A clock signal generation circuit provides an output clock signal to a digital system. The digital system is powered by a power supply voltage, VDD, that may include transients associated with the impedance of the packaged digital system. The clock signal generation circuit dynamically scales an output clock frequency based on monitored changed to VDD. The output clock frequency may be selected to approximate a maximum (margin-less) system Fmax for the monitored VDD. The average clock frequency may be improved compared with operating at a fixed output clock frequency.