Development Of Silicon Single Photon Avalanche Diode Gated Readout Circuits

The single photon detector gated readout circuit is a data readout interface circuit with clock gating,which converts the avalanche current of silicon single-photon avalanche diodes(referred to as Si-SPAD)into a voltage signal,and simultaneously realizes quenching function.However,strong differential noise will be generated on the sampling resistor in the gated circuit,and its amplitude is usually much larger than the avalanche signal,causing the avalanche signal to be completely submerged.How to extract the weak avalanche signal from the aliased signal becomes the primary problem when using the gated circuit for single photon detection.In this thesis,the influencing factors of differential noise are deeply studied,three differential noise suppression methods are designed and compared,and an avalanche signal gated readout circuit with a noise suppression ratio of 56.5 dB is realized.The main research contents are as follows:(1)Based on the constructed gated circuit,the factors that generate differential noise signals are studied.The voltage-time curves on the sampling resistors under the conditions of repetition frequency,duty cycle,rise time,excess voltage,and junction capacitance of different gating signals were tested.The experimental results show that when the gating signal is a pulse signal,The magnitude of the spike noise is inversely proportional to the rise time of the pulse signal,and proportional to the SPAD junction capacitance;when the gating signal is a sinusoidal signal,the amplitude of the sinusoidal differential noise becomes larger as the frequency of the gating signal increases,which is consistent with the simulation results.(2)Three kinds of gated differential noise suppression circuits are designed and developed:low-pass filter circuit,band-stop filter circuit and differential circuit.Based on the simulation verification results of the three circuits by Cadence Orcad Pspice,the circuits were built and tested,and the avalanche signal was successfully extracted from the differential noise.The noise rejection ratios of the three circuits reached 42.3 dB(20 MHz),51.1 dB(159 MHz)and 56.5 dB(250 MHz).Differential noise generated by different types of gating signals at different frequencies can be suppressed by using the adjustable capacitance differential circuit,so as to avoid being affected by the working bandwidth range of the filter.(3)Preliminary application of the three circuits.Under the condition of operating temperature of 18℃ and excess voltage of 1 V,the dark count rate of the low-pass filter circuit is 2.54 × 10-3/gate,and the dark count rate of the band-stop filter circuit is 4.66 × 10-4/gate.In the differential circuit,when the gate control signal is a sine wave of 250 MHz,the dark count rate is 1.52×10-4/gate.