Integrable bias solution for avalanche photodiodes

A bias circuit for avalanche photodiodes (APDs) based on a dual-rail charge pump configuration operating from a 5V supply that is capable of supplying a bias voltage in excess of 50V is presented. For shallow-junction planar APDs that operate between 25 and 45V this circuit is capable of delivering more that 50mW of power, allowing avalanche currents in the mA range. The circuit design requires only two external capacitors, while the rest of the circuit can be implemented as an application-specific integrated circuit which makes the circuit highly integrable. The bias voltage can be accurately controlled and easily adjusted by the end user using the shunt regulator incorporated for voltage control.