Design Of Noise Suppressed Single Photon Detection Circuit Applied To Quantum Communication

With the rapid development of optical quantum communication,the rate of quantum communication continues to increase,and the requirements for single-photon detectors are also increasing.Fixed gated single photon detection system as an architecture for single photon detectors.In the case where the photon arrival frequency is known,Based on Avalanche Photodiode(APD)working in Geiger Mode(GM).Through the method of gate pulse control,the APD can be periodically changed in the two states of the test-quenching,and the high frequency gating frequency can effectively suppress the dark count of the APD and improve the detection efficiency.Due to the capacitive nature of the APD,the higher gating frequency produces a spike noise signal with a larger amplitude and frequency than the avalanche signal,which in turn affects the detection of photons.In this thesis,a GHz gated single photon detection circuit for quantum communication is designed.The peak noise is eliminated by differential structure,and the avalanche signal is extracted and amplified.The specific scheme is to use two APDs with uniform capacitive characteristics,one for sensitization and the other for shading.The two channels generate the same spike noise signal and are eliminated by a fully differential low noise amplifier circuit.The APD cathode is connected to the high voltage bias through a high resistance.The bias voltage is slightly lower than the AGP mode voltage.When the gate signal is high,the APD is in the mode to be tested.Otherwise,the APD is quenched.The photosensitive APD generates an avalanche signal when receiving photons in the mode to be tested,and extracts and amplifies the avalanche signal through a 50? sampling resistor,and outputs a high level through the comparator to facilitate counting.Under the Cadence software platform,the circuit design and layout design of the GHz differential gated single photon detection system is completed by TSMC 0.35?m 3.3V CMOS standard process.Simulation of the system circuit,the results meet the design specifications.The system circuit is fabricated and tested.The test results show that the gated differential single photon detection circuit designed in this paper can eliminate the spike noise signal,amplify the avalanche signal and perform digital quantization.Transmission delay is less than 6ns.That is,the photon frame rate is less than 160 MHz,and the detection can be normally performed;Peak noise suppression ratio is-36.2dB;the circuit detection efficiency is 90.6%.Finally,the reasons for the degradation of the test results are given and feasible improvements are given.