A Low Frequency Band-Pass Filter with Independent Tunability and Selectivity

Abstract

A scheme to realize a band-pass filter with independent tuning and selectivity control for application in the instrumentation areas, where very low frequency and high Q are required is presented following a modification in the state-variable approach. A simplified scheme that dispenses with one of the op-amp chips without practically affecting the circuit performance is also presented. As a rational consequence, a single-element-controlled low- distortion-low-frequency sine wave oscillator is shown to evolve from the latter scheme. Performance specifications of the circuits have been evaluated and the results have been confirmed by experiments.

Indexing Terms:

• Bond-Pass Filter
• Active-RC Filters