Patent ID: 7672648
Filing Date: 2010-03-02
Classification: H03C,H03F,H03G,H04B

Abstract:
1. Apparatus for linear amplitude modulation of a multi-stage amplifier, the apparatus comprising: a processing circuit that receives an amplitude modulation signal and a transmit control signal and produces at a first output a first amplifier control signal to control a first stage of the multi-stage amplifier and at a second output a second amplifier control signal to control a second stage of the multi-stage amplifier; a detector circuit coupled to the output of the multi-stage amplifier to generate, at an output, a signal representing the output of the multi-stage amplifier; a summing circuit having a first input coupled to the second output of the processing circuit to receive the second amplifier control signal and a second input coupled to the output of the detector circuit; and a network coupled to an output of the summing circuit to controls a bias or a gain signal of the multi-stage amplifier to linearize the amplifier's amplitude control.