Closed loop voltage control using adjustable delay lines

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.