Ring based impedance control of an output driver

• US 7,889,014 B1
• Filed: 11/20/2007
• Issued: 02/15/2011
• Est. Priority Date: 11/04/2004
• Status: Expired due to Fees

• Current Assignee: Intellectual Ventures Funding LLC (Intellectual Ventures LLC)
• Original Assignee: Intellectual Ventures Funding LLC (Intellectual Ventures LLC)
• Inventors: Stoiber, Steven T., Siu, Stuart
• Primary Examiner(s): Pascal; Robert
• Assistant Examiner(s): Goodley; James E
• Application Number:
  US11/986,337
• Time in Patent Office: 1,183 Days
• Field of Search: 331/46, 331/57, 331/74, 331/176
• US Class Current: 331/74
• CPC Class Codes: H03K 19/0005 Modifications of input or output impedance
• CPC Class Codes: H03K 2005/00143 Avoiding variations of delay due to temperature
• CPC Class Codes: H03K 3/0315 Ring oscillators

Abstract

One embodiment in accordance with the invention is a method that can include utilizing a ring oscillator module to determine a process corner of an integrated circuit as fabricated that includes the ring oscillator module. The impedance of an output driver of the integrated circuit can be altered based on the process corner of the integrated circuit as fabricated.

Claims

1. A method comprising:

determining an operating parameter of an integrated circuit based on a first input from an NFET ring oscillator and a second input from a PFET ring oscillator, wherein the integrated circuit includes an output driver; and

altering an output impedance of the output driver based on the operating parameter, wherein said determining the operating parameter and said altering the output impedance are independent of a load value, wherein the NFET ring oscillator comprises NMOS transistors and excludes PMOS transistors and wherein the PFET ring oscillator comprises PMOS transistors and excludes NMOS transistors.

2. The method of claim 1, wherein the operating parameter is associated with a process corner of the integrated circuit.

3. The method of claim 2, wherein the process corner is associated with a voltage and a temperature of the integrated circuit.

4. The method of claim 1 further comprising:

determining a plurality of operating parameters based on an input from a plurality of ring oscillators, wherein the plurality of operating parameters are associated with a respective ring oscillator of the plurality of ring oscillators; and

altering the output impedance of the output driver based on the plurality of operating parameters.

5. The method of claim 4, wherein the plurality of operating parameters comprise an NFET process corner and a PFET process corner.

6. An apparatus comprising:

a plurality of ring oscillators, wherein the ring oscillators include an NFET ring oscillator and a PFET ring oscillator; and

at least one component coupled to the plurality of ring oscillators, wherein the at least one component is configured to determine an operating parameter of an integrated circuit based on a first input from the NFET ring oscillator and a second input from the PFET ring oscillator, wherein the integrated circuit includes an output driver, wherein the at least one component is further configured to alter an output impedance of the output driver based on the operating parameter, and wherein the at least one component is further configured to determine the operating parameter and to alter the output impedance independently of a load value, wherein the NFET ring oscillator comprises NMOS transistors and excludes PMOS transistors and wherein the PFET ring oscillator comprises PMOS transistors and excludes NMOS transistors.

7. The apparatus of claim 6, wherein the operating parameter is associated with a process corner of the integrated circuit.

8. The apparatus of claim 7, wherein the process corner is associated with a voltage and a temperature of the integrated circuit.

9. The apparatus of claim 6, wherein the operating parameter comprises an NFET process corner.

10. The apparatus of claim 6, wherein the operating parameters comprises a PFET process corner.

11. A device comprising:

an integrated circuit including;

an output driver; and

a control component coupled to the output driver, wherein the control component includes;

a plurality of ring oscillators, wherein the ring oscillators include an NFET ring oscillator and a PFET ring oscillator; and

at least one component coupled to the plurality of ring oscillators, wherein the at least one component is configured to determine an operating parameter of the integrated circuit based on a first input from the NFET ring oscillator and a second input from the PFET ring oscillator, wherein the at least one component is further configured to alter an output impedance of the output driver based on the operating parameter, and wherein the at least one component is further configured to determine the operating parameter and to alter the output impedance independently of a load value, wherein the NFET ring oscillator comprises NMOS transistors and excludes PMOS transistors and wherein the PFET ring oscillator comprises PMOS transistors and excludes NMOS transistors.

12. The device of claim 11, wherein the operating parameter is associated with a process corner of the integrated circuit.

13. The device of claim 12, wherein the process corner is associated with a voltage and a temperature of the integrated circuit.

14. The device of claim 11, wherein the operating parameter comprises an NFET process corner.

15. The device of claim 11, wherein the operating parameters comprises a PFET process corner.

16. A system comprising:

means for determining an operating parameter of an integrated circuit based on a first input from an NFET ring oscillator and a second input from a PFET ring oscillator, wherein the integrated circuit includes an output driver; and

means for altering an output impedance of the output driver based on the operating parameter, wherein the means for determining the operating parameter and the means for altering the output impedance operate independently of a load value, wherein the NFET ring oscillator comprises NMOS transistors and excludes PMOS transistors and wherein the PFET ring oscillator comprises PMOS transistors and excludes NMOS transistors.

17. The system of claim 16, wherein the operating parameter is associated with a process corner of the integrated circuit.

18. The system of claim 17, wherein the process corner is associated with a voltage and a temperature of the integrated circuit.

19. The system of claim 16,

wherein the operating parameter comprises an NFET process corner.

20. The system of claim 16, wherein the operating parameters comprises a PFET process corner.

21. An integrated circuit comprising:

a plurality of ring oscillators, wherein the ring oscillators include an NFET ring oscillator and a PFET ring oscillator;

an output driver; and

at least one component coupled to the plurality of ring oscillators and the output driver, wherein the at least one component is configured to determine an operating parameter of the integrated circuit based on a first input from the NFET ring oscillator and a second input from the PFET ring oscillator, wherein the at least one component is further configured to alter an output impedance of the output driver based on the operating parameter, and wherein the at least one component is further configured to determine the operating parameter and to alter the output impedance independently of a load value, wherein the NFET ring oscillator comprises NMOS transistors and excludes PMOS transistors and wherein the PFET ring oscillator comprises PMOS transistors and excludes NMOS transistors.

22. The integrated circuit of claim 21 further comprising:

a plurality of measurement components coupled to the plurality of ring oscillators, wherein the measurement components are configured to measure a respective oscillation frequency for a respective ring oscillator from the plurality of ring oscillators.

23. The integrated circuit of claim 21, wherein the at least one component is implemented using at least one hardware component.

24. The integrated circuit of claim 21, wherein the at least one component is implemented using at least one software component.

25. The integrated circuit of claim 21, wherein the output driver comprises a pull-up structure and a pull-down structure.

26. The integrated circuit of claim 21, wherein the operating parameter is associated with a process corner of the integrated circuit.

27. The integrated circuit of claim 26, wherein the process corner is associated with a voltage and a temperature of the integrated circuit.