Novel GaAs MMIC components and multifunction circuits

Since the demonstration of FET based MMICs in the mid 1970s these devices have started to work a revolution in the microwave industry in many ways similar to that created by Si ICs many years ago. Compared to microwave hybrids, MMICs offer small size, low weight, repeatability, reliability and in volume, low cost. However the authors consider that the present generation of GaAs MMICs have only scratched the surface of the medium capability. The large majority of MMICs use conventional microstrip design rules, albeit realised with photolithographic accuracy on the GaAs substrate. This is not utilising the potential of the monolithic medium and it is the authors´ purpose to show how novel circuit elements, combined with the proven high yield of the advanced Plessey process can lead to very much smaller MMIC chips or, perhaps more significantly for the future, truly effective multifunction circuits