Relationships between common source, common gate, and common drain FETs

This paper comprehensively analyzes the relationship between common source (CS), common gate (CG), and common drain (CD) field-effect transistors (FETs). The signal and noise parameters of the CG and CD configuration can be obtained directly by using a simple set of formulas from CS signal and noise parameters. All the relationships provide a bi-directional bridge for the transformation between CS, CG, and CD FETs. This technique is based on the combination of an equivalent-circuit model and conventional two-port network signal/noise correlation matrix technique. The derived relationships have universal validity, but they have been verified at 2×40 μm gatewidth (number of gate fingers × unit gatewidth) double-heterojunction δ-doped AlGaAs/InGaAs/GaAs pseudomorphic high electron-mobility transistor with 0.25-μm gate length. Good agreement has been obtained between calculated and measured results.