Integrated circuit design using dynamic voltage scaling

1. A method for designing an integrated circuit (“IC”), comprising:

(a) designing the IC to meet a voltage dependent frequency specification, the IC design including feedback circuitry for controlling a power supply voltage to a fabricated instance of the IC design;

(b) characterizing a fabrication process for corner lots for the IC design at a range of power supply voltage levels achievable by the feedback circuitry; and

(c) validating the IC design against the fabrication process if the frequency specification is achievable for essentially all instances of the IC design fabricated in accordance with the fabrication process by adjustment of the power supply voltage levels applied to such instances of the IC design within the range of the power supply voltage levels achievable by the feedback circuitry, and repeating (b) when essentially all fabricated instances of the IC design do not meet the frequency specification, wherein the feedback circuitry in each IC resulting from the IC design is operable to respectively adjust the power supply voltage of each IC resulting from the IC design by reducing the power supply voltage if the IC is from a fast corner lot and increasing power supply voltage if the IC is from a slow corner lot.

2. The method of claim 1 , wherein the feedback circuitry comprises:

(a) at least one ring oscillator distributed on each IC resulting from the IC design for measurement of local voltage dependent characteristics, each such ring oscillator outputting a corresponding voltage dependent frequency signal;

(b) a comparator for comparison of at least one voltage dependent frequency signal to a selected reference frequency and for outputting a signal that reflects the difference in frequency between at least one ring oscillator and the selected reference frequency; and

(c) a closed-loop feedback control circuit for adjusting the power supply voltage to an IC of the IC design as a function of the comparator output signal.

3. The method of claim 1 , wherein the feedback circuitry comprises:

(a) means for measuring local voltage dependent die characteristics;

(b) means for comparing the measured characteristics to a standard; and

(c) means for responding to the comparison for feedback control of the power supply voltage for an IC resulting from the IC design.

4. A method for designing an integrated circuit (“IC”), comprising:

(a) designing the IC to meet a voltage dependent frequency specification, the IC design including feedback circuitry for controlling a power supply voltage to a fabricated instance of the IC design;

(b) characterizing a fabrication process by means of corner lots for the IC design at a range of power supply voltage levels achievable by the feedback circuitry; and

(c) validating the IC against the fabrication process if the frequency specification is achievable in all corners of the corner lots for essentially all ICs resulting from the IC design fabricated in accordance with the fabrication process by adjustment of the power supply voltage levels applied to such ICs resulting from the IC design within the range of the power supply voltage levels achievable by the feedback circuitry, and repeating (b) when essentially all fabricated instances of the IC design do not meet the frequency specification, wherein feedback circuitry in each IC resulting from the IC design is operable to respectively adjust the power supply voltage of each IC resulting from the IC design by reducing the power supply voltage if the IC is from a fast corner lot and increasing power supply voltage if the IC is from a slow corner lot.

5. The method of claim 4 , wherein the feedback circuitry comprises:

(a) at least one ring oscillator distributed on an IC resulting from the IC design for measurement of local voltage dependent characteristics, each such ring oscillator outputting a corresponding voltage dependent frequency signal;

(b) a comparator for comparison of at least one voltage dependent frequency signal to a selected reference frequency and for outputting a signal that reflects the difference in frequency between at least one ring oscillator and the selected reference frequency; and

(c) a closed-loop feedback control circuit for adjusting the power supply voltage to the IC resulting from the IC design as a function of the comparator output signal.

6. The method of claim 4 wherein the feedback circuitry comprises:

(a) means for measuring local voltage dependent die characteristics;

(b) means for comparing the measured characteristics to a standard; and

(c) means for responding to the comparison for feedback control of the power supply voltage for an IC resulting from the IC design.

7. An integrated circuit (“IC”) prepared by a process comprising:

(a) designing the IC to meet a voltage dependent frequency specification, the IC design including feedback circuitry for controlling a power supply voltage to an IC resulting from the IC design;

(b) characterizing a fabrication process for the IC design at a range of power supply voltage levels achievable by the feedback circuitry;

(c) validating the IC design against the fabrication process if the frequency specification is achievable for essentially all ICs resulting from the IC design fabricated in accordance with the fabrication process by adjustment of the power supply voltage levels applied to such ICs resulting from the IC design within the range of the power supply voltage levels achievable by the feedback circuitry, and repeating (b) when essentially all fabricated instances of the IC design do not meet the frequency specification, wherein feedback circuitry is operable to adjust the power supply voltage of the IC by increasing the power supply voltage if the IC is from a slow corner lot and decreasing the power supply voltage if the IC is from a fast corner lot.

8. The integrated circuit (“IC”) of claim 7 , wherein the feedback circuitry comprises:

(a) at least one ring oscillator distributed on the IC for measurement of local voltage dependent characteristics, each such ring oscillator outputting a corresponding voltage dependent frequency signal;

(b) a comparator for comparison of at least one voltage dependent frequency signal to a selected reference frequency and for outputting a signal that reflects the difference in frequency between at least one ring oscillator and the selected reference frequency; and

(c) a closed-loop feedback control circuit for adjusting the power supply voltage to the IC as a function of the comparator output signal.

9. The integrated circuit (“IC”) of claim 7 , wherein the feedback circuitry comprises:

(a) means for measuring local voltage dependent die characteristics;

(b) means for comparing the measured characteristics to a standard; and

(c) means for responding to the comparison for feedback control of the power supply voltage for the IC.

10. An integrated circuit (“IC”) prepared by a process comprising:

(a) designing the IC to meet a voltage dependent frequency specification, the IC design including feedback circuitry for controlling a power supply voltage to an IC resulting from the IC design;

(b) characterizing a fabrication process by means of corner lots for the IC design at a range of power supply voltage levels achievable by the feedback circuitry; and

(c) validating the IC against the fabrication process if the frequency specification is achievable in all corners of the corner lots for essentially all ICs resulting from the IC design fabricated in accordance with the fabrication process by adjustment of the power supply voltage levels applied to such ICs resulting from the IC design within the range of the power supply voltage levels achievable by the feedback circuitry, and repeating (b) when essentially all fabricated instances of the IC design do not meet the frequency specification, wherein the feedback circuitry is operable to adjust the power supply voltage of the IC using the feedback circuitry by reducing the power supply voltage if the IC is from a fast corner lot and increasing power supply voltage if the IC is from a slow corner lot.

11. The integrated circuit (“IC”) of claim 10 , wherein the feedback circuitry comprises:

(a) at least one ring oscillator distributed on the IC for measurement of local voltage dependent characteristics, each such ring oscillator outputting a corresponding voltage dependent frequency signal;

(b) a comparator for comparison of at least one voltage dependent frequency signal to a selected reference frequency and for outputting a signal that reflects the difference in frequency between at least one ring oscillator and the selected reference frequency; and

(c) a closed-loop feedback control circuit for adjusting the power supply voltage to the IC as a function of the comparator output signal.

12. The integrated circuit (“IC”) of claim 10 , wherein the feedback circuitry comprises:

(a) means for measuring local voltage dependent die characteristics;

(b) means for comparing the measured characteristics to a standard; and

(c) means for responding to the comparison for feedback control of the power supply voltage for the IC.

13. An integrated circuit (“IC”) including feedback circuitry for controlling a power supply voltage to the IC to meet a voltage dependent frequency specification, wherein the adjustment of the power supply voltage is determined by (1) characterization of a fabrication process for the IC at a range of power supply voltage levels achievable by the feedback circuitry, and (2) validation of the design of the IC against the fabrication process if the voltage dependent frequency specification is achievable for essentially all instances of the IC fabricated in accordance with the fabrication process and repeating (1) when essentially all fabricated instances of the IC design do not meet the voltage dependent frequency specification, wherein the feedback circuitry is operable to adjust power supply voltage levels in each instance of the IC within the range of the power supply voltage levels achievable by the feedback circuitry by reducing the power supply voltage if the IC is from a fast corner lot and increase the power supply voltage if the IC is from a slow corner lot.

14. The integrated circuit (“IC”) of claim 13 , wherein the feedback circuitry comprises:

(a) at least one ring oscillator distributed on the IC for measurement of local voltage dependent characteristics, each such ring oscillator outputting a corresponding voltage dependent frequency signal;

(b) a comparator for comparison of at least one voltage dependent frequency signal to a selected reference frequency and for outputting a signal that reflects the difference in frequency between at least one ring oscillator and the selected reference frequency; and

(c) a closed-loop feedback control circuit for adjusting the power supply voltage to the IC as a function of the comparator output signal.

15. The integrated circuit (“IC”) of claim 13 , wherein the feedback circuitry comprises:

(a) means for measuring local voltage dependent die characteristics;

(b) means for comparing the measured characteristics to a standard; and

(c) means for responding to the comparison for feedback control of the power supply voltage for the IC.