Advanced Saw Products Sa

David P Morgan

Clinton S Hartmann

Victor P Plessky

Thor Thorvaldsson

Sergei N Kondratyev

A SAW filter comprising at least one group of N tracks, where N is an integer greater than 2, and including at least one input interdigitated transducer (IDT) spaced apart from at least one output IDT and a reflector disposed substantially collinear with and adjacent the input and output IDTs. The respective tracks are adapted to have different effective electro-acoustic lengths such that SAWs launched from respective input IDTs undergo at least one reflection at corresponding output IDTs and at least one reflection from the respective input IDTs prior to generating coherent signals from respective output IDTs. The different effective electro-acoustic lengths may be substantially provided by there being different physical separation between input and output IDTs of respective tracks, or by IDTs of respective tracks having different polarity connections of electrodes or different amounts of material disposed in respective tracks between the input and output IDTs.

Multi-track SAW filter with reflectors and reversed polarity IDT

A SAW filter comprising a group of N tracks, where N is an odd integer greater than 2, and including an input interdigitated transducer (IDT) spaced apart from an output IDT. The respective tracks are selectable to have different effective electro-acoustic lengths such that surface acoustic waves launched from respective input IDTs undergo at least one reflection at corresponding output IDTs and at least one reflection from the respective input IDTs prior to generating coherent signals from respective output IDTs. The different effective electro-acoustic lengths may be substantially provided by there being different physical separation between input and output IDTs of respective tracks, or by IDTs of respective tracks having different polarity connections of electrodes or different amounts of material deposited in respective tracks between the input and output IDTs.

Saw filter with wave reflections and phase differences

A SAW filter having an even number of tracks, each track comprising reflective input and output IDTs having a partially reflecting grating disposed between them. One of the IDTs of each pair of tracks has its electrodes connected in opposite polarity to those of the other IDTs of the pair of tracks and the separation of the input and output IDTs of respective tracks of each pair of tracks is substantially the same. The relative dispositions of the partially reflecting gratings are such that waves launched into respective tracks of a pair of tracks undergo at least one reflection from the partially reflecting grating prior to being coherently incident on the output IDTs. By virtue of the oppositely connected electrodes of one of the IDTs, direct coupling through the tracks is inhibited at substantially all frequencies.

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Northampton, United Kingdom

David P Morgan