The HCNR200/201 high-linearity analog optocoupler consists of a high-performance AlGaAs LED that illumi nates two closely matched photodiodes. The input photodiode can be used to monitor, and therefore stabilize, the light output of the LED. As a result, the non-linearity and drift characteristics of the LED can be virtually eliminated. The output photodiode produces a photocur rent that is linearly related to the light output of the LED. The close matching of the photo-diodes and advanced design of the package ensure the high linearity and stable gain characteristics of the optocoupler.