Patent ID: 6861905

Claim:
A power amplifier system comprising: a Schottky barrier sate metal semiconductor field effect transistor (“MESFET”) having a source, a drain and a gate electrode, wherein the gate electrode is formed on a semiconductor region so as to form a Schottky diode between the gate electrode and the semiconductor region, and a gate current flows as a forward direction current of the Schottky diode by increasing a gate bias voltage to be supplied to the gate electrode, and wherein materials of the gate electrode and the semiconductor region are arranged so that a gate bias voltage which is to be supplied to the gate electrode and which is defined by a gate current value of 100 microamperes (μA) per gate electrode width of 100 micrometers (μm) is greater than or equal in value to 0.65 volts (V); and a bias circuit arranged to receive a unipolar power supply, and to provide the gate bias voltage to be supplied to the gate electrode, wherein the MESFET amplifies an input signal superposed with the gate bias voltage provided from the bias circuit.