| 摘要 |
PURPOSE:To provide a characteristic compensating a group delay characteristic of an external circuit by shifting a main lobe from the center of a converter to a remote side to a normal IDT. CONSTITUTION:The pitch of a side lobe formed by the 10th-30th IDTs is slightly larger than the pitch of a main lobe formed by the 40th-80th IDTs. Since the position of input/output IDTs is decided so that the side lobe approaches from the main lobe to the output IDT, a signal near a chrominance carrier is advanced timewise than the signal near the center frequency of a filter. The frequency characteristic of the group delay time is an excellent flat characteristic of about 750+ or -50ns at the frequency band between a video carrier frequency fp and a chrominance signal carrier frequency fc+500kHz,and advanced sequentially as nearly 650ns at the fc and nearly 300ns at (fc-500kHz) in the frequency below fc+500Hz and the difference between values at the flat region and (fc-500kHz) is nearly 450ns.
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