Time-to-analog conversion circuit applied to single photon detector

Abstract

The invention provides a time-to-analog conversion circuit applied to a single photon detector. The time-to-analog conversion circuit comprises a quenching circuit, an RS trigger F, a transmission gate TG, a single-pole double-throw switch S, a sampling capacitor C and a source follower circuit; and quenching reset controls a quenching reset of an SPAD and controls transmission of an avalanche signal, the RS trigger is controlled via the avalanche signal to sample a triangular wave synchronized with an exposure signal by a tracking and holding circuit, so that a voltage value linearly relatedto the photon flight time is obtained, and the RS trigger plays a role in resetting for a sample tracking circuit. The single-pole double-throw switch provides different reference signals to the tracking and holding circuit during reset and photon flight time measurement phases. The time-to-analog conversion circuit comprises the trigger, has the advantages of simple circuit structure, the less control time sequence signals and the small occupied area, and is suitable for a large-scale pixel array; and a high filling factor can be reached. The time-to-analog conversion circuit has a high output range, so the time-to-analog conversion circuit has small time resolution and is suitable for the relatively precise measurement for photon flight time.

Description

technical field [0001] The invention relates to the field of optoelectronic technology, in particular to a time-to-analog conversion circuit applied to a single photon detector. Background technique [0002] Single-photon avalanche diode (SPAD) has significant advantages such as large avalanche gain, fast response speed, high detection efficiency, low cost, and low power consumption. 3D imaging and other aspects have broad application prospects. In applications such as SPAD-based fluorescence lifetime imaging, time-correlated single-photon counting (TCSPC) techniques are used to determine the time-of-flight of photons and thus the distance to objects. Currently, a time-to-digital converter (TDC) converts the detected time into a digital signal, and then extracts the position information to restore a 3D image. The detection time of TDC is affected by the time resolution. If the detection distance is long, the measured flight time will also be long, which requires a geometri...

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Problems solved by technology

However, the measurement time range of traditional TAC circuits is shorter, usually ranging from a few nanoseconds to tens of nanoseconds, so t

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