DocumentCode :
845292
Title :
An adaptive impedance tuning CMOS circuit for ISM 2.4-GHz band
Author :
Sjoblom, Peter ; Sjöland, Henrik
Author_Institution :
Lund Univ., Sweden
Volume :
52
Issue :
6
fYear :
2005
fDate :
6/1/2005 12:00:00 AM
Firstpage :
1115
Lastpage :
1124
Abstract :
The difficulties encountered in matching an antenna to its optimal impedance are reduced with an adaptive 0.35-μm 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 Ω→50 Ω transformation, a break-even point at VSWR=1.5, and a 3-dB increase in delivered power for VSWR= 4.3.
Keywords :
CMOS integrated circuits; UHF integrated circuits; antennas; circuit tuning; impedance matching; inductors; switched capacitor networks; 0.35 micron; 1 dB; 2.4 GHz; CMOS circuit; ISM band; LTCC substrate; antenna tuning unit; capacitor banks; circuit simulations; impedance matching; impedance tuning unit; low-temperature cofired ceramic; reconfigurable matching; series inductors; switched capacitor; switched shunt capacitors; Adaptive arrays; Ceramics; Circuit optimization; Circuit simulation; Frequency; Impedance; Inductors; Shunt (electrical); Switched capacitor circuits; Switching circuits; Antenna tuning unit (ATU); CMOS; ISM; capacitor bank; impedance matching; impedance tuning unit (ITU); reconfigurable matching; switched capacitor;
fLanguage :
English
Journal_Title :
Circuits and Systems I: Regular Papers, IEEE Transactions on
Publisher :
ieee
ISSN :
1549-8328
Type :
jour
DOI :
10.1109/TCSI.2005.849116
Filename :
1440634
Link To Document :
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