CARRIER MODULATOR FOR USE IN A TRANSMITTER OR TRANSCEIVER

摘要

A transmitter has a quadrature modulator that provides a modulated signal at a first frequency. The transmitter has a phase locked loop of which a voltage controlled oscillator is coupled between a phase comparator of the phase locked loop and further has a transmit power amplifier in a transmit signal path of the transmitter. The phase locked loop further has a down-converter in a feedback path from an output of the transmit power amplifier and a feedback input of the phase comparator. The transmitter further has an amplitude restoration arrangement that restores amplitude information contained in a feedback signal provided by the down-converter and in the quadrature modulated signal. In operation, the phase locked loop replicates at a carrier frequency angle information contained in the quadrature modulated signal, and the amplitude restoration arrangement controls the gain of the transmit power amplifier such that input signals at the phase comparator substantially are equal.