文章提出一种使用对数转换器进行宽量程、高精度暗电流测试的方案,分析了电流计的通用模型,并开发出一套测试系统,测试灵敏度可达0.1pA,远高于目前国内能够提供的测试仪表.仪器自带偏压输出,除用于光电探测器暗电流的测试、微弱光功率测量外,还可以测量器件的击穿电压、材料的绝缘电阻等.该仪器亦能通过串口与计算机组成功能更强的测试系统. This paper presents a scheme of using a logarithmic converter for wide-range and high-precision dark current testing. The general model of the ammeter is analyzed and a test system is developed. The test sensitivity is up to 0.1pA, much higher than that of the current domestic The instrument comes with a bias output, in addition to dark current for the photodetector test, weak optical power measurement, but also can measure the breakdown voltage of the device, the insulation resistance of the material, etc. The instrument can also be through the serial port A more powerful test system with a computer.