Low-Loss Device Using Multistrip Coupler Ring Configuration with Ripple Cancellation

Although there are now many different methods of attaining low-loss operation in SAW devices, each method has its own advantages and disadvantages. The ring configuration with multistrip couplers has the important advantages of (1) single-level fabrication, (2) simple external matching circuitry and (3) ability to use conventional design techniques for bidirectional transducers. In addition a new technique is shown for cancelling the triple-transit susceptibility inherent to the ring configuration. Experiment results are shown for a wideband device with a low shape factor, high rejection and with a loss of less than 7 dB and for a narrow band device with a loss of less than 4 dB, with both devices showing little or no reflection ripple.

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