US 11,843,418 B2
DC and offset cancellation for fully differential optical receiver
Daniel Micusik, Nuremberg (DE); Sachidanandam Sundarraju, Nuremberg (DE); Jan Sundermeyer, Nuremberg (DE); and Juergen Hauenschild, Bochum (DE)
Assigned to CISCO TECHNOLOGY, INC., San Jose, CA (US)
Filed by Cisco Technology, Inc., San Jose, CA (US)
Filed on Sep. 16, 2021, as Appl. No. 17/476,969.
Prior Publication US 2023/0084591 A1, Mar. 16, 2023
Int. Cl. H04B 10/69 (2013.01)
CPC H04B 10/69 (2013.01) 14 Claims
OG exemplary drawing
 
1. A method comprising:
receiving differential optical signals;
converting, with photodetectors, the differential optical signals to differential current signals representative of the differential optical signals;
converting, using a transimpedance amplifier, the differential current signals to differential intermediate voltage signals;
amplifying, using a main amplifier, the differential intermediate voltage signals to generate differential output voltage signals;
cancelling a DC component of the differential output voltage signals using a fully differential DC cancellation circuit; and
regulating, fully differentially, common-mode voltage of the differential intermediate voltage signals by detecting common mode voltage at both an input and an output of the transimpedance amplifier using, at least, a voltage divider spanning inputs to the transimpedance amplifier.