A 20MHz monolithic DC-DC converter manufactured with the first commercially viable silicon magnetics technology

This paper presents a Power System on Chip (Power-SoC), switch-mode DC-DC synchronous buck converter with switching frequency of 20 MHz, which monolithically integrates high-speed power MOSFET switches, controller and drive circuits, the compensation network, and more importantly, a silicon-based inductor. The new device implements a type III voltage mode control scheme with wide loop bandwidth, which offers ultra-fast transient with tiny small ceramic capacitor and ultra-low ripple (> 8mV peak-peak). The compact design facilitates encapsulation in a 3×4.5×0.9 mm DFN package, while its high efficiency eliminates the necessity of a heat sink. The fully integrated design only requires input and output capacitors, and offers an excellent size and cost-effective alternative to a comparable LDO for high-speed transient and noise sensitive applications. The controller chip is fabricated in a standard 0.25µm CMOS process including high speed, high voltage LDMOS devices used for the integrated power switches. The proprietary magnetics-on-silicon inductor is implemented using a magnetic alloy on silicon die mounted on a substrate coil-in-package to achieve an ultrasmall solution. Performance results show that the new converter can provide up to 1000mA of continuous DC output current, at up to 90% peak efficiency in Pulse-Width-Modulation (PWM) mode. The device is in production with the first commercially viable silicon magnetics technology deployed in a standard foundry.