Patent ID: 8742844

Claim:
A power amplifier device comprising: a first power amplifier that is configured to amplify an amplitude of an RF input signal with a first gain and to output a first amplified signal; a second power amplifier that is configured to amplify the first amplified signal with a second gain and to output a second amplified signal; a filter that is configured to filter the second amplified signal and to output the filtered second amplified signal; a buffer that is configured to amplify the RF input signal with a third gain and to output the amplified RF input signal as a first comparison signal; an attenuator that is configured to attenuate the filtered second amplified signal and output the attenuated filtered second amplified signal as a second comparison signal; an amplitude comparator that is configured to compare an amplitude of the first comparison signal with an amplitude of the second comparison signal, and to output an amplitude comparison signal based on the comparison result; and a control circuit configured to adjust one of the first gain of the first power amplifier, the third gain of the buffer, a gain of the amplitude comparator, and an attenuation rate of the attenuator, so as to make the amplitudes of the first and second comparison signals more equal to each other, such that if the amplitude of the first comparison signal is larger than the amplitude of the second comparison signal, the first gain is decreased or the attenuation rate is increased, or if the amplitude of the first comparison signal is smaller than the amplitude of the second comparison signal, the first gain is increased or the attenuation rate is decreased, wherein the second power amplifier is configured to adjust the second gain based on the amplitude comparison signal so as to make the amplitudes of the first and second comparison signals more equal to each other.