Galvanically isolated signal conditioning system

• US 7,288,940 B2
• Filed: 12/06/2004
• Issued: 10/30/2007
• Est. Priority Date: 12/06/2004
• Status: Active Grant

• Current Assignee: Analog Devices, Inc.
• Original Assignee: Analog Devices, Inc.
• Inventors: Hynes, Eamon, Wynne, John
• Primary Examiner(s): DEB, ANJAN K
• Application Number:
  US11/005,608
• Publication Number:
  US 20060153495A1
• Time in Patent Office: 1,058 Days
• Field of Search: 324/415, 324/76.66, 324/705, 324/658, 324/678
• US Class Current: 324/415
• CPC Class Codes: G01D 5/24 by varying capacitance
• CPC Class Codes: G11C 27/024 using a capacitive memory element G11C27/04 takes precedence
• CPC Class Codes: H01H 2059/0054 Rocking contacts or actuating members

Abstract

A galvanically isolated signal conditioning system includes a signal conditioning circuit on an integrated circuit chip; a flying capacitor; and a galvanically isolating MEMS switching device on an integrated circuit chip for selectively switching the flying capacitor from across a pair of input terminals in one state to across the input terminals of the signal conditioning circuit in another state.

Claims

1. A galvanically isolated signal conditioning system for data acquisition, the system comprising:

a signal conditioning circuit on an integrated circuit chip;

a flying capacitor; and

a galvanically isolating MEMS switching device on an integrated circuit chip for selectively switching said flying capacitor from across a pair of input terminals in one state to across the input terminals of said signal conditioning circuit in another state, said system isolating a differential voltage from a larger common mode voltage both present at the input terminals.

2. The galvanically isolated signal conditioning system of claim 1 in which said signal conditioning circuit includes an analog to digital converter.

3. The galvanically isolated signal conditioning system of claim 1 in which said signal conditioning circuit includes a difference amplifier circuit.

4. The galvanically isolated signal conditioning system of claim 1 in which said signal conditioning circuit includes a holding capacitor at its input.

5. The galvanically isolated signal conditioning system of claim 1 in which said signal conditioning circuit is on a first chip and said MEMS switching device is on a second MEMS chip.

6. The galvanically isolated signal conditioning system of claim 1 in which said signal conditioning circuit and said MEMS switching device are on the same chip.

7. The galvanically isolated signal conditioning system of claim 5 in which said first chip is a CMOS chip and said second chip is an SOI chip.

8. The galvanically isolated signal conditioning system of claim 6 in which said first chip is an SOI chip.

9. The galvanically isolated signal conditioning system of claim 5 in which said second chip is mounted on said first chip.

10. The galvanically isolated signal conditioning system of claim 9 in which said second chip is electrically connected by wire bonding to said first chip.

11. The galvanically isolated signal conditioning system of claim 9 in which said second chip is electrically connected by bump-attach mounting to said first chip.

12. The galvanically isolated signal conditioning system of claim 5 in which said second chip is disposed adjacent said first chip and is electrically connected to it by wire bonding.

13. The galvanically isolated signal conditioning system of claim 1 in which said flying capacitor is mounted with said MEMS switching device.

14. The galvanically isolated signal conditioning system of claim 1 in which said flying capacitor is mounted external to said MEMS switching device.

15. The galvanically isolated signal conditioning system of claim 1 in which said MEMS switching device is a capped, tested MEMS device.

16. The galvanically isolated signal conditioning system of claim 4 in which said holding capacitor is disposed with said MEMS switching device.

17. The galvanically isolated signal conditioning system of claim 4 in which said holding capacitor is disposed with said signal conditioning circuit.

18. The galvanically isolated signal conditioning system of claim 4 in which said holding capacitor is disposed external to said signal conditioning circuit and MEMS switching device.

19. The galvanically isolated signal conditioning system of claim 4 in which said holding capacitor and said flying capacitor are disposed in said MEMS switching device.

20. The galvanically isolated signal conditioning system of claim 4 in which said holding capacitor and said flying capacitor are external to said MEMS switching device and said signal conditioning circuit.

21. The galvanically isolated signal conditioning system of claim 1 in which said MEMS switching device includes a pair of cantilevered beams.