A Fully Integrated Single Photon Avalanche Diode Detector in 130 nm CMOS Technology

Measurement of weak optical signals is becoming more and more prevalent in different fields of science. Single Photon Avalanche Diode (SPAD) is one of the most important active devices that are able to detect photons. When a photon is detected, the SPAD will generate an increasing current and a short duration voltage pulse. As a result, this SPAD device must be biased by a quenching circuit, which, after rapid sensing of the avalanche current, must be able to switch off and reset the diode to its initial condition as fast as possible. Since the number of pulses generated by a SPAD in a particular time interval is proportional to the intensity of the photons falling on the SPAD, a readout approach based upon 2D arrays is therefore created. In this paper, a compact active quenching circuit and an innovative readout circuit are both presented. Compared to other quenching and readout circuitry in many literatures, the active quenching circuit performs ultrafast and the readout circuit provides two different output methods. The whole circuitry is extremely compact that can be embedded in the limited area between SPADs in a 2D array, which is the most outstanding advantage.