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LTC1065 - DC Accurate, Clock-Tunable Linear Phase 5th Order Bessel Lowpass Filter

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 internal or external clock. The clock-to-cutoff frequency ratio is 100:1. The on-board clock is nearly power supply independent and it is programmed via an external RC. The 50µVRMS clock feedthrough of the device is considerably lower than other existing monolithic filters.

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 obtained with input levels between 2VRMS and 2.5VRMS.

The LTC1065 is available in 8-pin miniDIP and 16-pin SOL. For a Butterworth response, see LTC1063 data sheet. The LTC1065 is pin compatible with the LTC1063.

Features 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 µ8V Power Supplies Self-Clocking with 1 RC Typical Application

Applications Strain Gauge Amplifiers Anti-Aliasing Filters Low Level Filtering Digital Voltmeters Smoothing Filters Reconstruction Filters Packaging