Radio frequency amplifier circuit and mobile communication terminal using the same

A radio frequency amplifier circuit for amplifying a radio frequency signal, comprising:

• a bias circuit operable to generate a bias current, wherein an amount of the bias current is changeable in accordance with a control signal, and
• an amplifier operable to amplify, by using the bias current supplied by the bias circuit, the radio frequency signal having been inputted thereto,
• wherein each of the first bias circuit and the second bias circuit includes:
• a bias supply transistor operable to supply, to each of the first amplifier and the second amplifier, each of the first bias current and the second bias current in accordance with a base current supplied thereto;
• a first temperature compensation transistor operable to pass a current in accordance with a reference voltage;
• a second temperature compensation transistor operable to correct, in accordance with the current passed by the first temperature compensation transistor, the base current to be supplied to the bias supply transistor, so as to compensate a temperature characteristic represented by the bias supply transistor;
• and
• a bias changing section, connected to a base of the second temperature compensation transistor, operable to change, in accordance with the control signal, an amount of the base current to be supplied to the bias supply transistor.

A mobile communication terminal comprising a radio frequency circuit block which includes a synthesizer section, a transmission section, a reception section, a common use unit, and a control signal output section, wherein

• the transmission section includes
• a modulator operable to convert an inputted modulation signal into a transmission signal of a predetermined transmission frequency;
• a radio frequency amplifier circuit, capable of changing a gain, operable to amplify the transmission signal obtained by conversion performed by the modulator;
• a band-pass filter operable to extract a signal of a predetermined band from the transmission signal having been amplified by the radio frequency amplifier circuit;
• the radio frequency amplifier circuit according to claim 1 operable to amplify, using a fixed gain, the signal extracted by the band-pass filter;
• and
• an isolator, provided between the common use unit and the radio frequency amplifier circuit using the fixed gain, operable to unidirectionally pass a signal to the common use unit from the radio frequency amplifier circuit using the fixed gain.