Improved Circuits for Single-photon Avalanche Photodiode Detectors

A CMOS photo detection bias quenching circuit is developed to be used with single photon avalanche photodiodes (SPADs) operating in Geiger mode for the detection of weak optical signals. The proposed bias quenching circuits for the performance improvement reduce the circuit size as well as improve the performance of the quenching operation. They are fabricated in a 0.18-mu m standard CMOS technology to verify the effectiveness of this technique with the chip area of only 300 mu m(2), which is about 60 % of the previous reported circuit. Two types of proposed circuits with resistive and capacitive load demonstrated improved performance of reduced quenching time. With a commercial APD by HAMAMATSU, the dead time can be adjusted as small as 50 ns.