Research On Time-to-Amplitude Converter Applied To Single Photon Detector

Single photon detection technology is an effective technology to detect single photon signal.Single photon detector technology is widely used in quantum mechanics,aerospace,laser ranging,biological diffusion tomography and other research fields.The single-photon detector is mainly used for detecting weak photoelectric signals,processing the time interval between high-frequency laser emitting and receiving photons,and establishing a functional relationship between photon detection and time between periodic photon signals.The single photon detector mainly includes a laser emitting device,a single photon detector device,a time measurement module,and an analog-to-digital conversion module.Among them,the time measurement module can effectively detect the time interval between the photon emission and the reception,and its performance is decisived for the performance of the single photon detection system.How to improve the time resolution,dynamic measurement range and reduction small power consumption is a hot topic in current research.Based on the research background of laser ranging,this article focuses on the research and analysis of the time-to-amplitude converter used in single-photon detectors,and selects single-photon avalanche photodiodes as detection according to actual needs.Aiming at the design requirements of time resolution and dynamic measurement range of the time-to-amplitude converter,the unit modules in the TAC system are analyzed and designed.1. In the readout circuit of a single photon detector,a transimpedance amplifier is used to convert the weak optical signal detected by the detector into an electrical signal,and the received photoelectricity is converted by a time-to-amplitude converter.The signal is converted into a time signal,and finally the short-range information of the detected object is obtained through the time distance formula.2. In order to achieve a higher time resolution and dynamic measurement range, this paper improves the design of a start-stop time-to-amplitude converter,which mainly includes a fully differential operational amplifier,a bandgap reference voltage source,a bandgap reference current source,and voltage-current conversion circuit composition.The op-amp is optimized to achieve a higher gain of 101 d B,a swing of-1.075 to 2.457 V,and a power supply voltage rejection ratio of 104.07 d B.The optimal design of the bandgap reference source is simulated,and the temperature drift coefficient is 7.26 ppm/?,which improves the power supply voltage rejection ratio to 104 d B to ensure that the circuit provides stable voltage and current.At the same time,a control logic sequence circuit is designed to provide a clock pulse signal for the circuit and control the integration time of the integration circuit.3. Using Cadence series simulation software,based on the Korean Dong Bu 0.18?m CMOS process,the TAC related circuit is simulated and designed.By calculating the time resolution is less than 50 ps,the dynamic range can reach ns level.The results show that by improving the circuit structure,the performance indicators of key circuits are improved,and simulations can effectively improve the time resolution and dynamic measurement range of TAC.To draw the layout for the corresponding circuit design,the chip layout area of the TAC system is 870×480?m~2.