Acoustic surface wave filter for band pass filters and oscillators, has odd number of individual filters containing three series transducers arranged with defined separation relationship

摘要

The filter has several parallel individual filters (2-4) on a piezoelectric substrate (1). These have interdigital transducers (21-23;31-33;41-43), for sending and receiving acoustic surface waves, and reflection grids (24,25,34,35,44,45). All transmitting or receiving transducers are identical and connected in parallel to form a transducer group (6,7). Each individual filter contains three transducers in series and the filters are arranged with a defined separation relationship. The outer transducer groups are connected in parallel. There are an odd number of individual filters.