A design method for high efficiency class F HBT amplifiers

Abstract

In this paper, we report on the class F operation of HBTs. A temperature dependent model of a 240 /spl mu/m/sup 2/ GaInP-GaAs HBT (THOMSON-CSF) was extracted from pulsed I/V and pulsed S-parameter measurements and validated by load-pull measurements. An extensive large signal HB analysis, based on "the substitute generator technique", was achieved to optimize the load impedance at harmonic frequencies required for class F operation. Furthermore, the performances of the transistor in terms of added power, power added efficiency and dissipated power, were investigated under different bias modes (i.e.: constant base voltage, constant base current and self bias modes). We show that the bias mode has a great influence on the HBT linearity.