The advent of the multichannel amplifer (MCA) has brought with it strigent intermodulation distortion (IMD) requirements. This thesis explores the issue of thirdorder intermodulation distortion (/M3) in M C A ’s from two seperate viewpoints. Firstly, the prediction of IM 3 levels in MCA’s is investigated and a novel software based prediction tool is presented. The amplifier is viewed as a black-box nonlinear circuit and is characterised by carrying out an IMD test using 3 tones of equal amplitude. Then, by using the Volterra-series approach and linear interpolation, an IM :i prediction can be made for an arbitrary number of input tones of different amplitudes. To demonstrate and verify the capability of this technique predicted and measured results are compared for single and cascaded stages. Secondly and finally, a novel amplifier configuration which reduces these IM 3 levels and simultaneously improves the overall efficiency of the M C A is presented. This approach uses a scaled version of the extracted envelope of the mult-tone signal to actively bias the amplifier. This technique is of paramount importance in multichannel power amplifier (MCPA) design where an increase in linearity is usually achieved by a decrease in efficiency. Practical results are presented which illustrate the effectiveness of this technique.