Field effect transistor circulators

Field-effect-transistor circulators that are compatible with monolithic microwave integrated circuit technology are described. These passive nonreciprocal components are formed with inductors, capacitors, transmission line sections, and microwave transistors, and all can be integrated on a single IC chip the size of a pinhead. The operating principle, power-handling capability, and noise performance of these components are discussed for both narrowband and wideband applications, and examples of their practical implementation are given. The transistor-based 2-, 3-, and 4-port passive nonreciprocal components described offer an alternative to ferrite miniature circulators with potential advantages of small size and lower cost in production volume