Method and apparatus for controlling supply voltage levels for integrated circuits

• US 6,737,925 B1
• Filed: 09/24/2002
• Issued: 05/18/2004
• Est. Priority Date: 09/24/2002
• Status: Active Grant

• Current Assignee: Xilinx, Inc. (Advanced Micro Devices, Inc.)
• Original Assignee: Xilinx, Inc. (Advanced Micro Devices, Inc.)
• Inventors: Lesea, Austin H., Logue, John D., Percey, Andrew R.
• Primary Examiner(s): Pascal, Robert
• Assistant Examiner(s): Chang, Joseph
• Application Number:
  US10/253,275
• Time in Patent Office: 602 Days
• Field of Search: 331/2, 331/113.R, 331/185, 365/227
• US Class Current: 331/2
• CPC Class Codes: H03L 7/00 Automatic control of frequency or phase; Synchronisation

Abstract

Method and apparatus for providing a controlled voltage to an integrated circuit is described. A first frequency value indicative of a first voltage is compared to a second frequency value indicative of a second voltage. The second frequency value is adjusted by the second voltage until the second frequency value is within a range of the first frequency value. Additionally, the second voltage may be adjusted to maintain the second frequency value within the range.

Claims

1. A method for controlling voltage provided to an integrated circuit, comprising:

generating a first frequency value responsive to a first voltage;

generating a second frequency value responsive to a second voltage; and

adjusting the second voltage until the second frequency value is within range of the first frequency value; and

powering the integrated circuit with the second voltage.

2. The method of claim 1, wherein the generating of the first frequency value comprises associating the first frequency value with a frequency from a voltage controlled oscillator controlled by the first voltage.

3. The method of claim 2, further comprising:

storing the first frequency value; and

comparing the second frequency value to the first frequency value stored.

4. The method of claim 2, further comprising comparing the second frequency value to a stored first frequency value.

5. The method of claim 4, wherein powering the integrated circuit with the second voltage occurs when the second frequency value is within range of the stored first frequency value.

6. A method for controlling voltage provided to an integrated circuit, comprising:

generating a first frequency count indicative of a first voltage;

storing the first frequency count;

generating a second frequency count responsive to a second voltage;

comparing the second frequency count to the first frequency count stored; and

adjusting the second frequency count using the second voltage so that the second frequency count is within a frequency range of the first frequency count stored.

7. The method of claim 6, wherein the generating of the first frequency count comprises setting a voltage control oscillator with the first voltage to provide a first frequency to be counted.

8. The method of claim 6, wherein the storing of the first frequency comprises:

counting the first frequency; and

storing a first frequency count value.

9. The method of claim 6, wherein the generating of the second frequency comprises controlling a voltage control oscillator with the second voltage to provide the second frequency count.

10. The method of claim 6, wherein the comparing comprises:

generating a first binary value for the first frequency count stored; and

comparing the first binary value to a second binary value indicative of the second frequency count to determine a difference.

11. The method of claim 10, further comprising when the first binary value is outside a binary range of the second binary value, adjusting the second voltage until the second binary value is within the binary range.

12. The method of claim 6, wherein the adjusting of the second voltage comprises increasing and decreasing the second voltage until the second frequency count is within the frequency range of the first frequency count.

13. A method for controlling a voltage supply configured to power at least a portion of at least one integrated circuit, comprising:

converting a first voltage to a first frequency value;

converting an output voltage of the voltage supply to a second frequency value, wherein the second frequency value varies as a function of the output voltage;

comparing the first frequency value to the second frequency value;

adjusting the output voltage until the first frequency value and the second frequency value are within a range; and

maintaining the second frequency value within the range of the first frequency value.

14. The method of claim 13, wherein the converting of the first voltage comprises measuring the first frequency to determine a value.

15. The method of claim 13, wherein the converting of the output voltage comprises measuring the second frequency to determine a value.

16. The method of claim 13, wherein the comparing comprises determining a difference between the second frequency value and the first frequency value.

17. The method of claim 13, wherein the adjusting comprises increasing and decreasing the output voltage to vary the second frequency value.

18. An apparatus to control voltage, comprising:

a voltage controlled oscillator;

a first voltage supply having a first voltage output;

a second voltage supply having a second voltage output;

the first voltage output and second voltage output selectively coupled to the voltage controlled oscillator, the voltage controlled oscillator having an output frequency responsive to a selected one of the first voltage output and the second voltage output;

a voltage control loop circuit coupled to the voltage controlled oscillator and configured to;

compare a first frequency value of the voltage controlled oscillator associated with the first voltage output with a second frequency value associated with second voltage output; and

adjust the second voltage output until the second frequency value is within a range of the first frequency value.

19. The apparatus of claim 18, wherein the voltage control loop circuit comprises a frequency counting circuit configured to count the output frequency.

20. The apparatus of claim 18, wherein the voltage control circuit comprises a frequency measurement storage circuit to store the first frequency value.

21. The apparatus of claim 18, wherein the voltage control circuit comprises a frequency comparison circuit configured to measure a first frequency associated with the first frequency value and a second frequency associated with the second frequency value and to provide a voltage control signal to the second supply indicative of a difference between the first frequency value and the second frequency value.

22. The apparatus of claim 18, wherein the frequency comparison circuit comprises a frequency measurement storage circuit configured to store the first frequency value as a first binary value.

23. The apparatus of claim 18, wherein the frequency comparison circuit further comprises a binary comparison circuit configured to compare the first binary value to a second binary value indicative of the second frequency value.