PWM模拟信号光电耦合隔离电路的研制

DEVELOPMENT OF A PWM ANALOG SIGNAL PHOTOCOUPLER ISOLATION CIRCUIT

本文提出一种运用PWM(脉冲调宽)原理设计低价格、低漂移、高线性模拟信号光电耦合隔离电路的方案。这种方案仅用普通的光电耦合器件。实验结果表明,这种隔离电路的非线性度不劣于0.02％,温度漂移低于0.002％/℃。本文还讨论了光电耦合器件的关断时间t_（OFF）对隔离电路动态范围的影响,并着重指出,关断时间温度系数（?）是影响隔离电路温度稳定性的主要因素。

This paper provides a scheme of PWM analog signal photocouplcr isolation circuit with a low cost, low drift and high linearity. In the circuit only a conventional photocouplcr is used. The experimental data shows that the linearity of the isolation circuit is less than o.02%, and the temperature drift is less than 0.002% / ℃. The Turn-off-Time (tOFF) of a conventional photocouplcr has influence on the dynamic range of the isolation circuit is discussed. It is also emphasized that the temperature coefficient of tOFF of a photocouplcr is the main reason to cause temperature drift of an isolation circuit.