SURFACE ACOUSTIC WAVE DEVICE, COMMUNICATION SYSTEM AND COMMUNICATION EQUIPMENT

摘要

PURPOSE:To improve the performance of the matched filter type surface acoustic wave (SAW) device and to improve the performance of the code spread spectrum communication equipment. CONSTITUTION:The modulation of a spread code is turned to phase modulation excepting for 0 deg. and 180 deg., and the positions of interdigital electrodes 2 and 3 at the SAW device are shifted corresponding to the modulation. The opening direction of an unwanted cross part is made different from a main propagation axis. Structure not to generate unwanted cross is provided. The electric/ mechanical coupling coefficient of the inter-digital electrode part with less electrode logarithm between the input and output interdigital electrodes 2 and 3 is enlarged in comparison with the opposite side interdigital electrode part. The interdigital electrode part of the larger electrode logarithm is divided into tracks vertically to the propagating direction of surface acoustic waves, and the respective divided interdigital electrode groups are respectively, electrically and serially connected. The respective crossing parts of the interdigital electrode parts are respectively electrically and serially connected.