LTC1264_15 Datasheet, PDF (1/16 Pages) Linear Technology – High Speed, Quad Universal Filter Building Block

LTC1264
High Speed, Quad Universal
Filter Building Block
FEATURES
■ _{High Speed, Up to 250kHz Center Frequency}
■ _{Four Identical Filters in a 0.3" Wide Package}
■ _{Clock-to-Center Frequency Ratio of 20:1}
■ _{Double-Sampling, Improved Aliasing}
■ _{Operates from ±2.37V to ±8V Power Supplies}
■ _{Customized Version with Internal Resistors Available}
■ _{Low Noise}
■ _{Low Harmonic Distortion}
■ _{Available in 24-Pin DIP and SO Wide Packages}
U
APPLICATIO S
■ _{Digital Communications}
■ _{Spread Spectrum Communications}
■ _{Spectral Analysis}
■ _{Loran Receivers}
■ _{Instrumentation}
, LTC and LT are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
DESCRIPTIO
The LTC^®1264 consists of four identical, high speed 2nd
order switched-capacitor filter building blocks designed
for center frequencies up to 250kHz. Each building block,
together with three to five resistors, can provide 2nd order
functions like lowpass, highpass, bandpass and notch.
The center frequency of each 2nd order section is tuned via
an external clock. The clock-to-center frequency ratio is
internally set to 20:1, but it can be modified via external
resistors.
The aliasing performance of the LTC1264 is improved by
double-sampling each 2nd order section. Input signal
frequencies can reach up to twice the clock frequency
before any alias products will be detectable.
For Q ≤ 5 and for T_A < 85°C, the maximum center
frequency is 160kHz. For Q ≤ 2, the maximum center
frequency is 250kHz. Up to 8th order filters can be realized
by cascading all four 2nd order sections.
A customized monolithic version of the LTC1264 includ-
ing internal thin film resistors can be obtained.
TYPICAL APPLICATIO
Clock-Tunable 8th Order Bandpass Filter, f_CENTER = f_CLK/20
50k
50k
IN
10k
50k
MAXIMUM POWER
f_CENTER SUPPLY
160kHz ±7.5V
120kHz ±5V
60kHz Single 5V
0.1µF
INV B
INV C
HPB/NB HPC/NC
BPB
BPC
LPB
LPC
SB
SC
LTC1264
AGND
V^–
V⁺
CLK
SA
SD
10k
50k
f_CLK
0.1µF
LPA
LPD
50k
OUT
BPA
10k
BPD
50k
HPA/NA HPD/ND
10k
INV A
INV D
50k
50k
1264 TA01
Gain vs Frequency
100kHz Bandpass, f_–3dB Bandwidth = f_CENTER/10
10
0
–10
–20
–30
–40
–50
–60
–70
–80
10k
100k
FREQUENCY (Hz)
1M
1264 TA02
1264fb
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