A New Tapping Design for Low-Distortion SAW Tapped Delay Lines

Jiro TEMMYO  Takahiro INAMURA  Isamu KOTAKA  Shokichiro YOSHIKAWA  

IEICE TRANSACTIONS (1976-1990)   Vol.E62   No.11   pp.775-778
Publication Date: 1979/11/25
Online ISSN: 
Print ISSN: 0000-0000
Type of Manuscript: PAPER
Category: Other Devices

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Frequency characteristics of SAW tapped delay lines (TDL's) with equal tap spacing and in-line array are investigated. It is found that reflected SAW echo signals in SAW TLD's cause pulse-like ripples and sharp stopband distortions periodically in the frequency passbands. Tapping design techniques are proposed to remove spurious interference distortion influences on SAW TDL frequency responses. Their applicability is confirmed experimentally. Typical features of a SAW TDL with 101 taps at a 20 MHz bit rate employing 128 rotated Y-cut and X-propagation LiNbO3 substrate are as follows: center frequency is 55.4 MHz, frequency bandwidth is 10 MHz, insertion losses are 3239 dB, and ripples in the passband are about 4 dB.