Closed-loop techniques for adjusting the duty cycle of a cyclical signal, e.g., a clock signal, to approach a target value. In an exemplary embodiment, a charge pump is coupled to a charge and sample module, which drives a de-skew circuit in a negative feedback loop. The charge and sample module couples the charge pump to the integration capacitor during two of four successive phases, and also couples the integration capacitor to sampling capacitors during the other two of the four successive phases. The voltages across the sampling capacitors may be used to control the de-skew circuit, which adjusts the duty cycle of a cyclical signal to be adjusted.