DC Accurate, Clock-Tunable 5th Order Butterworth Lowpass Filter

The LTC1063 is the first monolithic filter providing both clock-tunability, low DC output offset and over 12-bit DC accuracy. The frequency response of the LTC1063 closely approximates a 5th order Butterworth 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 80dB.

The filter cutoff frequency is controlled either by an internal or external clock. The clock-to-cut off frequency ratio is 100:1. The on-board clock is power supply independent, and it is programmed via an external RC. The 50µVRMS clock feed through is considerably reduced over existing monolithic filters.

The LTC1063 wideband noise is 95µVRMS, and it can process large AC input signals with low distortion. With ±7.5V supplies, for instance, the filter handles up to 4VRMS (92dB S/N ratio) while the standard 1kHz THD is below 0.02%; 80dB dynamic ranges (S/N +THD) is ob-tained with input levels between 1VRMS and 2.3VRMS.

The LTC1063 is available in 8-pin miniDIP and 16-pin SO wide packages. For a linear phase response, see LTC1065 data sheet.

Applications

* Audio

* Strain Gauge Amplifiers

* Anti-Aliasing Filters

* Low Level Filtering

* Digital Voltmeters

* 60Hz Lowpass Filters

* Smoothing Filters

* Reconstruction Filters

* Clock-Tunable Cutoff Frequency

* 1mV DC Offset (Typical)

* 80dB CMRR (Typical)

* Internal or External Clock

* 50µVRMS Clock Feedthrough

* 100:1 Clock-to-Cutoff Frequency Ratio

* 95µVRMS Total Wideband Noise

* 0.01% 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

* Available in 8-Pin DIP and 16-Pin SO Wide Packages