Adaptive Impedance-Matching Techniques for Controlling L Networks

A. Bezooijen, van, M.A. de Jongh, F.E. van Straten, R. Mahmoudi, A.H.M. Roermund, van

Research output: Contribution to journalArticleAcademicpeer-review

69 Citations (SciVal)


The link quality of mobile phones suffers from antenna mismatch due to fluctuating body effects. Techniques for adaptive control of impedance-matching L networks are presented, which provide automatic compensation of antenna mismatch. To secure reliable convergence, a cascade of two control loops is proposed for independent control of the real and imaginary parts of impedance. A secondary feedback path is used to enforce operation into a stable region when needed. These techniques exploit the basic properties of tunable series and parallel LC networks. A generic quadrature detector that offers a power-independent orthogonal reading of the complex impedance value is presented, which is used for direct control of variable capacitors. This approach renders calibration and elaborate software computation superfluous and allows for autonomous operation of adaptive antenna-matching modules.
Original languageEnglish
Pages (from-to)495-505
Number of pages11
JournalIEEE Transactions on Circuits and Systems. I, Fundamental Theory and Applications
Issue number2
Publication statusPublished - 2010


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