Performance-temperature optimization by cooperatively varying the voltage and frequency of a circuit

• US 5,940,785 A
• Filed: 04/29/1996
• Issued: 08/17/1999
• Est. Priority Date: 04/29/1996
• Status: Expired due to Term

• Current Assignee: GlobalFoundries, Inc.
• Original Assignee: International Business Machines Corporation
• Inventors: Georgiou, Christos John, Larsen, Thor Arne, Kirkpatrick, Edward Scott
• Primary Examiner(s): ASSOUAD, PATRICK J
• Application Number:
  US08/639,586
• Time in Patent Office: 1,205 Days
• Field of Search: 364/557, 364/550, 364/571.03, 364/152, 364/528.34, 395/750.01, 395/750.03, 395/750.04, 395/750.05, 395/750.06, 395/750.07, 395/750.08, 361/103, 361/106, 330/289, 324/224, 331/176, 327/8, 327/113, 327/512, 327/544, 374/178, 374/182, 236/91 R, 236/91 D, 236/101 C, 455/574, 702/130, 702/132, 713/300, 713/322, 713/323, 713/324
• US Class Current: 702/132
• CPC Class Codes: G05D 23/1913 delivering a series of pulses
• CPC Class Codes: G05D 23/24 the sensing element having a resistance varying with temperature, e.g. a thermistor
• CPC Class Codes: G06F 1/206 comprising thermal management
• CPC Class Codes: G06F 1/3203 Power management, i.e. event-based initiation of a power-saving mode
• CPC Class Codes: G06F 1/324 by lowering clock frequency
• CPC Class Codes: G06F 1/3296 by lowering the supply or operating voltage
• CPC Class Codes: Y02D 10/00 Energy efficient computing, e.g. low power processors, power management or thermal management

Abstract

A system and method using thermal feedback to cooperatively vary a voltage and frequency of a circuit to control heating while maintaining synchronization. Preferably, on-chip thermal sensors are used for feedback. A system having features of the invention includes: a thermal sensor coupled to the circuit, the thermal sensor generating a temperature signal which is a function of a temperature associated with the functional unit; a temperature decoder having an input and an output, the input coupled to the thermal sensor for decoding the temperature signal; a comparator having one input coupled to the decoder for comparing a decoded temperature signal with a predetermined temperature threshold signal coupled to a second input, the comparator enabling a voltage/clock control signal as a function of the decoded temperature signal and the predetermined temperature threshold; an adjustable voltage regulator coupled to the voltage/clock control signal; and a clock selector coupled to the voltage/clock control signal; wherein the voltage regulator and the clock selector are adapted to cooperatively vary the voltage and the frequency of the circuit to a predetermined voltage-frequency pair, responsive to the voltage/clock control signal and switching factor means, coupled to the comparator, for varying the switching factor of the circuit, wherein the switching factor is the fraction of clock cycles that the circuit is dissipating power.

Claims

1. A method of using thermal feedback to cooperatively vary a voltage and a frequency applied to a synchronous circuit to control heating while maintaining synchronization, said method comprising the steps of:

generating a temperature signal which is a function of a temperature associated with the circuit;

comparing the temperature signal with a predetermined temperature threshold signal;

cooperatively varying the voltage and the frequency of the circuit to a predetermined voltage-frequency pair, responsive to said step of comparing; and

varying the switching factor of the circuit wherein the switching factor is a fraction of clock cycles that the circuit is dissipating power, responsive to said step of comparing.

2. A method as claimed in claim 1 wherein said step of cooperatively varying further comprises the step of:

controlling an adjustable voltage regulator which outputs the voltage and a clock selector which outputs the frequency, responsive to said comparing step.

3. A method as claimed in claim 1, further comprising the steps of:

generating a second temperature signal subsequent to the temperature signal; and

comparing the second temperature signal with the predetermined temperature threshold signal; and

cooperatively varying the voltage and the frequency of the circuit to a predetermined voltage-frequency pair, responsive to said step of comparing the second temperature signal.

4. A method as claimed in claim 1, wherein a plurality of circuits includes a plurality of functional units for processing data stored in a memory, further comprising the steps of:

generating the temperature signal for each functional unit and identifying a functional unit associated with the temperature signal;

generating a sequence of current source signals to an adjustable voltage regulator, responsive to said comparing step;

cooperatively varying the voltage and the frequency of the functional unit to a predetermined voltage-frequency pair, responsive to said step of comparing.

5. A method as claimed in claim 1, further comprising the steps of:

generating a temperature delay signal, responsive to said comparing step; and

wherein said step of varying the switching factor comprises reducing the switching factor as a function of the temperature delay signal.

6. A method as claimed in claim 4 wherein the functional units comprise one of a superscalar microprocessor and a distributed parallel processor and a digital signal processor.

7. A method of using thermal feedback to cooperatively vary a voltage and a frequency applied to a synchronous circuit to control heating while maintaining synchronization, wherein the circuit comprises a plurality of functional units for processing data in a data processing system, the method comprising the steps of:

generating a first temperature signal for a first functional unit and a second temperature signal for a second functional unit, each temperature signal being a function of a temperature associated with said each functional unit;

identifying the first functional unit and the second functional unit associated with said each temperature signal, responsive to said generating step;

comparing the first temperature signal with a first predetermined temperature threshold signal;

cooperatively varying the voltage and the frequency of the functional unit to a predetermined voltage-frequency pair, responsive to said step of comparing; and

varying the switching factor of the circuit wherein the switching factor is a fraction of clock cycles that the circuit is dissipating power, responsive to said step of comparing.

8. A system using thermal feedback to cooperatively vary a voltage and a frequency applied to a synchronous circuit to control heating while maintaining synchronization, said system comprising:

a thermal sensor coupled to the circuit, the thermal sensor generating a temperature signal which is a function of a temperature associated with the functional unit;

a temperature decoder having an input and an output, the input coupled to the thermal sensor for decoding the temperature signal;

a comparator having one input coupled to the decoder for comparing a decoded temperature signal with a predetermined temperature threshold signal coupled to a second input, the comparator enabling a voltage/clock control signal as a function of the decoded temperature signal and the predetermined temperature threshold;

an adjustable voltage regulator coupled to the voltage/clock control signal;

a clock selector coupled to the voltage/clock control signal;

wherein the voltage regulator and the clock selector are adapted to cooperatively vary the voltage and the frequency of the circuit to a predetermined voltage-frequency pair, responsive to the voltage/clock control signal; and

switching factor means for varying the switching factor of the circuit wherein the switching factor is a fraction of clock cycles that the circuit is dissipating power, wherein the switching factor means is coupled to the comparator.

9. A system as claimed in claim 8, wherein a plurality of circuits includes a plurality of functional units for processing data stored in a memory, comprising:

the thermal sensor generating the temperature signal for each functional unit; and

the temperature decoder including means for identifying a functional unit associated with the temperature signal;

wherein the voltage regulator and the clock selector are adapted to cooperatively vary the voltage and the frequency of the functional unit to a predetermined voltage-frequency pair, responsive to the voltage/clock control signal.

10. A system as claimed in claim 9 wherein the functional units comprise one of a superscalar microprocessor and a distributed parallel processor and a digital signal processor.

12. A system as claimed in claim 9, further comprising means for generating a temperature delay signal coupled to the to comparator, wherein said switching factor means comprises means for reducing the switching factor as a function of the temperature delay signal.

11. A system using thermal feedback to cooperatively vary a voltage and frequency of a synchronous circuit to control heating while maintaining synchronization, wherein the circuit comprises a plurality of functional units for processing data stored in a memory, the system comprising:

thermal sensor means for generating a first temperature signal for a first functional unit and a second temperature signal for a second functional unit, each temperature signal being a function of a temperature associated with said each functional unit;

control logic means for identifying the first functional unit and the second functional unit associated with said each temperature signal;

a comparator for comparing the first temperature signal with a first predetermined temperature threshold signal;

a decoder coupled to the comparator, the decoder generating a voltage/clock control signal, responsive to said comparator;

adjustable on-chip voltage regulator means, coupled to the decoder;

clock selector means, coupled to the decoder;

wherein the voltage regulator means and the clock selector means include means for cooperatively varying the voltage and the frequency of the functional unit to a predetermined voltage-frequency pair; and

switching factor means for varying the switching factor of the circuit wherein the switching factor is a fraction of clock cycles that the circuit is dissipating power, wherein said switching factor means is coupled to the comparator.