De-Embedding Method Using EM Simulator for Characterization of FETs and Its Applicability to Lossy Substrates

Accurate characterization of field effect transistors (FETs) is necessary for accurate design of monolithic-microwave integrated-circuit (MMIC). Extraction of FET parameters is difficult because the FET is embedded in the parasitic circuit, which is referred to as test element group (TEG), as shown in Fig.1 to connect probe and biases. De-embedding method using open/shortTEG [1] had been widely used in the characterization of FET. But this method has difficulties, especially in high frequencies, mainly in two reasons; (1) incompleteness of open and short pattern, and (2) approximation of a parasitic circuit by an equivalent circuit topology. In order to overcome these problems, the de-embedding method using EM simulator was proposed [2][3]. And it is shown by the authors that the de-embedding method using EM simulator has higher accuracy than the conventional de-embedding method using open/short-TEG [4]. In this paper, applicability of the de-embedding method using EM simulator for a coplanartype TEG with lossy substrates is investigated because the FET characterization on Si CMOS is very serious problem in the millimeter-wave band.