Ring based impedance control of an output driver

• US 8,624,680 B2
• Filed: 02/15/2011
• Issued: 01/07/2014
• Est. Priority Date: 11/04/2004
• Status: Active Grant

• Current Assignee: Steven T. Stoiber, Stuart Siu
• Original Assignee: Steven T. Stoiber, Stuart Siu
• Inventors: Stoiber, Steven T., Siu, Stuart
• Primary Examiner(s): Johnson, Ryan
• Application Number:
  US13/028,112
• Publication Number:
  US 20120038427A1
• Time in Patent Office: 1,057 Days
• Field of Search: 331/57, 331/46, 331/44, 331/74, 331/176
• US Class Current: 331/57
• 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

In one embodiment, there 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 using a first input from an NFET ring oscillator and a second input from a PFET ring oscillator, wherein the first input comprises an NFET oscillating frequency that is independent of PFET-type devices, and wherein the second input comprises a PFET oscillating frequency that is independent of NFET-type devices; and

altering an output impedance of an output driver included in the integrated circuit using the operating parameter.

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 using inputs from the NFET ring oscillator and the PFET ring oscillator; and

altering the output impedance of the output driver using 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. The method of claim 1, wherein the NFET ring oscillator comprises NFET transistors and excludes PFET transistors, and wherein the PFET ring oscillator comprises PFET transistors and excludes NFET transistors.

7. 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 operable to determine an operating parameter of an integrated circuit using a first input from the NFET ring oscillator and a second input from the PFET ring oscillator, wherein the first input comprises an NFET oscillating frequency that is independent of PFET-type devices, wherein the second input comprises a PFET oscillating frequency that is independent of NFET-type devices, and wherein the at least one component is further operable to alter an output impedance of an output driver included in the integrated circuit using the operating parameter.

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

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

10. The apparatus of claim 7, wherein the operating parameter comprises an NFET process corner.

11. The apparatus of claim 7, wherein the operating parameter comprises a PFET process corner.

12. The apparatus of claim 7, wherein the NFET ring oscillator comprises NFET transistors and excludes PFET transistors, and wherein the PFET ring oscillator comprises PFET transistors and excludes NFET transistors.

13. 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 using a first input from the NFET ring oscillator and a second input from the PFET ring oscillator, wherein the first input comprises an NFET oscillating frequency that is independent of PFET-type devices, wherein the second input comprises a PFET oscillating frequency that is independent of NFET-type devices, and wherein the at least one component is further configured to alter an output impedance of the output driver using the operating parameter.

14. The integrated circuit of claim 13, 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.

15. The integrated circuit of claim 13, wherein the output driver comprises a pull-up structure and a pull-down structure.

16. The integrated circuit of claim 13, wherein the operating parameter is associated with a process corner of the integrated circuit.

17. The integrated circuit of claim 16, wherein the process corner is associated with a voltage and a temperature of the integrated circuit.

18. The integrated circuit of claim 13, wherein the operating parameter comprises an NFET process corner.

19. The integrated circuit of claim 13, wherein the operating parameter comprises a PFET process corner.

20. The integrated circuit of claim 13, wherein the NFET ring oscillator comprises NFET transistors and excludes PFET transistors, and wherein the PFET ring oscillator comprises PFET transistors and excludes NFET transistors.