Control and Implementation Aspects of a Multiphase Inductor-Based FIVR in 14 nm Bulk CMOS for Microprocessor Applications

Abstract

This work investigates control and implementation aspects of a four-phase inductor-based Fully Integrated Voltage Regulator (FIVR) for microprocessor applications using the 14 nm Bulk CMOS technology. The considered converter system has a rated input voltage of $ V^{in} = 1.6 V $ and delivers an output power of $ P^{out} = 1 W $ at a nominal output voltage of $ V^{out} = 0.8 V $ to a microprocessor load. Voltage regulation allows varying the microprocessor supply voltage in the range of 0.6 V to 1.0 V, which enables Dynamic Voltage and Frequency Scaling. From an in-depth evaluation of suitable control schemes, the $ V^{2}I^{C} $ control scheme, which uses the output voltage and the output capacitor current information as feedforward signals, is selected due to its fast response during transients and low implementation complexity, compared to fixed frequency hysteretic current mode control. The $ V^{2}I^{C}-controlled$ converter is implemented in transistor-level using models of the Global foundries’ 14 nm LPP technology and Cadence simulation results confirm very fast output voltage recovery of 14.39 ns during 625mA / 0.5ns load current transients at nominal voltage and a settling time of 35 ns during reference output voltage transients from 0.6 V to 1.0 V at nominal current.