Transimpedance amplifier with differential photodiode current sensing

This paper presents a balanced receiver structure suitable for wireless infrared data communications. The receiver provides a fixed photodiode bias voltage with the use of a regulated cascode input stage. Together with an active feedback loop used to eliminate dc photocurrents, the receiver implements ac coupling without the need for matching capacitors. Differential sensing of the photodiode current improves sensitivity. Designed for a 0.35 /spl mu/m digital CMOS process, simulation results show that the circuit consumes 12 mW at 3 V, provides 40 k/spl Omega/ transimpedance gain over a bandwidth of 200 MHz, and has a minimum power supply rejection ratio of 40 dB over the entire operating bandwidth.