| 摘要 |
PURPOSE: A high efficiency power amplifier is provided, which makes a power supply voltage by switching a battery power supply voltage with a PWM(Pulse Width Modulation) pulse according to an output power of a high frequency signal and then by filtering it with a low pass filter. CONSTITUTION: The high efficiency power amplifier comprises a coupler(100) detecting an input signal, and an envelope detector(200), and a DC amplifier(300) amplifying a detected DC voltage, and a PWM(Pulse Width Modulation) modulation part(400) performing a PWM modulation according to the amplified DC voltage, and a switching power supply part(500) turning on/off a power supply according to the PWM signal and performing a low pass filtering. The PWM signal is generated in a CPU directly and then is applied to the switching power supply part, and therefore the power of the amplifier and a bias voltage are varied below a battery voltage according to the amplitude of an input signal.
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