Circuits and methods for supply voltage detection and timing monitoring

A monitoring circuit comprising:

• a tunable delay circuit that delays a delayed signal relative to a clock signal using a supply voltage;
• a control circuit that adjusts a delay provided by the tunable delay circuit to the delayed signal relative to the clock signal;
• and
• a time-to-digital converter circuit that generates a digital code that is indicative of the delay provided by the tunable delay circuit to the delayed signal, wherein the time-to-digital converter circuit adjusts the digital code based on changes in the supply voltage;
• and
• a counter circuit that converts the digital code to a binary code, wherein the control circuit maintains the delay provided by the tunable delay circuit to the delayed signal constant based on a value of the binary code equaling an alignment value.

A method for monitoring a supply voltage in an integrated circuit, wherein the method comprises:

• generating a delayed signal using a tunable delay circuit, wherein the tunable delay circuit receives the supply voltage;
• adjusting a delay provided by the tunable delay circuit to the delayed signal using a control circuit;
• converting the delay provided by the tunable delay circuit to the delayed signal to a digital code using a time-to-digital converter circuit;
• causing the tunable delay circuit to maintain the delay provided to the delayed signal constant in response to a value of the digital code reaching an alignment value;
• and
• adjusting the digital code based on a change in the supply voltage using the time-to-digital converter circuit.