LINER LTC2204 16-bit, 20msps adc Datasheet

LTC2201
16-Bit, 20Msps ADC
FEATURES
DESCRIPTION
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The LTC®2201 is a 20Msps, sampling 16-bit A/D converter
designed for digitizing high frequency, wide dynamic range
signals with input frequencies up to 380MHz. The input
range of the ADC can be optimized with the PGA front end.
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Sample Rate: 20Msps
81.6dB SNR and 100dB SFDR (2.5V Range)
90dB SFDR at 70MHz (1.667VP-P Input Range)
PGA Front End (2.5VP-P or 1.667VP-P Input Range)
380MHz Full Power Bandwidth S/H
Optional Internal Dither
Optional Data Output Randomizer
Single 3.3V Supply
Power Dissipation: 211mW
Clock Duty Cycle Stabilizer
Out-of-Range Indicator
Pin Compatible Family
25Msps: LTC2203 (16-Bit)
10Msps: LTC2202 (16-Bit)
48-Pin (7mm × 7mm) QFN Package
The LTC2201 is perfect for demanding applications, with
AC performance that includes 81.6dB SNR and 100dB
spurious free dynamic range (SFDR). Maximum DC specs
include ±5LSB INL, ±1LSB DNL (no missing codes).
A separate output power supply allows the CMOS output
swing to range from 0.5V to 3.6V.
A single-ended CLK input controls converter operation. An
optional clock duty cycle stabilizer allows high performance
at full speed with a wide range of clock duty cycles.
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
APPLICATIONS
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Telecommunications
Receivers
Cellular Base Stations
Spectrum Analysis
Imaging Systems
ATE
TYPICAL APPLICATION
Integral Nonlinearity (INL)
vs Output Code
3.3V
SENSE
2.2μF
AIN
1.25V
COMMON MODE
BIAS VOLTAGE
1.5
1.0
+
S/H
AMP
–
0.5V TO 3.6V
1μF
OF
CLKOUT+
CLKOUT–
+
ANALOG
INPUT
AIN
2.0
OVDD
INTERNAL ADC
REFERENCE
GENERATOR
–
16-BIT
PIPELINED
ADC CORE
OUTPUT
DRIVERS
CORRECTION
LOGIC AND
SHIFT REGISTER
INL ERROR (LSB)
VCM
D15
t
t
t
D0
CMOS
OUTPUTS
CLK
3.3V
VDD
GND
PGA
SHDN
DITH
MODE
OE
RAND
0.0
–0.5
–1.0
OGND
CLOCK/DUTY
CYCLE
CONTROL
0.5
1μF
1μF
1μF
–1.5
–2.0
0
16384
32768
CODE
2201 TA01
49152
65536
2201 TA02
ADC CONTROL INPUTS
2201f
1
LTC2201
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
GND 9
CLK 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 Supply Voltage (OVDD) ......... –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
LTC2201C ............................................... 0°C to 70°C
LTC2201I ............................................ –40°C to 85°C
Storage Temperature Range ................. –65°C to 150°C
UK PACKAGE
48-LEAD (7mm s 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
LTC2201CUK#PBF
LTC2201CUK#TRPBF
LTC2201UK
48-Lead (7mm × 7mm) Plastic QFN
0°C to 70°C
LTC2201IUK#PBF
LTC2201IUK#TRPBF
LTC2201UK
48-Lead (7mm × 7mm) Plastic QFN
–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/
2201f
2
LTC2201
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
CONDITIONS
MIN
Resolution (No missing codes)
TYP
MAX
UNITS
16
Integral Linearity Error
Differential Analog Input (Note 5)
l
±1.5
±5
LSB
Differential Linearity Error
Differential Analog Input
l
±0.3
±1
LSB
Offset Error
(Note 6)
l
±2
±10
mV
Gain Error
External Reference
l
±0.2
Full-Scale Drift
Internal Reference
External Reference
±30
±15
ppm/°C
ppm/°C
Transition Noise
External Reference (2.5V Range, PGA = 0)
1.92
LSBRMS
Offset Drift
±10
μV/°C
±1.5
%FS
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
PARAMETER
CONDITIONS
VIN
Analog Input Range (AIN+ – AIN–)
MIN
TYP
MAX
UNITS
3.135V ≤ VDD ≤ 3.465V
VIN, CM
Analog Input Common Mode
Differential Input (Note 7)
l
1
1.5
V
IIN
Analog Input Leakage Current
0V ≤ AIN+, AIN– ≤ VDD (Note 9)
l
–1
1
μA
ISENSE
SENSE Input Leakage Current
0V ≤ SENSE ≤ VDD (Note 10)
l
–3
3
μA
IMODE
MODE Pin Pull-Down Current to GND
10
μA
IOE
OE Pin Pull-Down Current to GND
10
μA
CIN
Analog Input Capacitance
10.5
1.4
pF
pF
tAP
Sample-and-Hold
Acquisition Delay Time
0.9
ns
tJITTER
Sample-and-Hold
Acquisition Delay Time Jitter
200
fsRMS
CMRR
Analog Input
Common Mode Rejection Ratio
1V < (AIN+ = AIN–) <1.5V
80
dB
BW-3dB
Full Power Bandwidth
RS < 20Ω
380
MHz
1.667 or 2.5
1.25
Sample Mode CLK = 0
Hold Mode CLK = 0
VP-P
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
Signal-to-Noise Ratio
1MHz Input (2.25V Range, PGA = 0)
1MHz Input (1.667V Range, PGA = 1)
MIN
TYP
MAX
UNITS
81.6
79.4
dBFS
dBFS
81.6
79.4
dBFS
dBFS
12.5MHz Input (2.5V Range, PGA = 0)
12.5MHz Input (1.667V Range, PGA = 1)
81.4
79.3
dBFS
dBFS
30MHz Input (2.5V Range, PGA = 0)
30MHz Input (1.667V Range, PGA = 1)
80.8
78.9
dBFS
dBFS
70MHz Input (2.5V Range, PGA = 0)
70MHz Input (1.667V Range, PGA =1 )
78.3
77.2
dBFS
dBFS
5MHz Input (2.5V Range, PGA = 0)
5MHz Input (1.667V Range, PGA = 1)
l
80
2201f
3
LTC2201
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
SFDR
Spurious Free
Dynamic Range
2nd or 3rd Harmonic
1MHz Input (2.5V Range, PGA = 0)
1MHz Input (1.667V Range, PGA = 1)
SFDR
S/(N+D)
Spurious Free
Dynamic Range
4th Harmonic or Higher
Signal-to-Noise
Plus Distortion Ratio
Spurious Free
Dynamic Range
at –25dBFS
Dither “OFF”
TYP
MAX
UNITS
100
100
dBc
dBc
100
100
dBc
dBc
12.5MHz Input (2.5V Range, PGA = 0)
12.5MHz Input (1.667V Range, PGA = 1)
95
100
dBc
dBc
30MHz Input (2.5V Range, PGA = 0)
30MHz Input (1.667V Range, PGA = 1)
90
95
dBc
dBc
70MHz Input (2.5V Range, PGA = 0)
70MHz Input (1.667V Range, PGA = 1)
85
90
dBc
dBc
1MHz Input (2.5V Range, PGA = 0)
1MHz Input (1.667V Range, PGA = 1)
100
100
dBc
dBc
100
100
dBc
dBc
12.5MHz Input (2.5V Range, PGA = 0)
12.5MHz Input (1.667V Range, PGA = 1)
100
100
dBc
dBc
30MHz Input (2.5V Range, PGA = 0)
30MHz Input (1.667V Range, PGA = 1)
100
100
dBc
dBc
70MHz Input (2.5V Range, PGA = 0)
70MHz Input (1.667V Range, PGA = 1)
90
90
dBc
dBc
1MHz Input (2.5V Range, PGA = 0)
1MHz Input (1.667V Range, PGA = 1)
81.5
79.3
dBFS
dBFS
81.5
79.3
dBFS
dBFS
12.5MHz Input (2.5V Range, PGA = 0)
12.5MHz Input (1.667V Range, PGA = 1)
81.3
79.2
dBFS
dBFS
30MHz Input (2.5V Range, PGA = 0)
30MHz Input (1.667V Range, PGA = 1)
80.6
78.6
dBFS
dBFS
70MHz Input (2.5V Range, PGA = 0)
70MHz Input (1.667V Range, PGA = 1)
78.1
77
dBFS
dBFS
1MHz Input (2.5V Range, PGA = 0)
1MHz Input (1.667V Range, PGA = 1)
105
105
dBFS
dBFS
5MHz Input (2.5V Range, PGA = 0)
5MHz Input (1.667V Range, PGA = 1)
105
105
dBFS
dBFS
12.5MHz Input (2.5V Range, PGA = 0)
12.5MHz Input (1.667V Range, PGA = 1)
105
105
dBFS
dBFS
30MHz Input (2.5V Range, PGA = 0)
30MHz Input (1.667V Range, PGA = 1)
105
105
dBFS
dBFS
70MHz Input (2.5V Range, PGA = 0)
70MHz Input (1.667V Range, PGA = 1)
100
100
dBFS
dBFS
5MHz Input (2.5V Range, PGA = 0)
5MHz Input (1.667V Range, PGA = 1)
5MHz Input (2.5V Range, PGA = 0)
5MHz Input (1.667V Range, PGA = 1)
5MHz Input (2.5V Range, PGA = 0)
5MHz Input (1.667V Range, PGA = 1)
SFDR
MIN
l
l
l
85
90
79.7
2201f
4
LTC2201
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
SFDR
Spurious Free
Dynamic Range
at –25dBFS
Dither “ON”
1MHz Input (2.5V Range, PGA = 0)
1MHz Input (1.667V Range, PGA = 1)
MIN
TYP
115
115
MAX
UNITS
dBFS
dBFS
5MHz Input (2.5V Range, PGA = 0)
5MHz Input (1.667V Range, PGA = 1)
115
115
dBFS
dBFS
12.5MHz Input (2.5V Range, PGA = 0)
12.5MHz Input (1.667V Range, PGA = 1)
115
115
dBFS
dBFS
30MHz Input (2.5V Range, PGA = 0)
30MHz Input (1.667V Range, PGA = 1)
115
115
dBFS
dBFS
70MHz Input (2.5V Range, PGA = 0)
70MHz Input (1.667V Range, PGA = 1)
110
110
dBFS
dBFS
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
CONDITIONS
MIN
TYP
MAX
UNITS
VCM Output Voltage
IOUT = 0
1.15
1.25
1.35
V
VCM Output Tempco
IOUT = 0
±40
ppm/°C
VCM Line Regulation
3.135V ≤ VDD ≤ 3.465V
1
mV/ V
VCM Output Resistance
1mA ≤ | IOUT | ≤ 1mA
2
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
CONDITIONS
MIN
TYP
MAX
UNITS
LOGIC INPUTS (CLK, OE, DITH, PGA, SHDN, RAND)
VIH
High Level Input Voltage
VDD = 3.3V
l
VIL
Low Level Input Voltage
VDD = 3.3V
l
IIN
Digital Input Current
VIN = 0V to VDD
l
CIN
Digital Input Capacitance
(Note 7)
High Level Output Voltage
VDD = 3.3V
2
V
0.8
V
±10
μA
1.5
pF
3.299
3.29
V
V
LOGIC OUTPUTS
OVDD = 3.3V
VOH
VOL
Low Level Output Voltage
VDD = 3.3V
IO = –10μA
IO = –200μA
l
IO = 160μA
IO = 1.6mA
l
3.1
0.01
0.10
0.4
V
V
ISOURCE
Output Source Current
VOUT = 0V
–50
mA
ISINK
Output Sink Current
VOUT = 3.3V
50
mA
VOH
High Level Output Voltage
VDD = 3.3V
IO = –200μA
2.49
V
VOL
Low Level Output Voltage
VDD = 3.3V
IO = 1.60mA
0.1
V
VOH
High Level Output Voltage
VDD = 3.3V
IO = –200μA
1.79
V
VOL
Low Level Output Voltage
VDD = 3.3V
IO = 1.60mA
0.1
V
OVDD = 2.5V
OVDD = 1.8V
2201f
5
LTC2201
POWER REQUIREMENTS
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
l
MIN
TYP
MAX
3.135
3.3
3.465
UNITS
VDD
Analog Supply Voltage
PSHDN
Shutdown Power
OVDD
Output Supply Voltage
l
3.6
V
IVDD
Analog Supply Current
l
64
80
mA
PDIS
Power Dissipation
l
211
264
mW
SHDN = VDD , CLK = VDD
2
0.5
V
mW
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
fS
Sampling Frequency
tL
CLK Low Time
tH
CLK High Time
tAP
Sample-and-Hold
Aperture Delay
tD
CLK to DATA Delay
CL = 5pF (Note 7)
l
1.3
3.1
4.9
ns
tC
CLK to CLKOUT Delay
CL = 5pF (Note 7)
l
1.3
3.1
4.9
ns
tSKEW
DATA to CLKOUT Skew
CL = 5pF (Note 7)
l
–0.6
0
0.6
ns
DATA Access Time
Bus Relinquish Time
CL = 5pF (Note 7)
(Note 7)
l
l
5
5
15
15
ns
ns
l
1
Duty Cycle Stabilizer Off
Duty Cycle Stabilizer On
l
l
20
5
Duty Cycle Stabilizer Off
Duty Cycle Stabilizer On
l
l
20
5
TYP
MAX
20
MHz
25
25
500
500
ns
ns
25
25
500
500
ns
ns
0.9
Pipeline
Latency
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 = 20MHz, input range = 2.5VP-P with
differential drive (PGA = 0), unless otherwise speciﬁed.
UNITS
7
ns
Cycles
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.
Note 9: Dynamic current from switched capacitor inputs is large compared
to DC leakage current, and will vary with sample rate.
Note 10: Leakage current will experience transient at power up. Keep
resistance < 1kΩ.
2201f
6
LTC2201
TIMING DIAGRAM
tAP
ANALOG
INPUT
N+1
N+4
N
N+3
N+2
tL
tH
CLK
tD
N–7
D0-D15, OF
N–6
N–5
N–4
N–3
tC
CLKOUT +
CLKOUT –
2201 TD01
TYPICAL PERFORMANCE CHARACTERISTICS
Differential Nonlinearity (DNL)
vs Output Code
Integral Nonlinearity (INL)
vs Output Code
AC Grounded Input Histogram
(256k Samples)
1.0
2.0
60000
0.8
1.5
50000
0.6
0.5
0.0
–0.5
–1.0
0.0
30000
–0.2
20000
–0.4
10000
–0.8
–1.0
0
16384
32768
16384
0
65536
49152
CODE
2201 G01
SFDR vs Input Level,
fIN = 5MHz, PGA = 0, Dither “Off”
32768
CODE
0
32812 32816
65536
49152
2201 G02
SFDR vs Input Level,
fIN = 5MHz, PGA = 0, Dither “On”
140
120
120
120
80
60
40
20
0
–70
SFDR (dBc AND dBFS)
140
100
100
80
60
40
–50
–40
–30
–20
INPUT LEVEL (dBFS)
–10
0
2201 G04
0
–70
32832
32828
2201 G03
100
80
60
40
20
20
–60
32820 32824
OUTPUT CODE
SFDR vs Input Level, fIN = 12.7MHz,
PGA = 0, Dither “Off”
140
SFDR (dBc AND dBFS)
SFDR (dBc AND dBFS)
40000
–0.6
–1.5
–2.0
0.4
0.2
COUNT
DNL ERROR (LSB)
INL ERROR (LSB)
1.0
–60
–50
–40
–30
–20
INPUT LEVEL (dBFS)
–10
0
2201 G05
0
–70
–60
–50 –40 –30 –20
INPUT LEVEL (dBFS)
–10
0
2201 G06
2201f
7
LTC2201
TYPICAL PERFORMANCE CHARACTERISTICS
SFDR vs Input Level, fIN = 30.1MHz,
PGA = 0, Dither “Off”
140
120
120
120
100
80
60
40
SFDR (dBc AND dBFS)
140
20
100
80
60
40
–60
–50 –40 –30 –20
INPUT LEVEL (dBFS)
–10
2201 G07
SFDR vs Input Level, fIN = 70.1MHz,
PGA = 0, Dither “Off”
80
60
40
0
–70
0
0
–80 –70 –60 –50 –40 –30 –20 –10
INPUT LEVEL (dBFS)
2201 G08
0
100
20
20
0
–70
140
110
120
120
105
60
40
20
80
60
40
–60
–50 –40 –30 –20
INPUT LEVEL (dBFS)
–10
–60
2201 G10
82
110
81
–50 –40 –30 –20
INPUT LEVEL (dBFS)
LOWER LIMIT
76
90
PGA = 0
85
70
0
0
20
40
80
60
INPUT FREQUENCY (MHz)
2201 G11
100
2201 G12
IVDD vs Sample Rate,
5MHz Sine Wave, –1dBFS
68
SFDR
100
IVDD (mA)
77
2201 G09
65
SNR SFDR (dBFS)
SNR (dBFS)
PGA = 1
0
105
PGA = 0
78
–10
UPPER LIMIT
80
79
–10
PGA = 1
95
SNR and SFDR vs Supply Voltage
(VDD), fIN = 5MHz
SNR vs Input Frequency
–20
75
0
–70
0
–30
80
20
0
–70
–40
100
100
SFDR (dBc)
80
–50
SFDR (HD2 or HD3)
vs Input Frequency
140
100
–60
INPUT LEVEL (dBFS)
SFDR vs Input Level, fIN = 70.1MHz,
PGA = 0, Dither “On”
SFDR (dBc AND dBFS)
SFDR (dBc AND dBFS)
SFDR vs Input Level, fIN = 30.1MHz,
PGA = 0, Dither “On”
140
SFDR (dBc AND dBFS)
SFDR (dBc AND dBFS)
SFDR vs Input Level, fIN = 12.7MHz,
PGA = 0, Dither “On”
95
90
85
SNR
75
62
59
56
80
74
73
0
20
40
60
80 100 120 140
INPUT FREQUENCY (MHz)
2201 G13
75
2.8
2.9
3.0
3.1
3.2
3.3
3.4 3.5 3.6
SUPPLY VOLTAGE (V)
2201 G14
53
0
4
12
16
8
SAMPLE RATE (Msps)
20
2201 G15
2201f
8
LTC2201
TYPICAL PERFORMANCE CHARACTERISTICS
Normalized Full Scale
vs Temperature, Internal
Reference, 5 Units
SFDR vs Input Common Mode
Voltage, fIN = 5MHz, –1dBFS,
PGA = 0
Offset Voltage
vs Temperature, 5 Units
6
1.01
110
105
1
0.995
100
95
2
SFDR (dBc)
OFFSET VOLTAGE (mV)
1.005
0
–2
90
85
80
75
70
–4
65
–20
0
20
40
TEMPERATURE (°C)
60
80
–6
–40
2201 G16
60
–20
40
20
0
TEMPERATURE (˚C)
80
60
2201 G17
1.0
5
0.8
4
0.6
3
0.4
0.2
0
–0.2
–0.4
2
2201 G18
1
0
–1
–2
–3
–0.8
–4
0
0.75
1.25 1.50 1.75
1
INPUT COMMON MODE VOLTAGE (V)
2
–0.6
–1.0
0.5
Full-Scale Settling After Wake
Up from Shutdown or Starting
Encode Clock
Mid-Scale Settling After Wake
Up from Shutdown or Starting
Encode Clock
FULL-SCALE ERROR (%)
0.99
–40
FULL-SCALE ERROR (%)
NORMALIZED FULL SCALE
4
50 100 150 200 250 300 350 400 450 500
TIME AFTER WAKE-UP OR CLOCK START (μs)
2201 G19
–5
0 100 200 300 400 500 600 700 800 900 1000
TIME FROM WAKE-UP OR CLOCK START (μs)
2201 G20
2201f
9
LTC2201
PIN FUNCTIONS
SENSE (Pin 1): Reference Mode Select and External Reference Input. Tie SENSE to VDD with 1k Ω or less 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 2.5V (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, 9, 11, 15, 48, 49): ADC Power
Ground.
AIN+ (Pin 6): Positive Differential Analog Input.
AIN– (Pin 7): Negative Differential Analog Input.
CLK (Pin 10): Clock Input. The hold phase of the sampleand-hold circuit begins on the falling edge. The output
data may be latched on the rising edge of CLK.
SHDN (Pin 16): Power Shutdown Pin. SHDN = low results
in normal operation. SHDN = high results in powered
down analog circuitry and the digital outputs are 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 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. The 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 2.5VP-P. High
selects a front-end gain of 1.5, input range of 1.667VP-P.
GND (Exposed Pad, Pin 49): ADC Power Ground. The exposed pad on the bottom of the package must be soldered
to ground.
2201f
10
LTC2201
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
CLKOUT +
CLKOUT –
OF
SENSE
PGA
VCM
ADC
REFERENCE
LOW JITTER
CLOCK
DRIVER
CONTROL
LOGIC
OUTPUT
DRIVERS
t
t
t
BUFFER
VOLTAGE
REFERENCE
OGND
CLK
SHDN PGA RAND M0DE DITH
D15
D14
D1
D0
2201 F01
OE
Figure 1. Functional Block Diagram
2201f
11
LTC2201
APPLICATIONS INFORMATION
DYNAMIC PERFORMANCE
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.
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.
Signal-to-Noise Ratio
Spurious Free Dynamic Range (SFDR)
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.
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.
Total Harmonic Distortion
Full Power Bandwidth
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:
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.
Signal-to-Noise Plus Distortion Ratio
THD = –20Log(√(V22 + V32 + V42 + ... VN2)/V1)
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.
Aperture Delay Time
The time from when CLK reaches 0.45 of VDD to the
instant that the input signal is held by the sample-andhold 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)
2201f
12
LTC2201
APPLICATIONS INFORMATION
CONVERTER OPERATION
The LTC2201 is a CMOS pipelined multistep converter
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.
Each pipelined stage shown in Figure 1 contains an ADC,
a reconstruction DAC and an interstage 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.
The phase of operation is determined by the state of the
CLK input pin.
When CLK is high, 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 CLK transitions from high to low, the voltage
on the sample capacitors is held. While CLK is low, 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 low phase of
CLK. When CLK goes back high, 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 CLK goes low, 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.
SAMPLE/HOLD OPERATION AND INPUT DRIVE
Sample/Hold Operation
Figure 2 shows an equivalent circuit for the LTC2201 CMOS
differential sample and hold. The differential analog inputs
are sampled directly onto sampling capacitors (CSAMPLE)
through NMOS transitors. The capacitors shown attached
to each input (CPARASITIC) are the summation of all other
capacitance associated with each input.
LTC2201
VDD
RON
20Ω
RPARASITIC
3Ω
AIN+
CSAMPLE
9.1pF
CPARASITIC
1.4pF
VDD
AIN–
RPARASITIC
3Ω
RON
20Ω
CSAMPLE
9.1pF
CPARASITIC
1.4pF
CLK
2201 F02
Figure 2. Equivalent Input Circuit
During the sample phase when CLK is high, the NMOS
transistors connect the analog inputs to the sampling
capacitors and they charge to, and track the differential
input voltage. When CLK transitions from high to low, the
sampled input voltage is held on the sampling capacitors.
During the hold phase when CLK is high, the sampling
capacitors are disconnected from the input and the held
voltage is passed to the ADC core for processing. As CLK
transitions from low to high, 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 at the input of
the converter. If the change between the last sample and
2201f
13
LTC2201
APPLICATIONS INFORMATION
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 may
swing ±0.625V for the 2.5V range (PGA = 0) or ±0.417V
for the 1.667V 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.
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.
VCM
2.2μF
0.1μF
ANALOG
INPUT
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.
Figure 3 shows the LTC2201 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
AIN+
0.1μF
12pF
12pF
25Ω
AIN–
25Ω
T1 = COILCRAFT WBCI-IT OR
MA/COM ETC1-1T.
RESISTORS, CAPACITORS ARE
0402 PACKAGE SIZE, EXCEPT 2.2μF.
12pF
2201 F03
Figure 3. Single-Ended to Differential Conversion
Using a Transformer. Recommended for Input
Frequencies from 1MHz to 100MHz
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 4 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.
VCM
2.2μF
0.1μF
10Ω
25Ω AIN+
25Ω
0.1μF
4.7pF
25Ω
10Ω
ANALOG
INPUT
LTC2201
0.1μF
INPUT DRIVE CIRCUITS
25Ω
LTC2201
25Ω
Input Drive Impedence
As with all high performance, high speed ADCs the dynamic performance of the LTC2201 can be inﬂuenced
by the input drive circuitry, particularly the second and
third harmonics. Source impedance and input reactance can inﬂuence SFDR. At the rising edge of CLK the
sample and hold circuit will connect the 9.1pF sampling
capacitor to the input pin and start the sampling period.
The sampling period ends when CLK falls, 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/(2FCLK); 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.
T1
1:1
T1
1:1
4.7pF
T1 = MA/COM ETC1-1-13.
RESISTORS, CAPACITORS
ARE 0402 PACKAGE SIZE,
EXCEPT 2.2μF.
4.7pF
25Ω AIN–
2201 F04
Figure 4. Using a Transmission Line Balun Transformer.
Recommended for Input Frequencies from 50MHz to 250MHz
2201f
14
LTC2201
APPLICATIONS INFORMATION
Figure 5 demonstrates the use of an LTC1994 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 will limit the
SFDR at high input frequencies.
VCM
2.2 μF
499Ω
100pF
523Ω
499Ω
–
LTC2201
+
100pF
CM LT1994
+
AIN+
25Ω
–
53.6Ω
The internal programmable gain ampliﬁer provides the
internal reference voltage for the ADC. This ampliﬁer has
very stringent settling requirements and is not accessible
for external use.
LTC2201
TIE TO VDD TO USE
INTERNAL 2.5V
REFERENCE
OR INPUT FOR
EXTERNAL 2.5V
REFERENCE
OR INPUT FOR
EXTERNAL 1.25V
REFERENCE
RANGE
SELECT
AND GAIN
CONTROL
INTERNAL
ADC
REFERENCE
SENSE
PGA
2.5V
BANDGAP
REFERENCE
AIN–
25Ω
100pF
499Ω
VCM
2201 F05
BUFFER
1.25V
2.2μF
Figure 5. DC Coupled Input with Differential Ampliﬁer
2201 F06
The 25Ω resistors and 12pF capacitor on the analog
inputs serve two purposes: isolating the drive circuitry
from the sample-and-hold charging glitches and limiting
the wideband noise at the converter input.
Reference Operation
Figure 6 shows the LTC2201 reference circuitry consisting
of a 2.5V bandgap reference, a programmable gain ampliﬁer and control circuit. The LTC2201 has 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 the 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 2.5VP-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.
Figure 6. Reference Circuit
The SENSE pin can be driven ±5% around the nominal 2.5V
or 1.25V external reference input. 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 at least a 1μF ceramic capacitor.
VCM
1.25V
2.2μF
LTC2201
3.3V
1μF
2
LT1461-2.5
4
6
SENSE
2.2μF
2201 F07
Figure 7. A 2.5V Range ADC
with an External 2.5V Reference
2201f
15
LTC2201
APPLICATIONS INFORMATION
PGA Pin
The PGA pin selects between two gain settings for the ADC
front-end. PGA = 0 selects an input range of 2.5VP-P; PGA =
1 selects an input range of 1.667VP-P. The 2.5V 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 2.4dB worse. See the
Typical Performance Characteristics section.
Driving the Clock Input
The CLK input can be driven directly with a CMOS or TTL
level signal. A sinusoidal clock can also be used along with a
low-jitter squaring circuit before the CLK pin (Figure 8).
CLEAN 3.3V
SUPPLY
4.7μF
FERRITE
BEAD
0.1μF
SINUSOIDAL
CLOCK
INPUT
1k
0.1μF
CLK
56Ω
1k
LTC2201
NC7SVU04
2201 F08
Figure 8. Sinusoidal Single-Ended CLK Drive
The noise performance of the LTC2201 can depend on the
clock signal quality as much as on the analog input. Any
noise present on the clock signal will result in additional
aperture jitter that will be RMS summed with the inherent
ADC aperture jitter.
In applications where jitter is critical, such as when digitizing high input frequencies, use as large an amplitude
as possible. It is also helpful to drive the CLK pin with a
low-jitter high frequency source which has been divided
down to the appropriate sample rate. If the ADC is clocked
with a sinusoidal signal, ﬁlter the CLK signal to reduce
wideband noise and distortion products generated by
the source.
Maximum and Minimum Conversion Rates
The maximum conversion rate for the LTC2201 is 20Msps.
For the ADC to operate properly the CLK signal should
have a 50% (±10%) duty cycle. Each half cycle must have
at least 20ns for the LTC2201 internal circuitry to have
enough settling time for proper operation.
An on-chip clock duty cycle stabilizer may be activated if
the input clock does not have a 50% duty cycle. This circuit
uses the falling edge of CLK pin to sample the analog input.
The rising edge of CLK is ignored and an internal rising
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 LTC2201 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 LTC2201 is 1Msps.
2201f
16
LTC2201
APPLICATIONS INFORMATION
DIGITAL OUTPUTS
Data Format
Digital Output Buffers
The LTC2201 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 9 shows an equivalent circuit for a single output
buffer in CMOS Mode. 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 makes the output appear as 50Ω
to external circuitry and 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 LTC2201 should drive a small 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 43Ω on chip.
Lower OVDD voltages will also help reduce interference
from the digital outputs.
LTC2201
OVDD
VDD
0.5V
TO 3.6V
VDD
0.1μF
OVDD
DATA
FROM
LATCH
PREDRIVER
LOGIC
43Ω
TYPICAL
DATA
OUTPUT
Table 1. MODE Pin Function
OUTPUT FORMAT
CLOCK DUTY
CYCLE STABILIZER
0(GND)
Offset Binary
Off
1/3VDD
Offset Binary
On
2/3VDD
2’s Complement
On
VDD
2’s Complement
Off
MODE
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.
Output Clock
The ADC has a delayed version of the CLK 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 clock. 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.
OGND
2201 F09
Figure 9. Equivalent Circuit for a Digital Output Buffer
2201f
17
LTC2201
APPLICATIONS INFORMATION
Digital Output Randomizer
Output Driver Power
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.
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. For
example, if the converter is driving a DSP powered by a
1.8V supply, then OVDD should be tied to that same 1.8V
supply. In CMOS mode OVDD can be powered with any
logic voltage up to 3.6V. 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 .
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.
PC BOARD
FPGA
CLKOUT
OF
LTC2201
D15/D0
CLKOUT
D15
CLKOUT
D14/D0
OF
D14
OF
LTC2201
D15
D15/D0
D2/D0
t
t
t
D2
D14
D2
D14/D0
D1
t
t
t
D0
D2/D0
D1
RAND = HIGH,
SCRAMBLE
ENABLED
D1/D0
D0
D1/D0
RAND
2201 F11
Figure 11. Descrambling a Scrambled Digital Output
D0
D0
2201 F10
Figure 10. Functional Equivalent of Digital Output Randomizer
2201f
18
LTC2201
APPLICATIONS INFORMATION
Internal Dither
Grounding and Bypassing
The LTC2201 is a 16-bit ADC with a very linear transfer
function; 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’s location
on the ADC transfer curve, resulting in improved SFDR
for low signal levels.
The LTC2201 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
LTC2201 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.
As shown in Figure 12, 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.
CLKOUT +
CLKOUT –
OF
D15
t
t
t
D0
LTC2201
+
AIN
ANALOG
INPUT
S/H
AMP
16-BIT
PIPELINED
ADC CORE
DIGITAL
SUMMATION
OUTPUT
DRIVERS
AIN–
CLOCK/DUTY
CYCLE
CONTROL
PRECISION
DAC
MULTIBIT DEEP
PSEUDO-RANDOM
NUMBER
GENERATOR
2201 F12
CLK
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 LTC2201 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 LTC2201 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.
DITH
DITHER ENABLE
HIGH = DITHER ON
LOW = DITHER OFF
Figure 12. Functional Equivalent Block Diagram of
Internal Dither Circuit
2201f
19
R24
OPEN
OPEN
OPEN
C6
C4
0Ω
0Ω
LTC2206CUK
LTC2205CUK
LTC2204CUK
LTC2203CUK
LTC2202CUK
LTC2201CUK
DC919A-C
DC919A-D
DC919A-E
DC919A-F
DC919A-G
0Ω
0.01μF
0.01μF
0.01μF
R13
OPEN
R12
OPEN
R11
OPEN
DC < AIN < 70MHz
DC < AIN < 70MHz
DC < AIN < 70MHz
DC < AIN < 70MHz
DC < AIN < 70MHz
DC < AIN < 70MHz
DC < AIN < 70MHz
1
BITS
16
16
16
16
16
16
16
R8
51Ω
C7
8.2pF
C3
8.2pF
20
10
25
40
65
80
105
MSPS
GND
2
C15
0.1μF
3
OSC1
OPT. FO
VDD
4
VDD
J3
ENCODE
INPUT
C5
8.2pF
C28
0.1μF
EN
R27
10Ω
R29
1k
VDD
INPUT FREQUENCY
C9
0.1μF
0.01μF
DC919A-B
R33
LTC2207CUK
3
2
1
DC919A-A
ETC1-1T
T1
U1
4
5
ASSEMBLY TYPE
* VERSION TABLE
J2
ANALOG
INPUT
R32
0
R26
10Ω
R9
OPEN
J4
R31
O
VDD
C17
0.1μF
R33 *
C8
2.2μF
100μF
6.3V OPT
+ C27
C16
0.1μF
R30
OPEN
R28
33
5.1Ω
R10
5.1Ω
1
E4
E3
C23
4.7μF
E1
VDD
GND
VDD
+ 3.3V
GND
3
VDD
VDD
GND
GND/ENC –
GND/ENC +
GND
AIN –
AIN +
GND
VDD
VDD
VCM
JP4
RAND
R1
10K
SENSE
2
C20
10μF
6.3V
VDD
GND
JP6
DITH
R21
10k
R20
10k
12
11
10
9
8
7
6
5
4
3
2
1
C2
2.2μF
GND
3
VDD
JP3
OPEN PGA
VDD
JP2
SENSE
48
GND
DCIN+
2
1
3
2
R2
10K
2 2
R23
100K
R22
105K
1
3
R6
OPEN
R3
1K
44
U1*
EXPOSED PAD
VDD
OVP
GND
JP6
DITH
R7
1K
R4
OPEN
C21
0.01μF
4
3
2
1
1
3
OVDD
D5
D6
D7
CLKOUT –
CLKOUT +
OGND
D8
D9
D10
D11
OVDD
OVP
GND
OVDD
38
VDD
47
14
VDD
13
46
PGA
VDD
45
RAND
15
OE
DITH
17
GND
16
43
OF
D0
18
MODE
42
D15
19
SHDN
41
20
D1
40
D14
D2
39
D13
D3
21
D12
D4
GND
GND
SHDN
GND
25
26
ADJ
BYP
VDD
4
C18
0.1μF
U4
NC7SV86P5X
C19
0.1μF
4
11
19
18
17
16
15
14
13
12
11
B7
OE
B0
B1
B2
B3
B4
B5
B6
B7
OVP
U2
74VCX245BQX
VCC
20
OVP
A7
A7
GND
T/R
A0
A1
A2
A3
A4
A5
A6
10
1
2
3
4
5
6
7
8
9
8
R17
10K
R18
10K
RN1B, 33
RN1A, 33
5
6
7
1
C22
1.0μF
5
OE
B0
B1
B2
B3
B4
B5
B6
C25
0.1μF
OVP
C26
0.1μF
U5
NC7SV86P5X 3
19
18
17
16
15
14
13
12
1
2
C14
0.1μF
4
3
2
1
U3
74VCX245BQX
VCC
20
10
A3
A2
A1
SDA
SCL
WP
5
6
7
R19
10K
RN4D, 33
2
1
RN4C, 33
RN4B, 33
RN4A, 33
RN3D, 33
RN3C, 33
3
4
5
6
7
RN3B, 33
8
U6
24LC025
VCC
A0
GND
T/R
A0
A1
A2
A3
A4
A5
A6
RN3A, 33
9
RN2D, 33
RN2C, 33
RN2B, 33
RN2A, 33
RN1D, 33
3
5
27
R25
1
2
RN1C, 33
8
C1
0.1μF
OVP
28
29
30
31
32
33
34
35
36
IN
U7
LT1763
2
OUT
22
OGND
OGND
23
OVDD
24
GND
49
20
37
Evaluation Circuit Schematic of the LTC2201
C13
0.1μF
R5
33
39
37
35
33
31
29
27
25
40
38
36
34
32
30
28
26
24
22
23
20
18
16
14
12
10
8
6
4
21
J1
3201S-40G1
2
19
17
15
13
11
9
7
5
3
1
OGND
2201 F013
LTC2201
APPLICATIONS INFORMATION
2201f
LTC2201
APPLICATIONS INFORMATION
Silkscreen Top
Inner Layer 2
Silkscreen Topside
Inner Layer 3
2201f
21
LTC2201
APPLICATIONS INFORMATION
Silkscreen Bottom Side
Silkscreen Bottom
2201f
22
LTC2201
PACKAGE DESCRIPTION
Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings.
UK Package
48-Lead Plastic QFN (7mm × 7mm)
(Reference LTC DWG # 05-08-1704 Rev C)
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
2201f
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.
23
LTC2201
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
LTC2202
16-Bit, 10Msps, 3.3V ADC
140mW, 81.6dB SNR, 100dB SFDR, 48-Pin QFN
LTC2203
16-Bit, 25Msps, 3.3V ADC
220mW, 81.6dB SNR, 100dB SFDR, 48-Pin QFN
LTC6404-1
600MHz Low Noise, Low Distortion, Differential
ADC Driver
1.5nV/√Hz Noise, –90dBc Distortion at 10MHz
LT1994
Low Noise, Low Distortion Fully
Differential Input/Output Ampliﬁer/Driver
Low Distortion: –94dBc at 1MHz
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, 77.1dB SNR, 100dB SFDR, 64-Pin QFN
LTC2224
12-Bit, 135Msps, 3.3V ADC, High IF Sampling
630mW, 67.6dB SNR, 84dB SFDR, 48-Pin QFN
LTC2242-12
12-Bit, 250Msps, 2.5V ADC, LVDS Outputs
740mW, 65.4dB SNR, 84dB SFDR, 64-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, 50Ω Single Ended
RF and LO Ports
2201f
24
Linear Technology Corporation
LT 0412 • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 l FAX: (408) 434-0507
l
www.linear.com
© LINEAR TECHNOLOGY CORPORATION 2012

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