Electrostatic discharge circuit

• US 20040100744A1
• Filed: 11/27/2002
• Published: 05/27/2004
• Est. Priority Date: 11/27/2002
• Status: Active Grant

• Current Assignee: Endevco Corporation (Illinois Tool Works Inc.)
• Original Assignee: Endevco Corporation (Illinois Tool Works Inc.)
• Inventors: Levinzon, Felix A.
• Granted Patent: US 6,987,654 B2
• Time in Patent Office: Days
• US Class Current: 361/56
• CPC Class Codes: G01H 1/006 of the rotor of turbo machines

Abstract

A circuit includes at least one input node, at least one output node, a signal conditioning circuit, and an electrostatic discharge (ESD) circuit. The signal conditioning circuit is characterized by a transfer function and adapted to receive input signals from and provide conditioned output signals to the input and output node(s), respectively. The signal conditioning circuit processes the input signal and outputs the conditioned output signal as a function of the transfer function. The ESD protection circuit is adapted to the signal conditioning circuit (i) to suppress electrostatic discharge signals applied to at least one of the input or output node(s) to levels electrically non-destructive to the signal conditioning circuit and (ii) to interact with the signal conditioning circuit in a manner substantially maintaining the transfer function.

Claims

1. A circuit, comprising:

at least one input node;

at least one output node;

a signal conditioning circuit, characterized by a transfer function, adapted to receive an input signal from said at least one input node and provide a conditioned output signal at said at least one output node according to the transfer function; and

an electrostatic discharge protection circuit adapted to the signal conditioning circuit (i) to suppress electrostatic discharge signals applied to said at least one node to levels electrically non-destructive to the signal conditioning circuit and (ii) to interface with the signal conditioning circuit in a manner substantially maintaining the transfer function.

2. The circuit according to claim 1 wherein the electrostatic discharge protection circuit suppresses electrostatic discharge signals greater than about 2000 Vpp.

3. The circuit according to claim 1 wherein the electrostatic discharge protection circuit suppresses electrostatic discharge signals up to about 4000 Vpp.

4. The circuit according to claim 1 further including a transducer coupled to the input nodes to provide the input signal.

5. The circuit according to claim 4 wherein the transducer is an accelerometer.

6. The circuit according to claim 1 wherein the signal conditioning circuit includes a high impedance input stage.

7. The circuit according to claim 6 wherein the high impedance input stage is a charge amplifier.

8. The circuit according to claim 1 wherein the electrostatic discharge protection circuit includes at least one capacitor.

9. The circuit according to claim 8 wherein said at least one capacitor is coupled to the signal conditioning circuit at said at least one of the nodes.

10. The circuit according to claim 8 wherein the electrostatic discharge protection circuit is absent non-linear circuit elements.

11. The circuit according to claim 8 wherein at least one of said at least one capacitor has capacitance values matching a capacitance value of a transducer providing the input signal.

12. The circuit according to claim 8 wherein the signal conditioning circuit includes an input stage including an operational amplifier, said at least one capacitor being electrically coupled between the input terminals of the operational amplifier.

13. The circuit according to claim 1 wherein the electrostatic discharge protection circuit reduces an oscillation frequency or a peak of an oscillation voltage, caused by the electrostatic discharge signal, at at least one input or output node.

14. The circuit according to claim 1 used to measure vibration of an aircraft engine during operation.

15. A method for conditioning a signal, comprising:

receiving the signal;

conditioning the signal according to a transfer function;

suppressing electrostatic discharge signals to levels electrically non-destructive to the conditioning and in a manner substantially maintaining the transfer function; and

outputting the conditioned signal.

16. The method according to claim 15 wherein the electrostatic discharge signals are greater than 2000 Vpp.

17. The method according to claim 15 wherein the electrostatic discharge signals are about 4000 Vpp.

18. The method according to claim 15 further including converting mechanical energy into the signal.

19. The method according to claim 18 wherein the converting includes detecting accelerations.

20. The method according to claim 15 wherein conditioning the signal includes using a high impedance input stage to amplify the signal.

21. The method according to claim 20 wherein amplifying the signal includes charge amplifying the signal.

22. The method according to claim 15 wherein suppressing electrostatic discharge signals includes capacitively discharging the signal.

23. The method according to claim 22 wherein capacitively discharging the signal occurs while receiving the signal.

24. The method according to claim 22 wherein capacitively discharging the signal occurs absent non-linear circuit elements.

25. The method according to claim 22 wherein capacitively discharging the signal includes at least one capacitor having a value matching a capacitance value of a transducer providing the signal.

26. The method according to claim 22 wherein conditioning the signal includes actively amplifying the signal.

27. The method according to claim 15 wherein suppressing the electrostatic discharge signals includes reducing an oscillation frequency or a peak of an oscillation voltage.

28. The method according to claim 15 used to measure vibration of an aircraft engine during operation.

29. A circuit for conditioning a signal, comprising:

means for receiving the signal;

means for conditioning the signal according to a transfer function;

means for suppressing electrostatic discharge signals to levels electrically non-destructive to the conditioning and in a manner substantially maintaining the transfer function; and

means for outputting the conditioned signal.