LTC1064-1
Low Noise, 8th Order, Clock
Sweepable Elliptic Lowpass Filter
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FEATURES
DESCRIPTIO
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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.
8th Order Filter in a 14-Pin Package
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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
An external TTL or CMOS clock programs the value of the
filter’scutofffrequency.Theclocktocutofffrequencyratio
is 100:1.
Noexternalcomponentsareneededforcutofffrequencies
up to 20kHz. For cutoff frequencies over 20kHz two low
valuecapacitorsarerequiredtomaintainpassbandflatness.
The LTC1064-1 features low wideband noise and low
harmonic distortion even for input voltages up to 3VRMS
InfacttheLTC1064-1overallperformancecompleteswith
equivalent multiple op amp RC active realizations.
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APPLICATIO S
.
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Antialiasing Filters
Telecom PCM Filters
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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
Frequency Response
15
1
2
3
4
5
6
7
14
13
12
11
10
9
R(h, I)
INV C
0
–15
–30
–45
–60
–75
–90
–105
V
COMP2*
V
IN
IN
–
–8V
V
AGND
LTC1064-1
0.1µF
+
CLOCK
f
V
8V
CLK
(TTL, ≤5MHz)
0.1µF
NC
AGND
V
COMP1*
INV A
V
OUT
OUT
8
NC
1064 TA01
20
FREQUENCY (kHz)
0
5
10 15
25 30 35 40
NOTE: THE POWER SUPPLIES SHOULD BE BYPASSED BY A 0.1µF
CAPACITOR CLOSE TO THE PACKAGE.
1064 TA02
8th ORDER CLOCK SWEEPABLE LOWPASS ELLIPTIC ANTIALIASING
FILTER MAINTAINS, FOR 0.1Hz ≤ f ≤ 10kHz, A ±0.15dB PASSBAND
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.
CUTOFF
RIPPLE AND 72dB STOPBAND ATTENUATION AT 1.5 × f
.
CUTOFF
TOTAL WIDEBAND NOISE = 150µV
, THD = 0.03% FOR V = 1V
RMS IN RMS
10641fa
1