Patent ID: 6677821
Filing Date: 2004-01-13
Classification: H03F

Abstract:
A distortion compensating device for performing predistortion on power amplifying means whose distortion is to be compensated, comprising:envelope detecting means to which a high-frequency signal generating an envelope change is supplied for detecting an envelope of said high-frequency signal and producing an envelope signal; amplitude correction memory means for storing an inverted distortion amplitude value of a distortion generated in said power amplifying means with digital data obtained by digitalizing said envelope signal from said envelope detecting means as an address; gain variable means disposed in a prestage of said power amplifying means to which said high-frequency signal generating said envelope change is supplied for controlling a passage gain of said high-frequency signal passed therethrough, wherein said inverted distortion data of said amplitude correction memory means are converted to analog data and supplied to said gain variable means so as to compensate for amplitude distortion of said power amplifying means; phase correction memory means located in parallel with said amplitude correction memory means and that stores an inverted distortion phase value of distortion to be generated in said power amplifying means, with digital data obtained by digitalizing said envelope signal from said envelope detecting means as an address; and phase-shifting means that controls a passage phase of said high frequency signal by supplying analog data that said inverted distortion data of said phase correction memory means are converted into analog data, wherein said phase-shifting means is connected with said gain variable means in series at said prestage of said power amplifying means, wherein delay means for adjusting a difference of delay time between a main path having said power amplifying means and said gain variable means and a corrective control signal route having said envelope detecting means for supplying a control signal to said gain variable means and said amplitude correction memory means is provided in said main path, and wherein by detecting an envelope signal from an output stage of said power amplifying means and feeding back a differential signal obtained by comparing said detected signal with an envelope signal output from said envelope detecting means to said delay means said delay time is controlled.