CPC H03F 3/211 (2013.01) [H03F 2200/222 (2013.01); H03F 2200/387 (2013.01); H03F 2200/451 (2013.01)] | 20 Claims |
1. A power amplifier circuit comprising:
a first transistor having a first terminal to which a variable power supply voltage is supplied from a power supply terminal and a second terminal to which a radio-frequency signal is supplied, the first transistor being configured to amplify the radio-frequency signal;
a bias circuit configured to supply a bias current or bias voltage to the second terminal of the first transistor; and
an adjustment circuit configured to adjust the bias current or bias voltage in accordance with the variable power supply voltage supplied from the power supply terminal,
the bias circuit including
a first diode having an anode to which a bias control voltage or current is supplied, and a cathode,
a second diode having an anode connected to the cathode of the first diode and a cathode connected to ground, and
a bias transistor having a first terminal to which a power supply voltage is supplied, a second terminal connected to the anode of the first diode, and a third terminal connected to the second terminal of the first transistor,
the adjustment circuit including
a first resistor, and
an adjustment transistor having a first terminal connected to the power supply terminal via the first resistor, a second terminal connected to the anode of the first diode, and a third terminal connected to the anode of the second diode.
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