Telefonaktiebolaget Lm Ericsson (publ)

Krister I Ripstrand

Peter M Petersson

Thorsten Nygren

A method and apparatus for controlling a feed-forward compensated power amplifier system is disclosed which uses a spread spectrum technique to cover a control signal or signals and injects a composite signal at a suitable point into the feed-forward amplifier system to reduce distortion. The amount of bandwidth spread is governed by the amount of processing gain needed in the remapping process and the needed time response of the system. Control signals after remapping of the spread spectrum at the output of the system are correlated in a match filter correlator and the result is used to control, in either polar or cartesian coordinates, the injection, in anti-phase, of the extracted distortion into the feed forward amplifier output.

Linear amplifier control

In a frequency synthesizer of the type having a phase locked loop, a variable frequency divider is coupled to the output of the phase locked loop and a variable divider for dividing a reference signal is coupled to a frequency source for the frequency synthesizer. The phase lock loop also includes a variable divider for dividing the signal fed back from a voltage controlled oscillator to a phase detector. The division numbers or divisors of the variable frequency dividers are controlled such that a predetermined relationship exists among the frequency dividers. The frequency synthesizer is capable of switching reference frequencies without causing phase jumps. The reference frequency is selected depending upon the choice of a division number for the frequency divider coupled to the output of the frequency synthesizer.

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Uppsala, Sweden

Krister I Ripstrand