Patent ID: 7535246

Claim:
A field-effect-transistor characteristic measuring method in which a bias voltage output from a bias output terminal of a measuring system is applied to a drain of a field-effect transistor and a pulse output from a pulse generator is applied to a gate of the field-effect transistor; the generated drain current is converted by an input impedance of voltage measuring unit, connected to an alternating-current output terminal of the measuring system, into a corresponding voltage; and the converted voltage is measured by the voltage measuring unit, the measuring method comprising: a step of determining a coefficient indicating a relationship between a measurement voltage of the voltage measuring unit and a voltage drop in the bias voltage due to the drain current, based on at least: an S parameter of the measuring system connected between the field-effect-transistor and the voltage measuring unit, wherein the measuring system comprises: a bias tee; and at least one other component; and the input impedance of the voltage measuring unit; a step of determining the voltage drop corresponding to the measurement voltage of the voltage measuring unit, based on the coefficient; and a step of determining a value of bias voltage actually applied to the drain of the field-effect transistor, based on the determined voltage drop.