Adjustable saw device

• US 6,291,924 B1
• Filed: 07/01/1999
• Issued: 09/18/2001
• Est. Priority Date: 07/01/1999
• Status: Expired due to Term

• Current Assignee: Northrop Grumman Systems Corporation (Northrop Grumman Corporation)
• Original Assignee: TRW Limited (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Inventors: Yen, Kuo-Hsiung, Housholder, Steven E., Lau, Kei-Fung, Kasparek, Ronald D., Kong, Alvin M., Stokes, Robert B.
• Primary Examiner(s): Budd, Mark O.
• Application Number:
  US09/346,081
• Time in Patent Office: 810 Days
• Field of Search: 310/313.R, 310/313.B, 310/334, 333/150-155
• US Class Current: 310/313.00R
• CPC Class Codes: H03H 9/145 for networks using surface acoustic waves
• CPC Class Codes: H03H 9/6403 Programmable filters

Abstract

An adjustable surface acoustic wave (SAW) transducer is fabricated on a piezoelectric substrate. The adjustable SAW transducer includes a plurality of SAW interdigital transducer (IDT) fingers disposed on the substrate. Miniature switches are used to provide a plurality of interconnection patterns between the SAW IDT fingers such that a plurality of SAW characteristics can be generated from a single set of SAW IDT fingers.

Claims

1. An adjustable surface acoustic wave (SAW) device comprising:

a piezoelectric substrate;

a plurality of SAW interdigital transducer (IDT) fingers formed on said substrate, the SAW IDT fingers together comprising one set of SAW IDT fingers; and

,

a plurality of mechanical switches disposed on said substrate and configured to provide a plurality of interconnection patterns between selected SAW IDT fingers, each mechanical switch being selectively controllable between an open and a closed state, said open and closed states of each of the mechanical switches together defining each of the interconnection patterns, selectively changing said open and closed state of each of the mechanical switches providing said plurality of interconnection patterns, whereby said plurality of mechanical switches comprises;

a plurality of control lines formed on said substrate, each control line positioned distal each SAW IDT finger;

a plurality of electrically conductive flexible arms; and

a plurality of DC return-to-ground means coupled to each said flexible arm,

each flexible arm being electrostatically attractable toward each control line upon application of a DC voltage on each control line, selective application of said DC voltage causing selected flexible arms to form said closed state, selective removal of said DC voltage causing selected flexible arms to form said open state, selectively varying said application of said DC voltages selectively varying said open and closed states of each switch.

2. An adjustable SAW device as in claim 1, wherein the open and closed states of the switches are remotely programmable.

3. An adjustable SAW device as in claim 1, wherein said adjustable SAW device is configured as an adjustable filter.

4. An adjustable SAW device as in claim 3, wherein said adjustable SAW device is configured as an adjustable notched filter.

5. An adjustable SAW device as in claim 3, wherein said adjustable SAW device is configured as an adjustable bandpass filter.

6. An adjustable SAW device as in claim 1, wherein said adjustable SAW device is configured as an electrically operated equalizer.

7. An adjustable SAW device as in claim 1, wherein said adjustable filter is disposed in a RADAR system, said adjustable filter configured to generate a RADAR signal having preselected RADAR pulses, each RADAR pulses having an amplitude and a bandwidth adjustable by selectively changing said open and closed states of said switches.

8. An adjustable SAW device as in claim 7, wherein said adjustable SAW device is configured as an anti-jam RADAR matched filter.

9. An adjustable SAW device as in claim 1, wherein said adjustable SAW device is configured as an adaptive filter.

10. An adjustable SAW device as in claim 1, wherein said adjustable SAW device is configured as an adjustable rate signal processing matched filter element.

11. An adjustable SAW devices as in claim 1, wherein said adjustable SAW device is configured as a programmable tapped delay line.

12. An adjustable SAW devices as in claim 1, wherein said adjustable SAW device is configured as a chirped transducer.

13. An adjustable SAW transducer comprising:

a piezoelectric substrate;

a plurality of surface-acoustic wave (SAW) interdigital transducer (IDT) fingers formed on said substrate, each said SAW IDT finger having two ends; and

a plurality of switches selectively changeable between an open state and a closed state, said plurality of switches comprising;

a plurality of control lines formed on said substrate each said control line positioned such that a first gap is formed between each said control line and one of the ends of each said SAW IDT finger;

a plurality of dielectric layers, one each attached to a preselected number of said control lines;

a plurality of electrically conductive plates, each attached to one of the dielectric layers;

a plurality of DC return-to-ground means coupled to each said plate;

a plurality of electrically conductive flexible cantilever arms attached to said plates, each said cantilever arm extending over one said first gap and partially over a portion of one of the control lines forming a plurality of second gaps between said cantilever arms and said SAW IDT fingers;

said portion of each cantilever arm above said control line being electrostatically attractable toward said control line upon application of a DC voltage on each said control line, selective application of said DC voltage causing selected cantilever arms to make electrical contact with selected SAW fingers to close selected second gaps between said selected cantilever arms and said selected SAW IDT fingers whereby said selected cantilever arms and said selected SAW fingers form said closed state, selective removal of said DC voltage causing selected cantilever arms to cease electrical contact with selected SAW IDT fingers whereby said selected cantilever arms and said selected SAW IDT fingers form said open state, selectively varying said application of said DC voltages selectively varying said open and closed states of each switch.

14. An adjustable SAW transducer as in claim 13, further comprises a plurality of metal traces formed on said substrate, each said metal trace having a first and a second end, said first end of each metal trace electrically coupled to one end of each SAW IDT finger, said metal traces dispersing in the substrate so that the spacing between adjacent metal traces increases from said first end to said second end wherein each said first gap is formed between one control line and said second end of one metal trace.

15. An adjustable SAW transducer as in claim 14, wherein each metal trace has a width which increases monotonically with said dispersion of each metal trace in the substrate.

16. An adjustable SAW transducer as in claim 13, wherein each said control line comprises a first end and a second end, said first end disposed closer to said SAW IDT fingers than said second end, said control lines disperse in said substrate such that said spacing between said control lines increases between said first and second ends.

17. An adjustable SAW transducer as in claim 13, wherein said adjustable SAW transducer is remotely programmable.

19. An adjustable SAW device as in claim 13, wherein the open and closed states of the switches are remotely programmable.

20. An adjustable SAW device as in claim 13, wherein said adjustable SAW device is configured as an adjustable filter.

21. An adjustable SAW device as in claim 13, wherein said adjustable SAW device is configured as an adjustable notched filter.

22. An adjustable SAW device as in claim 13, wherein said adjustable SAW device is configured as an adjustable bandpass filter.

23. An adjustable SAW device as in claim 13, wherein said adjustable SAW device is configured as an electrically operated equalizer.

24. An adjustable SAW device as in claim 13, wherein said adjustable filter is disposed in a RADAR system, said adjustable filter configured to generate a RADAR signal having preselected RADAR pulses, each RADAR pulse having an amplitude and a bandwidth adjustable by selectively changing said open and closed states of said switches.

25. An adjustable SAW device as in claim 24, wherein said adjustable SAW device is configured as an anti-jam RADAR matched filter.

26. An adjustable SAW device as in claim 13, wherein said adjustable SAW device is configured as an adaptive filter.

27. An adjustable SAW device as in claim 13, wherein said adjustable SAW device is configured as an adjustable rate signal processing matched filter element.

28. An adjustable SAW device as in claim 13, where said adjustable SAW device is configured as a programmable tapped delay line.

29. An adjustable SAW device as in claim 13, where said adjustable SAW device is configured as a chirped transducer.

18. An apparatus for detecting and recovering a transmit signal comprising:

a first adjustable filter disposed in a transmit system configured to transmit said transmit signal, said first adjustable filter comprising;

a first piezoelectric substrate;

a plurality of first SAW IDT fingers disposed on said first substrate; and

,

a plurality of first mechanical switches disposed on said first substrate and configured to provide a plurality of first interconnection patterns between selected first SAW IDT fingers, said plurality of first mechanical switches comprising;

a plurality of first control lines formed on said first substrate, each first control line positioned such that a first gap is formed between each first control line and each first SAW IDT finger;

a plurality of first electrically conductive flexible arms a portion of which extends over the first SAW IDT fingers forming a plurality of second gaps between the first flexible arms and the first SAW IDT fingers; and

a plurality of first DC return-to-ground means coupled to each first flexible arm,

said portion of each first flexible arm above each first control line being electrostatically attractable toward said first control line upon application of a first DC voltage on each first control line, selective application of said first DC voltage causing selected first flexible arms to form said closed state, selective removal of said first DC voltage causing selected flexible arms to form said open state, selectively varying said application of said first DC voltages selectively varying said open and closed states of each first mechanical switch; and

a second adjustable filter disposed in a receive system and configured to detect and recover said transmit signal, said second adjustable filter comprising;

a second piezoelectric substrate;

a plurality of second SAW IDT fingers disposed on said second substrate; and

,

a plurality of second mechanical switches disposed on said second substrate and configured to provide a plurality of second interconnection patterns between selected second SAW IDT fingers, said plurality of second mechanical switches comprising;

a plurality of second control lines formed on said second substrate, each second control line positioned such that a third gap is formed between each second control line and each second SAW IDT finger;

a plurality of second electrically conductive flexible arms a portion of which extends over the second SAW IDT fingers forming a plurality of fourth gaps between the second flexible arms and the second SAW IDT fingers; and

a plurality of second DC retum-to-ground means coupled to each second flexible arm,

said portion of each second flexible arm above said second control line being electrostatically attractable toward said second control line upon application of a second DC voltage on each second control line, selective application of said second DC voltage causing selected second flexible arms to form said closed state, selective removal of said second DC voltage causing selected second flexible arms to form said open state, selectively varying said application of said second DC voltages selectively varying said open and closed states of each second mechanical switch,

said first and second interconnection patterns configured so that said first and second adjustable filters are matched filters, whereby signal detection and recovery of said transmit signal can be optimally achieved.

30. An apparatus for detecting and recovering a transmit signal comprising:

a first adjustable filter disposed in a transmit system configured to transmit said transmit signal, said first adjustable filter comprising;

a first piezoelectric substrate;

a plurality of first SAW IDT fingers disposed on said first substrate, the first SAW IDT fingers together comprising a first set of SAW IDT fingers and defining a SAW propagation direction, each first SAW IDT finger having a submicron to micron width dimension in the SAW propagation direction, adjacent first SAW IDT fingers being a submicron to micron distance apart in the SAW propagation direction; and

,

a plurality of first mechanical switches disposed on said first substrate and configured to provide a plurality of first interconnection patterns between selected first SAW IDT fingers, each first mechanical switch having a submicron to micron width dimension in the SAW propagation direction, each first mechanical switch selectively changeable between a first open state and a first closed state, said plurality of first mechanical switches comprising;

a plurality of first control lines formed on said first substrate each first control line positioned such that a first gap is formed between each first control line and one first SAW IDT finger;

a plurality of first dielectric layers, one each attached to a preselected number of first control lines;

a plurality of first electrically conductive plates, each attached to one of the first dielectric layers;

a plurality of first DC return-to-ground means coupled to each first conductive plate;

a plurality of first electrically conductive flexible cantilever arms attached to said first conductive plates, each first cantilever arm extending over one first gap and partially over a portion of one of said first control lines forming a plurality of second gaps between said first cantilever arms and said first SAW IDT fingers,

said portion of each first cantilever arm above said first control line being electrostatically attractable toward said first control line upon application of a first DC voltage on each first control line, selective application of said first DC voltage causing selected first cantilever arms to make electrical contact with selected first SAW IDT fingers to close selected second gaps between said selected first cantilever arms and said selected first SAW IDT fingers whereby said selected first cantilever arms and said selected SAW IDT fingers form said first closed state, selective removal of said first DC voltage causing selected first cantilever arms to cease electrical contact with selected first SAW IDT fingers whereby said selected first cantilever arms and said selected first SAW IDT fingers form said first open state, selectively varying said application of said first DC voltages selectively varying said first open and first closed states of each first switch; and

,

a second adjustable filter disposed in a receive system and configured to detect and recover said transmit signal, said second adjustable filter comprising;

a second piezoelectric substrate;

a plurality of second SAW IDT fingers disposed on said second substrate, the second SAW IDT fingers together comprising a second set of SAW IDT fingers, each second SAW IDT finger having a submicron to micron width dimension in the SAW propagation direction, adjacent second SAW IDT fingers being a submicron to micron distance apart in the SAW propagation direction; and

,

a plurality of second mechanical switches disposed on said second substrate and configured to provide a plurality of second interconnection patterns between selected second SAW IDT fingers, each second mechanical switch having a submicron to micron width dimension in the SAW propagation direction, each second mechanical switch selectively changeable between a second open state and a second closed state, said plurality of second mechanical switches comprising;

a plurality of second control lines formed on said second substrate each second control line positioned such that a third gap is formed between each second control line and one second SAW IDT finger;

a plurality of second dielectric layers, one each attached to a preselected number of second control lines;

a plurality of second electrically conductive plates, each attached to one of the second dielectric layers;

a plurality of second DC retum-to-ground means coupled to each second conductive plate;

a plurality of second electrically conductive flexible cantilever arms attached to said second conductive plates, each second cantilever arm extending over one third gap and partially over a portion of one of said second control lines forming a plurality of fourth gaps between said second cantilever arms and said second SAW IDT fingers,

said portion of each second cantilever arm above said second control line being electrostatically attractable toward said second control line upon application of a second DC voltage on each second control line, selective application of said second DC voltage causing selected second cantilever arms to make electrical contact with selected second SAW IDT fingers to close selected fourth gaps between said selected second cantilever arms and said selected second SAW IDT fingers whereby said selected second cantilever arms and said selected SAW IDT fingers form said second closed state, selective removal of said second DC voltage causing selected second cantilever arms to cease electrical contact with selected second SAW IDT fingers whereby said selected second cantilever arms and said selected second SAW IDT fingers form said second open state, selectively varying said application of said second DC voltages selectively varying said second open and second closed states of each second switch,

said first and second interconnection patterns configured so that said first and second adjustable filters are matched filters, whereby signal detection and recovery of said transmit signal can be optimally achieved.