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ElectroComponent Science and Technology
Volume 8 (1981), Issue 1-2, Pages 53-59

Integrated Monolithic Crystal Filter for Citizen Band Transceivers

Fujitsu Limited, 1015 Kamikodanaka, Nakahara-ku, Kawasaki 211, Japan

Copyright © 1981 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


This paper will describe a SSB 10.7 MHz IF filter for CB band transceivers employing an integrated capacitor circuit and four dual mode Monolithic Crystal Filters (MCFs) of AT cut Quartz. With a narrow bandwidth of 2 × 10−4, an insertion loss of less than 5 dB, and a low temperature coefficient of the center frequency of within ± 20 ppm over the range of − 35 to + 65℃, this filter also meets mechanical shock-resistance requirements. The integrated capacitor circuit consists of thin film Ta2O5 capacitors and interdigital gap capacitors formed on both sides of a Fine Grain Alumina (FGA) substrate. Four MCFs are directly soldered to the substrate of the integrated capacitor circuit, allowing this filter to be made smaller and lighter and have better resistance to mechanical shock. Also important, the manufacturing process is suitable for mass production.