Description

Photorelays (MOSFET output photocouplers) have a variety of advantages, and replacement from mechanical relays is progressing. However, there are some points that must be taken into consideration in comparison with mechanical relays when they are used in high-frequency circuits such as semiconductor testers and measuring instrument applications. This application note mainly describes precautions when controlling high-frequency signals with photorelays. Here, signals with a frequency ranging from several hundred MHz to several ten GHz are positioned as high-frequency signals. In addition, assume that a 1-Form-A photorelay (a photorelay in which the output-side MOSFET is turned on when the input-side LED signal is on) is used as a precondition.