An Efficient Nonlinear Capacitance Model for SOIFET Used as A Switch

Silicon-on-insulator field effect transistors (SOIFETs) are used in various radio frequency antenna switches with their superior performance. The nonlinearity of the SOIFETs produces unwanted harmonics with a certain excitation signal, which generates the electromagnetic radiation spurious emission (RSE) problem. This paper proposes an efficient inter-electrode nonlinear capacitance model to predict the nonlinear behavior for SOIFET used as a switch. The capacitance expressions between the SOIFET gate-source, gate-drain and gate-substrate are calculated by the voltage-current characteristics. As a consequence, the predicted fundamental, second and third harmonic power results from the inter-electrode nonlinear capacitance model are close to the test results obtained from the nonlinear test system. This proves that the method can provide guideline in designing process.