Analog counting circuit with high counting range applied to single photon avalanche diode (SPAD) detector

Abstract

The invention discloses an analog counting circuit with a high counting range applied to a single photon avalanche diode (SPAD) detector. The circuit is composed of a counting capacitor C, a resistor R and fifteen MOS transistors, wherein a Cascode biasing circuit is formed by the NMOS transistors MN3 and MN4, the PMOS transistors MP6, MP7, MP8 and MP9, and the resistor R for providing bias for the counting circuit; meanwhile, the biasing circuit also provides a current source load for an output follower of the counting circuit, so that linear output of a counter is ensured; the biasing circuit also provides a biasing voltage with high level for the current-limiting PMOS transistor, thus playing a role in preventing the breakover current from being excessive on a charging branch of the counting capacitor. The invention also provides a counting method by using the analog counting circuit with the high counting range applied to the SPAD detector. The method comprises three stages consisting of a resetting stage, a counting stage and a reading stage. The analog counting circuit provided by the invention can reduce capacitor area and is large in counting range, and also has the advantage of high filling coefficient of a pixel unit.

Description

technical field [0001] The invention provides a linear analog counting circuit and method based on avalanche pulse rising edge trigger counting, belonging to the technical field of single photon detection. Background technique [0002] SPAD (Single Photon Avalanche Diode) is a single photon avalanche photodiode. In the field of photodetection, the photomultiplier tube (PMT) in the traditional sense can no longer satisfy the detection under high-speed and low-light conditions. Traditional imaging technology is limited in terms of imaging speed and pixel sensitivity, so solid-state photomultipliers began to appear. tube, the single photon avalanche diode detector. In recent years, the use of modern standard CMOS technology to manufacture high-density, highly integrated SPAD array detectors has become the development trend of this single-photon avalanche diode detector. [0003] The traditional counting circuit adopts the way of digital counting, directly processes the avalan...

AI Technical Summary

Problems solved by technology

[0005] Aiming at the problem that the counting range of the traditional analog counting circuit is restricted by the counting capacitance and the pulse width of the input avalanche signal, the present invention proposes an analog counting circuit with a high counting range applied to the SPAD detector

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