Dynamic voltage and frequency scaling (DVFS) allows on-the-fly frequency adjustment according to existing system performance requirements. By lowering the frequency, it is possible to lower the operating voltage and dramatically reduce the power consumption. There are two common implementations of this methodology, hardware assisted and software enabled. The DVFS hardware mechanism automatically monitors the processor load and controls supply voltage and frequency with minimal software and operating system involvement. State-retention power gating (SRPG) is a technique that allows the voltage supply to be reduced to zero for the majority of a block’s logic gates while maintaining the supply for the state elements of that block. SRPG can thereby greatly reduce power consumption when the application is in stop mode, yet it still accommodates fast wake up times. Reducing the supply to zero in stop mode allows both dynamic and static power to be removed. It is easy to see the ability to dynamically control the power supply voltages including taking them all the way to zero and back again in a controlled fashion are necessary to make it all work.