Longitudinal double-mode saw filter utilizing electrode...

Details Longitudinal double-mode saw filter utilizing electrode... Longitudinal double-mode saw filter utilizing electrode...

2005-08-30

2005-08-30

Summons, Barbara (Department: 2817)

Wave transmission lines and networks

Coupling networks

Electromechanical filter

C310S31300R, C310S31300R, C333S196000

Reexamination Certificate

active

06937116

ABSTRACT:
The invention provides a longitudinal double-mode SAW filter that has a large reflection coefficient by the electrode conductors and having flat pass band characteristics. In the longitudinal double-mode SAW filter, nearly all of higher-order natural mode oscillation displacements A0,S1and A1are made present in the first and second interdigital transducer regions. An electrode finger phase weighting is formed to correspond to a BPSK sign where a phase sign changes into 0 or π at a polarity-changing point on an electrode charge distribution function Q(x) that generates on the electrode due to natural modes of oscillation. A single pair of natural modes, which exist stationary in the direction X of propagation of the surface acoustic waves that are utilized, is selected. A symmetrical mode charge distribution (Q(x), −Q(x)) and an obliquely symmetrical mode charge distribution (Q(x), Q(x)) are generated in order to correspond to the regions of IDT1and IDT2.The PTNG in the control IDT3region is set to be in the range of 1.02 to 1.04 so as to couple the two together.

REFERENCES:
patent: 5717367 (1998-02-01), Murai
patent: 6259336 (2001-07-01), Ichikawa
patent: 6335667 (2002-01-01), Takagi et al.
patent: 6570471 (2003-05-01), Inoue et al.
patent: A 61-285814 (1986-12-01), None
patent: A 1-231417 (1989-09-01), None

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