Closed loop voltage control using adjustable delay lines

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.

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.