Fully integrated high density SPAD array detector

Since the traditional digital readout circuits occupy a very large area, the array density of single photon avalanche detector (SPAD) is very low. The paper presents a high-density SPAD array by use of analog readout technique. Each SPAD pixel consists of a compact quenching and analog readout circuits, resulting into the significant improvement of pixel duty. More importantly, the presented analog readout mode can make use of CMOS-APS imaging device array architecture, which greatly enhances the pixel density. The analog readout signal of pixel is subsequently processed by multiplexer, correlated double sampling and analog-digital converter circuits, and finally digital signal is output. The proposed high density SPAD array could be used in high resolution imagers capable of imaging in low light level.