ENVELOPE TRACKING APPARATUS AND METHOD FOR RF POWER AMPLIFIER

摘要

PURPOSE: An envelope tracking device and a method thereof are provided to resolve a linearity reduction problem of a radio frequency power amplifier due to envelope tracking by supplying drain voltage with an optimum condition. CONSTITUTION: An envelope tracking device includes a first envelope detector, a control unit(420), a multiple voltage supply unit(430) and a harmonics elimination unit(450). The first envelope detector detects a first envelope signal with respect to an RF input signal input to a main amplifier of the RF power amplifier. A control unit generates a first control signal based on the detected first envelope signal. The first control signal has the maximum amplitude corresponding to each vertex from the predetermined reference level of the time-variant first envelope signal and corresponds to a square wave signal having a pulse width corresponding to the time between the start time of rise greater than the reference level and the start time of fall smaller than the reference level with respect to each vertex. The multiple voltage supply unit generates multiple voltage corresponding to the square wave signal based on the first control signal and supplies to the main amplifier. The harmonics elimination unit eliminates harmonics of the multiple voltage. [Reference numerals] (330) Delay circuit; (340) Amplifier; (400,460) AGC and envelope detector; (420) Control unit(digital signal processor); (430) Multi-voltage selector; (440) Multi-voltage programmable SMPS; (450) Variable inductance LPF; (480,490) Smoothing circuit and ADC;