Abstract: A semiconductor device comprises a plurality of gate electrodes, drain electrodes, and source electrodes axi-symmetrically formed on opposite sides of a gate pad and drain pad. Two source pads are arranged at ends of these electrodes, to which the source electrodes are connected, so that a gate width can be shortened. Therefore, an output power, gain, etc., can be increased, and the high-frequency characteristics can be improved. Further, when arranging a plurality of semiconductor devices in parallel, the semiconductor chip can be formed in the shape of a square, i.e., the aspect ratio thereof can be reduced, and therefore, cracks in the semiconductor chip (semiconductor device) can be avoided.

Abstract: A high efficiency RF power amplifier includes a field effect transistor having a grounded source, a gate receiving an input signal, and a drain. A first inductor has a first end coupled to the drain via a lead inductance, and a second end through which an amplified output signal is output. A first capacitor has a first end grounded and a second end coupled to the second end of the first inductor. A second inductor has a first end receiving a drain bias voltage and a second end coupled to the second end of the first inductor. The second inductor is formed of a distributed-constant element. The first capacitor and the second inductor form a parallel resonant circuit coupled to the drain at a fundamental operating frequency of the high efficiency RF power amplifier, so that the drain is set to a high-impedance state.