Osvaldo Enrico Zambetti

Transient frequency modulation: A new approach to beat-frequency current sharing issues in multiphase switching regulators

Under high-frequency load transient conditions, conventional multiphase voltage regulators (VRs) suffer from large beat-frequency oscillations of the phase currents. This phenomenon can result in extra electrical and thermal stress on power components, so compromising system reliability. In this paper, a novel multiphase switching regulator topology is proposed, which is composed of a conventional multiphase PWM modulator, a frequency modulator and a load transient detector. The proposed topology, when compared to the conventional multi-phase PWM modulators during repetitive load transients, significantly reduces current oscillations, guaranteeing system reliability and current balancing for any load frequency higher or lower than switching frequency.

Isolated resonant full-bridge converter with magnetic integration

Nowadays technological developments in modern microprocessors have brought better computing performance and have triggered the demand for high-efficiency power supply. The common trend in networking applications is to have a 48V dc distribution bus to increase system efficiency, while the supply of the microprocessor is usually obtained by a two-stage conversion process having an intermediate 12V dc bus. This paper presents a single-stage approach for the isolated voltage regulation module (VRM) based on a resonant topology that inherently integrates the multi-phase approach. In order to fit the layout constraints of the processor mother board, this paper also presents some magnetic architectures which integrate the magnetic parts. Compared to a classical discrete implementation, the proposed integrated magnetic structures have smaller total volume. In this paper we will compare the magnetic structures in the same application that is a processor power supply conversion from 48V bus. The proposed integrated magnetic architectures can be applied to other topologies as conventional ZVS full bridge. Experimental results on a 250A, 1.8 V multiphase isolated conversion are provided to show the effectiveness of the proposed solutions.

Digital multiphase Constant on-time regulator supporting energy proportional computing

During the last decade the technologys evolution of modern microprocessors has brought better computing performance; but now energy efficiency is a new goal for general-purpose computing architecture. This target is now one of the most important technology drivers from the mobile to networking applications. Energy management has become a key issue for server and data center operation, considering all energy-related costs. The server architecture research is working focusing on energy proportional machines that would ideally consume no power when idle, and gradually more power as the computation level increase. This performance can be supported by a server architecture and power management architecture that guarantees a high efficiency with a high range of load. Moreover faster processors require high performance during the transient. In this paper a Constant on time digital control loop will be described that has a high performance transient response, easily implements a fast phase shedding technique and has an efficient light load working condition. The controller has been implemented in 0.16um lithography together with a DPWM with 195ps resolution and 40Ms/s ADC 7 bits pipeline converter. Experimental results of a 100 A, 1.8 V multiphase buck converter with a constant on-time controller are provided to show the effectiveness of the discussed system. This electronic document is a “live” template and already defines the components of your paper [title, text, heads, etc.] in its style sheet.

Autotuning technique for digital constant on-time controllers

This paper addresses the design and practical implementation of a digital constant on-time controller for switched-mode DC-DC converters with self-tuning capabilities. The proposed tuning techniques are based on the sinusoidal signal injection in the control loop in order to measure the linear loop gain transfer function at the desired crossover frequency. This autotuning method is applied in closed-loop condition, hence the stability and the regulation are assured during the tuning process. The proposed tuning technique is presented and the complexity of the control and tuning blocks is analyzed. The proposed approach is simple, accurate, and robust. Experimental results on a 175 A, 1.8 V multiphase buck converter with a constant on-time control IC realized in 0.16μm BCD technology are provided to show the effectiveness of the discussed system.

An Isolated Quasi-Resonant Multiphase Single-Stage Topology for 48-V VRM Applications

In order to increase the efficiency of modern microprocessors power supplies used in data centers, the 48-V dc distribution bus is gaining growing attention. For such applications, voltage regulation modules (VRMs) are currently obtained using two-stage conversion systems with an intermediate 12-V dc bus. This paper presents an innovative single-stage approach for the 48-V VRM based on a quasi-resonant constant on-time (COT) operation. The proposed topology inherently integrates the multiphase approach, providing fast phase shedding and flat high-efficiency curves even at light load conditions. This is a unique advantage, usually not available in the two-stage approach, that is very important in server architectures, where high efficiency is required even at light load conditions. The paper analyses the circuit topology, and proposes a control architecture for fast transient response, including the current sharing capabilities, and a solution for implementing the integrated magnetics. The digital controller has been implemented in 0.16-

48V to 12V isolated resonant converter with digital controller

\mu

Multi-phase voltage regulator

m lithography together with a digital pulse-width-modulation with a 195 ps resolution, and a 40 MS/s, 7-bit ADC. Experimental results show an efficiency of 93.1% for a 250 A, 1.8 V VRM, and of 93.2% for a 102 A, 1.2-V double data rate (DDR) power supply.

Method for controlling a multiphase interleaving converter and corresponding controller

Growth of electricity consumption for data center increases rapidly as computation continues to move into the cloud computing. Energy management has become a key issue for the next generation of data center. 48V to 12V step-down isolated converters are often required in server, telecom and automotive applications. Using resonant topology such as LLC realizes ZVS turn-on for all switches over the entire load range using magnetizing current and can achieve high level of efficiency [1], [2]. In this paper the control system and application of an Isolated dc-dc resonant converter is proposed for a conversion from 48V to 12V. The controller IC has been implemented in 0.16um lithography together with a DPWM with 195ps resolution and 40Ms/s ADC 7 bits pipeline converter. Experimental results of a 45A, 12V provided to show the effectiveness of the discussed system.