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MOSFET Current Source Gate Drivers and Topologies for High Efficiency and High Frequency Voltage Regulator Modules

ABSTRACT In this seminar, the state of the art research on Voltage Regulators (VRs) or Voltage Regulator Modules (VRMs) for microprocessors is introduced. The background information covers the computer power architectures, the problems of today’s VR solutions and the challenges and trend of the future VRMs etc. The resonant gate driver technique and soft-switching technology are also reviewed to provide the fundamental theory. After the introduction part is finished, four new ideas will be presented. The first one is an accurate analytical loss model of a power MOSFET with a Current-Source Driver (CSD). The impact of the parasitic components is investigated. Based on the proposed loss model, a general method to optimize the CSD is presented. With the proposed optimization method, the CSD improves the efficiency from 79.4% using the conventional voltage source driver to 83.6% at 12V input, 1.5V/30A output and 1MHz. The second one is a new continuous CSD for a synchronous buck converter. The proposed CSD is able to drive the control and Synchronous Rectifier (SR) MOSFETs independently with different drive currents enabling optimal design. At 12V input, 1.5 V/30A output and 1MHz, the proposed CSD improves the efficiency from 79.4% using a conventional driver to 83.9%. The third one is a new discontinuous CSD. The most important advantage of the new CSD is the small inductance (typically, 20nH at 1MHz switching frequency). A hybrid gate drive scheme for a synchronous buck converter is also proposed. The idea of the hybrid gate driver scheme is to use the CSD to achieve switching loss reduction for the control MOSFET, while use the conventional voltage source driver for the SR. At 12V input, 1.3V/25A output and 1MHz, the proposed CSD improves the efficiency from 80.7% using the conventional driver to 83.1%. The final contribution is new self-driven zero-voltage-switching (ZVS) non-isolated full-bridge converters for 12V input VRM applications. The proposed converter achieves the duty cycle extension, ZVS operation and SRs gate energy recovery. At 12V input, 1.3V output and 1MHz, the proposed converter improves the efficiency from 80.7% using the buck converter to 83.6% at 50A.