A fast adaptive technique for impedance matching networks

Doss, M. M.

doi:10.1109/melcon.1996.551610

Cited by 3 publications

(2 citation statements)

References 7 publications

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“…reflected power or VSWR. These are mainly gradient descent like methods [13]- [15] or trial&error methods [16] [17]. The disadvantage of exact computation of the state of the adaptive matching network is that the antenna impedance must be measured exactly, which usually involves voltage and current measurements at RF-frequencies.…”

Section: Automatic Antenna Tunersmentioning

confidence: 99%

An Automatic Antenna Tuning System Using Only RF Signal Amplitudes

Firrao

Annema

Nauta

2008

IEEE Trans. Circuits Syst. II

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Abstract-The operating environment of mobile phones fluctuates continuously, due to changing handling conditions and nearby objects. The resulting fluctuations in antenna impedance cause both a decrease in link quality and a higher standing wave ratio, that requires more robust and hence less efficient PA implementations. In this paper an automatic antenna tuner system for handheld applications is presented that uses two series reactances combined with 3 simple RF-peak detectors to sense both reactive and real impedance mismatches. The control loop only requires low-frequency electronics which makes it low cost, low power and relatively easy to integrate. Measurements on a demonstrator system show correct behaviour for VSWR up to 10.Index Terms-Impedance matching, antenna tuning, high efficiency power amplifiers, wireless communication systems.

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Section: Automatic Antenna Tunersmentioning

confidence: 99%

An Automatic Antenna Tuning System Using Only RF Signal Amplitudes

Firrao

Annema

Nauta

2008

IEEE Trans. Circuits Syst. II

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“…Automatic antenna tuners are used to match an antenna impedance to an impedance close to the nominal impedance, which is typically 50 . An antenna tuner [6]- [25] is generally implemented through a system consisting of impedance sensing circuitry, a tunable matching network and a control loop that implements the tuning procedure [26]- [30] of the matching network. The tunable matching network can be a continuous tunable matching network or a switchable matching network; typically a switchable matching network is used [6]- [25].…”

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confidence: 99%

Hardware Implementation Overhead of Switchable Matching Networks

Firrao

Annema

Vliet

et al. 2017

IEEE Trans. Circuits Syst. I

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Nowadays, more and more RF systems include switchable matching networks to decrease the impact of the environment-dependent antenna impedance on the RF front end performance. This paper reviews the theoretical lower limit on the required number of matching states to match VSWR ranges and then presents an analysis of hardware implementations to actually implement a suitable switchable matching network. A number of matching network topologies are analyzed: PI networks, loaded transmission lines, branch line coupler based circuits, single circulators and cascaded circulators. In our investigation only narrow-band applications are targeted. For the various circuit implementations the required number of matching states for each hardware implementation is compared to the theoretical minimum number of states required for the same matching in order to benchmark their hardware implementation overhead. It appears that a matching network using cascaded circulators is the closest to the theoretical optimum for networks with a relatively low number of states: this type of matching network was implemented and analyzed in more detail.

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