NOTCH FILTER FOR RIPPLE REDUCTION IN CHOPPER STABILIZED AMPLIFIERS

摘要

A chopper-stabilized amplifier receiving an input signal includes a first operational transconductance amplifier (2) having an input chopper and an output chopper for chopping an output signal produced by the first operational transconductance amplifier. A switched capacitor notch filter (15) will filter the chopped output signal by operating synchronously with the chopping frequency of output chopper to filter ripple voltages that otherwise would be produced by the output chopper. In one embodiment a second operational transconductance amplifier amplifies the notch filter output. The input signal is fed forward, summed with the output of the second operational transconductance amplifier, and applied to the input of a fourth operational transconductance amplifier. Ripple noise and offset are substantially reduced.