Differential operational amplifier based sliding filter - has high pass filter to inverting input with negative feedback via parallel rC network

摘要

The sliding filter is for use with a pilot signal derived from a rectifier circuit. The amplifier (11) is used in a differential mode and has a non-selective frequency input circuit (R14, R15) connected to the non-inverting input (13). Input to the inverting terminal (12) is via a high pass RC circuit. Overall negative feedback between the amplifier output and the inverting input is by a parallel RC network (R18, C19). The output ripple level is maintained approx. equal and their phases opposite at the two inputs by adjustment of the high-pass filter and non-inverting input circuit.