US Patent 10587253 Ring oscillator-based programmable delay line

A programmable delay line includes a pulse generator configured to generate a pulse in response to a transition of an input signal; an oscillator configured to generate a clock in response to the pulse; a counter configured to change a current count from a first value towards a second value in response to periods of the clock; and a gating device configured to output the transition of the input signal to generate an output signal in response to the current count reaching the second value. The delay of the input signal is a function of the difference between the first value and the second value. The delay line may be used in different applications, such as a dynamic variation monitor (DVM) configured to detect supply voltage droop. The DVM may be in an adaptive clock distribution (ACD) to reduce the clock frequency for a datapath in response to a droop.