Low impedance automatic gain control circuit
US5012202A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Mar 15, 1990 |
| Grant date | Apr 30, 1991 |
| Priority date | — |
| Expiry date | Mar 15, 2010 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03F3/45076
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
An optical receiver circuit for an incoming optical signal having a variable power level includes an optical detector for receiving the optical signal and generating a current therefrom which varies with the optical signal power level. The current so generated is applied to a transimpedance amplifier. An automatic gain control (AGC) drive circuit is connected around the amplifier thereby increasing its dynamic range. The AGC drive circuit drives a FET which has one side thereof connected to the transimpedance amplifier for shunting current from the input thereof. A negative feedback circuit comprising an amplifier is connected across the FET, which comprises the resistive feedback element, thus reducing the FET resistance by a factor of 1+T, where T is the feedback circuit loop gain.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.