Saw filter and a receiver for remote keyless entry and tire pressure monitoring systems using same

摘要

A SAW filter includes at least four electrically interconnected DMS tracks. First and second tracks of the at least four DMS tracks are connected in parallel in opposite directions to form a first filter element. The first and second tracks have two resonant frequencies that are offset from one another from track to track within the first filter element such that they define a common passband by virtue of a lower-frequency resonance of the first track being in phase at the same frequency as a higher-frequency resonance of the second track. Third and fourth tracks of the at least four DMS tracks can be connected in a similar fashion to form a second filter element. The passbands of the first and second filter elements are offset from one another and each comprise one of two channels of a two-channel filter.

主权项

1. A SAW filter, comprising:
at least four electrically interconnected DMS tracks, wherein first and second tracks of the at least four DMS tracks are connected in parallel in opposite directions to form a first filter element, wherein the first and second tracks have two resonant frequencies that are offset from one another from track to track within the first filter element such that they define a common passband by virtue of a lower-frequency resonance of the first track being in phase at the same frequency as a higher-frequency resonance of the second track, wherein third and fourth tracks of the at least four DMS tracks are connected in parallel in opposite directions to form a second filter element, wherein the third and fourth tracks have two resonant frequencies that are offset from one another from track to track within the second filter element such that they define a common passband by virtue of a lower-frequency resonance of the third track being in phase at the same frequency as a higher-frequency resonance of the fourth track, wherein the passbands of the first and second filter elements are offset from one another and each comprises one of two channels of a two-channel filter, wherein an interval between auxiliary modes and principal modes is set in the first and second filter elements such that for a given offset for the passbands the auxiliary modes of one of the filter elements are each arranged in phase with a principal resonance of the other of the filter elements.