SPAD (Single Photon Avalanche Diode) array-stage readout circuit adopting quadratic correlation double sampling technology

Abstract

The invention discloses an SPAD (Single Photon Avalanche Diode) array-stage readout circuit adopting a quadratic correlation double sampling technology. The circuit comprises a CDS (Correlated DoubleSampling) readout circuit and a sample hold circuit; a first-stage CDS readout circuit is composed of one voltage follower, two switching circuits and one sampling capacitor, and is connected to eachuniversal serial bus for ensuring fast readout of information of a pixel unit, and eliminating fixed pattern noises in the pixel unit; and a second-stage CDS readout circuit is composed of two voltagefollowers, two switching circuits and two sampling capacitors, and is used for eliminating fixed pattern noises in the readout circuit. A quadratic correlation double sampling array-stage readout circuit requires only two control signals, and a time sequence signal is simple. The SPAD array-stage readout circuit adopting the quadratic correlation double sampling technology provided by the invention has the advantages of being simple in time sequence control and fast in readout speed; two stages of CDS require only two control signals, and the readout speed is fast, which improves the workingefficiency of the readout circuit, therefore, the advantages are obvious in large-scale pixel array circuits.

Description

technical field [0001] The invention belongs to the field of optoelectronic technology, and relates to a correlated double-sampling noise-reduction readout circuit applied to a high-density single-photon avalanche diode array detector. Background technique [0002] Single-photon avalanche diode (SPAD) has been widely used in fluorescence lifetime imaging, Raman spectroscopy, 3D imaging and other technical fields due to its high sensitivity and sub-second time resolution. At present, single-photon avalanche diodes are developing towards low-cost, high-density, high-reliability deep submicron CMOS process array image sensors. A SPAD array detector includes numerous SPAD pixel units and peripheral readout and control circuits, wherein each SPAD pixel unit is composed of a SPAD device, a quenching reset circuit and a counting readout circuit. The value of the pixel readout voltage measured by the analog counting method can reflect the number of detected photons, and can effecti...

AI Technical Summary

Problems solved by technology

Traditional correlated double sampling uses a fully differential amplifier as a sampling op amp, which requires a large integration capacitor and consumes a lot of power; while the CDS readout circuit designed using a transconductance amplifier requires more complex timing signals

Although the CDS readout circuit based on the current mirror structure can ensure a small occupied area and a relatively simple sequential circuit, the effective input range is small, and it cannot work effectively when the input range is large.

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