Temperature dependence of the power gain and scattering parameters S 11 and S 22 of an RF nMOSFET with advanced RF‐CMOS technology

In this paper, we demonstrate analyses of the effects of temperature (from −50°C to 200°C) on the power gain and scattering parameters S 11 and S 22 of an RF nMOSFET with advanced RF CMOS technology for the first time. It is found that the maximum stable power gain/maximum available power gain ( G ms / G Amax ) and the square of the short‐circuit current gain | H 21 | 2 decrease with increasing temperature but show a reverse behavior within a higher frequency range. This phenomenon can be explained by the negative temperature coefficient of the transconductance g m and the positive temperature coefficient of the substrate resistance R sub . In addition, the decrease of the measurement temperature can enhance the kink phenomenon of both S 11 and S 22 , mainly due to the increase of g m . The present analysis enables RF engineers to understand more clearly the temperature dependence of the power gains and S ‐parameters of RF MOSFETs, and hence is helpful for them to design less temperature‐sensitive RF MOSFETs and radio‐frequency integrated circuits (RF‐ICs). © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 44: 180–185, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20581