Pulse circuit

• US 6,429,674 B1
• Filed: 04/28/2000
• Issued: 08/06/2002
• Est. Priority Date: 04/28/1999
• Status: Expired due to Term

• Current Assignee: John R. Richner, Jon E. Barth
• Original Assignee: John R. Richner, Jon E. Barth
• Inventors: Richner, John R., Barth, Jon E.
• Primary Examiner(s): Sherry, Michael J.
• Assistant Examiner(s): TANG, MINH NHUT
• Application Number:
  US09/561,312
• Time in Patent Office: 830 Days
• Field of Search: 324/763, 324/765, 324/158.1, 324/602, 324/637, 324/676, 324/678, 333/20
• US Class Current: 324/762.01
• CPC Class Codes: G01R 31/001 Measuring interference from external sources to, or emission from, the device under test, e.g. EMC, EMI, EMP or ESD testing measuring electromagnetic fields G01R29/08; circuits for generating HV pulses in dielectric strength testing G01R31/14
• CPC Class Codes: G01R 31/002 where the device under test is an electronic circuit
• CPC Class Codes: G01R 31/2822 of microwave or radiofrequency circuits of attenuation, gain, e.g. using network analyzers G01R27/28
• CPC Class Codes: G01R 31/2839 using signal generators, power supplies or circuit analysers G01R31/2879 takes precedence; multimeters G01R15/12, network analysers G01R27/28

Abstract

A pulse generator generates a pulse that is transmitted to a device under test through a signal path that has a substantially constant impedance along its entire length. A voltage on the signal path and a current therethrough is measured in response to the pulse being generated.

Claims

1. Apparatus for measuring a pulse that is transmitted to and reflected from a device under test:

a pulse generator;

a signal path that connects the output of said pulse generator to the device under test, said signal path having a constant impedance along its entire length that substantially equals the output impedance of said generator;

a personal computer connected to said pulse generator, a substantially undistorted pulse being transmitted through said signal path by said pulse generator in response to a pulse timing signal provided by said computer;

a voltage measuring network that provides a digital signal representation of a signal voltage on said signal path in response to said pulse being transmitted; and

a current measuring network that provides a digital signal representation of a signal current through said signal path in response to said pulse being transmitted.

2. In the apparatus of claim 1 wherein said voltage measuring network comprises:

a voltage probe coupled to said signal path, said voltage probe providing an analog signal representation of said signal voltage; and

a digitizer connected to said voltage probe and to said computer, said digitizer providing said digital signal representation of said signal voltage to said computer where it is stored.

3. In the apparatus of claim 2 wherein said voltage probe is coupled at a location remote from said device under test.

4. In the apparatus of claim 2 wherein said current measuring network comprises a current probe coupled to said signal path and connected to said digitizer, said current probe providing to said digitizer an analog signal representation of said signal current, said digitizer providing said digital signal representation of said signal current to said computer where it is stored.

5. In the apparatus of claim 4 wherein said current probe is coupled at a location remote from said device under test.

6. In the apparatus of claim 4 additionally comprising a device that provides a visual display of a pulse data point having orthogonal coordinates proportional to said signal voltage and said signal current, respectively.

7. In the apparatus of claim 6 additionally comprising:

a source measuring unit connected to said computer;

a balun having its balanced terminals connected to said device under test;

a switch that is connected to said computer, said switch being operable to connect a coaxial terminal of said balun to said source measuring unit and interrupt said signal path, said source measuring unit providing to said computer a digital signal representation of a DC voltage applied through said balun to said device under test and a digital signal representation of a DC current produced in response to said DC voltage.

8. The apparatus of claim 7 wherein said computer stores said digital signal representation of said DC voltage and said digital signal representation of said DC current, said device providing a visual display of a DC data point having orthogonal coordinates proportional to said DC voltage and said DC current, respectively.

9. The apparatus of claim 8 wherein said DC data point and said pulse data point are displayed simultaneously.

10. The apparatus of claim 1 additionally comprising a filter network connected in said signal path through a transmission line to the output of said pulse generator, said transmission line having a characteristic impedance substantially equal to said constant impedance.

11. The apparatus of claim 10 wherein said filter network comprises:

a plurality of low pass Gaussian filters; and

means for placing one or more of said filters in said signal path.

12. The apparatus of claim 11 wherein said means for placing is a coax switch connected to said computer.

13. The apparatus of claim 1 additionally comprising a balun in said signal path, balanced terminals of said balun being connected to said device under test.

14. The apparatus of claim 13 additionally comprising a reversing switch, said balun being connected to said device under test through said reversing switch.

15. The apparatus of claim 1 wherein said pulse generator comprises:

a transmission line;

an attenuation network;

a DC power supply; and

a switch connected to said transmission line, to said attenuator network, to the output of said DC power supply and to said computer, said switch being operable in response to a signal from said computer to connect the output of said DC power supply to said transmission line whereby said transmission line is charged and to connect said charged transmission line to said attenuation network.

16. The apparatus of claim 15 wherein said attenuator network comprises:

a high voltage attenuator that provides a fixed attenuation of an applied voltage; and

a step attenuator connected in series with said high voltage attenuator and connected to said controller, said step attenuator providing a selectable attenuation in response to a signal from said computer.

17. Apparatus for providing a pulse to a device under test, comprising:

a transmission line;

an attenuation network connected to the device under test through a signal path that has a substantially constant impedance along its entire length;

means for charging said transmission line; and

means for discharging said transmission line to produce a pulse that is applied to said attenuation network.

18. The apparatus of claim 17 wherein said charging means comprises:

a DC power supply;

a personal computer; and

a switch that connects said power supply to said transmission line in response to a signal from said computer.

19. The apparatus of claim 18 additionally comprising means for measuring a voltage on said signal path and a current therethrough.

20. The apparatus of claim 19 wherein said measuring means comprises:

a voltage probe coupled to said signal path, said voltage probe providing a signal proportional to said signal path voltage;

a current probe coupled to said signal path, said current probe providing a signal proportional to said signal path current; and

a digitizer connected to said computer and to said probes, said digitizer being operable to provide a digital signal representation of said signal path voltage and said signal path current.

21. The apparatus of claim 19 additionally comprising a filter network in said signal path intermediate to said measuring means and said attenuation network.

22. The apparatus of claim 21 wherein said filter network comprises:

a plurality of Gaussian low pass filters; and

means for placing a selected one or more of said filters in said signal path.

23. The apparatus of claim 22 wherein said means for placing is a coax switch connected to said computer.

24. The apparatus of claim 17 additionally comprising a balun that has its balanced terminals connected to the device under test.

25. The apparatus of claim 24 additionally comprising a reversing switch, said balun being connected to said device under test through said reversing switch.

26. The apparatus of claim 25 additionally comprising:

a source measuring unit; and

a switch that is operable to interrupt said signal path and connect said source measuring unit to said device under test through said balun and said reversing switch, said source measurement unit providing a signal representation of leakage current through said device under test in response to an application of a voltage.