| 摘要 |
PURPOSE: An envelope tracking amplifier having improved efficiency is provided to comprise a circuit for compensating an impedance change generated by a power level and an operation point of a power amplifier. Therefore, entire efficiency caused by an impedance matching effect using an impedance tuner, accompanied by an SHF(Super High Frequency) adjustable inductance element or an actuator is increased. CONSTITUTION: Directional couplers extract RF input or output signals. Envelope detectors detect envelope signals from the extracted input or the output signals. At least one SHF(Super High Frequency) adjustable inductance elements are coupled with the output signals of the envelope detectors. At least one impedance compensating circuits are connected to an input side or an output side of an active element, or input/output sides. Even though a signal level of an RF signal or an operation point of an amplifier is changed, or both of the signal level and the operation point are changed, the active element receives compensated inputs or output impedances to perform an input matching or an output matching, or input/output matching. |
