this invention relates to high power linear amplifiers . a high power linear amplifier is disclosed for communications such as cdma communication systems . in accordance with the invention , there is provided a power amplifier comprising a power amplifier , a feedback circuit and a control element ; wherein the architecture proposed uses an envelope detector to generate a baseband signal representing the amplitude envelope of the system input rf signal . this is digitised and used to generate phase and gain correction signals . the correction signals modulate the input signal to create a pre - distorted signal : which is applied to the power amplifier for amplification . the pre - distortion is such as to cancel the am - am and am - pm distortion of the power amplifier thus resulting in an amplified output of improved spectral purity . in order to achieve the very high levels of spectral purity required by 3g cellular and multi - carrier 2g cellular systems , the correction coefficients in the lookup table need to be very precisely set . the method proposed incorporates an adaptation system whereby the pre - distorter can ‘ learn ’ the contents of the lookup table as it operates .