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Removing the effects of baseband impedance on distortion in FET amplifiers

Research output: Contribution to journalArticle

Original languageEnglish
Article numberIssue 5
Pages (from-to)401 - 406
Number of pages6
JournalIEE Proceedings Microwaves, Antennas & Propagation
Journal issue5
StatePublished - Oct 2006


The baseband drain node impedance of FETs has previously been found to influence the distortion produced by amplifiers employing such devices. For a two tone test, variations in this impedance lead to variations in the magnitude and phase of the intermodulation distortion products. This results in distortion characteristics which vary with tone separation, and consequently limits the performance of many linearisation schemes. A scheme capable of removing the dependency of intermodulation distortion on baseband drain node impedance is presented, and operates over a bandwidth of 30 MHz. Practical tests conducted on a real amplifier subjected to a two tone input signal show that the scheme can suppress phase asymmetry variations of up to 70deg

Additional information

Publisher: Institution of Electrical Engineers (IEE) Rose publication type: Journal article Sponsorship: The authors wish to acknowledge the Engineering Physical Sciences Research Council (EPSRC) and Milmega Ltd for their financial support. The first author would like to thank Milmega Ltd for their suggestions, comments and donating the transistors used in this work.

    Research areas

  • FET amplifiers, baseband impedance

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