Optoelectronics as applied to functional electronic blocks

The combination of a GaAs light source and a silicon photodetector in a Functional Electronic Block (FEB) provides signal coupling with electrical isolation. Circuit functions not previously available in microelectronic form can be realized with optical coupling. The characteristics of the GaAs light source, the silicon photodetector and optical coupling techniques of importance in FEB design are discussed. Several useful FEB´s which employ optical coupling to achieve electrical isolation are described; these include a multiplex switch, an isolated gate p-n-p-n-type switch, a photon-coupled transistor and an optoelectronic pulse amplifier.