| 摘要 |
<p>Provided is a power amplifier of the envelope tracking type capable of reducing generation of nonlinear distortion even in small input while maintaining high efficiency. In the power amplifier, a gate voltage adjusting section (130) has a comparator (131) for comparing the size of a predetermined threshold voltage with that of an envelope signal. If the result of the comparison shows that the amplitude of the envelope signal is smaller than the predetermined threshold voltage, the gate voltage adjusting section (130) switches over so that a voltage (V1) is applied to the gate terminal of a high power amplifier (150). If the amplitude of the envelope signal is not smaller than the predetermined threshold voltage, it switches over so that a voltage (V2) (V1 > V2) is applied to the gate terminal thereof. At this time, the voltage (V1) is determined as a gate voltage that the high power amplifier (150) operates in an AB-class and the voltage (V2) is determined as a voltage that the high power amplifier (150) operates in a C-class.</p> |
