE
22054 G01
22054 G02
LTC2205: 64K Point FFT,
fIN = 5.1MHz, –1dBFS,
PGA = 0, DITH = 0
LTC2205: 64K Point FFT,
fIN = 5.1MHz, –25dBFS,
PGA = 0, DITH = 0
–20
–20
–20
–40
–40
–40
–80
–100
AMPLITUDE (dBFS)
0
AMPLITUDE (dBFS)
0
–60
–60
–80
–100
–120
–120
5
20
15
25
10
FREQUENCY (MHz)
0
30
–60
–80
–100
–120
–140
–140
5
20
15
25
10
FREQUENCY (MHz)
–140
30
0
–20
–20
–20
–40
–40
–40
–120
AMPLITUDE (dBFS)
0
AMPLITUDE (dBFS)
0
–100
–60
–80
–100
–120
–140
5
20
15
25
10
FREQUENCY (MHz)
30
22054 G07
–60
–80
–100
–120
–140
0
30
LTC2205: 64K Point FFT,
fIN = 5.1MHz, –40dBFS,
PGA = 0, DITH = 1
0
–80
20
15
25
10
FREQUENCY (MHz)
22054 G06
LTC2205: 64K Point FFT,
fIN = 5.1MHz, –40dBFS,
PGA = 0, DITH = 0
–60
5
22054 G05
22054 G04
LTC2205: 64K Point FFT,
fIN = 5.1MHz, –25dBFS,
PGA = 0, DITH = 1
8 10
22054 G03
LTC2205: 64K Point FFT,
65Msps, fIN = 5.1MHz, –1dBFS,
PGA = 1, DITH = 0
0
0
–10 –8 –6 –4 –2 0 2 4 6
CODE FROM MID-SCALE
8192 16384 24576 32768 40960 49152 57344 65536
CODE
AMPLITUDE (dBFS)
80,000
–0.5
–2.0
AMPLITUDE (dBFS)
LTC2205: Grounded Input
Histogram
2.0
DNL (LSB)
INL (LSB)
LTC2205: INL (Integral NonLinearity) vs Code
0
5
20
15
25
10
FREQUENCY (MHz)
30
22054 G08
–140
0
5
20
15
25
10
FREQUENCY (MHz)
30
22054 G09
22054fb
7
LTC2205/LTC2204
TYPICAL PERFORMANCE CHARACTERISTICS
LTC2205: 64K Point FFT,
65Msps, fIN = 15.1MHz, –1dBFS,
PGA = 1, DITH = 0
0
–20
–20
–20
–40
–40
–40
–60
–80
–100
AMPLITUDE (dBFS)
0
–60
–80
–100
–120
–120
0
5
20
15
25
10
FREQUENCY (MHz)
0
30
5
20
15
25
10
FREQUENCY (MHz)
–80
–100
–140
30
0
–20
–20
–40
–40
–40
–100
–120
AMPLITUDE (dBFS)
–20
AMPLITUDE (dBFS)
0
–60
–80
–100
–120
–140
5
20
15
25
10
FREQUENCY (MHz)
30
–60
–80
–100
–120
–140
0
–140
0
5
20
15
25
10
FREQUENCY (MHz)
22054 G13
30
0
–20
–20
–40
–40
–40
–100
–120
AMPLITUDE (dBFS)
–20
AMPLITUDE (dBFS)
0
–60
–80
–100
–120
–140
0
5
20
15
25
10
FREQUENCY (MHz)
30
22054 G16
30
LTC2205: 64K Point FFT,
65Msps, fIN = 70.1MHz, –25dBFS,
PGA = 0, DITH = 0
0
–80
20
15
25
10
FREQUENCY (MHz)
22054 G15
LTC2205: 64K Point FFT,
65Msps, fIN = 70.1MHz, –1dBFS,
PGA = 1, DITH = 0
0
–60
5
22054 G14
LTC2205: 64K Point FFT,
65Msps, fIN = 70.1MHz, –1dBFS,
PGA = 0, DITH = 0
30
LTC2205: 64K Point FFT,
65Msps, fIN = 15.1MHz, –40dBFS,
PGA = 0, DITH = 1
0
–80
20
15
25
10
FREQUENCY (MHz)
22054 G12
LTC2205: 64K Point FFT,
65Msps, fIN = 15.1MHz, –40dBFS,
PGA = 0, DITH = 0
0
–60
5
22054 G11
22054 G10
LTC2205: 64K Point FFT,
65Msps, fIN = 15.1MHz, –25dBFS,
PGA = 0, DITH = 1
AMPLITUDE (dBFS)
–60
–120
–140
–140
AMPLITUDE (dBFS)
LTC2205: 64K Point FFT,
65Msps, fIN = 15.1MHz, –25dBFS,
PGA = 0, DITH = 0
0
AMPLITUDE (dBFS)
AMPLITUDE (dBFS)
LTC2205: 64K Point FFT,
65Msps, fIN = 15.1MHz, –1dBFS,
PGA = 0, DITH = 0
–60
–80
–100
–120
–140
–140
0
5
20
15
25
10
FREQUENCY (MHz)
30
22054 G17
0
5
20
15
25
10
FREQUENCY (MHz)
30
22054 G18
22054fb
8
LTC2205/LTC2204
TYPICAL PERFORMANCE CHARACTERISTICS
LTC2205: 64K Point FFT,
65Msps, fIN = 70.1MHz, –40dBFS,
PGA = 0, DITH = 0
0
–20
–20
–20
–40
–40
–40
–60
–80
–100
AMPLITUDE (dBFS)
0
–60
–80
–100
–120
–120
0
5
20
15
25
10
FREQUENCY (MHz)
0
30
5
20
15
25
10
FREQUENCY (MHz)
–80
–100
–140
30
0
–20
–20
–40
–40
–40
–120
AMPLITUDE (dBFS)
–20
AMPLITUDE (dBFS)
0
–100
–60
–80
–100
0
5
20
15
25
10
FREQUENCY (MHz)
–80
–100
–140
–140
30
–60
–120
–120
–140
0
5
20
15
25
10
FREQUENCY (MHz)
22054 G22
0
30
–20
–20
–40
–40
–40
AMPLITUDE (dBFS)
–20
AMPLITUDE (dBFS)
0
–100
–60
–80
–100
–120
–120
0
5
20
15
25
10
FREQUENCY (MHz)
30
22054 G25
–60
–80
–100
–120
–140
–140
30
22054 G24
0
–80
20
15
25
10
FREQUENCY (MHz)
LTC2205: 64K Point FFT,
65Msps, fIN = 140.1MHz,
–40dBFS, PGA = 0, DITH = 1
0
–60
5
22054 G23
LTC2205: 64K Point FFT,
65Msps, fIN = 140.1MHz,
–40dBFS, PGA = 0, DITH = 0
LTC2205: 64K Point FFT,
65Msps, fIN = 140.1MHz,
–25dBFS, PGA = 0, DITH = 1
30
LTC2205: 64K Point FFT,
65Msps, fIN = 140.1MHz,
–25dBFS, PGA = 0, DITH = 0
0
–80
20
15
25
10
FREQUENCY (MHz)
22054 G21
LTC2205: 64K Point FFT,
fIN = 140.1MHz, –1dBFS,
PGA = 1, DITH = 0
0
–60
5
22054 G20
22054 G19
LTC2205: 64K Point FFT,
65Msps, fIN = 140.1MHz, –1dBFS,
PGA = 0, DITH = 0
AMPLITUDE (dBFS)
–60
–120
–140
–140
AMPLITUDE (dBFS)
LTC2205: 64K Point FFT,
65Msps, fIN = 70.1MHz, –40dBFS,
PGA = 0, DITH = 1
0
AMPLITUDE (dBFS)
AMPLITUDE (dBFS)
LTC2205: 64K Point FFT,
65Msps, fIN = 70.1MHz, –25dBFS,
PGA = 0, DITH = 1
0
5
20
15
25
10
FREQUENCY (MHz)
30
22054 G26
–140
0
5
20
15
25
10
FREQUENCY (MHz)
30
22054 G27
22054fb
9
LTC2205/LTC2204
TYPICAL PERFORMANCE CHARACTERISTICS
LTC2205: 64K Point FFT,
fIN1 = 64.1MHz, –7dBFS,
fIN2 = 20.1MHz, –7dBFS, PGA = 0
0
0
–20
–20
–40
–40
–80
–100
–80
–100
–120
–140
–140
0
5
20
15
25
10
FREQUENCY (MHz)
30
110
–60
–120
22054 G28
100
90
80
70
60
50
40
30
0
5
20
15
25
10
FREQUENCY (MHz)
20
–80 –70 –60 –50 –40 –30 –20 –10
INPUT LEVEL (dBFS)
30
22054 G29
LTC2205: SFDR vs Input Level,
fIN = 15.1MHz,
DITH = 1, RAND = 1, PGA = 0
130
120
120
110
110
110
100
100
100
80
70
60
50
SFDR (dBFS AND dBc)
130
120
SFDR (dBFS AND dBc)
130
90
90
80
70
60
50
90
80
70
60
50
40
40
40
30
30
30
20
–80 –70 –60 –50 –40 –30 –20 –10
INPUT LEVEL (dBFS)
20
–80 –70 –60 –50 –40 –30 –20 –10
INPUT LEVEL (dBFS)
0
20
–80 –70 –60 –50 –40 –30 –20 –10
INPUT LEVEL (dBFS)
0
22054 G32
22054 G31
LTC2205: SFDR vs Input Level,
fIN = 140.1MHz,
DITH = 0, RAND = 1, PGA = 0
130
120
120
110
110
110
100
100
100
80
70
60
50
SFDR (dBFS AND dBc)
130
120
SFDR (dBFS AND dBc)
130
90
90
80
70
60
50
90
80
70
60
50
40
40
40
30
30
30
20
–80 –70 –60 –50 –40 –30 –20 –10
INPUT LEVEL (dBFS)
20
–80 –70 –60 –50 –40 –30 –20 –10
INPUT LEVEL (dBFS)
0
22054 G34
0
22054 G33
LTC2205: SFDR vs Input Level,
fIN = 70.1MHz,
DITH = 1, RAND = 1, PGA = 0
LTC2205: SFDR vs Input Level,
fIN = 70.1MHz,
DITH = 0, RAND = 1, PGA = 0
0
22054 G30
LTC2205: SFDR vs Input Level,
fIN = 15.1MHz,
DITH = 0, RAND = 1, PGA = 0
LTC2205: SFDR vs Input Level,
fIN = 5.1MHz,
DITH = 1, RAND = 1, PGA = 0
SFDR (dBFS AND dBc)
130
SFDR (dBFS AND dBc)
–60
SFDR (dBFS AND dBc)
LTC2205: SFDR vs Input Level,
fIN = 5.1MHz,
DITH = 0, RAND = 1, PGA = 0
120
AMPLITUDE (dBFS)
AMPLITUDE (dBFS)
LTC2205: 64K Point FFT,
fIN1 = 14.9MHz, –7dBFS,
fIN2 = 20.1MHz, –7dBFS, PGA = 0
0
22054 G35
20
–80 –70 –60 –50 –40 –30 –20 –10
INPUT LEVEL (dBFS)
0
22054 G36
22054fb
10
LTC2205/LTC2204
TYPICAL PERFORMANCE CHARACTERISTICS
LTC2205: SFDR vs Input Level,
fIN = 140.1MHz,
DITH = 1, RAND = 1, PGA = 0
LTC2205: SFDR vs Input
Frequency, DITH = 0, RAND = 0
130
LTC2205: SNR vs Input Frequency,
DITH = 0, RAND = 0
110
80
120
79
78
100
100
80
70
60
50
90
SNR (dBFS)
77
90
SFDR (dBc)
SFDR (dBFS AND dBc)
110
PGA = 1
76
74
73
PGA = 0
80
PGA = 0
75
PGA = 1
72
40
71
30
20
–80 –70 –60 –50 –40 –30 –20 –10
INPUT LEVEL (dBFS)
70
0
0
50
150
200
100
INPUT FREQUENCY (MHz)
70
250
22054 G37
22054 G38
22054 G39
LTC2205: SFDR and SNR vs
Supply Voltage, fIN = 5.1MHz,
65Msps, PGA = 0
LTC2205: SFDR and SNR vs
Sample Rate, fIN = 5.1MHz,
–1dBFS, PGA = 0
LTC2205: IVDD vs Sample Rate,
fIN = 5.1MHz, –1dBFS
110
110
210
VDD = 3.47V
90
80
SFDR
100
190
IVDD (mA)
100
SFDR (dBc) AND SNR (dBFS)
SFDR (dBc) AND SNR (dBFS)
200
SFDR
400
200
100
300
INPUT FREQUENCY (MHz)
0
90
VDD = 3.3V
180
170
VDD = 3.13V
160
80
150
SNR
SNR
140
70
70
2.4
0 10 20 30 40 50 60 70 80 90 100 110
SAMPLE RATE (Msps)
2.6
2.8
3.0
3.2
3.4
SUPPLY VOLTAGE
130
3.6
0 10 20 30 40 50 60 70 80 90 100 110
SAMPLE RATE (Msps)
22054 G41
22054 G40
LTC2205: Gain Error Drift with
Internal Reference vs Temperature
22054 G42
LTC2205: Gain Drift with External
Reference vs Temperature
1
0.8
0
0.6
LTC2205: VCM Drift vs Temperature
0
0.4
–2
–3
–4
0.2
–1
0
VCM (mV)
GAIN DRIFT (mV)
DRIFT (mV)
–1
–0.2
–0.4
–0.6
–5
–3
–0.8
–6
–7
20 40 60
–60 –40 –20 0
TEMPERATURE (°C)
–2
–1.0
80
100
22054 G43
–1.2
–60 –40 –20 0
20 40 60
TEMPERATURE (°C)
80
100
22054 G44
–4
–40
–20
0
20
40
TEMPERATURE (°C)
60
80
22054 G45
22054fb
11
LTC2205/LTC2204
TYPICAL PERFORMANCE CHARACTERISTICS
LTC2205: SFDR and SNR vs
Input Common Mode Voltage,
fIN = 5.1MHz
LTC2205: SFDR and SNR vs
Temperature, fIN = 5.1MHz
120
100
90
SNR
80
70
– 40
0
20
40
60
TEMPERATURE (°C)
– 20
90
80
SNR
70
0.50
80
–40
–60
–80
–100
–120
0.75 1.00 1.25 1.50 1.75
INPUT COMMON MODE VOLTAGE (V)
–140
2.00
0
LTC2204: 64K Point FFT,
40Msps, fIN = 5.1MHz, –25dBFS,
PGA = 0, DITH = 1
0
–20
–20
–20
–40
–40
–40
–100
AMPLITUDE (dBFS)
0
AMPLITUDE (dBFS)
0
–80
–60
–80
–100
–120
–120
0
5
0
20
15
10
FREQUENCY (MHz)
–60
–80
–100
–120
–140
–140
5
–140
20
15
10
FREQUENCY (MHz)
0
LTC2204: 64K Point FFT,
40Msps, fIN = 15.1MHz, –1dBFS,
PGA = 0, DITH = 0
0
–20
–20
–20
–40
–40
–40
–100
AMPLITUDE (dBFS)
0
AMPLITUDE (dBFS)
0
–80
–60
–80
–100
0
5
15
10
FREQUENCY (MHz)
20
22054 G51
–80
–100
–140
–140
–140
–60
–120
–120
–120
20
15
10
FREQUENCY (MHz)
22054 G50
LTC2204: 64K Point FFT,
40Msps, fIN = 5.1MHz, –40dBFS,
PGA = 0, DITH = 1
–60
5
22054 G49
22054 G48
LTC2204: 64K Point FFT,
40Msps, fIN = 5.1MHz, –40dBFS,
PGA = 0, DITH = 0
20
15
10
FREQUENCY (MHz)
22054 G47
LTC2204: 64K Point FFT,
40Msps, fIN = 5.1MHz, –25dBFS,
PGA = 0, DITH = 0
–60
5
29701 G46b
22054 G46
LTC2204: 64K Point FFT,
40Msps, fIN = 5.1MHz, –1dBFS,
PGA = 1, DITH = 0
AMPLITUDE (dBFS)
–20
SFDR
100
AMPLITUDE (dBFS)
SFDR
SNR (dBFS) AND SFDR (dBc)
SFDR (dBc) AND (dBFS)
0
110
110
AMPLITUDE (dBFS)
LTC2204: 64K Point FFT,
40Msps, fIN = 5.1MHz, –1dBFS,
PGA = 0, DITH = 0
0
5
15
10
FREQUENCY (MHz)
20
22054 G52
0
5
15
10
FREQUENCY (MHz)
20
22054 G53
22054fb
12
LTC2205/LTC2204
TYPICAL PERFORMANCE CHARACTERISTICS
0
0
–20
–20
–20
–40
–40
–40
–60
–80
–100
AMPLITUDE (dBFS)
0
–120
–60
–80
–100
5
15
10
FREQUENCY (MHz)
20
0
5
15
10
FREQUENCY (MHz)
22054 G54
–100
0
20
–20
–20
–40
–40
–40
–100
–120
AMPLITUDE (dBFS)
–20
AMPLITUDE (dBFS)
0
–60
–80
–100
0
5
15
10
FREQUENCY (MHz)
0
5
15
10
FREQUENCY (MHz)
–100
0
20
22054 G59
–20
–20
–40
–40
–40
–120
AMPLITUDE (dBFS)
–20
AMPLITUDE (dBFS)
0
–100
–60
–80
–100
5
15
10
FREQUENCY (MHz)
20
22054 G60
–80
–100
–140
–140
0
–60
–120
–120
–140
20
LTC2204: 64K Point FFT,
40Msps, fIN = 70.1MHz, –25dBFS,
PGA = 0, DITH = 1
0
–80
15
10
FREQUENCY (MHz)
22054 G58
0
–60
5
LTC2204: 64K Point FFT,
40Msps, fIN = 70.1MHz, –25dBFS,
PGA = 0, DITH = 0
22054 G57
LTC2204: 64K Point FFT,
40Msps, fIN = 70.1MHz,
–1dBFS, PGA = 1, DITH = 0
–80
–140
–140
20
–60
–120
–120
–140
20
LTC2204: 64K Point FFT,
40Msps, fIN = 70.1MHz,
–1dBFS, PGA = 0, DITH = 0
0
–80
15
10
FREQUENCY (MHz)
22054 G56
LTC2204: 64K Point FFT,
40Msps, fIN = 15.1MHz, –40dBFS,
PGA = 0, DITH = 1
0
–60
5
22054 G55
LTC2204: 64K Point FFT,
40Msps, fIN = 15.1MHz, –40dBFS,
PGA = 0, DITH = 0
AMPLITUDE (dBFS)
–80
–140
–140
0
–60
–120
–120
–140
AMPLITUDE (dBFS)
LTC2204: 64K Point FFT,
40Msps, fIN = 15.1MHz, –25dBFS,
PGA = 0, DITH = 1
LTC2204: 64K Point FFT,
40Msps, fIN = 15.1MHz, –25dBFS,
PGA = 0, DITH = 0
AMPLITUDE (dBFS)
AMPLITUDE (dBFS)
LTC2204: 64K Point FFT,
40Msps, fIN = 15.1MHz, –1dBFS,
PGA = 1, DITH = 0
0
5
15
10
FREQUENCY (MHz)
20
22054 G61
0
5
15
10
FREQUENCY (MHz)
20
22054 G62
22054fb
13
LTC2205/LTC2204
TYPICAL PERFORMANCE CHARACTERISTICS
0
0
–20
–20
–20
–40
–40
–40
–80
–100
AMPLITUDE (dBFS)
0
–60
–60
–80
–100
0
5
15
10
FREQUENCY (MHz)
0
20
5
15
10
FREQUENCY (MHz)
–100
0
20
–20
–20
–40
–40
–40
–120
AMPLITUDE (dBFS)
–20
AMPLITUDE (dBFS)
0
–100
–60
–80
–100
0
5
15
10
FREQUENCY (MHz)
–80
–100
–140
–140
20
–60
–120
–120
–140
0
5
15
10
FREQUENCY (MHz)
22054 G66
0
20
–20
–20
–20
–40
–40
–40
–120
AMPLITUDE (dBFS)
0
AMPLITUDE (dBFS)
0
–100
–60
–80
–100
5
15
10
FREQUENCY (MHz)
20
22054 G69
–80
–100
–140
–140
0
–60
–120
–120
–140
20
22054 G68
0
–80
15
10
FREQUENCY (MHz)
LTC2204: 64K Point FFT,fIN1 =
14.9MHz, –7dBFS,fIN2 = 20.1MHz,
–7dBFS, PGA = 0, DITH = 0
LTC2204: 64K Point FFT,
40Msps, fIN = 140.1MHz,
–40dBFS, PGA = 0, DITH = 1
–60
5
22054 G67
LTC2204: 64K Point FFT,
40Msps, fIN = 140.1MHz,
–25dBFS, PGA = 0, DITH = 0
20
LTC2204: 64K Point FFT,
40Msps, fIN = 140.1MHz,
–25dBFS, PGA = 0, DITH = 1
0
–80
15
10
FREQUENCY (MHz)
22054 G65
LTC2204: 64K Point FFT,
40Msps, fIN = 140.1MHz,
–25dBFS, PGA = 0, DITH = 0
0
–60
5
22054 G64
22054 G63
LTC2204: 64K Point FFT,
40Msps, fIN = 140.1MHz, –1dBFS,
PGA = 1, DITH = 0
AMPLITUDE (dBFS)
–80
–140
–140
–140
–60
–120
–120
–120
AMPLITUDE (dBFS)
LTC2204: 64K Point FFT,
40Msps, fIN = 140.1MHz, –1dBFS,
PGA = 0, DITH = 0
LTC2204: 64K Point FFT,
40Msps, fIN = 70.1MHz, –40dBFS,
PGA = 0, DITH = 1
AMPLITUDE (dBFS)
AMPLITUDE (dBFS)
LTC2204: 64K Point FFT,
40Msps, fIN = 70.1MHz, –40dBFS,
PGA = 0, DITH = 0
0
5
15
10
FREQUENCY (MHz)
20
22054 G70
0
5
15
10
FREQUENCY (MHz)
20
22054 G71
22054fb
14
LTC2205/LTC2204
TYPICAL PERFORMANCE CHARACTERISTICS
LTC2204: 64K Point FFT, fIN1 =
65.1MHz, –7dBFS, fIN2 = 70.1MHz,
–7dBFS, PGA = 0, DITH = 0
SFDR (dBFS AND dBc)
–60
–80
–100
–120
5
20
15
10
FREQUENCY (MHz)
120
110
110
100
90
80
70
60
80
70
60
50
40
30
–80 –70 –60 –50 –40 –30 –20 –10
INPUT LEVEL (dBFS)
0
22054 G73
LTC2204: SFDR vs Input Level,
fIN = 70.1MHz,
DITH = 0, RAND = 1
130
120
120
110
110
110
90
80
70
60
SFDR (dBFS AND dBc)
130
120
SFDR (dBFS AND dBc)
130
100
100
90
80
70
60
100
90
80
70
60
50
50
50
40
40
40
30
–80 –70 –60 –50 –40 –30 –20 –10
INPUT LEVEL (dBFS)
30
–80 –70 –60 –50 –40 –30 –20 –10
INPUT LEVEL (dBFS)
0
22054 G75
30
–80 –70 –60 –50 –40 –30 –20 –10
INPUT LEVEL (dBFS)
0
LTC2204: SFDR vs Input Level,
fIN = 140.1MHz,
DITH = 0, RAND = 1
LTC2204: SFDR vs Input Level,
fIN = 140.1MHz,
DITH = 1, RAND = 1
130
130
120
120
120
110
110
110
SFDR (dBFS AND dBc)
130
100
90
80
70
60
100
90
80
70
60
100
90
80
70
60
50
50
50
40
40
40
30
–80 –70 –60 –50 –40 –30 –20 –10
INPUT LEVEL (dBFS)
30
–80 –70 –60 –50 –40 –30 –20 –10
INPUT LEVEL (dBFS)
0
22054 G78
0
22054 G77
22054 G76
LTC2204: SFDR vs Input Level,
fIN = 70.1MHz,
DITH = 1, RAND = 1
0
22054 G74
LTC2204: SFDR vs Input Level,
fIN = 15.1MHz,
DITH = 1, RAND = 1
LTC2204: SFDR vs Input Level,
fIN = 5.1MHz, DITH = 0, RAND = 1
SFDR (dBFS AND dBc)
90
40
22054 G72
SFDR (dBFS AND dBc)
100
50
30
–80 –70 –60 –50 –40 –30 –20 –10
INPUT LEVEL (dBFS)
–140
0
130
120
SFDR (dBFS AND dBc)
AMPLITUDE (dBFS)
–20
130
SFDR (dBFS AND dBc)
0
–40
LTC2204: SFDR vs Input Level,
fIN = 5.1MHz, DITH = 1, RAND = 1
LTC2204: SFDR vs Input Level,
fIN = 5.1MHz, DITH = 0, RAND = 1
0
22054 G79
30
–80 –70 –60 –50 –40 –30 –20 –10
INPUT LEVEL (dBFS)
0
22054 G80
22054fb
15
LTC2205/LTC2204
TYPICAL PERFORMANCE CHARACTERISTICS
LTC2204: SFDR vs Input
Frequency, DITH = 0, RAND = 0
LTC2204: SFDR and SNR vs Sample
Rate, fIN = 5.1MHz, –1dBFS,
PGA = 0, DITH = 0, RAND = 0
LTC2204: SNR vs Input Frequency,
DITH = 0, RAND = 0
110
80
110
79
100
SFDR
SFDR (dBc) AND SNR (dBFS)
78
SNR (dBFS)
SFDR (dBc)
77
90
PGA = 1
80
PGA = 0
76
PGA = 0
75
74
PGA = 1
73
70
72
100
90
80
SNR
71
60
0
50
150
200
100
INPUT FREQUENCY (MHz)
70
70
250
22054 G81
SNR (dBFS) AND SFDR (dBc)
VDD = 3.3V
IVDD (mA)
160
150
VDD = 3.13V
140
80
2.6
2.8
3.0
3.2
3.4
SUPPLY VOLTAGE (V)
SFDR
100
90
80
SNR
130
3.6
22054 G84
90
VDD = 3.47V
100
2.4
80
110
170
SFDR
70
30 40 50 60 70
SAMPLE RATE (Msps)
LTC2204: SNR and SFDR vs
Input Common Mode Voltage,
DITH = 0, RAND = 0
180
110
SNR
20
22054 G83
LTC2204: IVDD vs Sample Rate,
fIN = 5.1MHz, dBFS, DITH = 0,
RAND = 0
90
10
22054 G82
LTC2204: SFDR and SNR vs
Supply Voltage, DITH = 0,
RAND = 0
SFDR (dBC) AND SNR (dBFS)
0
400
200
100
300
INPUT FREQUENCY (MHz)
0
120
0
10
20
30 40 50 60 70
SAMPLE RATE (Msps)
80
90
22054 G85
70
0.50
0.75 1.00 1.25 1.50 1.75
INPUT COMMON MODE VOLTAGE (V)
2.00
22054 G86
22054fb
16
LTC2205/LTC2204
PIN FUNCTIONS
SENSE (Pin 1): Reference Mode Select and External
Reference Input. Tie SENSE to VDD to select the internal
2.5V bandgap reference. An external reference of 2.5V or
1.25V may be used; both reference values will set a full
scale ADC range of 2.25V (PGA = 0).
VCM (Pin 2): 1.25V Output. Optimum voltage for input common mode. Must be bypassed to ground with a minimum
of 2.2µF. Ceramic chip capacitors are recommended.
VDD (Pins 3, 4, 12, 13, 14): 3.3V Analog Supply Pin.
Bypass to GND with 0.1µF ceramic chip capacitors.
GND (Pins 5, 8, 11, 15, 48, 49): ADC Power Ground.
AIN+ (Pin 6): Positive Differential Analog Input.
AIN
– (Pin 7): Negative Differential Analog Input.
ENC+ (Pin 9): Positive Differential Encode Input. The
sampled analog input is held on the rising edge of ENC+.
Internally biased to 1.6V through a 6.2kΩ resistor. Output
data can be latched on the rising edge of ENC+.
ENC– (Pin 10): Negative Differential Encode Input. The
sampled analog input is held on the falling edge of ENC–.
Internally biased to 1.6V through a 6.2kΩ resistor. Bypass to ground with a 0.1µF capacitor for a single-ended
Encode signal.
SHDN (Pin 16): Power Shutdown Pin. SHDN = low results
in normal operation. SHDN = high results in powered down
analog circuitry and the digital outputs placed in a high
impedance state.
DITH (Pin 17): Internal Dither Enable Pin. DITH = low
disables internal dither. DITH = high enables internal dither.
Refer to Internal Dither section of this data sheet for details
on dither operation.
D0-D15 (Pins 18-22, 26-28, 32-35 and 39-42): Digital
Outputs. D15 is the MSB.
OGND (Pins 23, 31 and 38): Output Driver Ground.
OVDD (Pins 24, 25, 36, 37): Positive Supply for the Output Drivers. Bypass to ground with 0.1µF ceramic chip
capacitors.
CLKOUT– (Pin 29): Data Valid Output. CLKOUT– will toggle
at the sample rate. Latch the data on the falling edge of
CLKOUT–.
CLKOUT+ (Pin 30): Inverted Data Valid Output. CLKOUT+
will toggle at the sample rate. Latch the data on the rising
edge of CLKOUT+.
OF (Pin 43): Over/Under Flow Digital Output. OF is high
when an over or under flow has occurred.
OE (Pin 44): Output Enable Pin. Low enables the digital
output drivers. High puts digital outputs in Hi-Z state.
MODE (Pin 45): Output Format and Clock Duty Cycle
Stabilizer Selection Pin. Connecting MODE to 0V selects
offset binary output format and disables the clock duty
cycle stabilizer. Connecting MODE to 1/3VDD selects offset
binary output format and enables the clock duty cycle stabilizer. Connecting MODE to 2/3VDD selects 2’s complement
output format and enables the clock duty cycle stabilizer.
Connecting MODE to VDD selects 2’s complement output
format and disables the clock duty cycle stabilizer.
RAND (Pin 46): Digital Output Randomization Selection
Pin. RAND low results in normal operation. RAND high
selects D1-D15 to be EXCLUSIVE-ORed with D0 (the
LSB). The output can be decoded by again applying an
XOR operation between the LSB and all other bits. This
mode of operation reduces the effects of digital output
interference.
PGA (Pin 47): Programmable Gain Amplifier Control Pin. Low
selects a front-end gain of 1, input range of 2.25VP-P. High
selects a front-end gain of 1.5, input range of 1.5VP-P.
GND (Exposed Pad, Pin 49): ADC Power Ground. The exposed pad on the bottom of the package must be soldered
to ground.
22054fb
17
LTC2205/LTC2204
BLOCK DIAGRAM
AIN+
AIN–
VDD
INPUT
S/H
FIRST PIPELINED
ADC STAGE
SECOND PIPELINED
ADC STAGE
THIRD PIPELINED
ADC STAGE
FOURTH PIPELINED
ADC STAGE
FIFTH PIPELINED
ADC STAGE
GND
DITHER
SIGNAL
GENERATOR
CORRECTION LOGIC
AND
SHIFT REGISTER
ADC CLOCKS
RANGE
SELECT
OVDD
SENSE
PGA
VCM
BUFFER
ADC
REFERENCE
DIFFERENTIAL
INPUT
LOW JITTER
CLOCK
DRIVER
CLKOUT +
CLKOUT –
OF
CONTROL
LOGIC
OUTPUT
DRIVERS
•
•
•
VOLTAGE
REFERENCE
OGND
ENC+
ENC–
SHDN PGA RAND M0DE
OE
D15
D14
D1
D0
22054 F01
DITH
Figure 1. Functional Block Diagram
22054fb
18
LTC2205/LTC2204
OPERATION
DYNAMIC PERFORMANCE
Signal-to-Noise Plus Distortion Ratio
The signal-to-noise plus distortion ratio [S/(N+D)] is the
ratio between the RMS amplitude of the fundamental input
frequency and the RMS amplitude of all other frequency
components at the ADC output. The output is band limited to frequencies above DC to below half the sampling
frequency.
Signal-to-Noise Ratio
The signal-to-noise (SNR) is the ratio between the RMS
amplitude of the fundamental input frequency and the RMS
amplitude of all other frequency components, except the
first five harmonics.
Total Harmonic Distortion
Total harmonic distortion is the ratio of the RMS sum
of all harmonics of the input signal to the fundamental
itself. The out-of-band harmonics alias into the frequency
band between DC and half the sampling frequency. THD
is expressed as:
THD = –20Log√(V22 + V32 + V42 + ... VN2)/V12
where V1 is the RMS amplitude of the fundamental frequency and V2 through VN are the amplitudes of the second
through nth harmonics.
Intermodulation Distortion
If the ADC input signal consists of more than one spectral
component, the ADC transfer function nonlinearity can
produce intermodulation distortion (IMD) in addition to
THD. IMD is the change in one sinusoidal input caused
by the presence of another sinusoidal input at a different
frequency.
If two pure sine waves of frequencies fa and fb are applied
to the ADC input, nonlinearities in the ADC transfer function
can create distortion products at the sum and difference
frequencies of mfa ± nfb, where m and n = 0, 1, 2, 3, etc.
For example, the 3rd order IMD terms include (2fa + fb),
(fa + 2fb), (2fa – fb) and (fa – 2fb). The 3rd order IMD is
defined as the ratio of the RMS value of either input tone
to the RMS value of the largest 3rd order IMD product.
Spurious Free Dynamic Range (SFDR)
The ratio of the RMS input signal amplitude to the RMS
value of the peak spurious spectral component expressed
in dBc. SFDR may also be calculated relative to full scale
and expressed in dBFS.
Full Power Bandwidth
The Full Power bandwidth is that input frequency at which
the amplitude of the reconstructed fundamental is reduced
by 3dB for a full scale input signal.
Aperture Delay Time
The time from when a rising ENC+ equals the ENC– voltage
to the instant that the input signal is held by the sampleand-hold circuit.
Aperture Delay Jitter
The variation in the aperture delay time from conversion
to conversion. This random variation will result in noise
when sampling an AC input. The signal to noise ratio due
to the jitter alone will be:
SNRJITTER = –20log (2π • fIN • tJITTER)
22054fb
19
LTC2205/LTC2204
APPLICATIONS INFORMATION
CONVERTER OPERATION
The LTC2205/LTC2204 are CMOS pipelined multistep
converters with a front-end PGA. As shown in Figure 1, the
converter has five pipelined ADC stages; a sampled analog
input will result in a digitized value seven cycles later (see the
Timing Diagram section). The analog input is differential for
improved common mode noise immunity and to maximize
the input range. Additionally, the differential input drive
will reduce even order harmonics of the sample and hold
circuit. The encode input is also differential for improved
common mode noise immunity.
The LTC2205/LTC2204 have two phases of operation,
determined by the state of the differential ENC+/ENC– input pins. For brevity, the text will refer to ENC+ greater
than ENC– as ENC high and ENC+ less than ENC– as
ENC low.
Each pipelined stage shown in Figure 1 contains an
ADC, a reconstruction DAC and a residue amplifier. In
operation, the ADC quantizes the input to the stage, and
the quantized value is subtracted from the input by the
DAC to produce a residue. The residue is amplified and
output by the residue amplifier. Successive stages operate out of phase so that when odd stages are outputting
their residue, the even stages are acquiring that residue
and vice versa.
When ENC is low, the analog input is sampled differentially directly onto the input sample-and-hold capacitors,
inside the “input S/H” shown in the block diagram. At the
instant that ENC transitions from low to high, the voltage
on the sample capacitors is held. While ENC is high, the
held input voltage is buffered by the S/H amplifier which
drives the first pipelined ADC stage. The first stage acquires
the output of the S/H amplifier during the high phase of
ENC. When ENC goes back low, the first stage produces
its residue which is acquired by the second stage. At the
same time, the input S/H goes back to acquiring the analog
input. When ENC goes high, the second stage produces
its residue which is acquired by the third stage. An identical process is repeated for the third and fourth stages,
resulting in a fourth stage residue that is sent to the fifth
stage for final evaluation.
Each ADC stage following the first has additional range to
accommodate flash and amplifier offset errors. Results
from all of the ADC stages are digitally delayed such that
the results can be properly combined in the correction
logic before being sent to the output buffer.
LTC2005/LTC2004
VDD
CSAMPLE
4.9pF
AIN+
CPARASITIC
1.8pF
VDD
CSAMPLE
4.9pF
AIN–
CPARASITIC
1.8pF
VDD
1.6V
6k
ENC+
ENC–
6k
1.6V
22054 F02
Figure 2. Equivalent Input Circuit
22054fb
20
LTC2205/LTC2204
APPLICATIONS INFORMATION
SAMPLE/HOLD OPERATION AND INPUT DRIVE
Sample/Hold Operation
Figure 2 shows an equivalent circuit for the LTC2205/
LTC2204 CMOS differential sample and hold. The differential analog inputs are sampled directly onto sampling
capacitors (CSAMPLE) through NMOS transistors. The
capacitors shown attached to each input (CPARASITIC) are
the summation of all other capacitance associated with
each input.
During the sample phase when ENC is low, the NMOS
transistors connect the analog inputs to the sampling
capacitors which charge to, and track the differential input voltage. When ENC transitions from low to high, the
sampled input voltage is held on the sampling capacitors.
During the hold phase when ENC is high, the sampling
capacitors are disconnected from the input and the held
voltage is passed to the ADC core for processing. As ENC
transitions for high to low, the inputs are reconnected to
the sampling capacitors to acquire a new sample. Since
the sampling capacitors still hold the previous sample,
a charging glitch proportional to the change in voltage
between samples will be seen at this time. If the change
between the last sample and the new sample is small,
the charging glitch seen at the input will be small. If the
input change is large, such as the change seen with input
frequencies near Nyquist, then a larger charging glitch
will be seen.
Common Mode Bias
The ADC sample-and-hold circuit requires differential
drive to achieve specified performance. Each input should
swing ±0.5625V for the 2.25V range (PGA = 0) or ±0.375V
for the 1.5V range (PGA = 1), around a common mode
voltage of 1.25V. The VCM output pin (Pin 2) is designed
to provide the common mode bias level. VCM can be tied
directly to the center tap of a transformer to set the DC
input level or as a reference level to an op amp differential
driver circuit. The VCM pin must be bypassed to ground
close to the ADC with 2.2µF or greater.
Input Drive Impedance
As with all high performance, high speed ADCs the
dynamic performance of the LTC2205/LTC2204 can be
influenced by the input drive circuitry, particularly the
second and third harmonics. Source impedance and input reactance can influence SFDR. At the falling edge of
ENC the sample-and-hold circuit will connect the 4.9pF
sampling capacitor to the input pin and start the sampling
period. The sampling period ends when ENC rises, holding the sampled input on the sampling capacitor. Ideally,
the input circuitry should be fast enough to fully charge
the sampling capacitor during the sampling period
1/(2FENCODE); however, this is not always possible and the
incomplete settling may degrade the SFDR. The sampling
glitch has been designed to be as linear as possible to
minimize the effects of incomplete settling.
For the best performance it is recommended to have a
source impedance of 100Ω or less for each input. The
source impedance should be matched for the differential
inputs. Poor matching will result in higher even order
harmonics, especially the second.
INPUT DRIVE CIRCUITS
Input Filtering
A first order RC lowpass filter at the input of the ADC
can serve two functions: limit the noise from input circuitry and provide isolation from ADC S/H switching. The
LTC2205/LTC2204 have a very broadband S/H circuit, DC
to 700MHz; it can be used in a wide range of applications;
therefore, it is not possible to provide a single recommended RC filter.
Figures 3, 4a and 4b show three examples of input RC
filtering at three ranges of input frequencies. In general
it is desirable to make the capacitors as large as can be
tolerated—this will help suppress random noise as well
as noise coupled from the digital circuitry. The LTC2205/
LTC2204 do not require any input filter to achieve data sheet
specifications; however, no filtering will put more stringent
noise requirements on the input drive circuitry.
22054fb
21
LTC2205/LTC2204
APPLICATIONS INFORMATION
Transformer Coupled Circuits
Figure 3 shows the LTC2205/LTC2204 being driven by
an RF transformer with a center-tapped secondary. The
secondary center tap is DC biased with VCM, setting the
ADC input signal at its optimum DC level. Figure 3 shows
a 1:1 turns ratio transformer. Other turns ratios can be
used; however, as the turns ratio increases so does the
impedance seen by the ADC. Source impedance greater
than 50Ω can reduce the input bandwidth and increase
high frequency distortion. A disadvantage of using a
transformer is the loss of low frequency response. Most
small RF transformers have poor performance at frequencies below 1MHz.
Center-tapped transformers provide a convenient means
of DC biasing the secondary; however, they often show
poor balance at high input frequencies, resulting in large
2nd order harmonics.
Figure 4a shows transformer coupling using a transmission line balun transformer. This type of transformer has
much better high frequency response and balance than
flux coupled center tap transformers. Coupling capacitors
are added at the ground and input primary terminals to
allow the secondary terminals to be biased at 1.25V. Figure
4b shows the same circuit with components suitable for
higher input frequencies.
VCM
VCM
2.2µF
2.2µF
5Ω
5Ω AIN+
10Ω
0.1µF
T1
35Ω
8.2pF
0.1µF
10Ω
T1 = MA/COM ETC1-1T
RESISTORS, CAPACITORS
ARE 0402 PACKAGE SIZE
EXCEPT 2.2µF
35Ω
10Ω
5Ω
25Ω
0.1µF
4.7pF
25Ω
10Ω
ANALOG
INPUT
LTC2205/
LTC2204
8.2pF
0.1µF
5Ω AIN–
8.2pF
T1
1:1
4.7pF
T1 = MA/COM ETC1-1-13
RESISTORS, CAPACITORS
ARE 0402 PACKAGE SIZE
EXCEPT 2.2µF
22054 F03
Figure 3. Single-Ended to Differential Conversion Using a Transformer.
Recommended for Input Frequencies from 5MHz to 150MHz
5Ω
4.7pF
AIN+
LTC2205/
LTC2204
AIN–
22054 F04a
Figure 4a. Using a Transmission Line Balun Transformer.
Recommended for Input Frequencies from 70MHz to 250MHz
VCM
2.2µF
0.1µF
5Ω
ANALOG
INPUT
25Ω
0.1µF
T1
1:1
0.1µF
25Ω
T1 = MA/COM ETC1-1-13
RESISTORS, CAPACITORS
ARE 0402 PACKAGE SIZE
EXCEPT 2.2µF
AIN+
2.2pF
5Ω
2.2pF
LTC2205/
LTC2204
AIN–
22054 F04b
Figure 4b. Using a Transmission Line Balun Transformer.
Recommended for Input Frequencies from 250MHz to 500MHz
22054fb
22
LTC2205/LTC2204
APPLICATIONS INFORMATION
Direct Coupled Circuits
Figure 5 demonstrates the use of a differential amplifier to
convert a single ended input signal into a differential input
signal. The advantage of this method is that it provides
low frequency input response; however, the limited gain
bandwidth of any op amp or closed-loop amplifier will degrade the ADC SFDR at high input frequencies. Additionally,
wideband op amps or differential amplifiers tend to have
high noise. As a result, the SNR will be degraded unless
the noise bandwidth is limited prior to the ADC input.
very stringent settling requirements and is not accessible
for external use.
The SENSE pin can be driven ±5% around the nominal 2.5V
or 1.25V external reference inputs. This adjustment range
can be used to trim the ADC gain error or other system
gain errors. When selecting the internal reference, the
SENSE pin should be tied to VDD as close to the converter
as possible. If the sense pin is driven externally it should
be bypassed to ground as close to the device as possible
with 1µF (or larger) ceramic capacitor.
VCM
HIGH SPEED
DIFFERENTIAL
AMPLIFIER
ANALOG
INPUT
+
LTC2205/
LTC2204
2.2µF
AIN+
25Ω
12pF
+
LTC2205/
LTC2204
CM
–
–
AIN–
25Ω
AMPLIFIER = LTC6600-20,
LTC1993, ETC.
12pF
22054 F05
TIE TO VDD TO USE
INTERNAL 2.5V
REFERENCE
OR INPUT FOR
EXTERNAL 2.5V
REFERENCE
OR INPUT FOR
EXTERNAL 1.25V
REFERENCE
Figure 5. DC Coupled Input with Differential Amplifier
RANGE
SELECT
AND GAIN
CONTROL
INTERNAL
ADC
REFERENCE
SENSE
PGA
2.5V
BANDGAP
REFERENCE
VCM
BUFFER
1.25V
2.2µF
Reference Operation
Figure 6 shows the LTC2205/LTC2204 reference circuitry
consisting of a 2.5V bandgap reference, a programmable
gain amplifier and control circuit. The LTC2205/LTC2204
have three modes of reference operation: Internal Reference, 1.25V external reference or 2.5V external reference.
To use the internal reference, tie the SENSE pin to VDD. To
use an external reference, simply apply either a 1.25V or
2.5V reference voltage to the SENSE input pin. Both 1.25V
and 2.5V applied to SENSE will result in a full scale range
of 2.25VP-P (PGA = 0). A 1.25V output, VCM is provided
for a common mode bias for input drive circuitry. An
external bypass capacitor is required for the VCM output.
This provides a high frequency low impedance path to
ground for internal and external circuitry. This is also the
compensation capacitor for the reference; it will not be
stable without this capacitor. The minimum value required
for stability is 2.2µF.
22054 F06
Figure 6. Reference Circuit
VCM
1.25V
2.2µF
3.3V
1µF
2
LT1461-2.5
4
6
SENSE
LTC2205/
LTC2204
2.2µF
22054 F07
Figure 7. A 2.25V Range ADC with
an External 2.5V Reference
The internal programmable gain amplifier provides the
internal reference voltage for the ADC. This amplifier has
22054fb
23
LTC2205/LTC2204
APPLICATIONS INFORMATION
PGA Pin
The PGA pin selects between two gain settings for
the ADC front-end. PGA = 0 selects an input range of
2.25VP-P; PGA = 1 selects an input range of 1.5VP-P. The
2.25V input range has the best SNR; however, the distortion will be higher for input frequencies above 100MHz.
For applications with high input frequencies, the low input
range will have improved distortion; however, the SNR
will be worse by up to approximately 2dB to 6dB. See the
typical performance curves section.
Driving the Encode Inputs
The noise performance of the LTC2205/LTC2204 can
depend on the encode signal quality as much as on the
analog input. The encode inputs are intended to be driven
differentially, primarily for noise immunity from common
mode noise sources. Each input is biased through a 6k
resistor to a 1.6V bias. The bias resistors set the DC operating point for transformer coupled drive circuits and can
set the logic threshold for single-ended drive circuits.
Any noise present on the encode signal will result in additional aperture jitter that will be RMS summed with the
inherent ADC aperture jitter.
In applications where jitter is critical (high input frequencies), take the following into consideration:
1. Differential drive should be used.
2. Use as large an amplitude possible. If using transformer coupling, use a higher turns ratio to increase the
amplitude.
3. If the ADC is clocked with a fixed frequency sinusoidal
signal, filter the encode signal to reduce wideband
noise.
4. Balance the capacitance and series resistance at both
encode inputs such that any coupled noise will appear
at both inputs as common mode noise.
The encode inputs have a common mode range of 1.2V
to 3V. Each input may be driven from ground to VDD for
single-ended drive.
LTC2205/
LTC2204
VDD
TO INTERNAL
ADC CLOCK
DRIVERS
VDD 1.6V
ENC+
6k
0.1µF
ENCODE
INPUT
ETC1-1T
50Ω
100Ω
•
•
VDD 1.6V
50Ω
0.1µF
33pF
6k
ENC–
22054 F08
Figure 8. Transformer Driven Encode
22054fb
24
LTC2205/LTC2204
APPLICATIONS INFORMATION
3.3V
MC100LVELT22
ENC+
VTHRESHOLD = 1.6V
3.3V
130Ω
Q0
ENC+
D0
1.6V ENC–
LTC2205/
LTC2204
0.1µF
130Ω
ENC–
Q0
83Ω
LTC2205/
LTC2204
83Ω
22054 F09
22054 F10
Figure 9. Single-Ended ENC Drive,
Not Recommended for Low Jitter
Maximum and Minimum Encode Rates
The maximum encode rate for the LTC2205 is 65Msps.
The maximum encode rate for the LTC2204 is 40Msps.
For the ADC to operate properly the encode signal should
have a 50% (±2.5%) duty cycle. Achieving a precise 50%
duty cycle is easy with differential sinusoidal drive using
a transformer or using symmetric differential logic such
as PECL or LVDS. When using a single-ended ENCODE
signal asymmetric rise and fall times can result in duty
cycles that are far from 50%.
An optional clock duty cycle stabilizer can be used if the
input clock does not have a 50% duty cycle. This circuit
uses the rising edge of ENC pin to sample the analog input.
The falling edge of ENC is ignored and an internal falling
Figure 10. ENC Drive Using a CMOS to PECL Translator
edge is generated by a phase-locked loop. The input clock
duty cycle can vary from 30% to 70% and the clock duty
cycle stabilizer will maintain a constant 50% internal duty
cycle. If the clock is turned off for a long period of time,
the duty cycle stabilizer circuit will require one hundred
clock cycles for the PLL to lock onto the input clock. To
use the clock duty cycle stabilizer, the MODE pin must be
connected to 1/3VDD or 2/3VDD using external resistors.
The lower limit of the LTC2205/LTC2204 sample rate is
determined by droop of the sample and hold circuits. The
pipelined architecture of this ADC relies on storing analog
signals on small valued capacitors. Junction leakage will
discharge the capacitors. The specified minimum operating
frequency for the LTC2205/LTC2204 is 1Msps.
22054fb
25
LTC2205/LTC2204
APPLICATIONS INFORMATION
DIGITAL OUTPUTS
Data Format
Digital Output Buffers
The LTC2205/LTC2204 parallel digital output can be
selected for offset binary or 2’s complement format. The
format is selected with the MODE pin. This pin has a four
level logic input, centered at 0, 1/3VDD, 2/3VDD and VDD.
An external resistor divider can be user to set the 1/3VDD
and 2/3VDD logic levels. Table 1 shows the logic states
for the MODE pin.
Figure 11 shows an equivalent circuit for a single output
buffer. Each buffer is powered by OVDD and OGND, isolated
from the ADC power and ground. The additional N-channel
transistor in the output driver allows operation down to
low voltages. The internal resistor in series with the output
eliminates the need for external damping resistors.
As with all high speed/high resolution converters, the digital output loading can affect the performance. The digital
outputs of the LTC2205/LTC2204 should drive a minimum
capacitive load to avoid possible interaction between the
digital outputs and sensitive input circuitry. The output
should be buffered with a device such as a ALVCH16373
CMOS latch. For full speed operation the capacitive load
should be kept under 10pF. A resistor in series with the
output may be used but is not required since the ADC has
a series resistor of 33Ω on chip.
Table 1. MODE Pin Function
MODE
0(GND)
1/3VDD
2/3VDD
VDD
Output Format
Clock Duty
Cycle Stabilizer
Offset Binary
Offset Binary
2’s Complement
2’s Complement
Off
On
On
Off
Overflow Bit
An overflow output bit (OF) indicates when the converter
is over-ranged or under-ranged. A logic high on the OF
pin indicates an overflow or underflow.
Lower OVDD voltages will also help reduce interference
from the digital outputs.
LTC2205/LTC2204
OVDD
VDD
0.5V
TO 3.6V
VDD
0.1mF
OVDD
DATA
FROM
LATCH
PREDRIVER
LOGIC
33W
TYPICAL
DATA
OUTPUT
OGND
22054 F11
Figure 11. Equivalent Circuit for a Digital Output Buffer
22054fb
26
LTC2205/LTC2204
APPLICATIONS INFORMATION
Output Clock
The ADC has a delayed version of the encode input available
as a digital output. Both a noninverted version, CLKOUT+
and an inverted version CLKOUT – are provided. The
CLKOUT+/CLKOUT – can be used to synchronize the converter data to the digital system. This is necessary when
using a sinusoidal encode. Data can be latched on the
rising edge of CLKOUT+ or the falling edge of CLKOUT –.
CLKOUT+ falls and CLKOUT – rises as the data outputs
are updated.
Digital Output Randomizer
Interference from the ADC digital outputs is sometimes
unavoidable. Interference from the digital outputs may be
from capacitive or inductive coupling or coupling through
the ground plane. Even a tiny coupling factor can result in
discernible unwanted tones in the ADC output spectrum.
By randomizing the digital output before it is transmitted
off chip, these unwanted tones can be randomized, trading
a slight increase in the noise floor for a large reduction in
unwanted tone amplitude.
The digital output is “Randomized” by applying an exclusive-OR logic operation between the LSB and all other data
output bits. To decode, the reverse operation is applied;
that is, an exclusive-OR operation is applied between the
LSB and all other bits. The LSB, OF and CLKOUT output
are not affected. The output Randomizer function is active
when the RAND pin is high.
LTC2205/LTC2204
CLKOUT
CLKOUT
OF
OF
D15
D15/D0
D14
D2
D14/D0
•
•
•
D2/D0
D1
RAND = HIGH,
SCRAMBLE
ENABLED
D1/D0
RAND
D0
D0
22054 F12
Figure 12. Functional Equivalent of Digital Output Randomizer
22054fb
27
LTC2205/LTC2204
APPLICATIONS INFORMATION
Output Driver Power
Separate output power and ground pins allow the output
drivers to be isolated from the analog circuitry. The power
supply for the digital output buffers, OVDD, should be tied
to the same power supply as for the logic being driven.
OVDD can be powered with any logic voltage up to the VDD
of the ADC. OGND can be powered with any voltage from
ground up to 1V and must be less than OVDD. The logic
outputs will swing between OGND and OVDD.
Internal Dither
The LTC2205/LTC2204 are 16-bit ADCs with very linear
transfer functions; however, at low input levels even
slight imperfections in the transfer function will result in
unwanted tones. Small errors in the transfer function are
usually a result of ADC element mismatches. An optional
internal dither mode can be enabled to randomize the input
location on the ADC transfer curve, resulting in improved
SFDR for low signal levels.
As shown in Figure 14, the output of the sample-and-hold
amplifier is summed with the output of a dither DAC. The
dither DAC is driven by a long sequence pseudo-random
number generator; the random number fed to the dither
DAC is also subtracted from the ADC result. If the dither
DAC is precisely calibrated to the ADC, very little of the
dither signal will be seen at the output. The dither signal
that does leak through will appear as white noise. The
dither DAC is calibrated to result in less than 0.5dB elevation in the noise floor of the ADC, as compared to the
noise floor with dither off.
PC BOARD
FPGA
CLKOUT
OF
D15/D0
D15
LTC2205/
LTC2204
D14/D0
D14
D2/D0
•
•
•
D2
D1/D0
D1
D0
D0
22054 F13
Figure 13. Descrambling a Scrambled Digital Output
22054fb
28
LTC2205/LTC2204
APPLICATIONS INFORMATION
Grounding and Bypassing
The LTC2205/LTC2204 require a printed circuit board with a
clean unbroken ground plane; a multilayer board with an
internal ground plane is recommended. The pinout of the
LTC2205/LTC2204 has been optimized for a flowthrough
layout so that the interaction between inputs and digital
outputs is minimized. Layout for the printed circuit board
should ensure that digital and analog signal lines are
separated as much as possible. In particular, care should
be taken not to run any digital track alongside an analog
signal track or underneath the ADC.
High quality ceramic bypass capacitors should be used
at the VDD, VCM, and OVDD pins. Bypass capacitors must
be located as close to the pins as possible. The traces
connecting the pins and bypass capacitors must be kept
short and should be made as wide as possible.
The LTC2205/LTC2204 differential inputs should run
parallel and close to each other. The input traces should
be as short as possible to minimize capacitance and to
minimize noise pickup.
Heat Transfer
Most of the heat generated by the LTC2205/LTC2204 is
transferred from the die through the bottom-side exposed
pad. For good electrical and thermal performance, the
exposed pad must be soldered to a large grounded pad
on the PC board. It is critical that the exposed pad and all
ground pins are connected to a ground plane of sufficient
area with as many vias as possible.
LTC2205/LTC2204
AIN+
ANALOG
INPUT
AIN–
16-BIT
PIPELINED
ADC CORE
S/H
AMP
CLOCK/DUTY
CYCLE
CONTROL
PRECISION
DAC
DIGITAL
SUMMATION
CLKOUT
OF
D15
•
•
•
D0
OUTPUT
DRIVERS
MULTIBIT DEEP
PSEUDO-RANDOM
NUMBER
GENERATOR
22054 F14
ENC
+
ENC
–
DITH
DITHER ENABLE
HIGH = DITHER ON
LOW = DITHER OFF
Figure 14. Functional Equivalent Block Diagram of Internal Dither Circuit
22054fb
29
LTC2205/LTC2204
APPLICATIONS INFORMATION
RANDOMIZER
(REQUIRES CHANGE IN
SELECTED DEVICE IN PSCOPE)
0V
3.3V
NOT PROVIDED
BY DC718
JUMPERS ARE SHOWN
IN DEFAULT POSITIONS
CLOCK POLARITY
PGA
SENSE
CLOCK OUT
MSB
DIGITAL OUTPUTS TO
DC718 (2.5V CMOS)
ANALOG INPUT
(50Ω)
LSB ENABLE
22076 DC918C
DITHER
ENC CLOCK INPUT
(50Ω)
SHUTDOWN
Ordering Guide:
DEMO BOARD NUMBER
PART NUMBER
RESOLUTION
SPEED
INPUT FREQUENCY
USB I/F BOARD
DC918C-A
LTC2207CUK
16-Bit
105Msps
1MHz to 70MHz
DC718
DC918C-B
LTC2207CUK
16-Bit
105Msps
70MHz to 140MHz
DC718
DC918C-C
LTC2206CUK
16-Bit
80Msps
1MHz to 70MHz
DC718
DC918C-D
LTC2206CUK
16-Bit
80Msps
70MHz to 140MHz
DC718
DC918C-E
LTC2205CUK
16-Bit
65Msps
1MHz to 70MHz
DC718
DC918C-F
LTC2205CUK
16-Bit
65Msps
70MHz to 140MHz
DC718
DC918C-G
LTC2204CUK
16-Bit
40Msps
1MHz to 70MHz
DC718
DC918C-H
LTC2207CUK-14
14-Bit
105Msps
1MHz to 70MHz
DC718
DC918C-I
LTC2207CUK-14
14-Bit
105Msps
70MHz to 140MHz
DC718
DC918C-J
LTC2206CUK-14
14-Bit
80Msps
1MHz to 70MHz
DC718
DC918C-K
LTC2206CUK-14
14-Bit
80Msps
70MHz to 140MHz
DC718
DC918C-L
LTC2205CUK-14
14-Bit
65Msps
1MHz to 70MHz
DC718
See Web site for ordering details or contact local sales.
22054fb
30
LTC2205/LTC2204
APPLICATIONS INFORMATION
Silkscreen Top
Top Side
22054fb
31
LTC2205/LTC2204
APPLICATIONS INFORMATION
Inner Layer 2
Inner Layer 4
Inner Layer 3
Inner Layer 5
22054fb
32
LTC2205/LTC2204
APPLICATIONS INFORMATION
Bottom Side
Silkscreen Bottom
22054fb
33
C30
0.01µF
C10
0.01µF
R31
*
ASSEMBLY
TYPE
DC918C-A
DC918C-B
DC918C-C
DC918C-D
DC918C-E
DC918C-F
DC918C-G
DC918C-H
DC918C-I
DC918C-J
DC918C-K
DC918C-L
5
4
T2
1
2
U1
LTC2207CUK
LTC2207CUK
LTC2206CUK
LTC2206CUK
LTC2205CUK
LTC2205CUK
LTC2204CUK
LTC2207CUK-14
LTC2207CUK-14
LTC2206CUK-14
LTC2206CUK-14
LTC2205CUK-14
T3
MABAES0060
WBC1-1L
MABAES0060
WBC1-1L
MABAES0060
WBC1-1L
MABAES0060
MABAES0060
WBC1-1L
MABAES0060
WBC1-1L
MABAES0060
C12
0.01µF
C5
4.7pF
1.8pF
4.7pF
1.8pF
4.7pF
1.8pF
4.7pF
4.7pF
1.8pF
4.7pF
1.8pF
4.7pF
C15
0.1µF
R28
49.9Ω
C5
*
R26
5.1Ω
C7,
C28
8.2pF
3.9pF
8.2pF
3.9pF
8.2pF
3.9pF
8.2pF
8.2pF
3.9pF
8.2pF
3.9pF
8.2pF
C16
0.1µF
R29
5.1Ω
R30
86.6
182
86.6
182
86.6
182
86.6
86.6
182
86.6
182
86.6
1
R1
10k
AIN–
GND
AIN+
SENSE
VCM
VDD
VDD
3
1
JP5 3
SHDN
GND
VDD
R21, 10k
R20
10k
R6
OPEN
R2
10k
R3
1k
R7
1k
R4
OPEN
OVP
GND
JP1
U1*
2 2
1
3
GND
VDD
JP6
DITH
INPUT FREQUENCY
BITS Msps
1MHz < AIN < 70MHz
16
105
105
70MHz < AIN < 140MHz 16
1MHz < AIN < 70MHz
16
80
80
70MHz < AIN < 140MHz 16
16
65
1MHz < AIN < 70MHz
70MHz < AIN < 140MHz 16
65
16
40
1MHz < AIN < 70MHz
1MHz < AIN < 70MHz
14
105
70MHz < AIN < 140MHz 14
105
14
80
1MHz < AIN < 70MHz
80
70MHz < AIN < 140MHz 14
14
65
1MHz < AIN < 70MHz
VDD
GND
9
ENC+
10
ENC–
11
GND
12
VDD
1
2
3
4
5
6
7
8
C2
2.2µF
L1
56nH
18nH
56nH
18nH
56nH
18nH
56nH
56nH
18nH
56nH
18nH
56nH
3
JP3 1
JP4 1
PGA
RAND
2
2 VDD
VDD
GND
GND
OPEN
VDD
R31,
R32
86.6
43.2
86.6
43.2
86.6
43.2
86.6
86.6
43.2
86.6
43.2
86.6
C17
0.1µF
R33
100Ω
R10
10Ω
R14
10Ω
C11
8.2pF
C3
0.01µF
C8
2.2µF
R8
100Ω
R13
10Ω
R12
33.2Ω
R11
3 33.2Ω
R9
10Ω
R27
49.9Ω
1
1 5
C9
0.01µF
2
2
C6
0.01µF
3
R32
* 5
T1
MABA007159000000
4
3 4*T3
MABA-007159000000
C7
*
* L1
* VERSION TABLE
J3
ENCODE
INPUT
C28
*
C4
0.01µF
J2
ANALOG
INPUT
* R30
2
JP2
SHDN
GND 48
PGA 47
RAND 46
MODE 45
OE 44
13
VDD
14
VDD
15
GND
16
SHDN
17
DITH
18
D0
19
D1
20
D2
21
D3
22
D4
23
3
1
3
2
DD
36
35
34
33
32
31
30
CLKOUT–
+
29
28
D7
27
D6
26
D5
25
OVDD
OVDD
D11
D10
D9
D8
OGND
CLKOUT+
OF 43
D15 42
D14 41
D13 40
D12 39
OGND 38
37
OV
OGND
OVDD
34
24
VDD
C27
100µF
6.3V
OPT.
C1
0.1µF
3
5
E4
E3
A7
A6
A5
A4
A3
A2
A1
A0
T/R
GND
VCC
20
OVP
A7
A6
A5
A4
A3
A2
A1
A0
T/R
GND
VCC
20
OVP
4
5
C22
1µF
9
8
7
6
5
4
3
2
1
10
9
8
7
6
5
4
3
2
1
10
C14
0.1µF
LT1763
OVP
1 A0
2 A1
3
A2
4
A3
8
7
6
5
33
33
RN4C
RN4D
R23
100k
R22
105k
VCC
WP
SCL
SDA
C20
10µF
6.3V
R17
10k
33
33
33
33
RN3C
RN3D
RN4A
RN4B
33
33
33
33
RN1C
RN1D
RN2A
RN2B
33
33
33
33
33
33
RN1A
RN1B
RN2C
RN2D
RN3A
RN3B
33
R5
U6
24LC025
C21, 0.01µF
1
IN
OUT
2
7
GND
ADJ
3
6
GND GND
4
5
SHDN BYP
8
U7
1
2
74VCX245BQX
B7
B6
B5
B4
B3
B2
B1
B0
OE
U2
74VCX245BQX
B7
B6
B5
B4
B3
B2
B1
B0
OE
U2
C19
3
U5
0.1µF NC7SV86P5X
11
12
13
14
15
16
17
18
19
11
12
13
14
15
16
17
18
19
VDD VDD R25
3.3V
1Ω
4
U4
NC7SV86P5X
E1
C23
4.7µF
GND
C18
0.1µF
VDD
2
1
OVP
2
4
6
8
20
12
14
16
18
20
22
24
26
28
30
32
34
36
38
40
2
4
6
8
20
12
14
16
18
20
22
24
26
28
30
32
34
36
38
40
C25
0.1µF
OVP
R19
10k
C13
0.1µF
22054 F15
C26
0.1µF
3201S-40G1
OGND
1
3
5
7
9
11
13
15
17
19
21
23
25
27
29
31
33
35
37
39
J1
R18
10k
1
3
5
7
9
11
13
15
17
19
21
23
25
27
29
31
33
35
37
39
LTC2205/LTC2204
APPLICATIONS INFORMATION
22054fb
LTC2205/LTC2204
PACKAGE DESCRIPTION
UK Package
48-Lead Plastic QFN (7mm × 7mm)
(Reference LTC DWG # 05-08-1704)
0.70 ±0.05
5.15 ± 0.05
5.50 REF
6.10 ±0.05 7.50 ±0.05
(4 SIDES)
5.15 ± 0.05
PACKAGE OUTLINE
0.25 ±0.05
0.50 BSC
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED
7.00 ± 0.10
(4 SIDES)
0.75 ± 0.05
R = 0.10
TYP
R = 0.115
TYP
47 48
0.40 ± 0.10
PIN 1 TOP MARK
(SEE NOTE 6)
1
2
PIN 1
CHAMFER
C = 0.35
5.15 ± 0.10
5.50 REF
(4-SIDES)
5.15 ± 0.10
(UK48) QFN 0406 REV C
0.200 REF
0.00 – 0.05
NOTE:
1. DRAWING CONFORMS TO JEDEC PACKAGE OUTLINE MO-220 VARIATION (WKKD-2)
2. DRAWING NOT TO SCALE
3. ALL DIMENSIONS ARE IN MILLIMETERS
4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE
MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.20mm ON ANY SIDE, IF PRESENT
5. EXPOSED PAD SHALL BE SOLDER PLATED
6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE TOP AND BOTTOM OF PACKAGE
0.25 ± 0.05
0.50 BSC
BOTTOM VIEW—EXPOSED PAD
22054fb
Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However,
no responsibility is assumed for its use. Linear Technology Corporation makes no representation that
the interconnection of its circuits as described herein will not infringe on existing patent rights.
35
LTC2205/LTC2204
RELATED PARTS
PART NUMBER DESCRIPTION
COMMENTS
LTC1748
76.3dB SNR, 90dB SFDR, 48-Pin TSSOP Package
14-Bit, 80Msps 5V ADC
LTC1750
14-Bit, 80Msps, 5V Wideband ADC
Up to 500MHz IF Undersampling, 90dB SFDR
LT1993-2
High Speed Differential Op Amp
800MHz BW, 70dBc Distortion at 70MHz, 6dB Gain
LT1994
Low Noise, Low Distortion Fully Differential Input/
Output Amplifier/Driver
Low Distortion: –94dBc at 1MHz
LTC2202
16-Bit, 10Msps, 3.3V ADC, Lowest Noise
140mW, 81.6dB SNR, 100dB SFDR, 48-Pin QFN
LTC2203
16-Bit, 25Msps, 3.3V ADC, Lowest Noise
220mW, 81.6dB SNR, 100dB SFDR, 48-Pin QFN
LTC2204
16-Bit, 40Msps, 3.3V ADC
480mW, 79.1dB SNR, 100dB SFDR, 48-Pin QFN
LTC2205
16-Bit, 65Msps, 3.3V ADC
610mW, 79dB SNR, 100dB SFDR, 48-Pin QFN
LTC2206
16-Bit, 80Msps, 3.3V ADC
725mW, 77.9dB SNR, 100dB SFDR, 48-Pin QFN
LTC2207
16-Bit, 105Msps, 3.3V ADC
900mW, 77.9dB SNR, 100dB SFDR, 48-Pin QFN
LTC2208
16-Bit, 130Msps, 3.3V ADC, LVDS Outputs
1250mW, 77.7dB SNR, 100dB SFDR, 64-Pin QFN
LTC2220-1
12-Bit, 185Msps, 3.3V ADC, LVDS Outputs
910mW, 67.7dB SNR, 80dB SFDR, 64-Pin QFN
LTC2224
12-Bit, 135Msps, 3.3V ADC, High IF Sampling
630mW, 67.6dB SNR, 84dB SFDR, 48-Pin QFN
LTC2255
14-Bit, 125Msps, 3V ADC, Lowest Power
395mW, 72.5dB SNR, 88dB SFDR, 32-Pin QFN
LTC2284
14-Bit, Dual, 105Msps, 3V ADC, Low Crosstalk
540mW, 72.4dB SNR, 88dB SFDR, 64-Pin QFN
LT5512
DC-3GHz High Signal Level Downconverting Mixer DC to 3GHz, 21dBm IIP3, Integrated LO Buffer
LT5514
Ultralow Distortion IF Amplifier/ADC Driver with
Digitally Controlled Gain
450MHz to 1dB BW, 47dB OIP3, Digital Gain Control 10.5dB to 33dB in 1.5dB/Step
LT5515
1.5GHz to 2.5GHz Direct Conversion Quadrature
Demodulator
High IIP3: 20dBm at 1.9GHz, Integrated LO Quadrature Generator
LT5516
800MHz to 1.5GHz Direct Conversion Quadrature
Demodulator
High IIP3: 21.5dBm at 900MHz, Integrated LO Quadrature Generator
LT5517
40MHz to 900MHz Direct Conversion Quadrature
Demodulator
High IIP3: 21dBm at 800MHz, Integrated LO Quadrature Generator
LT5522
600MHz to 2.7GHz High Linearity Downconverting
Mixer
4.5V to 5.25V Supply, 25dBm IIP3 at 900MHz. NF = 12.5dB, 50W Single-Ended RF
and LO Ports
22054fb
36 Linear Technology Corporation
LT 0907 REV B • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900
●
FAX: (408) 434-0507 ● www.linear.com
© LINEAR TECHNOLOGY CORPORATION 2006