Hideo Ohnuki

Computer aided design of low-loss SAW filters employing IIDT for high performance mobile radio duplexer

The authors describe a computer-aided design method to optimize all the design parameters of the IIDT (interdigitated interdigital transducer)-type SAW (surface acoustic wave) filter so that it satisfies the required frequency and electrical characteristics. By connecting the admittance matrices of each IDT, each SAW propagation path, and each IIDT-track, a dual IIDT-track configuration is represented by a six-port admittance matrix in an equivalent circuit model. A merit function, which is defined as the sum of squared of deviations from the target specifications, is introduced to evaluate filter characteristics. By iterating calculations of the equivalent circuit model, the design parameters are determined so as to minimize the merit function. A high-performance filter which satisfies the requirement is thus achieved. Some design examples are given, and they are verified by experimental results.<<ETX>>

Three-Dimensional Actuator For Optical Head

This paper describes the design and characteristics of a three dimensional actuator for an optical readout head. In order to obtain enough servo gain, it is necessary to reduce the size and weight of the moving parts. Instead of the conventional galvano mirror, this actuator drives the objective lens, which is suspended in the collimated laser beam, towards three directions, vertical, radial and tangential, without tilting. The major advantages of this unique three dimensional actuator lie in reducing a cost of the objective lens and the number of the adjusting points.

Design of High-Frequency and Low-Loss SAW Filter Employing Multiple IDTs

This paper describes an accurate design method for the multi-IDTs type of SAW filters by equivalent circuit model analysis. Distances between IDTs are important design parameters to take account of mutual influence among all IDTs, especially in case of using single electrode transducers. Then, three-port admittance matrices of IDTs and two-port ones of SAW propagation paths are connected to compose a four-port admittance matrix. Iterative calculations of a four-port model are performed to determine numerous design parameters. Experimental results are in good agreement with calculation results. The experimental rejection level, however, is a little smaller than the calculated one because of electro-magnetic feed-through. Besides, the insertion loss is larger than the calculation in amount of two or three decibels.