Power amplifier circuit, control method for power amplifier circuit, and portable terminal apparatus for mobile communication

A power amplifier circuit, comprising:

• a first matching circuit which impedance-matches incoming input signals before outputting them;
• a first bias circuit connected to an output of said first matching circuit;
• a transistor connected to the output of said first matching circuit;
• a second bias circuit one end of which is connected to an output of said transistor;
• a second matching circuit which is connected to the output of said transistor and impedance-matches output signals of said transistor before outputting them;
• voltage transformation means whose output is connected to an other end of said second bias circuit and whose input is connected with a power supply;
• and
• control means of controlling operation of said voltage transformation means,
• wherein said voltage transformation means delivers output voltage under the control of said control means, and
• said control means determines according to output power from said power amplifier circuit whether to make said voltage transformation means carry out a step-up operation of raising said output voltage above a preset supply voltage or a step-down operation of lowering said output voltage below said supply voltage.

A control method for a power amplifier circuit which comprises:

• (1) a first matching circuit which impedance-matches incoming input signals before outputting them;
• (2) a first bias circuit connected to an output of said first matching circuit;
• (3) a transistor connected to the output of said first matching circuit;
• (4) a second bias circuit one end of which is connected to an output of said transistor;
• (5) a second matching circuit which is connected to the output of said transistor and impedance-matches output signals of said transistor before outputting them;
• (6) voltage transformation means whose output is connected to an other end of said second bias circuit and whose input is connected with a power supply;
• and
• (7) control means of controlling operation of said voltage transformation means,
• wherein load impedance on the output side of said power amplifier circuit is detected,
• said control means changes output voltage of said voltage transformation means based at least on said detected load impedance, and
• said output voltage is applied to said transistor as a supply voltage.