Optimum Biasing of Photodiodes As Used in Infrared Communications
Original Publication Date: 1987-Nov-01
Included in the Prior Art Database: 2005-Feb-02
A technique is described whereby an electrical circuit embodiment improves the signal-to-noise ratio of photodiode biasing circuits so as to increase the transmission capability without increasing the overall transmission power requirements of the infrared transmitter. The biasing improvement utilizes a number of photodiodes suspended by bias resistors, arranged in such a way as to cancel out noise glitches through the use of a differential amplifier. (Image Omitted) Prior-art photodiode biasing circuitry, which typically has parasitic capacitance 10, inherently placed in parallel with the photodiode 11, as shown in Fig. 1. Noise glitches, from related switching circuits, rip through the parasitic capacitance and are amplified by preamplifier 12.