LTC1164-8_09 Datasheet, PDF (1/12 Pages) Linear Technology – Ultraselective, Low Power 8th Order Elliptic Bandpass Filter with Adjustable Gain

LTC1164-8
OBSOLETE:
FOR INFORMATION PURPOSES ONLY
Contact Linear Technology for Potential Replacement
Ultraselective, Low Power
8th Order Elliptic Bandpass Filter
with Adjustable Gain
FEATURES
■ _{Ultraselectivity}
(50dB Attenuation at ±4% of Center Frequency)
■ _{Adjustable Passband Gain}
■ _{Noise Independent of Gain}
■ _{Filter Noise: 270μVRMS, VS = Single 5V Supply}
■ _{Clock-Tunable (Center Frequency = fCLK/100)}
■ _{Center Frequencies up to 5kHz, VS = ±5V}
(Typical I_SUPPLY = 3.2mA)
■ _{Center Frequencies up to 4kHz, VS = Single 5V Supply}
(Typical I_SUPPLY = 2.3mA)
U
APPLICATIONS
■ _{Asynchronous Narrowband Signal Detectors}
■ _{Low Frequency Asynchronous Demodulators}
■ _{Handheld Spectrum Analyzers}
■ _{In-Band Tone Signaling Detectors}
DESCRIPTION
The LTC^®1164-8 is a monolithic ultraselective, 8th order,
elliptic bandpass filter. The passband of the LTC1164-8 is
tuned with an external clock and the clock-to-center fre-
quency ratio is 100:1. The – 3dB pass bandwidth is typi-
cally 1% of the filter center frequency. The stopband
attenuation of the LTC1164-8 is greater than 50dB. The
lower and upper stopband frequencies are less than
0.96 • center frequency and greater than 1.04 • center
frequency, respectively.
The LTC1164-8 requires an external op amp and two
external resistors (see the circuit below). The filter’s gain
at center frequency is set by the ratio R_IN/R_F. For a gain
equal to one and an optimum dynamic range, R_F should be
set to 61.9k and R_IN should be 340k. For gains other than
one, R_IN = 340k/Gain. Gains up to 1000 are obtainable.
Setting the filter’s gain with input resistor R_IN does not
increase the filter’s wideband noise. The 270μV_RMS
wideband noise of the LTC1164-8 is independent of the
filter’s center frequency.
The LTC1164-8 is available in a 14-pin PDIP or a 16-pin
surface mount SO Wide package.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATION
Ultranarrow 1kHz Bandpass Filter with Gain = 10
Gain = 340k/R_IN, 1/(2π • R_F • C_F) ≥ 10 • Center Frequency
R_IN
34k
V_IN
5V
1
14
2
13
3
12
4 _LTC1164-8 11
5
10
6
9
7
8
–5V
100kHz
SHORT CONNECTION UNDER IC AND
SHIELDED BY A GROUND PLANE
C_F
200pF
R_F
61.9k
5V
2_–
7
LT^®1006
3₊
4
–5V
6
V_OUT
LTC1164-8 • TA01
Frequency Response
30
20
10
0
–10
–20
–30
–40
–50
–60
–70
0.90
50dB
0.95 1.00 1.05
FREQUENCY (kHz)
1.10 1.15
1164-8 TA02
11648fb
1