The optical coupling of analog signals

An optocoupling circuit based on the Siemens IL300 linear optocoupler and the methods to assess its static and dynamic performances are presented. It is shown that IL300, due to its built-in linearizing feedback photodiode, makes it possible to build coupling schemes that associate good linearity with the inherent properties of optical devices, as true galvanic isolation, high isolation voltage and transmission down to dc. The integral linearity, 0.029%, obtained on the coupling of typical nuclear spectroscopy pulses makes us believe that traditional capacitive coupling used in nuclear spectroscopy circuits can be replaced by optical coupling in the near future.