Invention Grant
- Patent Title: Transimpedance amplifier with automatic current control
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Application No.: US15844305Application Date: 2017-12-15
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Publication No.: US11060906B1Publication Date: 2021-07-13
- Inventor: Shih-Cheng Wang
- Applicant: Facebook, Inc.
- Applicant Address: US CA Menlo Park
- Assignee: Facebook, Inc.
- Current Assignee: Facebook, Inc.
- Current Assignee Address: US CA Menlo Park
- Agency: Baker Botts L.L.P.
- Main IPC: G01J1/44
- IPC: G01J1/44 ; H03F1/26 ; H03F1/02 ; H03F1/30 ; H03F3/08 ; H04B10/69 ; H04B10/11 ; H04B10/50

Abstract:
In one embodiment, a method includes receiving, at an input of a transimpedance amplifier, an input electrical-current signal. The electrical-current signal includes a photodetector current and a DC cancellation current. The photodetector current corresponds to an input optical signal and includes an alternating-current (AC) portion and a direct-current (DC) portion. The method also includes performing, by the transimpedance amplifier, a transimpedance amplification of the input electrical-current signal to produce, at an output of the transimpedance amplifier, an output voltage signal corresponding to the input electrical-current signal. The method further includes providing, by a current-control circuit coupled to the input and the output of the transimpedance amplifier, the DC cancellation current to the input of the transimpedance amplifier, where the DC cancellation current is based on the output voltage signal.
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