Double-resonance SAW filters.
IEEE Trans Ultrason Ferroelectr Freq Control
; 54(3): 659-67, 2007 Mar.
Article
en En
| MEDLINE
| ID: mdl-17375835
A novel surface acoustic wave filter on a leaky-wave substrate is studied. It features a hiccup-type resonance occurring around a distributed gap between two long interdigital transducers. Compared to a classical coupled resonator filter, it enables a relatively narrow passband (1% to 2% of center frequency) with low insertion loss, steep skirts, and improved suppression levels. The structure consists of long transducers having the number of fingers greater than 1/K2 and 1/kappa where K2 is the coupling coefficient of the substrate material and kappa is the reflectivity per wavelength, separated with short transducer sections constituting a distributed gap. A strong, localized resonance is formed in the gap region, in addition to the resonance arising in the long structures-hence, the name double-resonance filter. The substrate studied here is 42 degrees-rotated lithium tantalite. We show experimental results for both single-ended and unbalanced-to-balanced filters at 1.6 GHz, having a minimum insertion loss of 1.07 dB, suppressions of 30 dB, and absolute -3-dB bandwidth of 29 MHz (1.9% of the center frequency). For the balanced device, the amplitude imbalance over the passband ranges from -0.6 dB to 2 dB and the phase imbalance from 1 degrees to 4.5 degrees. Furthermore, we have measured the acoustical power distributions using a scanning laser interferometer, and we compare these results with the profiles simulated using a coupling-of-modes model.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Transductores
/
Acústica
/
Procesamiento de Señales Asistido por Computador
Idioma:
En
Revista:
IEEE Trans Ultrason Ferroelectr Freq Control
Asunto de la revista:
MEDICINA NUCLEAR
Año:
2007
Tipo del documento:
Article
País de afiliación:
Finlandia
Pais de publicación:
Estados Unidos