A c o u s t i c c o u p l i n g o c c u r s when two surface acoust i c wave (SAW) r e s o n a t o r s a r e a r r a n g e d i n a close, p a r a l l e l c o n f i g u r a t i o n on a s i n g l e q u a r t z p l a t e , r es u l t i n g i n two d i s t i n c t r e s o n a n c e modes. T h i s t y p e o f SAW r e s o n a t o r has been analyzed using a waveguide model t o d e s c r i b e t h e c l o s e , p a r a l l e l c o n f i g u r a t i o n and experiments were performed.The d i f f e r e n c e i n frequency between these two resonance modes was found t o depend p r i m a r i l y on t h e e l e c t r o d e o v e r l a p w i d t h i n t h e i n t e r d i g i t a l t r a n s d u c e r ( I D T ) o f t h e two resonators and on the space between the resonators. Experiments were made on 2-pole and 4-pole narrow bandpass f i l t e r s c o n s t r u c t e d u s i n g d o u b l emode SAW resonators. The c h a r a c t e r i s t i c s o f t h e 4-p o l e f i l t e r i n c l u d e a c e n t e r f r e q u e n c y o f 280MHz, a 3d6 b a n d w i d t h o f 220kH2, a minimum i n s e r t i o n l o s s o f 1.6dB, and an o u t -o f -b a n d r e j e c t i o n o f 55dB. The spurious response was i n v e s t i g a t e d t h r o u g h s t u d y o f t h e e n e r g y t r a p p i n g modes. I n t r o d u c t i o n I n r e c e n t y e a r s , t r a n s v e r s a l SAW f i l t e r s have been w i d e l y u s e d i n t e l e c o m m u n i c a t i o n e q u i p m e n t f o r t h e VHF and UHF r a n g e . W h i l e t h e s e f i l t e r s have been s u i t a b l e f o r medium-and wide-band applications, t h e i r b i -d i r e c t i o n a l l o s s has g e n e r a l l y p r o h i b i t e d applications where narrow-band, low-loss f i l t e r c h a ra c t e r i s t i c s a r e r e q u i r e d . U n t i l r e c e n t l y VHF and UHF range receivers have employed a double conversion system with two intermed i a t e f r e q u e n c i e s --t h e f i r s t a t 21.4MHz o r 10.7MHz and t h e second a t 455kHz. The need t o reduce equipment s i z e and complexity, however, has necessitated a s i n g l e c o n v e r s i o n s y s t e m f o r d i r e c t c o n v e r s i o n f r o m t h e r e c e i v e r f r e q u e n c y t o 455kHz, which req u i r e s a f i l t e r w i t h b o t h n a r r o w b a n d w i d t h and low l o s s . Several types of narrow-band, resonator filt e r s i n t h i s f r e q u e n c y r a n g e h a v e a l r e a d y b e e n r e p o r t e d . 1 ~3 T h i s p a p e r d e s c r i b e s t h e a n a l y s i s and experiment of a double-mode SAW r e s o n a t o r f i l t e r u t i l i z i n g waveguide coupling.4 W i t h SAW r e s o n a t o r s , t h e p r o p a g a t i o n v e l o c i t y t h r o u g h t h e i n t e r d i g i t a l e l e c t r o d e s e c t i o n i s l o w e r t h a n t h a t o n e i t h e r s i d e . F o r t h e o r e t i c a l a n a l y s i s we employed the surface acoustic waveguide model.5' Depending on the waveguide width, there are displacement d i s t r i b u t i o n modes o f d i f f e r e n t f r e q u ...
In a C‐axis aligned crystal (CAAC) IGZO TFT, contact between a CAAC‐IGZO film and source and drain electrode was good. In this study, we recognized the existence of n‐type IGZO layer serving as contact layer by a novel experimental method where a depth profile of the sheet resistance.
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