Light detector system with photo diode and current-mirror amplifier

A light detector system comprising a silicon photo-diode and a semiconductor integrated current-mirror circuit to provide amplification of the photo current generated by said photo-diode, said current-mirror amplifier circuit having at least one stage comprising a pair of d.c. power supply terminals, a bipolar output transistor and a bipolar input device having at least one p-n junction, said photo-diode being directly connected between said input device and one of said power supply terminals forming a series circuit wherein said photo-diode and said p-n junction are series connected with opposite polarities between said power supply terminals, the emitter of said output transistor being connected to the other of said power supply terminals, the base-emitter junction of said output transistor being directly connected in parallel with said at least one junction of said input device and in the same polarity, the area of said base-emitter junction of said output transistor being greater than the area of said at least one junction of said input device to provide a current gain in said at least one stage greater than 1.0, a circuit connection being made between the collector of said output transistor and said one terminal of said d.c. power supply to provide a path through which said amplified photo current will flow.