| 摘要 |
PURPOSE: A circuit for linearizing a high frequency power amplifier is provided to improve linear amplifying characteristics of the high frequency power amplifier, by equalizing phase changes of an amplified signal and non-linear amplitude amplifying characteristics caused by non-linear high frequency amplifier characteristics, and to reduce errors caused by an amplitude by comparing output signals of the high frequency power amplifier to use ratio changes of a compared phase difference and a compared amplitude. CONSTITUTION: A circuit for linearizing a high frequency power amplifier comprises an attenuator(11), a phase transition circuit(12), a high frequency power amplifier(13), a delayer(14), a digital phase comparator(20), a loop filter(21), a first buffer amplifier(5), a first instant power measurer(18), a second instant power measurer(19), a subtracter(17), and an integrator(22). The attenuator attenuates a high frequency power in proportion to an applied control voltage. The phase transition circuit transits a phase in proportion to the control voltage. The high frequency power amplifier amplifies a high frequency. The delayer applies a delay corresponding to a time delay of the high frequency power amplifier to a high frequency signal, while the high frequency signal is passed through. The digital phase comparator compares zero crossing points of inputted two high frequency signals to output pulses. The loop filter smooths the pulses according to time. The first buffer amplifier amplifies a control voltage output from the loop filter by adjusting the control voltage to an input of the phase transition circuit. The first instant power measurer converts an instant power of the inputted high frequency signal into an analog signal. The second instant power measurer converts an instant power of the output high frequency signal into an analog signal. The subtracter compares the inputted two analog signals and outputs an analog signal corresponding to a compared difference. The integrator integrates the analog signal according to time.
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