A Build-in Pseudo-Event Driven Readout Circuit for 3D dToF Image Sensor

The SPAD-based 3D dToF image sensor boasts a wide range of applications, attributed by its excellent photon sensitivity. However, increasing the number of time-to-digital converters (TDCs) per pixel does not necessarily enhance measurement efficiency, as photon throughput is limited by readout bandwidth. Moreover, an immense volume of TDC data put the readout circuit under enormous press. A $\mathbf{128}\times \mathbf{128}$ pixels image sensor with an integrated pseudo-event driven readout circuit and 8-bit shared TDC which is designed and fabricated in 180-nm CMOS technology is demonstrated for the ability of reducing data scale and increasing read bandwidth effectively. The proposed pseudo-event driven circuit substantially diminishes the amount of readout data, achieving 94% reduction in data volume at point rate 3%. The chip is capable of both grayscale and depth imaging paired with an area array laser, offering 3 cm accuracy and a maximum range of up to 200 m.