US 11,909,364 B2
Fast start up control circuit
Katsuyuki Yasukouchi, Nagoya (JP)
Assigned to Cypress Semiconductor Corporation, San Jose, CA (US)
Filed by Cypress Semiconductor Corporation, San Jose, CA (US)
Filed on May 25, 2021, as Appl. No. 17/330,130.
Prior Publication US 2022/0385250 A1, Dec. 1, 2022
Int. Cl. H03F 3/393 (2006.01); H03F 3/45 (2006.01); G05F 1/46 (2006.01)
CPC H03F 3/393 (2013.01) [G05F 1/461 (2013.01); G05F 1/468 (2013.01); H03F 2200/168 (2013.01)] 20 Claims
OG exemplary drawing
 
1. An apparatus, comprising:
a chopper amplifier comprising an operational amplifier and a notch filter, the notch filter to be operated by a chopping pulse and configured to:
receive as input, an output of the operational amplifier; and
produce a chopper amplifier output that is provided as a feedback signal to an inverting input of the operational amplifier;
a chopping delay switch connected to a first branch of the notch filter having a first capacitor, and connected to a second branch of the notch filter having a second capacitor; and
a control circuit configured to:
close the chopping delay switch to short-circuit the first branch and the second branch of the notch filter to each other;
detect establishment of the feedback signal at the chopper amplifier; and
in response to detecting the establishment of the feedback signal at the chopper amplifier, open the chopping delay switch.