Patent ID: 8306490
Filing Date: 2012-11-06
Classification: H03F,H03G

Abstract:
1. A mobile communication terminal, comprising: a base band circuit having a limiter that determines a maximum transmit power of the mobile communication terminal; a transmit variable gain amplifier that receives the control signal from the base band circuit; a power amplifier that amplifies a transmit signal from the transmit variable gain amplifier; a front end module coupled to the power amplifier; and an antenna coupled to the front end module, wherein the power amplifier includes two amplification stages for amplifying an input signal from a gain variable amplifier, wherein the power amplifier includes: a first amplification stage; a second amplification stage comprising a transistor, and electrically coupled to the first amplification stage; an output matching circuit that is coupled to an output side of the second amplification stage; and a first detection unit for detecting a voltage amplitude at a node between the transistor of the second amplification stage and the output matching circuit, and outputting the voltage amplitude as a first signal of gain control information of the gain variable amplifier, detecting a supply voltage being supplied to the second amplification stage, and outputting the supply voltage as a second signal of the gain control information of the gain variable amplifier, and wherein the gain variable amplifier is controlled based on the gain control information so as to limit a gain of the gain variable amplifier, upon the voltage amplitude exceeding a predetermined threshold voltage.