FOTODETEKTOR-SCHALTUNGSANORDNUNG

摘要

1503088 Avalanche photo-detectors STANDARD TELEPHONES & CABLES Ltd 22 July 1976 30604/76 Heading G1A [Also in Division H1] A photo-dector arrangement comprises an avalanche photodiode APD arranged to receive a major proportion (1-α) of the incident light and a secondary non-multiplying photodiode SPD arranged to receive a constant mirror proportion (α) of the incident light. A signal V 1 proportional to gain and a signal V2 proportional to the mean received signal are fed to a bias supply 6 which controls the gain of the APD either to a pre-set constant or to a value dependant on the received signal power. In a simpler circuit for providing constant gain Fig. 3 (not shown) only the SPD output is filtered, by a low-pass filter (7), and the filtered SPD photocurrent passes via an amplifier (8) with constant gain to the APD to provide the bias current. The photodiodes, transistor amplifier, and interconnections may be formed in an integrated circuit structure; see Division H1.