HIGH-PERFORMANCE INTEGRATED VOLTAGE REGULATORS FOR   ENERGY-EFFICIENCY SYSTEM-ON-CHIPS

Bai Noi Nguyen

To keep with up fast-paced evolution of advanced system-on-chip (SoC) technologies, a more effective power management system (PMS) has been considered as a key to extend battery life and reduce sizes and costs of modern mobile devices, as well as to enable self-sustainability of emerging internet-of-thing (IoT) applications. Highly integrated voltage regulators (IVRs) are hence attractive to facilitate high-performance PMS to meet stringent demands of next-generation SoCs, including higher power efficiency, more compact form-factor, smaller voltage ripple, and faster dynamic response. In this dissertation, three different IVRs with unique characteristics are presented to advance PMS’ that support energy-efficient SoCs for a variety of applications. The first IVR is fully integrated switched-capacitor voltage regulator (SCVR) for battery-connected applications in low-breakdown process technologies. It overcomes the challenging breakdown issues induced by a nominal 3.7-V Li-Ion battery voltage while improving power efficiency by using only non-stacked, thin-oxide MOSFETs. This is realized by using a 3-state, low-voltage-stress SCVR with a cross-phase-switching technique to decrease the output impedance and increase the total equivalent capacitance, thus approximately reducing power loss by 20%. The second work is a fully integrated analog-assisted inverter-based digital low dropout regulator (LDO) to obtain a fast response time. It also features a high current efficiency and an accurate load regulation in sub-1V operating range. The proposed LDO employs a dynamic-step quantizer and a trip-point controller to enable fast transient response without significantly compromising the power consumption and other performances of the LDO. Finally, the third work is a post-regulation PMS integrated circuit for IoT applications powered by energy harvesting. It incorporates a power budget tracking mechanism to adaptively control the power consumption of a near-threshold-voltage (NTV) microcontroller (MCU) based on the time-varying available input power. In addition, the proposed PMS adapts the clock frequency of the MCU to the supply voltage under the time-varying input available power to prevent timing violations for the sequential logics of the MCU. This adaptive power tracking structure enables the NTV MCU to maintain a continuous operation at optimized processing speed under the varying power condition without violating the timing requirements.

HIGH-PERFORMANCE INTEGRATED VOLTAGE REGULATORS FOR ENERGY-EFFICIENCY SYSTEM-ON-CHIPS

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