TRANSIMPEDANCE AMPLIFIERS

摘要

IMPROVEMENTS IN OR RELATING TO TRANSIMPEDANCE AMPLIFIERS A transimpedance amplifier allows an optical transmitter and receiver to be in close proximity to each other without fear of overloading the receiver. The improvement increases the dynamic range of the transimpedance amplifier and thereby the operating range of the receiver. A peak detector (22) at the output of an inverting amplifier (11) within the transimpedance amplifier turns on a field effect transistor (FET) circuit (23) when an AC component of an electrical signal becomes so large that the inverting amplifier would otherwise go into saturation whereby the FET circuit (23) acts as an AC shunt impedance at the input of the inverting amplifier and diverts the excess AC current to ground (30). Also, the FET circuit (23) acts as a DC resistance in concert with sense and sink current mirrors (21) and (24) to effectively divert an excessive DC component of the electrical signal away from the input of the inverting amplifier (11). Although the dynamic range of the transimpedance amplifier is increased, the optical sensitivity and the performance of the receiver remain unchanged.