A correlated detection technique combined with a SPAD array macro-pixel readout circuit of parent-child TDCs

Abstract

The application discloses a SPAD array macro-pixel readout circuit of a correlation detection technology combined with a parent-child TDC, which comprises an AQC, a time window generation circuit, a self-recovery circuit, a child TDC, a parent TDC, a correlation detection circuit and a parallel-to-serial conversion circuit. Each macro-pixel readout circuit is connected with 2*2 SPADs, each SPAD is connected with one AQC, the AQC outputs a high level after quenching a SPAD triggered by a photon, the high level generates a pulse with a fixed pulse width through the time window generation circuit, the pulse triggers the child TDC and starts the correlation detection to determine whether the photon information is retained, if yes, the parent TDC is started, otherwise, the child TDC is reset and the self-recovery circuit is started to reset the SPAD. The child TDC in the macro-pixel readout circuit measures the differential mode of TOF of the photons detected by different SPADs, and the parent TDC measures the common mode of TOF, so that the reduction of the lateral resolution caused by the traditional correlation detection is compensated under the condition that the power consumption and the area are limited.

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