GaAs Logic Characteristics Result in Integration Problems

In this third and final article in a series about GaAs circuit design, actual designs, interface to other logics, and tradeoffs that the resulting architecture inevitably requires for proper operation are discussed. Although differences do exist, GaAs technology has been proven to be compatible with TTL and ECL. However, thermal gradients within a GaAs device do not reduce noise immunity in GaAs as much as in ECL systems. For this reason, all circuits must track both input and output voltage levels. Traditional design techniques are not always applicable to GaAs devices at gigahertz frequencies. Debugging, however, might be easier. Several circuit schematics are supplied.