A bias and control circuit for gain stabilization in avalanche photodiodes

This paper describes a novel bias and gain control circuit for avalanche photodiodes (APDs) biased in linear mode. The circuit was implemented using a printed circuit board (PCB) and packaged APDs. Experimental results show that the circuit is capable of providing bias voltages up to 40 V for the APDs, precisely setting its gain (error <; 2.5 %) and compensating for the changes in the temperature to maintain a stable gain. A 5 V power supply is sufficient for the circuit and it operates without the need for external temperature sensing and control electronics thereby lowering the system cost and complexity. Moreover if the circuit is fabricated on-chip, then only one external component is required making it compact and attractive for integrated APD applications.