of am am characteristics fig6 by dynamically adjusting vds is preferably combined with a corresponding correction of am pm response which is also a function of input power pin as shown in fig5 as shown in fig5 the output stage amplifier exhibits a typical nonlinear response of phase vs instantaneous input envelope rf voltage for constant rf power amplifier gain e g set at 12 db the present invention allows for phase correction by providing control signal 18 c to the phase shifting circuit 18 fig1 as a function of the detected input envelope signal this dynamic phase correction is exemplified in fig7 now referring to fig7 a graphical representation 190 of the am pm response for phase vs input power pin for both a fixed drain supply voltage and a variable supply voltage are shown the regions of input power pin 105 110 and 115 are also shown as in fig6 the bottom curves show the voltage supply curves as a function of pin as in fig6 the present invention compensates for am pm nonlinear dynamic behavior introduced by the variable drain supply voltage by adjusting input phase shifter 18 with control signal 18 c provided by predistorter 27 fig1 so as to compensate for insertion phase introduced by the constant gain linearization method of operation using variable drain supply voltage described above the phase curve 160 corresponds to a fixed supply voltage and curves 175 and 180 show the phase adjustment provided by the predistorter 27 and phase shifter 18 for the variable power supply constant gain linearization method of the present invention as may be seen the phase is constant in the lower input signal power region 105 and then the phase is adjusted continuously beginning in the transition region 110 and.