Method and system for measuring equivalent series resistance of capacitors and method for decoupling power distribution systems

• US 6,195,613 B1
• Filed: 09/08/1998
• Issued: 02/27/2001
• Est. Priority Date: 06/18/1998
• Status: Expired due to Term

• Current Assignee: Oracle America, Inc. (Oracle Corporation)
• Original Assignee: Sun Microsystems Incorporated (Oracle Corporation)
• Inventors: Pelc, Thomas J., Roy, Tanmoy, Smith, Larry D., Anderson, Raymond E., Forehand, Douglas W.
• Primary Examiner(s): Hoff, Marc S.
• Assistant Examiner(s): Bui, Bryan
• Application Number:
  US09/149,164
• Time in Patent Office: 903 Days
• Field of Search: 702/65, 702/106, 702/191, 324/649, 324/650, 324/654, 324/717, 324/707, 324/430, 361/306.2, 361/321.4, 361/684
• US Class Current: 702/65
• CPC Class Codes: G06F 30/367 Design verification, e.g. using simulation, simulation program with integrated circuit emphasis [SPICE], direct methods or relaxation methods
• CPC Class Codes: H05K 2201/09309 Core having two or more power planes; Capacitive laminate of two power planes
• CPC Class Codes: H05K 3/0005 for designing circuits by computer

Abstract

A system and method for measuring the equivalent series resistance (ESR) of one or more capacitors using an impedance analyzer, whereby the capacitors are joined to the impedance analyzer with a conductive adhesive. The conductive adhesive may advantageously provide for an electrically and mechanically stable connection between the capacitor and the remainder of the electrical circuit used to measure the ESR of the capacitor. The conductive adhesive may include heat activated or cold solder, or conductive putty. The system comprises a measuring unit for sweeping a frequency range to find the minimum impedance for the capacitor and a connector assembly for holding the capacitor in an electrically and mechanically stable connection using the conductive adhesive. The connector assembly includes a mating portion adapted for electrically connecting the connector assembly to an I/O port of the measuring unit and a terminal portion that accommodates a connection to the capacitor using the conductive adhesive. The method comprises connecting a mating portion of the connector assembly to the impedance analyzer. Next, the impedance analyzer is calibrated, and the capacitor is then connected to a terminal portion of the connector assembly using the conductive adhesive. Finally, the impedance analyzer sweeps a frequency range to find the ESR for the capacitor. The method may also measure the ESR of each of a number of capacitors using an impedance analyzer. The method may connect in series the number of capacitors to the connector assembly using the conductive adhesive. The method determines the equivalent series resistance of each of the number of capacitors by dividing the minimum impedance by the number of capacitors. The method may also comprise selecting one or more capacitors, measuring the ESR of each of the capacitors, and determining a desired number of each of the capacitors for placing into a power distribution system.

Claims

1. A system for measuring equivalent series resistance of a capacitor, the system comprising:

a measuring unit configured to measure impedance over a frequency range to find the equivalent series resistance of the capacitor, wherein the measuring unit includes an input/output (I/O) port; and

a connector assembly having a mating portion adapted for electrically connecting the connector assembly to the I/O port of the measuring unit, wherein the connector assembly further includes a terminal portion connected to leads of the capacitor using conductive adhesive;

wherein the measuring unit is calibrated with the mating portion of the connector assembly connected to the input/output port of the measuring unit.

2. The system of claim 1, wherein the measuring unit is a computer connected to an impedance analyzer.

3. The system of claim 1, wherein the conductive adhesive is solder.

4. The system of claim 3, wherein the solder is heat activated.

5. The system of claim 3, wherein the solder is a cold solder.

6. The system of claim 5, wherein the cold solder is chemically activated.

7. The system of claim 1, wherein the conductive adhesive is a removable putty.

8. A method for measuring equivalent series resistance of a capacitor using an impedance analyzer including an input/output port, the method comprising:

connecting a mating portion of a connector assembly to the input/output port of the impedance analyzer;

calibrating the impedance analyzer, wherein the impedance analyzer is calibrated with the connector assembly connected to the input/output port of the impedance analyzer;

connecting leads of the capacitor to a terminal portion of the connector assembly with a conductive adhesive; and

sweeping a frequency range with the impedance analyzer to find the equivalent series resistance of the capacitor.

9. The method of claim 8, wherein said calibrating the impedance analyzer includes calibrating with a short, an open, and a test load with known impedance.

10. The method of claim 8, wherein said sweeping a frequency range with the impedance analyzer includes performing multiple sweeps through the frequency range with the impedance analyzer and averaging results of the multiple sweeps.

11. The method of claim 8, further comprising:

checking the calibration of the impedance analyzer after said sweeping.

12. The method of claim 11, wherein said checking the calibration of the impedance analyzer includes comparing a phase shift at the minimum impedance with approximately 180 degrees from a reference baseline.

13. A method for measuring an equivalent series resistance of each of a number of equivalent capacitors using an impedance analyzer including an input/output port, the method comprising:

connecting a mating portion of a connector assembly to the input/output port of the impedance analyzer;

calibrating the impedance analyzer, wherein the impedance analyzer is calibrated with the connector assembly connected to the input/output port of the impedance analyzer;

connecting the number of capacitors in series between contacts on a terminal portion of the connector assembly using a conductive adhesive;

sweeping a frequency range with the impedance analyzer to find the minimum impedance for the number of capacitors; and

determining the equivalent series resistance of each of the number of capacitors by dividing the minimum impedance by the number of capacitors.

14. A method for determining decoupling components for a power distribution system, the method comprising:

determining a target impedance for the power distribution system;

selecting one or more specific values of an electrical characteristic associated with decoupling components to be placed in the power distribution system;

measuring an equivalent series resistance of each of the one or more decoupling components, wherein said measuring the equivalent series resistance includes;

connecting a mating portion of a connector assembly to an input/output port of an impedance analyzer;

calibrating the impedance analyzer, wherein the impedance analyzer is calibrated with the connector assembly connected to the input/output port of the impedance analyzer;

connecting leads of a respective decoupling component to a terminal portion of the connecting assembly with a conductive adhesive; and

sweeping a frequency range with the impedance analyzer to find the equivalent series resistance of the respective decoupling component; and

determining the number of decoupling components of each specific value to be placed in the power distribution system; and

placing the decoupling components in the power distribution system in response to said determining the number of decoupling components.

15. The method of claim 14, wherein the number of decoupling components of each specific value is determined by choosing the smallest integer number of decoupling components which, when coupled in parallel, results in an impedance which is closest to but not greater than the target impedance.

16. The method of claim 14, wherein the number of decoupling components of each specific value is determined by choosing the smallest integer number with a value closest to but not less than the quotient obtained by dividing the equivalent series resistance of the respective decoupling component by the target impedance.

17. A method for determining decoupling components for a power distribution system for a given frequency, wherein the power distribution system includes a target impedance, the method comprising:

measuring an equivalent series resistance of a plurality of decoupling components, wherein said measuring the equivalent series resistance includes;

connecting a mating portion of a connector assembly to an input/output port of an impedance analyzer;

calibrating the impedance analyzer, wherein the impedance analyzer is calibrated with the connector assembly connected to the input/output port of the impedance analyzer;

connecting, in turn, leads of one of the plurality of decoupling components to a terminal portion of the connector assembly with a conductive adhesive; and

sweeping a frequency range with the impedance analyzer to find the equivalent series resistance for the one of the plurality of decoupling components;

selecting a particular one of the plurality of decoupling components, wherein the particular one has an associated resonance frequency approximately equal to the given frequency;

comparing the equivalent series resistance of the particular one of the decoupling components to the target impedance;

determining the number of the particular one of the plurality of decoupling components to be used in the power distribution system; and

placing the decoupling components in the power distribution system in response to said determining the number of the particular one of the plurality of decoupling components to be used.

18. The method of claim 17, wherein the number of the particular one of the plurality of decoupling components is determined by choosing the smallest integer number with a value closest to but not greater than the quotient obtained by dividing the equivalent series resistance of the particular one of the plurality of decoupling components by the target impedance.

19. The method of claim 17, wherein the given frequency comprises a frequency range, the method further comprising:

selecting a next particular one of the plurality of decoupling components, wherein the next particular one includes a new resonance frequency different from the resonance frequency of each previously selected particular one of the plurality of decoupling components, wherein the new resonance frequency is within the frequency range;

comparing the equivalent series resistance of the next particular one of the decoupling components to the target impedance; and

determining the number of the next particular one of the plurality of decoupling components to be used in the power distribution system; and

placing the number of the next particular one of the plurality of decoupling components in the power distribution system in response to said determining the number of the next particular one of the plurality of decoupling components to be used.

20. The method of claim 19, wherein the number of the particular one of the plurality of decoupling components is determined by choosing the smallest integer number with a value closest to but not greater than the quotient obtained by dividing the equivalent series resistance of the particular one of the plurality of decoupling components by the target impedance.