| 摘要 |
Provided is a Polar modulation apparatus which compensates for output characteristics of a power amplifier. A data generator generates an amplitude component signal and a phase component signal. A phase modulator generates a phase modulated signal obtained by phase modulating the phase component signal. An adder adds an amplitude offset voltage to the amplitude component signal. A power amplifier which includes a first hetero-junction bipolar transistor, amplifies the phase modulated signal by using the amplitude component signal. A monitor unit monitors the power amplifier and outputs a monitor voltage. The control unit calculates the amplitude offset voltage according to the monitor voltage and outputs the calculated amplitude offset voltage to the adder. The monitor unit includes a second hetero-junction bipolar transistor and outputs a collector emitter voltage of the second hetero-junction bipolar transistor as the monitor voltage.
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