Extraction of π -Capacitor Equivalent Circuit Elements for Field-Effect Transistors in Deep Pinch-Off

A heterojunction field-effect transistor in blocking (deep pinch-off) connected between two transmission lines (gate to drain) is represented as an asymmetric transmission-line gap. This configuration allows one to determine the
$\pi$
-capacitor equivalent network from
$S_{12}(\omega)$
or
$s_{21}(\omega)$
measurements only. We discuss the method of extracting equivalent-circuit element values and the limitations of this alternative approach to device intrinsic parameter de-embedding.