Non-contact circuit analyzer

• US 7,710,131 B1
• Filed: 08/18/2007
• Issued: 05/04/2010
• Est. Priority Date: 08/18/2007
• Status: Active Grant

• Current Assignee: Radiation Monitoring Devices, Inc. (Dynasil Corp. of America)
• Original Assignee: Radiation Monitoring Devices, Inc. (Dynasil Corp. of America)
• Inventors: Tiernan, Tim
• Primary Examiner(s): Patel; Paresh
• Application Number:
  US11/840,957
• Time in Patent Office: 990 Days
• Field of Search: None
• US Class Current: 324/754.29
• CPC Class Codes: G01R 23/20 Measurement of non-linear distortion
• CPC Class Codes: G01R 31/2834 Automated test systems [ATE]; using microprocessors or computers G01R31/317 takes precedence; ATE for detection of defective computer hardware G06F11/2736
• CPC Class Codes: G01R 31/302 Contactless testing G01R31/66 takes precedence
• CPC Class Codes: G01R 31/312 by capacitive methods
• CPC Class Codes: G01R 31/315 by inductive methods

Abstract

A non-contact circuit analyzer includes a computer system having a memory with circuit parameters stored therein wherein the circuit parameters specify acceptable operating characteristics for a circuit. The analyzer further includes a magnetic field detector coupled to the computer and configured to detect the magnetic field emitted from the circuit while operational. The magnetic field relates to current in the circuit. The analyzer further includes an electric field sensor coupled to the computer and configured to detect the electric field emitted from the circuit while operational. The electric field relates to voltage and/or operating frequency in the circuit. The magnetic field detector and the electric field detector are configured to send signals for the detected fields to the computer system. The computer system is configured to compare the signals to the circuit parameters to determine whether the circuit is operating within the circuit parameters.

Claims

1. A non-contact circuit analyzer comprising:

a computer system having a memory with circuit parameters stored therein wherein the circuit parameters specify acceptable operating characteristics for a circuit;

a magnetic field sensor coupled to the computer and configured to detect the magnetic field emitted from the circuit while operational, wherein the magnetic field relates to current in the circuit;

an electric field sensor coupled to the computer and configured to detect the electric field emitted from the circuit while operational, wherein the electric field relates to voltage and/or operating frequency in the circuit;

wherein the magnetic field sensor and the electric field sensor are configured to send signals for the detected fields to the computer system, and

wherein the computer system is configured to;

compare the signals to the circuit parameters to determine whether the circuit is operating within the circuit parameters,

Fourier transform the signals to separate the electric field information from the magnetic field information,

identify a first set of harmonics associated with detected electric field spikes associated with voltage transitions in the circuit,

identify a second set of harmonics associated with a substantially square wave associated with the detected magnetic fields and the current in the circuit,

compare the first and second sets of harmonics with the circuit parameters, and based on the comparison determine the performance of the circuit with respect to a standard circuit from which the circuit parameters are collected while the standard circuit is operational.

2. The non-contact circuit analyzer of claim 1, wherein the magnetic field sensor comprises a monolithic sensor array.

3. The non-contact circuit analyzer of claim 1, wherein the magnetic field sensor comprises a distributed sensor array.

4. The non-contact circuit analyzer of claim 1, wherein the magnetic field and electric field sensors comprise separate sensors.

5. The non-contact circuit analyzer of claim 1, wherein the electric field sensor includes at least one conductive member of a capacitive sensor.

6. The non-contact circuit analyzer of claim 5, wherein the circuit is another conductive member of the capacitive sensor.

7. The non-contact circuit analyzer of claim 1, wherein the computer system is configured to execute program code to operate the circuit in a known sequence of operations.

8. The non-contact circuit analyzer of claim 1, wherein the computer system is configured to direct operation of the circuit based on the signals received from the electric and magnetic field sensors.

9. The non-contact circuit analyzer of claim 1, wherein the computer system is configured to generate an IN curve for the circuit.

10. The non-contact circuit analyzer of claim 1, wherein the computer system is configured to generate a map of the detected electric and/or magnetic fields.

11. The non-contact circuit analyzer of claim 1, wherein the electric field sensor and the magnetic field sensor are a single sensor.

12. The non-contact circuit analyzer of claim 11, wherein the single sensor is a magnetoresistive sensor.

13. The non-contact circuit analyzer of claim 1, wherein the electric field sensor and the magnetic field sensor are an array of sensors, and wherein each sensor in the array of sensors is a magnetoresistive sensor.

14. The non-contact analyzer of claim 13, wherein the array of sensors is configured to be mounted to the circuit, and wherein the array of sensors is configured to detect electric and magnetic fields from the circuit in real time for age analysis of the circuit and circuit prognostics.

15. The non-contact circuit analyzer of claim 1, wherein the electric field signals and the magnetic field signals are identified by sampling the detected fields at different times during an operating cycle of the circuit.

16. The non-contact circuit analyzer of claim 1 further comprising:

a conductive shield disposed between the field sensor and the circuit; and

a switch configured to periodically ground the shield;

wherein the shield in a grounded state is configured to inhibit the circuit'"'"'s electric field from reaching the electric field sensor and permit the circuit'"'"'s magnetic field to reach the magnetic field sensor.

17. The non-contact analyzer of claim 1 further comprising:

a high permeability magnetic shield disposed between the circuit and the field sensor.

18. The non-contact analyzer of claim 17, wherein the high permeability magnet shield is configured to shield external magnetic fields from reaching the field sensor.

19. The non-contact circuit analyzer of claim 1 wherein the magnetic field sensor and the electric field sensor are a monolithic sensor array comprising a giant magnetoresistance (GMR) sensor or an anisotropic magnetoresistance (AMR) sensor.

20. A non-contact circuit analyzer comprising:

a computer system having a memory configured to store circuit parameters, wherein the circuit parameters specify acceptable operating characteristics for a circuit obtained by testing of a standard circuit;

a magnetoresistive sensor coupled to the computer and configured to detect substantially simultaneously electric fields and magnetic fields emitted from the circuit while operational, wherein;

the magnetoresistive sensor is configured to send signals for the electric fields and the magnetic fields to the computer system, and the computer system is configured to compare the signals for the circuit to the circuit parameters for the standard circuit and determine whether the circuit is operating substantially within a range of the circuit parameters.

21. A non-contact circuit analyzer comprising:

a computer system having a memory with circuit parameters stored therein wherein the circuit parameters specify acceptable operating characteristics for a circuit;

a magnetic field sensor coupled to the computer and configured to detect the magnetic field emitted from the circuit while operational, wherein the magnetic field relates to current in the circuit;

an electric field sensor coupled to the computer and configured to detect the electric field emitted from the circuit while operational, wherein the electric field relates to voltage and/or operating frequency in the circuit;

a conductive shield disposed between the field sensor and the circuit; and

a switch configured to periodically ground the shield,

wherein the shield in a grounded state is configured to inhibit the circuit'"'"'s electric field from reaching the electric field sensor and the magnetic field sensor and permit the circuit'"'"'s magnetic field to reach the electric field sensor and the magnetic field sensor, and

wherein the magnetic field sensor and the electric field sensor are configured to send signals for the detected fields to the computer system, and the computer system is configured to compare the signals to the circuit parameters to determine whether the circuit is operating within the circuit parameters.

22. The non-contact circuit analyzer of claim 21 wherein the magnetic field sensor and the electric field sensor are a monolithic sensor array comprising a giant magnetoresistance (GMR) sensor and an anisotropic magnetoresistance (AMR) sensor.