SAW filters with three bidirectional transducers
Abstract
Suppression of the triple-transit signal is considered in surface acoustic wave (SAW) filters with two bidirectional input transducers arranged asymmetrically about a central output transducer with capacitively weighted electrodes. Filter specimens with the following characteristics were fabricated: central frequency 50 MHz; passband 10 percent; signal suppression greater than 35 dB outside the passband; insertion losses 4.5-6.0 dB for a 1.5-2.0-dB ripple; triple-pass signal suppression by 10-12 dB, which is greater than in filters designed from two bidirectional transducers. Experiments revealed that the delay time can be decreased to about 1/delta(f), where delta(f) is the width of the filter passband, by using filters with three identical transducers and capacitively weighted electrodes. Lithium niobate filters with transducers spaced apart by approximately 100 microns (one-half the SAW wavelength) were fabricated to suppress electromagnetic pickup signals by more than 60 dB over a wide frequency band.
- Publication:
-
Zhurnal Tekhnicheskoi Fiziki
- Pub Date:
- August 1984
- Bibcode:
- 1984ZhTFi..54.1584G
- Keywords:
-
- Bandpass Filters;
- Signal Processing;
- Surface Acoustic Wave Devices;
- Transducers;
- Electric Potential;
- Electrodes;
- Insertion Loss;
- Time Lag;
- Electronics and Electrical Engineering