Dynamic power noise event counter

• US 8,013,669 B2
• Filed: 10/27/2009
• Issued: 09/06/2011
• Est. Priority Date: 10/27/2009
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Takayanagi, Toshinari, Suzuki, Shingo
• Primary Examiner(s): Hiltunen; Thomas J
• Application Number:
  US12/606,534
• Publication Number:
  US 20110096891A1
• Time in Patent Office: 679 Days
• Field of Search: 327/143
• US Class Current: 327/544
• CPC Class Codes: H03K 19/00369 Modifications for compensating variations of temperature, supply voltage or other physical parameters

Abstract

An apparatus and method for detecting noise in a power supply voltage. A circuit may include a voltage generation unit coupled to receive a power supply voltage, and a detection unit. The voltage generation unit may generate first and second voltages using the power supply voltage, and may vary the relationship therebetween responsive to fluctuations in the power supply voltage. A detection unit may detect the variations in the relationship between the first and second voltages that result from fluctuations in the power supply voltage. Responsive to detecting the variations, the detection unit may generate pulses to be provided to a counter. The counter may update a count value responsive to receiving pulses.

Claims

1. An apparatus comprising:

a voltage generation unit coupled to receive a power supply voltage, wherein the voltage generation unit is configured to generate first and second voltages responsive to the power supply voltage;

a detection unit coupled to receive the first and second voltages, wherein the detection unit is configured to detect power supply noise events based on values of the first and second voltages and to generate a count indicative of a number of power supply noise events; and

a power control unit coupled to receive the count from the detection unit and configured to change one or more parameters related to the power supply voltage responsive to receiving a count value exceeding a predetermined threshold value.

2. The apparatus as recited in claim 1, wherein the voltage generation unit includes first and second transistors each having respective gate terminals coupled to receive the power supply voltage, wherein the first transistor further includes a first terminal coupled to a first output node and wherein the second transistor further includes a second terminal coupled to a second output node, and wherein a width/length ratio of a channel of the first transistor is different from a width/length ratio of a channel of the second transistor.

3. The apparatus as recited in claim 2, wherein the voltage generation unit includes a filter capacitor coupled between the second output node and a ground node.

4. The apparatus as recited in claim 1, wherein the detection unit includes a differential amplifier coupled to receive the first voltage and the second voltage, wherein the differential amplifier is configured to generate pulses responsive to detected differences between the first voltage and the second voltage.

5. The apparatus as recited in claim 4, wherein the detection unit further includes a counter configured update the count responsive to the pulses generated by the differential amplifier.

6. A circuit comprising:

a first differential amplifier circuit, wherein the first differential amplifier circuit is coupled to receive a power supply voltage and is configured to generate first and second voltages responsive to a level of the power supply voltage;

a second differential amplifier circuit coupled to receive the first and second voltages, wherein the second differential amplifier circuit is configured to generate a pulse based on relative levels of the first voltage and the second voltage;

a pulse detection circuit configured to detect the pulse generated by the second differential amplifier, and further configured to generate a count indicative of a number of pulses received; and

a divider circuit coupled between the second differential amplifier and the pulse detection circuit, wherein the divider circuit is configured to cause the pulse detection circuit to increment M times for every N pulses, wherein M and N are integer values, and wherein N is greater than or equal to M.

7. The circuit as recited in claim 6, wherein the second differential amplifier is configured to generate the pulse responsive to the first voltage falling below the second voltage.

8. The circuit as recited in claim 6, wherein the second differential amplifier is configured to generate the pulse responsive to the first voltage becoming greater than the second voltage.

9. The circuit as recited in claim 6, wherein the first differential amplifier is configured to convey the first voltage on a first output and the second voltage on a second output, wherein the second output is coupled to a load circuit.

10. An integrated circuit comprising:

one or more noise monitoring units, wherein each of the one or more noise monitoring units includes;

a noise detection unit coupled to receive a power supply voltage and configured to vary at least one of a first and second output voltage based on the power supply voltage; and

an event detection unit coupled to receive the first and second output voltages, wherein the event detection unit is configured to detect a variation in the power supply voltage based on a variation of a relationship between the first and second output voltages, and further configured to generate a count value indicating a number of power supply variations detected; and

a power monitoring unit coupled to the event detection unit of each of the one or more noise monitoring units, wherein the power monitoring unit is configured to adjust one or more parameters related to the power supply voltage responsive to the counter value exceeding a predetermined counter threshold.

11. The integrated circuit as recited in claim 10, wherein the integrated circuit includes a plurality of noise monitoring units, and wherein the power monitoring unit is configured to generate a power noise map of the integrated circuit based on information received from the plurality of noise monitoring units.

12. The integrated circuit as recited in claim 10, wherein the integrated circuit includes at least one power gating switch and at least one core circuitry unit, wherein the power gating switch is configured to perform switching to alternately couple the power supply voltage to the core circuitry unit and decouple the power supply voltage from the core circuitry unit, and wherein power monitoring unit is configured to control a rate of said switching based on count values received from at least one of the one or more noise monitoring units.

13. The integrated circuit as recited in claim 10, wherein the noise detection unit of each of the one or more noise monitoring units includes:

a first differential amplifier coupled to the power supply voltage, wherein the first differential amplifier is configured to convey a first voltage on a first output and a second voltage on a second output; and

a filter coupled to the second output; and

wherein the event detection unit of each of the one or more noise monitoring units includes;

a second differential amplifier coupled to receive the first voltage on a first input and the second voltage on a second input, wherein the second differential amplifier is configured to generate a pulse responsive to a predetermined condition in a relationship between the first voltage and the second voltage; and

a counter configured to update the count value responsive to the second differential amplifier generating a predetermined number of pulses.

14. The integrated circuit as recited in claim 13, wherein the noise detection unit of each of the one or more noise monitoring units includes an enable input coupled to receive an enable signal, wherein the noise detection unit is configured to detect variation in the power supply voltage when the enable signal is active, and wherein the noise detection unit is further configured to ignore variations in the power supply voltage when the enable signal is inactive.

15. A method comprising:

generating a first voltage based on a power supply voltage;

generating a second voltage based on the power supply voltage;

responsive to a variations in the power supply voltage, generating corresponding pulses based on corresponding variations in a difference between the first voltage and the second voltage;

detecting the pulses;

providing a count value indicative of a number of a number of pulses detected; and

adjusting one or more parameters related to the power supply voltage responsive to the count value exceeding a predetermined threshold.

16. The method as recited in claim 15 further comprising generating a pulse when a level of the first voltage falls below a level of the second voltage.

17. The method as recited in claim 15 further comprising generating a pulse when a level of the first voltage become greater than a level of the second voltage.

18. The method as recited in claim 15 further comprising updating the count value responsive to receiving a predetermined number of pulses subsequent to a previous update of the count value.

19. The method as recited in claim 15 further comprising generating the first voltage and the second voltage to be at different levels when the power supply voltage is stable.

20. A noise detector comprising:

a first level shifter circuit coupled to receive a power supply voltage, wherein the first level shifter circuit is configured to provide a first voltage on a first output node based on the power supply voltage;

a second level shifter circuit coupled to receive the power supply voltage, wherein the second level shifter circuit is configured to provide a second voltage on a second output node based on the power supply voltage;

a filter coupled to the second output node;

a detector circuit coupled to receive the first voltage and the second voltage and configured to detect a noise event responsive to relative levels of the first and second voltages;

a counter configured to generate a count value based on a number of noise events detected by the detector circuit; and

a divider coupled between the detector circuit and the counter, wherein the divider is configured to cause the counter to increment M times for every N noise events detected by the detector, wherein M and N are integer values and wherein N is greater than or equal to M.

21. The noise detector as recited in claim 20, wherein the first level shifter circuit includes a first transistor having a gate terminal coupled to receive the power supply voltage, and a second transistor having a gate terminal coupled to receive the power supply voltage.

22. The noise detector as recited in claim 21, wherein the first transistor includes a first terminal coupled to a first output node and wherein the second transistor includes a second terminal coupled to a second output node, and wherein the second level shifter circuit includes a third transistor having a respective gate terminal coupled to the first output node and wherein the second level shifter includes a fourth transistor having a respective gate terminal coupled to the second output node, and wherein the third and fourth transistors include respective third and fourth terminals each coupled to a common node.

23. The noise detector as recited in claim 22, wherein the noise detector further includes a fifth transistor having a respective drain terminal coupled to the common node, a respective source terminal coupled to a ground node, and a respective gate terminal coupled to receive an enable signal.

24. The noise detector as recited in claim 21, wherein the first transistor has first channel width/length ratio and the second transistor has a second channel width/length ratio, wherein the first channel width/length ratio is different from the second channel width/length ratio.