Temperature dependence of the power gain and scattering parameters S11 and S22 of an RF nMOSFET with advanced RF-CMOS technology

In this paper, we demonstrate analyses of the effects of temperature (from -50degreesC to 200degreesC) 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-2t\(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 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). (C) 2004 Wiley Periodicals, Inc.