LTC1065
DC Accurate, Clock-Tunable
Linear Phase 5th Order Bessel
Lowpass Filter
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DESCRIPTIO
EATURE
Clock-Tunable Cutoff Frequency
1mV DC Offset (Typical)
80dB CMR (Typical)
Internal or External Clock
50µVRMS Clock Feedthrough
100:1 Clock-to-Cutoff Frequency Ratio
80µVRMS Total Wideband Noise
0.004% Noise + THD at 2VRMS Output Level
50kHz Maximum Cutoff Frequency
Cascadable for Faster Roll-Off
Operates from ±2.375 to ±8V Power Supplies
Self-Clocking with 1 RC
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The LTC1065 is the first monolithic filter providing both
clock-tunability with low DC output offset and over 12-bit
DC accuracy. The frequency response of the LTC1065
closely approximates a 5th order Bessel polynomial. With
appropriate PCB layout techniques the output DC offset is
typically 1mV and is constant over a wide range of clock
frequencies. With ±5V supplies and ±4V input voltage
range, the CMR of the device is typically 80dB.
The filter cutoff frequency is controlled either by an inter-
nalorexternalclock. Theclock-to-cutofffrequencyratiois
100 :1. The on-board clock is nearly power supply inde-
pendent and it is programmed via an external RC. The
50µVRMS clock feedthrough of the device is considerably
lower than other existing monolithic filters.
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PPLICATI
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Audio
The LTC1065 wideband noise is 80µVRMS and it can
process large AC input signals with low distortion. With
±7.5V supplies, for instance, the filter handles up to
4VRMS (94dB S/N ratio) while the standard 1kHz THD is
below 0.005%; 87dB dynamic range (S/N + THD) is ob-
Strain Gauge Amplifiers
Anti-Aliasing Filters
Low Level Filtering
Digital Voltmeters
Smoothing Filters
Reconstruction Filters
tained with input levels between 2VRMS and 2.5VRMS
.
TheLTC1065isavailablein8-pinminiDIPand16-pinSOL.
For a Butterworth response, see LTC1063 data sheet. The
LTC1065 is pin compatible with the LTC1063.
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O
TYPICAL APPLICATI
Frequency Response
3.4kHz Single 5V Supply Bessel Lowpass Filter
10
0
5V
1
2
3
4
8
7
6
5
–10
–20
–30
–40
–50
–60
–70
–80
–90
V
IN
4.99k
4.53k
V
OUT
+
LTC1065
13k*
1µF
0.1µF
5V
0.1µF
TANT
200pF*
*
SELF-CLOCKING SCHEME
1065 TA01
1
10
100
FREQUENCY (kHz)
1065 TA02
1