Patent ID: 11909364
Assignee: CYPRESS SEMICONDUCTOR CORPORATION
Field: Control (Instruments)
Classification: CPC H  G | IPC G  H

Claim 9:
10. A chopper amplifier circuit, comprising:
an operational amplifier circuit having an inverting input, a noninverting input and an output;
a notch filter circuit configured to be operated by a chopping pulse, the notch filter circuit comprising:
an input connected to the output of the operational amplifier circuit;
a first branch having a first plurality of switches and a first capacitor;
a second branch having a second plurality of switches and a second capacitor; and
an output connected as a feedback signal to the inverting input of the operational amplifier circuit;

a chopping delay switch connected to selectively short-circuit a portion of the first branch and a portion of the second branch to each other; and
a control circuit connected to the operational amplifier circuit and the chopping delay switch, the control circuit configured to:
detect establishment of the feedback signal at the operational amplifier circuit;
close the chopping delay switch to short-circuit the portion of the first branch and the portion of the second branch, prior to detecting the establishment of the feedback signal at the operational amplifier circuit; and
open the chopping delay switch, responsive to the detecting the establishment of the feedback signal at the operational amplifier circuit.