An approach for determining PHEMT small-signal circuit model parameters Up to 110GHz

This paper describes a method to determine the small-signal equivalent circuit model elements for Double Heterojunction δ-doped PHEMTs, which combines the analytical approach and empirical optimization procedure. The PAD capacitances are determined by measuring an open structure which consists of only the pads. Intrinsic elements determined by a conventional analytical parameter transformation technique are described as function of extrinsic elements. Variation ranges of extrinsic elements for optimization are obtained by using coldfet method. An excellent fit between measured and simulated S-parameters in the frequency range of 2-110GHz is obtained for 2×100um gate width (number of gate fingers × unit gate width) DH PHEMT.