What is the difference between Dynamic Voltage Scaling (DVS) and Adaptive Voltage Scaling (AVS)?
Dynamic voltage scaling schemes rely on pre-characterized frequency-to- voltage pair look-up tables that the processor uses to optimize dynamic power. Using DVS, when the processor wants to scale frequency, it will look up the corresponding voltage and command the power supply to transition to the desired voltage. Because DVS does not compensate for process and temperature variations, these voltages need to be high enough to maintain functionality over all power supply, process and temperature variations. As a result, DVS does not provide any energy savings in a fixed frequency system, and while DVS yields some energy savings over fixed voltage schemes at variable frequencies, it cannot match the energy savings of adaptive voltage scaling or “closed loop” scheme. Adaptive voltage scaling uses real-time feedback on process and temperature variations to request the appropriate voltage from the power supply. This voltage is updated continuously in closed loop and can is adjusted to compen
