20.3 A feedforward controlled on-chip switched-capacitor voltage regulator delivering 10W in 32nm SOI CMOS

Abstract

On-chip (or fully integrated) switched-capacitor (SC) voltage regulators (SCVR) have recently received a lot of attention due to their ease of monolithic integration [1-4]. The use of deep trench capacitors can lead to SCVR implementations that simultaneously achieve high efficiency, high power density, and fast response time [5]. For the application of granular power distribution of many-core microprocessor systems, the on-chip SCVR must maintain an output voltage above a certain minimum level U out, min in order for the microprocessor core to meet setup time requirements. Following a transient load change, the output voltage typically exhibits a droop due to parasitic inductances and resistances in the power distribution network. Therefore, the steady-state output voltage is kept high enough to ensure V OUT >V out, min at all times, thereby introducing an output voltage overhead that leads to increased system power consumption. The output voltage droop can be reduced by implementing fast regulation and a sufficient amount of on-chip decoupling capacitance. However, a large amount of on-chip decoupling capacitance is needed to significantly reduce the droop, and it becomes impractical to implement owing to the large chip area overhead required.