LINER LTC1064-1 Low noise, 8th order, clock sweepable elliptic lowpass filter Datasheet

LTC1064-1
Low Noise, 8th Order, Clock
Sweepable Elliptic Lowpass Filter
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FEATURES
■
■
■
■
■
■
■
■
DESCRIPTIO
8th Order Filter in a 14-Pin Package
No External Components
100:1 Clock to Center Ratio
150µVRMS Total Wideband Noise
0.03% THD or Better
50kHz Maximum Corner Frequency
Operates from ±2.37V to ±8V Power Supplies
Passband Ripple Guaranteed Over Full Military
Temperature Range
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APPLICATIO S
■
■
Antialiasing Filters
Telecom PCM Filters
The LTC®1064-1 is an 8th order, clock sweepable elliptic
(Cauer) lowpass switched capacitor filter. The passband
ripple is typically ±0.15dB, and the stopband attenuation
at 1.5 times the cutoff frequency is 68dB or more.
An external TTL or CMOS clock programs the value of the
filter’s cutoff frequency. The clock to cutoff frequency ratio
is 100:1.
No external components are needed for cutoff frequencies
up to 20kHz. For cutoff frequencies over 20kHz two low
value capacitors are required to maintain passband flatness.
The LTC1064-1 features low wideband noise and low
harmonic distortion even for input voltages up to 3VRMS.
In fact the LTC1064-1 overall performance completes with
equivalent multiple op amp RC active realizations.
The LTC1064-1 is available in a 14-pin DIP or 16-pin
surface mounted SW package.
The LTC1064-1 is pin compatible with the LTC1064-2.
, LTC and LT are registered trademarks of Linear Technology Corporation.
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TYPICAL APPLICATIO
8th Order Clock Sweepable Lowpass
Elliptic Antialiasing Filter
VIN
2
R(h, I)
INV C
VIN
COMP2*
14
0
13
3
8V
0.1µF
12
V–
AGND
4 + LTC1064-1
11
CLOCK
fCLK
V
(TTL, ≤5MHz)
5
10
NC
AGND
6
7
COMP1*
INV A
VOUT
NC
9
–15
–8V
0.1µF
VOUT
8
VOUT/VIN (dB)
1
Frequency Response
15
–30
–45
–60
–75
–90
–105
1064 TA01
NOTE: THE POWER SUPPLIES SHOULD BE BYPASSED BY A 0.1µF
CAPACITOR CLOSE TO THE PACKAGE.
0
5
10
15 20 25 30
FREQUENCY (kHz)
35
40
1064 TA02
FOR SERVO OFFSET NULLING APPLICATIONS, PIN 1 IS THE 2ND
STAGE SUMMING JUNCTION.
*FOR CUTOFF FREQUENCY ABOVE 20kHz, USE COMPENSATION
CAPACITORS (5pF TO 56pF) BETWEEN PIN 13 AND PIN 1
AND PIN 6 AND PIN 7.
8th ORDER CLOCK SWEEPABLE LOWPASS ELLIPTIC ANTIALIASING
FILTER MAINTAINS, FOR 0.1Hz ≤ fCUTOFF ≤ 10kHz, A ±0.15dB PASSBAND
RIPPLE AND 72dB STOPBAND ATTENUATION AT 1.5 × fCUTOFF.
TOTAL WIDEBAND NOISE = 150µVRMS, THD = 0.03% FOR VIN = 1VRMS
10641fa
1
LTC1064-1
W W
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ABSOLUTE
AXI U RATI GS
(Note 1)
Total Supply Voltage (V + to V –) ............................ 16.5V
Power Dissipation .............................................. 400mW
Storage Temperature Range ................. – 65°C to 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C
Operating Temperature Range
LTC1064-1M (OBSOLETE) ............... – 55°C to 125°C
LTC1064-1C/AC .................................. – 40°C to 85°C
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PACKAGE/ORDER I FOR ATIO
TOP VIEW
ORDER PART
NUMBER
INV C
1
14 R(h, l)
VIN
2
13 COMP2
AGND
3
12 V –
V+
4
11 fCLK
AGND
5
10 NC
COMP1
6
9
VOUT
INV A
7
8
NC
INV C 1
LTC1064-1CN
LTC1064-1ACN
VIN 2
AGND 3
V+ 4
AGND 5
N PACKAGE
14-LEAD PDIP
TJMAX = 110°C, θJA = 70°C/W
15 COMP2
14
LTC1064-1CSW
V–
13 NC
12 fCLK
11 NC
COMP1 7
10 NC
LTC1064-1MJ
LTC1064-1CJ
OBSOLETE PACKAGE
16 R(h, l)
NC 6
INV A 8
J PACKAGE
14-LEAD CERDIP
ORDER PART
NUMBER
TOP VIEW
9
VOUT
SW PACKAGE
16-LEAD PLASTIC (WIDE) SO
TJMAX = 150°C, θJA = 90°C/W
Consider the N14 Package for Alternate Source
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VS = ±7.5V, fCLK = 1MHz, R1 = 10k, C1 = 10pF, TTL or CMOS clock input
level unless otherwise specified.
PARAMETER
CONDITIONS
Passband Gain, LTC1064-1, 1A
Referenced to 0dB, 1Hz to 0.1fC
MIN
●
TYP
MAX
± 0.1
± 0.35
UNITS
dB
Gain TempCo
0.0002
dB/°C
Passband Edge Frequency, fC
10 ± 1%
kHz
Gain at fC
LTC1064-1
LTC1064-1A
Referenced to Passband Gain
●
●
–1.25
– 0.75
–3dB Frequency
Passband Ripple (Note 1)
LTC1064-1
LTC1064-1A
0.85
0.65
10.7
0.1fC to 0.85fC Referenced to Passband Gain,
Measured at 6.25kHz and 8.5kHz
± 0.15
± 0.1
●
●
Ripple TempCo
0.0004
Stopband Attenuation
LTC1064-1
LTC1064-1A
At 1.5fC Referenced to 0dB
Stopband Attenuation
LTC1064-1
LTC1064-1A
At 2fC Referenced to 0dB
dB
dB
kHz
± 0.32
± 0.19
dB
dB
dB/°C
●
●
66
68
72
72
dB
dB
●
●
67
68
72
72
dB
dB
10641fa
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LTC1064-1
ELECTRICAL CHARACTERISTICS
The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VS = ±7.5V, fCLK = 1MHz, R1 = 10k, C1 = 10pF, TTL or CMOS clock input
level unless otherwise specified.
PARAMETER
CONDITIONS
MIN
Input Frequency Range
TYP
0
Output Voltage Swing and
Operating Input Voltage Range
VS = ±2.37V
VS = ±5V
VS = ±7.5V
Total Harmonic Distortion
VS = ±5V, Input = 1VRMS at 1kHz
VS = ±7.5V, Input = 3VRMS at 1kHz
Wideband Noise
VS = ±5V, Input = GND 1Hz to 999kHz
VS = ±7.5V, Input = GND 1Hz to 999kHz
Output DC Offset
LTC1064-1
LTC1064-1A
Output DC Offset TempCo
VS = ±7.5V, Pin 2 Grounded
●
●
●
Clock Feedthrough
Maximum Clock Frequency
Power Supply Current
%
%
150
165
10
Source/Sink
kHz
V
V
V
VS = ±5V
Output Short-Circuit Current
fCLK/2
0.015
0.03
Input Impedance
f OUT = 10kHz
UNITS
±1
±3
±5
50
50
–100
Output Impedance
MAX
µVRMS
µVRMS
175
125
20
kΩ
2
Ω
3/1
mA
200
µVRMS
50% Duty Cycle, VS = ±7.5V
5
VS = ±2.37V
●
VS = ±5V
●
Power Supply Voltage Range
●
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
±2.37
MHz
10
22
mA
12
23
26
mA
mA
16
28
32
mA
mA
±8
V
●
VS = ±7.5V, f CLK = 1MHz
mV
mV
µV/°C
Note 2: For tighter specifications please contact LTC Marketing.
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TYPICAL PERFOR A CE CHARACTERISTICS
Gain vs Frequency
Phase vs Frequency
15
0
0
–45
–45
–60
–90
–105
1
10
FREQUENCY (kHz)
–180
–225
–270
–315
VS = ±5V
TA = 25°C
f CLK = 1MHz
fC = 10kHz ± 0.1dB
f –3dB = 10.7kHz
–75
GROUP DELAY (µs)
PHASE (DEG)
GAIN (dB)
–135
–30
1064 G01
VS = ±5V
450 TA = 25°C
400 f CLK = 1MHz
fC = 10kHz
350
300
250
200
150
–360
100
–405
50
–450
100
500
VS = ±5V
TA = 25°C
f CLK = 1MHz
fC = 10kHz
–90
–15
Group Delay
0
1
2
3
4 5 6 7 8
FREQUENCY (kHz)
9 10 11
1064 G02
0
0
1
2
3
4 5 6 7 8 9 10 11 12
FREQUENCY (kHz)
1064 G03
10641fa
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LTC1064-1
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TYPICAL PERFOR A CE CHARACTERISTICS
Gain vs Frequency
Gain vs Frequency
15
5
0
0
0
GAIN (dB)
–30
fCLK = 3MHz, fC = 30kHz
COMP1 = 24pF
COMP2 = 36pF
fCLK = 4MHz, fC = 40kHz
COMP1 = 36pF
COMP2 = 47pF
–45
–60
–75
–90
1
–30
–45
–60
fCLK = 5MHz, fC = 50kHz
COMP1 = 30pF
COMP2 = 47pF
–90
100
1
10
FREQUENCY (kHz)
1064 G04
Typical Wideband Noise
(151µVRMS) VS = ± 5V, TA = 25°C
f CLK = 1MHz, f C = 10kHz Input
Grounded
–10
–15
–20
VS = ±7.5V
fCLK = 5MHz 125°C GAIN PEAK =
f = 50kHz
1dB AT 35kHz
–30 C
COMP1 = 33pF
COMP2 = 56pF
–35
1
10
FREQUENCY (kHz)
–25
VS = ±7.5V
TA = 25°C
–105
10
FREQUENCY (kHz)
25°C GAIN PEAK =
0.4dB AT 30kHz
–5
fCLK = 4MHz, fC = 40kHz
COMP1 = 20pF
COMP2 = 30pF
–75
VS = ±5V
TA = 25°C
–105
fCLK = 3MHz, fC = 30kHz
COMP1 = 10pF
COMP2 = 15pF
–15
fCLK = 2MHz, fC = 20kHz
COMP1 NOT USED,
COMP2 = 20pF
GAIN (dB)
–15
GAIN (dB)
Gain vs Frequency
15
100
100
1064 G06
1064 G05
Total Harmonic Distortion
(0.025%) VS = ± 7.5V, TA = 25°C
f CLK = 1MHz, f C = 10kHz
Input = 1kHz at 3VRMS
Power Supply Current vs Power
Supply Voltage
48
POWER SUPPLY CURRENT (mA)
44
f CLK = 1MHz
40
36
32
28
24
TA = –55°C
TA = 25°C
TA = 125°C
20
16
12
8
4
0
0 2
4 6 8 10 12 14 16 18 20 22 24
TOTAL POWER SUPPLY VOLTAGE (V)
1064 G09
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PI FU CTIO S
(Pin Numbers Refer to the 14-Pin Package)
COMP1, INV A, COMP2, INV C (Pins 1,6,7, and 13): For
filter cutoff frequencies higher than 20kHz, in order to
minimize the passband ripple, compensation capacitors
should be added between Pin 6 and Pin 7 (COMP1) and
Pin 1 and Pin 13 (COMP2). For COMP1 (COMP2), add 1pF
(1.5pF) mica capacitor for each kHz increase in cutoff
frequency above 20kHz. For more detail refer to Gain vs
Frequency graphs.
is protected against static discharge. The device’s output,
Pin 9, is the output of an op amp which can typically source/
sink 3mA/1mA. Although the internal op amps are unity
gain stable, driving long coax cables is not recommended.
VIN, VOUT (Pins 2, 9): The input Pin 2 is connected to an
18k resistor tied to the inverting input of an op amp. Pin 2
AGND (Pins 3, 5): For dual supply operation these pins
should be connected to a ground plane. For single supply
When testing the device for noise and distortion, the
output, Pin 9, should be buffered (Figure 4). The op amp
power supply wire (or trace) should be connected
directly to the power source.
10641fa
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LTC1064-1
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PI FU CTIO S
(Pin Numbers Refer to the 14-Pin Package)
operation both pins should be tied to one half supply
(Figure 2). Also Pin 8 and Pin 10, although they are not
internally connected should be tied to analog ground or
system ground. This improves the clock feedthrough
performance.
V +, V – (Pins 4, 12): The V+ and V– pins should be
bypassed with a 0.1µF capacitor to an adequate analog
ground. Low noise, nonswitching power supplies are
recommended. To avoid latchup when the power supplies
exhibit high turn-on transients, a 1N5817 Schottky diode
should be added from the V + and V – pins to ground
(Figure 1).
INV A, R(h, I) (Pins 7, 14): A very short connection
between Pin 14 and Pin 7 is recommended. This connection should be preferably done under the IC package. In a
breadboard, use a one inch, or less, shielded coaxial cable;
the shield should be grounded. In a PC board, use a one
inch trace or less; surround the trace by a ground plane.
NC (Pins 8, 10): The “no connection” pins preferably
should be grounded.
fCLK (Pin 11): For ±5V supplies the logic threshold level is
1.4V. For ±8V and 0V to 5V supplies the logic threshold
levels are 2.2V and 3V respectively. The logic threshold
levels vary ±100mV over the full military temperature
range. The recommended duty cycle of the input clock is
50% although for clock frequencies below 500kHz the
clock “on” time can be as low as 200ns. The maximum
clock frequency for ±5V supplies is 4MHz. For ±7V supplies and above, the maximum clock frequency is 5MHz.
Do not allow the clock levels to exceed the power supplies.
For clock level shifting (see Figure 3).
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TYPICAL APPLICATIO S
1
2
VIN
R(h, I)
INV C
VIN
COMP2*
3
13
0.1µF
1N5817
5
6
7
NC
AGND
COMP1*
VOUT
NC
INV A
0.1µF
VIN
COMP2*
V+= 15V
0.1µF
5
5k
6
VOUT
V+/2
8
0.1µF
7
5k
NC
AGND
COMP1*
VOUT
NC
INV A
1064 F01
Figure 1. Using Schottky Diodes to Protect
the IC from Power Supply Spikes
2
VIN
3
4
V+
5
5k
6
0.1µF
5k
7
R(h, I)
INV C
VIN
COMP2*
VIN
12
V–
AGND
LTC1064-1
11
fCLK
V+
AGND
COMP1*
INV A
NC
VOUT
NC
10
9
0V TO 10V
10
9
VOUT
8
Figure 2. Single Supply Operation. If Fast Power Up
or Down Transients are Expected, Use a 1N5817
Schottky Diode Between Pin 4 and Pin 5.
14
13
13
1064 F02
1
1
14
12
V–
AGND
LTC1064-1
4 +
11
fCLK
V
V–
1N5817
R(h, I)
INV C
3
10
9
2
VIN
12
V–
AGND
4 + LTC1064-1
11
fCLK
V
V+
1
14
V+
2
INV C
VIN
POWER SOURCE
V+
V–
R(h, I) 14
COMP2*
13
3
12
V–
AGND
LTC1064-1
4 +
11
fCLK
V
2.2k
2L
T
LEVEL
5k 1µF
0.1µF
5
6
VOUT
NC
AGND
COMP1*
VOUT
7 INV A
NC
0.1µF
10k
10
9
10k
0.1µF
–
8
VOUT
+
8
1064 F03
Figure 3. Level Shifting the Input T2L Clock
for Single Supply Operation, V+ >6V.
RECOMMENDED OP AMPS:
LT1022, LT318, LT1056
1064 F04
0.1µF
Figure 4. Buffering the Filter Output. The Buffer Op Amp
Should Not Share the LTC1064-1 Power Lines.
10641fa
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LTC1064-1
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TYPICAL APPLICATIO S
Transitional Elliptic-Bessel Dual 5th Order Lowpass Filter
Amplitude Response
C
15
f –3dB = 5kHz
f CLK = 1MHz
0
47.5k
2
VIN1
R(h, I)
INV C
VIN
COMP2*
3
V+
0.1µF
7
47.5k
13
INV A
VOUT
NC
VOUT1
LT1056
V–
+
12
V–
COMP1*
–15
–
AGND
LTC1064-1
4 +
11 fCLK = 200
fCLK
V
× f–3dB
5
10
NC
AGND
6
C
14
9
VOUT/VIN (dB)
1
0.1µF
VOUT2
VOUT1
–30
–45
–60
–75
–90
VOUT2
8
C=
1064 TA06
5
f –3dB
–105
10
fIN (kHz)
1
(µF)
100
1064 TA09
OUTPUT1 WIDEBAND NOISE: 50µVRMS
OUTPUT2 WIDEBAND NOISE: 110µVRMS
VIN2
Transient Response to a 2V Step
Input VOUT2
Transient Response to a 2V Step
Input VOUT1
1V/DIV
1V/DIV
0.1ms/DIV
0.1ms/DIV
Adding an Output Buffer-Filter to Eliminate Any Clock Feedthrough
Over a 10:1 Clock Range, for fCLK = 2kHz to 20kHz
1
VIN
2
3
V+
0.1µF
4
5
6
7
R(h, I)
INV C
VIN
COMP2*
14
13
V–
12
V–
AGND
LTC1064-1
11
fCLK
V+
AGND
COMP1*
INV A
NC
VOUT
NC
10k
0.1µF
VOUT
200pF
10
9
8
4.99k
4.99k
–
50Ω
LT1056
430pF
+
0.027µF
1064 TA10
10641fa
6
LTC1064-1
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PACKAGE DESCRIPTIO
J Package
14-Lead CERDIP (Narrow 0.300, Hermetic)
(LTC DWG # 05-08-1110)
.200
(5.080)
MAX
.300 BSC
(7.62 BSC)
.015 – .060
(0.381 – 1.524)
.008 – .018
(0.203 – 0.457)
.785
(19.939)
MAX
.005
(0.127)
MIN
14
13
12
11
10
9
8
.220 – .310
(5.588 – 7.874)
.025
(0.635)
RAD TYP
0° – 15°
.045 – .065
(1.143 – 1.651)
.100
(2.54)
BSC
.014 – .026
(0.360 – 0.660)
NOTE: LEAD DIMENSIONS APPLY TO SOLDER DIP/PLATE
OR TIN PLATE LEADS
.125
(3.175)
MIN
2
1
3
4
5
6
7
J14 0801
OBSOLETE PACKAGE
N Package
14-Lead PDIP (Narrow 0.300)
(LTC DWG # 05-08-1510)
.770*
(19.558)
MAX
14
13
11
12
.300 – .325
(7.620 – 8.255)
10
9
.045 – .065
(1.143 – 1.651)
.130 ± .005
(3.302 ± 0.127)
8
.020
(0.508)
MIN
.065
(1.651)
TYP
.008 – .015
(0.203 – 0.381)
.255 ± .015*
(6.477 ± 0.381)
+.035
.325 –.015
1
2
3
5
4
(
7
6
8.255
+0.889
–0.381
.005
(0.125) .100
MIN (2.54)
BSC
.120
(3.048)
MIN
)
NOTE:
1. DIMENSIONS ARE
.018 ± .003
(0.457 ± 0.076)
INCHES
MILLIMETERS
*THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .010 INCH (0.254mm)
N14 1002
SW Package
16-Lead Plastic Small Outline (Wide .300 Inch)
(Reference LTC DWG # 05-08-1620)
.050 BSC .045 ±.005
.030 ±.005
TYP
.398 – .413
(10.109 – 10.490)
NOTE 4
16
N
15
14
13
12
11 10
9
N
.325 ±.005
.420
MIN
.394 – .419
(10.007 – 10.643)
NOTE 3
1
2
3
NOTE:
1. DIMENSIONS IN
N/2
N/2
RECOMMENDED SOLDER PAD LAYOUT
1
.291 – .299
(7.391 – 7.595)
NOTE 4
.010 – .029 × 45°
(0.254 – 0.737)
.005
(0.127)
RAD MIN
2
3
.093 – .104
(2.362 – 2.642)
4
5
6
7
8
.037 – .045
(0.940 – 1.143)
0° – 8° TYP
.009 – .013
(0.229 – 0.330)
NOTE 3
.016 – .050
(0.406 – 1.270)
.050
(1.270)
BSC
.014 – .019
(0.356 – 0.482)
TYP
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.
INCHES
(MILLIMETERS)
2. DRAWING NOT TO SCALE
3. PIN 1 IDENT, NOTCH ON TOP
AND CAVITIES ON THE BOTTOM
OF PACKAGES ARE THE
MANUFACTURING OPTIONS.
THE PART MAY BE SUPPLIED
WITH OR WITHOUT ANY OF THE
OPTIONS
4. THESE DIMENSIONS DO NOT
INCLUDE MOLD FLASH OR
PROTRUSIONS. MOLD FLASH OR
PROTRUSIONS SHALL NOT
EXCEED .006" (0.15mm)
.004 – .012
(0.102 – 0.305)
S16 (WIDE) 0502
10641fa
7
LTC1064-1
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TYPICAL APPLICATIO
Transitional Elliptic-Bessel 10th Order Lowpass Filter
C
47.5k
1
2
R(h, I)
INV C
VIN
COMP2*
14
–
13
LT1056
V–
3
12
V–
AGND
LTC1064-1
4 +
11 fCLK = 250
fCLK
V
× f–3dB
5
10
NC
AGND
V+
0.1µF
6
C
7
COMP1*
INV A
VOUT
NC
+
0.1µF
9
8
C=
47.5k
1064 TA03
VIN
VOUT
3
(µF)
f –3dB
OUTPUT WIDEBAND NOISE:110µVRMS
Amplitude Response
15
f –3dB = 3kHz
f CLK = 750kHz
0
Transient Response to a 2V Step Input
VOUT/VIN (dB)
–15
–30
–45
1V/DIV
–60
–75
–90
–105
0.1ms/DIV
1
10
fIN (kHz)
100
1064 TA05
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
LTC1069-1
8th Order Elliptic Lowpass
S0-8 Package, Low Power
LTC1069-6
Single Supply, 8th Order Elliptic Lowpass
S0-8 Package, Very Low Power
LTC1569-6
DC Accurate, 10th Order, Lowpass
Internal Precision Clock, Low Power
LTC1569-7
DC Accurate, 10th Order, Lowpass
Internal Precision Clock, S0-8 Package
10641fa
8
Linear Technology Corporation
LW/TP 1202 1K REV A • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
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 LINEAR TECHNOLOGY CORPORATION 1989
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