| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem that characteristics deteriorate with respect to temperature and device irregularity in the case power supply voltage for a power amplifier is controlled by analog signal processing. SOLUTION: In a high frequency amplifier circuit 10, a power detector 13 detects the input voltage, an A/D converter 14 converts the detected output into a digital signal, and a digital LPF 15 subsequently averages the converted digital signal to calculated the mean value data of an input power level. A memory 16 for DC-DC converter control gives control data corresponding to the means value data as a control voltage to a DC-DC converter 12 through a D/A means 17, and the DC-DC converter 12 thereby gives an output voltage Vdd being a low voltage as a circuit power supply voltage to the power amplifier 11 in a medium and small output power mode to make the power amplifier 11 highly efficient in the medium and small output power mode by suppressing the useless consumption current in the power amplifier 11.
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