Switching characteristics of logic gates addressed by picosecond light pulses

Detailed characteristics of the response of GaAs FET logic gates to picosecond light pulses are reported, from which optimum conditions for optically induced logic level switching are deduced. These characteristics include plots of photoinduced output electrical signals versus input dc voltages for the illumination of individual FET's in NOR gates and inverters. Optically induced logic level switching has applications in high-speed data processing in gigahertz-rate communications links, contactless diagnosis of logic circuits, and picosecond resolution measurements of on-chip response times of logic gates.