Closed loop voltage control using adjustable delay lines

Abstract

Controlling a power supply which supplies a voltage to target circuit of an integrated circuit. An adjustable delay line powered by the supply voltage is co-located on the IC with the target circuit. The adjustable delay line is subjected to substantially the same operating conditions as the target circuit. A control unit measures a delay time of the adjustable delay line. Based on the measured delay time, the control unit outputs a control signal by which the power supply adjusts the supply voltage. The adjustable delay line comprises multiple distinct delay elements, each with delay properties and responsivity to changes in operating conditions. Each delay element emulates delay properties of physical elements (e.g., gates and wires) in the target circuit. In this manner, power consumption may be reduced, while still maintaining proper operation of the target circuit.

What is claimed is: 
     
       1. A closed-loop voltage controller for controlling a supply voltage of a power supply which supplies a voltage to target circuit of an integrated circuit (IC), the closed-loop voltage controller comprising:
 an adjustable delay line powered by the supply voltage and co-located on the IC with the target circuit, the adjustable delay line subjected to substantially the same operating conditions as the target circuit; and 
 a control unit to measure a delay time of the adjustable delay line, and, based on the measured delay time, to output a control signal instructing the power supply to adjust the supply voltage; 
 wherein the adjustable delay line comprises multiple distinct delay elements, each with delay properties and responsivity to changes in operating conditions, wherein the delay elements emulate delay properties of physical elements in the target circuit; 
 wherein the delay elements are connected in series and arranged in segments, each segment including delay elements having delay times, wherein a delay element of a segment and another delay element of another segment have different delay times, and wherein the number of delay elements in each delay line segment is selectable, and 
 wherein the delay segments comprise:
 a first segment of standard threshold voltage (SVT) gate delay elements; 
 a second segment of high threshold voltage (HVT) gate delay elements; and 
 a third segment of wire delay elements. 
 
 
     
     
       2. The closed-loop voltage controller of  claim 1 , wherein the target circuit includes interconnected gates and each distinct delay element is constructed to emulate the delay properties of the gates and wires of the target circuit. 
     
     
       3. The closed-loop voltage controller of  claim 1 , wherein the control unit lowers the supply voltage if the measured delay time through the adjustable delay line is shorter than a lowest time in a predetermined time range, and raises the supply voltage if the measured delay time is longer than a longest time in the predetermined time range. 
     
     
       4. The closed-loop voltage controller of  claim 1 , wherein the power supply comprises an Inter-Integrated Circuit (I2C) interface slave, the power supply receives control signals via the I2C interface slave, and the power supply adjusts the supply voltage based on control signals received via the I2C interface slave. 
     
     
       5. The closed-loop voltage controller of  claim 4 , wherein the control unit outputs the control signal to an I2C interface master, and the I2C interface master forwards the control signal to the I2C interface slave of the power supply. 
     
     
       6. The closed-loop voltage controller of  claim 4 , wherein the I2C interface slave of the power supply receives control signals from other voltage controllers using the I2C protocol. 
     
     
       7. The closed-loop voltage controller of  claim 6 , wherein the I2C interface slave of the power supply receives control signals from a DVM based power manager using the I2C protocol. 
     
     
       8. A closed-loop voltage controller for controlling a supply voltage of a power supply which supplies a voltage to target circuit of an integrated circuit (IC), the closed-loop voltage controller comprising:
 an adjustable delay line powered by the supply voltage and co-located on the IC with the target circuit, the adjustable delay line subjected to substantially the same operating conditions as the target circuit; and 
 a control unit to measure a delay time of the adjustable delay line, and, based on the measured delay time, to output a control signal instructing the power supply to adjust the supply voltage; 
 wherein the adjustable delay line comprises multiple distinct delay elements, each with delay properties and responsivity to changes in operating conditions, wherein the delay elements emulate delay properties of physical elements in the target circuit; 
 wherein the delay elements are connected in series and arranged in segments, each segment including delay elements having delay times, wherein a delay element of a segment and another delay element of another segment have different delay times, and wherein the number of delay elements in each delay line segment is selectable; 
 wherein the delay segments comprise:
 a first segment of standard threshold voltage (SVT) gate delay elements; 
 a second segment of high threshold voltage (HVT) gate delay elements; and 
 a third segment of wire delay elements. 
 
 
     
     
       9. The closed-loop voltage controller of  claim 8 , wherein the adjustable delay line is configured to emulate a critical path of the target circuit. 
     
     
       10. The closed loop voltage controller of  claim 9 , wherein the adjustable delay line is configured such that a quantity of distinct delay elements used in the adjustable delay line is proportional to the quantity of distinct physical elements in the critical path. 
     
     
       11. The closed-loop voltage controller of  claim 9 , wherein the critical path to emulate is chosen based on a Dynamic Voltage Management (DVM) power management system. 
     
     
       12. The closed-loop voltage controller of  claim 9 , wherein the control unit measures the delay time based on a plurality of delay line measurements. 
     
     
       13. The closed-loop voltage controller of  claim 12 , wherein the plurality of delay line measurements are compared to a predetermined time. 
     
     
       14. The closed-loop voltage controller of  claim 13 , wherein the delay time is longer or shorter than the predetermined time. 
     
     
       15. The closed-loop voltage controller of  claim 14 , wherein the delay time of the adjustable delay line is adjusted for each measurement to indicate how much the delay time differs from the predetermined time, and wherein the delay time is adjusted without changing proportions of distinct delay elements used in the adjustable delay line. 
     
     
       16. A method for controlling a supply voltage of a power supply which supplies a voltage to a target circuit of an integrated circuit (IC), the method comprising:
 providing the supply voltage to an adjustable delay line co-located on the IC with the target circuit, wherein the adjustable delay line is subjected to substantially the same operating conditions as the target circuit; 
 measuring a delay time of the adjustable delay line; and 
 outputting a control signal, based on the measured delay time, instructing the power supply to adjust the supply voltage; 
 wherein the adjustable delay line comprises multiple distinct delay elements, each with delay properties and responsivity to changes in operating conditions, wherein the delay elements emulate delay properties of physical elements in the target circuit; 
 wherein the delay elements are connected in series and arranged in segments, each segment including delay elements having delay times, wherein a number of delay elements in each delay line segment is selectable; 
 wherein a delay element of a segment and another delay element of another segment have different delay times; and 
 wherein the delay segments comprise:
 a first segment of standard threshold voltage (SVT) gate delay elements; 
 a second segment of high threshold voltage (HVT) gate delay elements; and 
 a third segment of wire delay elements. 
 
 
     
     
       17. The method of  claim 16 , wherein the target circuit includes interconnected gates and each distinct delay element is constructed to emulate the delay properties of the gates and wires of the target circuit. 
     
     
       18. The method of  claim 16 , further comprising configuring the adjustable delay line to emulate a critical path of the target circuit. 
     
     
       19. The method of  claim 18 , wherein the adjustable delay line is configured such that a quantity of distinct delay elements used in the adjustable delay line is proportional to the corresponding quantity of distinct physical elements in the critical path. 
     
     
       20. The method of  claim 18 , further comprising choosing the critical path to emulate based on a Dynamic Voltage Management (DVM) power management system. 
     
     
       21. The method of  claim 18 , wherein the delay time is measured based on a plurality of delay line measurements. 
     
     
       22. The method of  claim 21 , wherein the plurality of delay line measurements are compared to a predetermined time. 
     
     
       23. The method of  claim 22 , wherein the delay time of the adjustable delay line is adjusted for each measurement to indicate how much the delay time differs from the predetermined time, and wherein the delay time is adjusted without changing proportions of distinct delay elements used in the adjustable delay line. 
     
     
       24. The method of  claim 16 , wherein the supply voltage is lowered if the measured delay time through the adjustable delay line is shorter than a lowest time in a predetermined time range, and the supply voltage is raised if the measured delay time is longer than a longest time in the predetermined time range. 
     
     
       25. The method of  claim 16 , wherein the power supply comprises an Inter-Integrated Circuit (I2C) interface slave, the power supply receives control signals via the I2C interface slave, and the power supply adjusts the supply voltage based on control signals received via the I2C interface slave. 
     
     
       26. The method of  claim 25 , wherein the control signal is output to an I2C interface master, and the I2C interface master forwards the control signal to the I2C interface slave of the power supply. 
     
     
       27. The method of  claim 25 , wherein the I2C interface slave of the power supply receives control signals from other voltage controllers using the I2C protocol. 
     
     
       28. The method of  claim 27 , wherein the I2C interface slave of the power supply receives control signals from a DVM based power manager using the I2C protocol. 
     
     
       29. An integrated circuit, comprising:
 a first operational circuit configured to receive a first supply voltage from a first voltage regulator that is external to the integrated circuit;   a first performance monitoring circuit, disposed on the integrated circuit, configured to generate at least a first indicator corresponding to at least one performance characteristic of the first operational circuit and output the first indicator to a voltage control and feedback generator circuit disposed on the integrated circuit; and   the voltage control and feedback generator circuit configured to receive the first indicator from the first performance monitoring circuit disposed on the integrated circuit and output a first feedback voltage signal to the first voltage regulator that is external to the integrated circuit, the first feedback voltage signal having a voltage level that varies as a function of at least the first indicator, the first voltage regulator being configured to regulate the first supply voltage as a function of the first feedback voltage signal.   
     
     
       30. The integrated circuit of claim 29, wherein the voltage control and feedback generator circuit is configured to output the first feedback voltage signal as a function of both the first indicator and the first supply voltage. 
     
     
       31. A method for controlling a supply voltage, comprising:
 generating in an integrated circuit, by a first performance monitoring circuit disposed on the integrated circuit, at least a first indicator corresponding to at least a performance characteristic of a first operational circuit operating under a first supply voltage provided by a first voltage regulator that is external to the integrated circuit;   outputting the first indicator to a voltage control and feedback generator circuit disposed on the integrated circuit;   receiving, by the voltage control and feedback generator circuit, the first indicator from the first performance monitoring circuit disposed on the integrated circuit; and   providing to the first voltage regulator that is external to the integrated circuit, a first feedback voltage signal as a function of at least the first indicator, the first voltage regulator regulating the first supply voltage based on the first feedback voltage signal.   
     
     
       32. The method of claim 31, wherein providing to the first voltage regulator the first feedback voltage signal as a function of at least the first indicator further comprises:
 providing the first feedback voltage signal as a function of both the first indicator and the first supply voltage.   
     
     
       33. An electronic system, comprising:
 a first voltage regulator configured to regulate a first supply voltage based on a first feedback voltage signal having a voltage level that varies as a function of at least a performance characteristic of an operational circuit of the electronic system; and   an integrated circuit that comprises:
 a first operational circuit configured to receive the first supply voltage from the first voltage regulator that is external to the integrated circuit; 
 a first performance monitoring circuit, disposed on the integrated circuit, configured to generate at least a first indicator corresponding to at least one performance characteristic of the first operational circuit and output the first indicator to a voltage control and feedback generator circuit disposed on the integrated circuit; and 
 the voltage control and feedback generator circuit configured to receive the first indicator from the first performance monitoring circuit disposed on the integrated circuit and output the first feedback voltage signal to the first voltage regulator that is external to the integrated circuit, the first feedback voltage signal having a voltage level that varies as a function of at least the first indicator, the first voltage regulator being configured to regulate the first supply voltage as a function of the first feedback voltage signal.