Method for reducing current surge using multi-stage ramp shunting

• US 6,661,281 B2
• Filed: 11/29/2001
• Issued: 12/09/2003
• Est. Priority Date: 11/29/2001
• Status: Expired due to Fees

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Lin, Shen, Nakagawa, Osamu Samuel, Xie, Weize, Chang, Norman, Huang, Xuejue
• Primary Examiner(s): Cunningham, Terry D.
• Assistant Examiner(s): TRA, ANH QUAN
• Application Number:
  US09/995,639
• Publication Number:
  US 20030098742A1
• Time in Patent Office: 740 Days
• Field of Search: 327/311, 327/551, 327/553, 327/554, 327/545, 327/558, 333/312-316
• US Class Current: 327/554
• CPC Class Codes: H02H 9/001 limiting speed of change of electric quantities, e.g. soft switching on or off progressive control of electronic switches for eliminating interferences H03K17/16
• CPC Class Codes: H03K 17/16 Modifications for eliminating interference voltages or currents

Abstract

A method reduces noise resulting from a current surge in a circuit. A plurality of loading elements, parallel with the circuit being protected, are connected sequentially and disconnected. The connection of the loading elements results in a ramping up of current through the circuit without a sudden surge. In a preferred embodiment, an apparatus for slowing a current change in a circuit is described. The apparatus comprises a plurality of loading elements placed in parallel with the circuit, each of the elements providing a path for current flow, and a control circuit for selectively opening or closing at least one of said paths to prevent or enable current flow through the at least one of the paths.

Claims

1. A method of reducing noise resulting from a current surge in a circuit, said method comprising:

sequentially connecting a plurality of loading elements in parallel with the circuit in response to a current surge; and

disconnecting the loading elements, wherein a connection of each parallel loading element creates a path for current flow and a disconnection removes the current flow paths.

2. The method of claim 1 wherein said loading elements are connected during a clock cycle.

3. The method of claim 1 wherein said loading elements are connected during at least one of successive clock cycles and alternating clock cycles.

4. The method of claim 1 wherein said loading elements are connected during fractional clock cycles.

5. The method of claim 1 wherein said step of sequentially connecting the plurality of loading elements comprises increasing the current flow through said plurality of loading elements.

6. The method of claim 1 wherein said step of disconnecting the loading elements comprises sequentially disconnecting the loading elements.

7. The method of claim 1 wherein said loading elements are capacitors.

8. The method of claim 1 wherein said elements are disconnected simultaneously.

17. The method of claim 1, wherein said step of disconnecting the loading elements comprises sequentially disconnecting the loading elements.

9. An apparatus for slowing a current change in a circuit, the apparatus comprising:

a plurality of loading elements placed in parallel with the circuit, each of the elements providing a path for current flow; and

a control circuit for selectively sequentially opening or closing at least one of said paths to prevent or enable current flow through the at least one of said paths, wherein said control circuit is configured to open the at least one path during a clock cycle.

12. The apparatus of claim 9 wherein said control circuit is configured to decrease the current flow to the circuit by decreasing the number of the at least one of said paths being opened.

13. The apparatus of claim 9 wherein said plurality of paths is four.

14. The apparatus of claim 9 wherein said loading elements are capacitors.

15. The apparatus of claim 9 wherein said control circuit is configured to sequentially close the at least one of said paths in response to the current change being detected.

10. An apparatus for slowing a current change in a circuit, the apparatus comprising:

a plurality of loading elements placed in parallel with the circuit, each of the elements providing a path for current flow; and

a control circuit for selectively sequentially opening or closing at least one of said paths to prevent or enable current flow through the at least one of said paths, wherein said control circuit is configured to open the at least one path by at least one of successive clock cycles and alternating clock cycles.

11. An apparatus for slowing a current change in a circuit, the apparatus comprising:

a plurality of loading elements placed in parallel with the circuit, each of the elements providing a path for current flow; and

a control circuit for selectively sequentially opening or closing at least one of said paths to prevent or enable current flow through the at least one of said paths, wherein said control circuit is configured to open the at least one path by fractional clock cycles.

16. A circuit for decreasing noise resulting from current surges, said circuit comprising:

a first node;

a second node;

a circuit block connected between the first node and the second node; and

a ramp loading circuit connected between the first node and the second node wherein said ramp loading circuit comprises;

a plurality of loading elements placed in parallel with the circuit block, each of the elements providing a path for current flow; and

a control circuit for selectively sequentially opening or closing at least one of said paths to prevent or enable current flow through the at least one of said paths, wherein said control circuit is configured to open the at least one of said paths during a clock cycle.

18. A method of reducing noise in a circuit, said method comprising:

determining whether a current surge is being delivered to the circuit; and

connecting a plurality of loading elements sequentially in parallel with the circuit to decrease delivery of a current flow of the current surge to the circuit.

19. The method according to claim 18, wherein said step of connecting the plurality of loading elements comprises incrementally increasing the current flow to the circuit.

20. The method according to claim 18, wherein said step of connecting the plurality of loading elements comprises sequentially connecting the plurality of loading elements during successive clock cycles.

21. The method according to claim 18, further comprising:

disconnecting the plurality of loading elements from the circuit.

22. The method according to claim 18, wherein said step of disconnecting the plurality of loading elements comprises disconnecting the plurality of loading elements sequentially.

23. The method according to claim 22, wherein said step of disconnecting the plurality of loading elements sequentially from the circuit comprises sequentially disconnecting the plurality of loading elements during successive clock cycles.

24. An apparatus for slowing a current change in a circuit, the apparatus comprising:

means for determining whether a current surge is being delivered to the circuit; and

means for incrementally increasing delivery of a current flow from the current surge to the circuit.

25. The apparatus according to claim 24, wherein the means for incrementally increasing delivery of the current flow comprises sequentially increasing the current flow to a plurality of loading element.

26. The apparatus according to claim 24, further comprising:

means for incrementally decreasing delivery of the current flow to the circuit.