US Patent 7443243 High frequency amplifier having an attenuator

An amplifier for amplifying a reception signal, having an input terminal for inputting the reception signal from an antenna, has a grounded gate transistor of which gate is grounded in a high frequency manner and of which source is connected to the input terminal, a load element disposed between the drain of the transistor and a power supply, an output terminal connected to a connection node between the drain and the load element, and an attenuator selectively inserted between the drain and the output terminal.