| 摘要 |
PURPOSE: A method for improving a gain of an envelope tracking amplifier is provided to elongate a life time of a battery by improving a gain of an amplifier by an impedance matching effect using a non linear semiconductor device. CONSTITUTION: In a method for improving a gain of an envelope tracking amplifier, a bias voltage is varied according to a power level of a power amplifier by a DC-DC converter. At an input terminal of the power amplifier is connected a directional coupler(1) so as to receive a weak radio frequency signal. An envelope detector(2) receives an output signal of the direction coupler(1), and converts the received signal into a direct current signal in proportion to the amplitude of the received signal. A non linear semiconductor device(5) is reverse-biased by the direct current signal transferred through a lambda/4 transfer line(4). At an end part of the transfer line(4) is connected a capacitor for a bypass in order to interrupt a flow of a radio frequency signal taken at a bias line of the non linear semiconductor device(5). |
