FAIL-SAFE SELECTABLE LOW-PASS FILTERING

摘要

This invention relates to a vital type of selectable active low-pass filtering circuit. The selectable low-pass filtering circuit includes a half section resistance-capacitance filter network and a variable gain transistor amplifier. The input of the transistor amplifier is coupled to the half section resistance-capacitance filter network and the output of the transistor amplifier is selectively coupled to one of a plurality of load resistors each of which establishes a different gain for the transistor amplifier.