Patent ID: 8457567
Filing Date: 2013-06-04
Classification: H03C,H03F

Abstract:
1. An apparatus for controlling a modulation signal for use in modulating a power supply of a power amplifier, comprising: a power controller configured to generate an indication of a desired mean output power of the power amplifier, the indication comprising a coarse control signal providing a relatively coarse indication and a fine control signal providing a relatively fine indication; a coarse amplitude controller configured to provide relatively coarse control of an amplitude of the modulation signal in response to the coarse control signal; and a fine amplitude controller configured to provide relatively fine control of the amplitude of the modulation signal in response to the fine control signal, wherein the modulation signal is provided as a digital modulation signal, and the apparatus comprises a digital-to-analog converter for converting the digital modulation signal to an analog modulation signal; wherein the digital-to-analog converter is adapted to provide the relatively fine control of the amplitude of the analog modulation signal in response to the fine control signal; and wherein the coarse amplitude controller comprises a variable gain amplifier coupled to an output of the digital-to-analog converter and having a gain responsive to the coarse control signal.