| 摘要 |
PROBLEM TO BE SOLVED: To provide a high frequency amplifier which amplifies a signal having a difference of high between a peak and an average at a broad band, and to provide an efficiency increasing method. SOLUTION: A discrimination amplifier 5 inputs a digital signal to monitor the signal level. When the signal level is equal to or less than a given input level of the digital signal, the discrimination amplifier supplies a switching power amplifier 2 with a power supply of a voltage v2, and outputs a pulse signal which has a different pulse duty and a fixed output amplitude, and is modulated by ΣΔ to the switching power amplifier 2, and when the signal level exceeds the given input level, the discrimination amplifier supplies a power supply of a voltage V1 higher than v2, outputs the pulse signal having the same pulse duty and amplitude as at the given input level to a ΣΔ modulator 1, and adds a signal of an amplitude corresponding to the exceeding level to an output signal of the switching power amplifier 2 to perform amplitude modulation. COPYRIGHT: (C)2011,JPO&INPIT |
