Patent ID: 7868699

Claim:
A semiconductor integrated circuit device for mobile communication equipment, comprising a high-frequency power amplifier, said high-frequency power amplifier including: a transistor having a gate inputted with a transmit signal, a source connected with a reference potential and a drain outputting a signal of said high-frequency power amplifier obtained by amplifying said transmit signal; a first bias circuit supplying a first bias voltage to said drain; and a second bias circuit supplying a second bias voltage to said gate, including a gate resistor and an inductance series-connected between a second bias power supply voltage and said gate, wherein an impedance value of said inductance is higher than an impedance value of said gate resistor for a first predetermined frequency range of said transmit signal, and said impedance value of said inductance is lower than said impedance value of said gate resistor for a second predetermined frequency range of said transmit signal, wherein said second predetermined frequency range is less than said first predetermined frequency range; wherein said first predetermined frequency range is in the order of GHz, and wherein said second predetermined frequency range is in the order of MHz; and wherein said gate resistor has a resistance value of substantially the same order as an input impedance of the transistor at said first predetermined frequency range, which is determined by the sum of a gate capacitance of the transistor and a feedback capacitance thereof.