Title :
An unbalanced/balanced MCF for cellular phone
Author :
Sakurai, Toshinobu ; Soeda, Akihiro ; Saitoh, Tetsuo ; Ishii, Osamu
Author_Institution :
TOYOCOM, Kanagawa, Japan
fDate :
6/23/1905 12:00:00 AM
Abstract :
In a monolithic crystal filter (MCF) which has an unbalanced-input and a balanced-output, the attenuation on the lower side has poor repeatability caused by the variation of capacitance between each electrode. We examined an unbalanced/balanced MCF that has good and repeatable attenuation characteristics. We obtained more than 90 dB at fo-900 kHz for a 2-pole MCF (center frequency is 109.65 MHz, 3rd overtone, terminating impedance is 800 ohm//-0.3 pF). We also examined an unbalanced/balanced 3-pole MCF which has good characteristics. This is because the capacitance between each electrode is close to zero due to the shield effect of the center electrodes
Keywords :
UHF filters; VHF filters; capacitance; cellular radio; crystal filters; passive filters; radiofrequency filters; telephone sets; 109.65 MHz; 3-pole filter; 900 kHz; RF filter; balanced-output; capacitance; cellular phone; center electrode shield effect; monolithic crystal filter; repeatable attenuation characteristics; unbalanced-input; unbalanced/balanced MCF; Attenuation; Capacitance; Cellular phones; Ceramics; Electrodes; Filters; Frequency; Impedance; Monolithic integrated circuits; Packaging;
Conference_Titel :
Frequency Control Symposium and PDA Exhibition, 2001. Proceedings of the 2001 IEEE International
Conference_Location :
Seattle, WA
Print_ISBN :
0-7803-7028-7
DOI :
10.1109/FREQ.2001.956342
