Introduction to the Special Issue on Microwave Circuits on Silicon Substrates

This article discusses the development of microwave circuits on silicon substrate. Silicon, even though inexpensive, did not provide the performance required for microwave circuits. Instead the development of microwave circuits used GaAs and InP substrates. With the development of commercial usages for microwave circuits, the costs of microwave circuits became an issue. The importance of cost, and the development of Si-device capabilities and fabrication techniques, such as molecular beam epitaxy, and ultra-high chemical vapor deposition. provided the circumstances where the development of microwave circuits on silicon is now possible.