Low-Loss GHz Range SAW Filter Using Group-Type Unidirectional Transducer ---New GUDT and New Phase Shifter---

Abstract

High performance filters in GHz range are required in communication systems. The Group-Type Unidirectional Transducer (GUDT) has an inherent property of having the low l o s s and passband ripple, which is advantageous in the design of filters. SAW filters on 128' rotated Y-cut LiNbO3 have been built at cetner frequencies between 1-3 GHz. The filters are analysed by using the equivalent circuit model including the phase shifter. The fine electrodes of the order of 0.2,um width have been fabricated using electron beam lithography, normal lift-off techniques and 02-plasma cleaning system. The insertion loss and the passband ripples are considerably less than the earlier reported ones. Experimental results of weighted transducer filters are also presented.A new Group-Type of Unidirectional Interdigital Transducer (New GUDT) and a new type of phase shifter employing the inter-layer thin film capacitance of the feeding electrode strips as one of its essential elements are reported in this paper.

Selective polarization of ferroelectrics in functional electronics

“…The acoustoelectronic devices on surface acoustic waves (SAW), for example, having evident advantages as compared to devices based on other physical principles, sometimes are inferior due to relatively large magnitude of inherent signal losses. This problem is often solved using complicated design of interdigital transformers (IDT) or by introduction of supplementary radio devices [4,5]. In the first case, the one-directional IDT, multiple-strip couplers, in the second case, the phase-shifters are used.…”