A digital droop detector for detecting whether a droop occurs in a power supply voltage, may include processing circuitry configured to, detect a voltage level change of a power supply voltage in response to a clock signal, the detecting the voltage level change including converting the detected voltage level change into a first code, correct at least one nonlinearity included in the first code, the correcting including converting the first code into a second code and a target range, and adjust a delay magnitude of the clock signal based on the second code.