针对近红外1550 nm单光子雪崩光电二极管(single photon avalanche photodiode,SPAD)的特性,为精确测量其参数性能,设计了高精度偏压控制电路及偏流检测电路系统。该系统以FPGA为控制核心,通过上位机软件下发偏压控制参数,采用高精度器件并经过电压放大滤波等操作实现对SPAD偏压的精准控制。采用电流检测器件,通过恒流源补偿的方案将偏流值检测转换成电压值的检测,利用模数转换器件进行电压采集上传给FPGA,上位机软件通过数据拟合推导得到最终的偏流值。通过实验测试验证了电路的可行性,偏压控制精度小于30 mV,输出电压纹波小于100 mV,偏流检测上传稳定。该偏压控制及偏流检测系统设计具有结构简单、偏压设置精度高、超低纹波、控制灵活的优点,已经应用于近红外1550 nm SPAD标定系统中,工作稳定可靠。
For the characteristics of near-infrared 1550 nm single-photon avalanche photodiode (SPAD),a high precision bias voltage control circuit and bias current detection circuit are designed to accurately measure its parameter performance. The system uses FPGA as the control core,and the bias voltage control parameters are issued by the host computer software. The high-precision device is used and the voltage amplification and filtering are used to achieve accurate control of the SPAD bias. The current detecting device is used to convert the bias current value detection into the voltage value detection by the constant current source compensation scheme,the voltage acquisition is reported to the FPGA by using an analog to digital conversion (ADC),and the upper computer software obtains the final bias value by data fitting. Through experimental tests,the bias voltage control accuracy is less than 30 mV,the output voltage ripple is less than 100 mV,and the bias current detection is reported to be stable. The bias voltage control and bias current detection circuit has the advantages of simple structure,high bias setting precision,ultra-low ripple,and flexible control. It has been applied in the near-infrared 1550 nm SPAD calibration system and is stable and reliable.