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An adaptive impedance tuning CMOS circuit for ISM 2.4-GHz band

Publiceringsår: 2005
Språk: Engelska
Sidor: 1115-1124
Publikation/Tidskrift/Serie: IEEE Transactions on Circuits and Systems Part 1: Fundamental Theory and Applications
Volym: 52
Nummer: 6
Dokumenttyp: Artikel i tidskrift
Förlag: IEEE--Institute of Electrical and Electronics Engineers Inc.


The difficulties encountered in matching an antenna to its optimal impedance are reduced with an adaptive 0.35-mu m CMOS circuit based on several switched shunt capacitors arranged in capacitor banks and on a few external series inductors. As high-quality inductors are difficult to obtain in CMOS, the inductors are placed either in an low-temperature cofired ceramic (LTCC) substrate or is a lumped component outside the core circuit. The circuits, presented here through a range of simulations, are optimized to function within the ISM 2.4-GHz band, but the general approach employed to improve matching can be used for other frequency bands as well. The circuits discussed provide a VSWR <= 2 match for every impedance with VSWR <= 5. There is a 1-dB power loss for a perfect 50 Omega -> 50 Omega transformation, a break-even point at VSWR = 1.5, and a 3-dB increase in delivered power for VSWR = 4.3.


  • Electrical Engineering, Electronic Engineering, Information Engineering
  • CMOS
  • antenna tuning unit (ATU)
  • impedance matching
  • impedance tuning
  • reconfigurable matching
  • unit (ITU)
  • ISM
  • capacitor
  • bank
  • switched capacitor


  • ISSN: 1057-7122

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