Optimized Transistor Output Power—Extending Cripps' Loadline Method to Cascode Stages

A method for analytical optimization of maximum distortionless output power in a class-A amplifier stage is presented. This method is based on Brown's ideas to optimize the load resistance of triode vacuum tubes and Cripps' loadline method. As a result, the maximum distortionless output power of a cascode stage can be directly calculated as a function of load impedance. The theoretical approach is demonstrated with the design of a 61.5-GHz low-noise amplifier involving a cascode stage as output stage.