Apparatus and method for amplifying optically sensed signals

摘要

An improved method and circuitry for amplifying and processing detected pairs of input signals, in a manner that provides excellent DC accuracy, wideband signal handling capability and fast overload recovery, are disclosed. The invention is particularly suitable for use as a preamplifier for pairs of sensed photodetector current signals. Common base and emitter coupled circuits are arranged in various configurations to simultaneously process pairs of detected signals to provide normalized analog differential output current signals that can be directly used by amplifier circuits without concern for overloading of the amplifier as a result of severe overload signals detected by the input sensors. The circuitry readily accommodates external real-time gain control.