| 摘要 |
<p>A two-pole monolithic crystal filter (200) includes grounded strip electrodes (203, 213) between input (201, 211) and output (205, 215) electrodes. The grounded strip electrodes (203, 213) have a higher resonating frequency than the input (201, 211) and output (205, 215) electrodes and also provide increased acoustical coupling and lower inter-electrode capacitance (702) between the input (201, 211) and output (205, 215) electrodes, while having little or no effect on the midband electrical characteristics of the filter. Because of the increased coupling, the input (201, 211) and output (205, 215) electrodes can be spaced further apart than heretofore possible in prior monolithic crystal filters. Moreover, further increases in the acoustical coupling can be achieved by arranging a plurality of strip electrodes (402, 412; 403, 413; and 404, 414) between the input (401, 411) and output (404, 414) electrodes. The inventive monolithic crystal filter (806) can be advantageously utilized for filtering the IF signal developed in the IF portion (804) of an FM radio receiver (800). </p> |
