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Prediction and reduction of third-order IMD in multichannel amplifiers

Sheridan, Paul (1999) Prediction and reduction of third-order IMD in multichannel amplifiers. Master of Engineering thesis, Dublin City University.

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.
Item Type:Thesis (Master of Engineering)
Date of Award:1999
Supervisor(s):Perry, Philip
Uncontrolled Keywords:Power amplifiers; Multichannel amplifer (MCA); Third order intermodulation distortion (IM3)
Subjects:Engineering > Electronic engineering
DCU Faculties and Centres:DCU Faculties and Schools > Faculty of Engineering and Computing > School of Electronic Engineering
Use License:This item is licensed under a Creative Commons Attribution-NonCommercial-No Derivative Works 3.0 License. View License
ID Code:19420
Deposited On:02 Oct 2013 10:58 by Celine Campbell . Last Modified 02 Oct 2013 10:58

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