| 摘要 |
<p>A transimpedance amplifier (54) in an optical communication system is provided with automatic gain control (AGC) (56) for increasing the input operating range while maintaining high stability. A photodetector (58) is used to convert an optical signal into a differential current for the transimpedance amplifier (54). An AGC circuit (56) has a gain control device connected across the differential input of the transimpedance amplifier (54). The gain control device has an impedance that varies as a function of a voltage at the differential output of the transimpedance (54). Preferably, the gain control device is a FET having a drain coupled to one of the differential inputs, a source coupled to the other differential input, and a gate for receiving an AGC voltage, the AGC voltage being a function of the voltage at the differential output.</p> |
