INVESTIGATION OF GAAS-MESFET EQUIVALENT-CIRCUITS USING TRANSIENT CURRENT-CONTINUITY EQUATION SOLUTIONS

Transient solutions of Poisson and electron current-continuity equations are made to investigate the dependence of the equivalent-circuit parameters C(ds), tau, and R(i) on the gate and drain biases. We find that C(ds) is related by a single time constant to R(ds). A new model for the Y21 matrix element is proposed that does not involve the parameter tau. At high frequencies, the frequency-dependent parts of the Y matrices are better modeled using four independent time constants. Comparisons of the simulations with equivalent-circuit parameters extracted for 0.22-mu-m and 1.15-mu-m gate-length MESFETs are made.