Comparison of Discrete Bipolar Transistors and MOSFETs for High-Speed Switching Application

Abstract

Switching performance analysis in this paper presents how Horizontal Current Bipolar Transistor (HCBT) performs under switching mode of operation compared to other commercially available bipolar and MOS transistors, focusing mainly on power efficiency. Rudimentary measurement setup is devised, with target frequency spectrum for this analysis up to 100 MHz. Measurements were performed at frequencies of 1 MHz, 10 MHz and 100 MHz. Signal waveforms were measured at the input and output of analysed device. Dissipated power at each component of test circuit was calculated from the measurements to determine efficiency. The results show similar performance among RF bipolar junction transistors analysed in this paper. All bipolar transistors exhibit efficiency around 80% at 100 MHz, whereas the best performing MOSFET has n = 54.31%. The analysed MOSFETs show somewhat better performance comparing to bipolar transistors at lower frequencies, but with larger performance degradation with the frequency increase. This analysis shows potential of HCBT to be used in switching part of Envelope Tracking (ET), hybrid power supply modulation, pulse width modulation (PWM) or multilevel power supply switching to obtain higher efficiencies. Most of the efficiency reduction is caused by nonideal input signal.