Envelope-tracking amplifier for improving gain, Method for improving efficiency thereof, and terminal device of mobile communication applied to the same

摘要

An inventive envelope-tracking amplifier is provided for improving gain and efficiency by dynamically shifting an operating point of active element (23) of power amplifying unit (10). A method for improving gain and efficiency is also developed for correcting an impedance of input, output or input/output of active element. An envelope DC current detected from RF signal is applied to variable impedance for radio frequency in an impedance matching circuit. Therefore, the variable impedance resulting from varying a signal level of a power amplifier corrects the variation of input or output impedance of active element by matching with the mated input, output or input/output. As a result, the gain and stability of amplifier is improved. A mobile communication terminal device is possibly adopting the same.