Design Of Single-photon Single-terminal Detection Circuit Based On Narrow Gating

The near-infrared Single Photon detection technology based on Single Photon Avalanche Photodiode(SPAD)is gradually developing towards the simpler and more efficient detection structure.By means of reducing the dark count and post-pulse probability of SPAD,improving the efficiency of photon detection,the security and the reliability of information transmission.Based on narrow gate detection single photon detection technology,which uses a very short gated detectable window,the avalanche signal triggered by photons can be quenched quickly to ensure the reliability of SPAD,effectively improve the transmission rate of information,and which is suitable for high-precision detection of photon signal with known arrival time.Due to the junction capacitance of InGaAs/InP SPAD,the avalanche signal triggered by photons and the gated spike noise can be aliased to varying degrees in both time domain and frequency domain under the condition of narrow gated bias.In order to extract weak avalanche signals,the interference of gated peak noise must be effectively suppressed.Based on the modeling analysis of the gated peak noise,the influencing factors and spectral characteristics of the gated peak noise are clarified.This paper designs a single-photon single-terminal detection circuit based on narrow gating detection to improve the efficiency of single-photon detection at a lower cost.It is based on the principle to use the different frequency characteristics of the peak noise and the avalanche signals,the cut-off frequency by appropriate low-pass filter circuit,which realizes the avalanche signals and noise peak effective separation in frequency domain,Through the amplification and identification circuit,the signal to noise ratio of the detection system is improved,and the sensitive detection of avalanche signal is realized.The TSMC 0.18?m 1.8V CMOS was used to complete the design of the key module circuit in this detection system on the platform of Cadence,including the low noise amplifier,the static comparator and the buffer driving circuit.To reduce the contradiction between circuit noise and impedance matching on the premise of ensuring low power consumption.The low noise amplifier adopts a common gate structure which combines the transconductance multiplier technology and double capacitance cross coupling.The static comparator adopts preamplifier and self-biased differential structure to achieve high speed and high precision resolution under low power consumption.Combined with the existing ten orders GM-C filter circuit in the laboratory,a complete single photon single terminal detection system is constructed.The test results show that under the condition of ideal excitation to simulate low-frequency avalanche signal,the single-photon detection system can realize accurate discrimination of avalanche signal with the highest frequency of50 MHz.Under the condition of 1GHz sinusoidal narrow gated bias,the dark current pulse generated by Si C detector is used to simulate the avalanche signal,the detection system can detect the avalanche signal in time when the pulse interval is more than 20 ns.By the laser source fixed frequency for 10 MHz of the signal that uses the InGaAs APD to link the optical system,the experimental results show that,the single-ended detection system can be sensitive to the frequency from 5 MHz to 20 MHz,the minimum voltage amplitude that the system can detect is about 10 m V.It shows that the detection circuit designed in this paper can be used in different gate control and APD detection systems and has a good engineering application value.