Dynamic voltage scaling

• US 7,739,531 B1
• Filed: 03/04/2005
• Issued: 06/15/2010
• Est. Priority Date: 03/04/2005
• Status: Active Grant

• Current Assignee: NVIDIA Corporation
• Original Assignee: NVIDIA Corporation
• Inventors: Krishnan, Musaravakkam Samaram
• Primary Examiner(s): CHEN, TSE W
• Application Number:
  US11/073,229
• Time in Patent Office: 1,929 Days
• Field of Search: 713300-340
• US Class Current: 713/322
• CPC Class Codes: G06F 1/3203 Power management, i.e. event-based initiation of a power-saving mode
• CPC Class Codes: Y02D 10/00 Energy efficient computing, e.g. low power processors, power management or thermal management

Abstract

An apparatus and method for dynamically controlling the maximum frequency of operation of the IC is provided. The invention optimizes power consumption in a device by measuring a current maximum frequency of operation and adjusting IC operating voltage to provide a desired maximum operating frequency. The invention provides an apparatus and method for controlling multiple voltages in an IC to independently adjust maximum operating frequencies for a plurality of separate portions of the IC. The invention may equally be applied to a group of ICs. The invention further provides a method for calibrating an IC. Thus, the apparatus facilitates the operation of an IC at a minimum voltage for a selected maximum frequency, thereby minimizing power consumption overall a wide range of operating frequencies.

Claims

1. A method for dynamically controlling maximum operating frequency of an integrated circuit (IC) using one or more integral oscillators, the method comprising:

measuring current frequency of operation for certain of the one or more oscillators;

identifying an operating point of the IC based on the current frequency and stored information, the stored information including a current voltage; and

adjusting one or more operating voltages of the IC to obtain a desired frequency of operation of the oscillator,

wherein each oscillator comprises a plurality of logic gates, the plurality of logic gates forming a ring and being positioned on the IC to provide a representative indication of the operating point, wherein the IC comprises a second circuit that comprises a gate that is unused by said second circuit, wherein said gate is utilized as a logic element of at least one of the one or more oscillators to monitor operating conditions of said second circuit.

2. The method of claim 1, wherein the second circuit is an arithmetic logic unit (ALU) of the IC.

3. The method of claim 2, wherein the logic gates of at least one oscillator are dispensed throughout the IC.

4. The method of claim 2, wherein the logic gates of at least one oscillator are located proximately to an area of interest on the IC.

5. The method of claim 1, wherein a logic gate of at least one oscillator is constructed using a cell library identical to a library used to construct the second circuit.

6. The method of claim 1, wherein the IC includes two or more portions, each portion supplied by an associated different operating voltage, and wherein the adjusting the operating voltage includes:

identifying an operating point for each of the portions; and

adjusting each of the different operating voltages independently to obtain a desired frequency of operation of an oscillator located in a position associated with the each voltage.

7. The method of claim 1, wherein the IC includes two or more oscillators, and wherein the identifying operating voltages includes:

identifying operating points for each of the oscillators; and

determining a maximum frequency of operation of the IC using information including information related to the operating points for each of the oscillators.

8. The method of claim 1, wherein the identifying an operating point includes obtaining a temperature of the IC from a temperature sensor.

9. The method of claim 1, wherein the identifying an operating point includes indexing characterization information using current operating voltage and the current frequency to obtain the operating point.

10. The method of claim 9, wherein the adjusting operating voltage includes indexing the characterization information based on the current operating point and the desired frequency to obtain a next operating voltage.

11. The method of claim 9, wherein the characterization information is obtained by recording frequencies of operation of the one or more oscillators for a plurality of combinations of operating voltage and temperature.

12. The method of claim 9, wherein the characterization information is stored on the IC.

13. The method of claim 9, wherein the characterization information is stored external to the IC.

14. The method of claim 9, further comprising the recording the current frequency and the current operating point in the characterization information.

15. The method of claim 1, wherein the desired information is determined by software.

16. The method of claim 1, wherein the desired information is determined by hardware.

17. An apparatus for optimizing power consumption and frequency of operation in an IC, the apparatus comprising:

a ring oscillator including a plurality of logic gates located on the IC, wherein the IC comprises a second circuit that comprises a gate that is unused by said second circuit, wherein said gate is utilized as a logic element of the ring oscillator to monitor operating conditions of said second circuit;

a counter for measuring cycles of the ring oscillator in a predetermined interval;

a variable voltage source providing voltages to the IC, wherein voltage level is set to obtain a desired frequency of operation, wherein

the measured cycles are compared to stored values to obtain a current operating point, and

the voltage level is set based on the current operating point.

18. The apparatus of claim 17, wherein the stored values include calibration information relating frequency of oscillation of the ring oscillator to a plurality of characteristics including operating temperature and operating voltage.

19. The apparatus of claim 17, wherein the second circuit is an arithmetic logic unit (ALU) of the IC.

20. The apparatus of claim 17, wherein the stored values are maintained external to the IC.

21. An apparatus according to claim 17, further comprising one or more additional ring oscillators, wherein the additional oscillators are configured to obtain operating points for different portions of the IC.

22. An apparatus according to claim 21, wherein the different portions include portions comprising elements constructed from a common cell library.

23. An apparatus according to claim 21, wherein the different portions include portions comprising elements constructed from different cell libraries.

24. An apparatus according to claim 21, wherein the different portions include portions contained within a selected area of the IC.

25. An apparatus according to claim 21, wherein the different portions include portions sharing a common power supply.

26. A method for characterizing an IC, the method comprising:

setting a voltage of operation for the IC;

after said setting, measuring frequency of operation of an oscillator integral to the IC, the oscillator comprises a plurality of logic gates, wherein the IC comprises a second circuit that comprises a gate that is unused by said second circuit, wherein said gate is a logic element of the oscillator that monitors operating conditions of said second circuit;

obtaining a temperature of the IC;

recording, in a table, the voltage, temperature and frequency; and

iteratively repeating the setting, measuring, obtaining and recording for a desired range of voltage and temperatures.