高输入阻抗测压电路

Circuit of measuring voltage with high input impedance

本文简要说明了电压测量电路要求具有较高输入阻抗的原理,针对直流电压测量技术中采用的实际电路介绍了几种高输入阻抗的测压电路,并简要分析它们的工作原理和特点。测量几伏或几百毫伏电压时,可采用场效应管差分式电路(输入阻抗达几百兆欧或上千兆欧);也可采用高阻型集成运放(如CA3130输入阻抗高达TΩ量级,即1012Ω)构成测压电路;当测量较低的电压(几毫伏或几十微伏)时,可采用高稳定度的高增益集成运放(如MAX420)构成测压电路。这些测压电路均可有效地减小测量误差,提高准确度。

This article briefly describes the circuit of measuring voltage requires a relatively high input impedance principle,introduced in DC voltage measurement technology used by several high input impedance circuit,and a brief analysis of their works and features.When measuring a few volts or hundreds of mV voltage,you can use field effect transistor differential circuit（input impedance up to several hundred MΩ or GΩ,i.e.108 ～ 109Ω）,or integrated operational amplifier with high-impedance（such as CA3130） composition of the circuit（input impedance up to TΩ,i.e.1012 Ω）.When measuring low voltage（several mV or dozens of μ V）,high stability and high-gain integrated operational amplifier（such as MAX 420） constitute a measure voltage circuit.These circuits can be effectively reduces measurement errors,increase accuracy.