| 摘要 |
PURPOSE:To obtain a filter with comb line characteristics over a broad frequency range, by equipping a comb line filter making use of elastic surface waves on a piezoelectric substrate with two output converters different in distance until an input converter. CONSTITUTION:By converters 13, 16, 19, and 22, electric signals supplied between input terminals 11 and 11' are converted into elastic surface waves and by converters 14, 15, 17, 18, 20, 21, 23, and 24, elastic surface waves are converted into electric signals and outputted to terminals 12 and 12'. Onto piezoelectric substrate 10, shield pattern 25 is provided which shields electrically between the input and output sides. The interval between two output converters is so set that the reciprocal number of the difference of the delay time of an electric signal extracted from the output converter will be an interchannel frequency in a television channel band. Four gropus of input and output converters constitute comb line filters of 1 to 3, 4 to 12, 13 to 37, and 38 to 62 channel bands of television. Consequently, a comb-line-characteristic filter can be obtained over a broad frequency range. |
