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Construction Method for Ladder Filters Employing Piezoelectric Ceramic Resonators
IEICE TRANSACTIONS (1976-1990) Vol.E69 No.7 pp.788-796
Publication Date: 1986/07/20
Print ISSN: 0000-0000
Type of Manuscript: PAPER
Full Text: PDF(776.4KB)
The construction method for ladder filters employing piezoelectric ceramic resonators, widely used in consumer radio communication equipments, is investigated with the object of obtaining low-cost high-performance filters. For the presented method, the resonant or antiresonant frequencies of the resonators included in a filter are staggered one after another, perceiving that a small difference in these frequencies between electrically adjacent resonators can be tolerated. The allowable frequency limits for this filter are about four times as great as those for a usual filter, designed using the image parameter or near-image parameter method. The filter can exhibit performances equal to the usual filter. The frequency adjustment process for resonators is able to be fairly well curtailed. Filters based on this construction method include ceramic filters for CB transceiver and pocket-bell receiver, which were designed and trially produced. As a result, low-ripple filters with rough frequency adjustment at most were obtained.