SPAD Based Digital Photon Counting Optical Distance Sensor in 150 nm CMOS Using Indirect Multiphase Time-of-Flight
In this work a single photon avalanche diode (SPAD) based phase measurement circuit for distance measurements using continuously modulated light in a 150 nm CMOS technology is presented. An on-chip quadruple-voltage quenching circuit, allowing up to 7.2 V excess bias for external SPADs, generates pulses synchronous to the detection times of single photons. Circuit simulations show, that a precision of 0.54 mm can be achieved for distance measurements in low background light environments, in a measurement time of 200 μs. The efficiency of background light suppression can be improved by increasing the measurement time. Even a factor of 100:1 of background to measurement light should allow sub-cm precision given a sufficient measurement time. Correlation frequencies up to 1 GHz are possible. One correlator block has a size of 230×210 µm2 and the power consumption for each correlator is 391 µW.