Breaking the power delivery wall using voltage stacking

Abstract

We propose the use of voltage stacking for addressing some of the power delivery issues for many-core processors. To demonstrate the effectiveness of our method we first design a proxy for a many-core stacked processor in the form of a regular structure using multiple ring oscillators where we can control the voltage, frequency and switching activity for individual rings. For intermediate voltage rail regulation, we propose a push pull-based switched capacitor regulator designed specifically for balancing the stacked loads. Detailed Spice simulation results for the prototype model show a 4× reduction in supply current when using 4 layers of voltage stacking. We further validate our method by designing a voltage-stacked structure using two PIC cores.