Process- and technology-independent power switching transistor figures of merit

It is becoming important to properly choose among the many semiconductor switch technologies available when designing efficient high-speed power switches, due to required circuit energy efficiency improvements. In a world of wide bandwidth and high frequency signals, the desirable operating frequency of switch-mode circuitry increases correspondingly. This paper proposes two figures of merit (FoM) combining FET channel ON resistance with gate-charge and gate-source voltage to perform such comparisons. Beyond just comparison, one FoM is shown to be useful in design and evaluation of high speed, high power switches and their drivers. Using these comparisons, silicon FETs are shown to have a huge disadvantage for high speed switching applications including RF power amplifiers.