Fully Integrated Switched-Inductor-Capacitor Voltage Regulator With 0.82-A/mm2 Peak Current Density and 78% Peak Power Efficiency

Abstract

Fully integrated voltage regulators (FIVRs) can improve the performance and reduce the power consumption of a system-on-chip (SoC) by providing point-of-load voltage regulation with dynamic voltage scaling. The desirable attributes of FIVRs include high power efficiency, high power density, and fast transient response, which are difficult to achieve due to on-chip area constraint and parasitic effects. Low-quality and low-density on-chip inductors and capacitors are currently the main performance-limiting factors. This article presents a switched-inductor-capacitor (SIC) voltage converter that can operate more efficiently with compact on-chip air-cored metal-tracked inductors than existing step-down voltage converters. The SIC converter consists of an inductor, a flying capacitor, and three power switches, and it can provide fine-grained voltage regulation by using pulsewidth-modulation (PWM) control. The unique SIC converter topology eases the on-chip inductor integration by positioning the inductor at the input power supply and reducing the current stress of the inductor. A proof-of-concept fully integrated SIC voltage regulator is fabricated in a 65-nm CMOS process, with an area of 1.3 mm × 0.5 mm excluding pads. The output voltage can be regulated from 0.6 to 0.9 V given a 1.2-V input power supply. The output voltage ripple is below 56 mV over the entire range of output voltages and load currents. The peak power efficiency is 78% at an output of 0.9 V and 406 mA. The peak power density is 730 mW/mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , and the peak current density is 820 mA/mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> .