Linear Analysis of High-Frequency Field-Effect Transistors Using the CN-FDTD Method

The Crank-Nicolson finite-difference time-domain (CN-FDTD) method is used for the linear analysis of a field-effect transistor (FET) based on the distributed model, wherein the FET is considered as an active multiconductor transmission line (AMCTL). The telegrapher's equations governing the AMCTL are derived and discretized by the CN-FDTD method. The results are compared with measurements and the leapfrog (LF)-FDTD method. Unconditional stability of the CN scheme is investigated. Agreement with measured results is preserved in an acceptable level even by increasing the time step-size by a factor of 1500 to that of the LF-FDTD method.