TY - GEN
T1 - Improvement of insertion loss of band pass tunable filter using SAW resonators and GaAs diode variable capacitors
AU - Kadota, Michio
AU - Esashi, Masayoshi
AU - Tanaka, Shuji
AU - Ida, Yasuyuki
AU - Kimura, Tetsuya
PY - 2013
Y1 - 2013
N2 - Tunable filters with a wide band tunable range are required for mobile phones with multi-bands and cognitive radio systems to simplify their circuits. Previously, the authors prototyped a band pass tunable filter, which continuously changes frequency from 1734 to 1844 MHz (6.1%) using surface acoustic wave (SAW) resonators and Si diode variable capacitors (varicap). However, the insertion loss was large compared with calculated one because the Q factor of the Si diode varicap was as low as 1 at 1.8 GHz. In this study, the authors improved the insertion loss of the tunable filter using GaAs varicaps. Compared with the Si varicap, the GaAs varicap has a higher Q factor of about 41 at 1.8 GHz. The authors fabricated a tunable filter composed of two SAW resonators and the GaAs varicaps instead of the Si varicaps on a printed circuit board (PCB). As a result, the insertion loss was drastically improved by 12 dB at the maximum, and the frequency characteristic approached the calculated one. The tunable range was also improved from 6.1% to 6.8%.
AB - Tunable filters with a wide band tunable range are required for mobile phones with multi-bands and cognitive radio systems to simplify their circuits. Previously, the authors prototyped a band pass tunable filter, which continuously changes frequency from 1734 to 1844 MHz (6.1%) using surface acoustic wave (SAW) resonators and Si diode variable capacitors (varicap). However, the insertion loss was large compared with calculated one because the Q factor of the Si diode varicap was as low as 1 at 1.8 GHz. In this study, the authors improved the insertion loss of the tunable filter using GaAs varicaps. Compared with the Si varicap, the GaAs varicap has a higher Q factor of about 41 at 1.8 GHz. The authors fabricated a tunable filter composed of two SAW resonators and the GaAs varicaps instead of the Si varicaps on a printed circuit board (PCB). As a result, the insertion loss was drastically improved by 12 dB at the maximum, and the frequency characteristic approached the calculated one. The tunable range was also improved from 6.1% to 6.8%.
KW - Band pass tunable filter
KW - GaAs diode variable capacitor
KW - Insertion loss
KW - SAW
UR - http://www.scopus.com/inward/record.url?scp=84894305821&partnerID=8YFLogxK
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U2 - 10.1109/ULTSYM.2013.0425
DO - 10.1109/ULTSYM.2013.0425
M3 - Conference contribution
AN - SCOPUS:84894305821
SN - 9781467356862
T3 - IEEE International Ultrasonics Symposium, IUS
SP - 1668
EP - 1671
BT - 2013 IEEE International Ultrasonics Symposium, IUS 2013
T2 - 2013 IEEE International Ultrasonics Symposium, IUS 2013
Y2 - 21 July 2013 through 25 July 2013
ER -