Modeling and Design for a Novel Adaptive Voltage Positioning (AVP) Scheme for Multiphase VRMs

Abstract

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> Adaptive voltage positioning (AVP) has been used in multiphase voltage regulator module (VRM) applications. A novel scheme, called AVP<formula formulatype="inline"> <tex>$+$</tex></formula>, is analyzed in this paper. Small signal model is used to look into the control performance issues such as output impedance and stability. The model has been verified in the experiments and simulations. Compared to a conventional AVP schemes, the present scheme provides better stability margin and output-impedance performance. This is especially true for the prevailing trend of using ceramic output capacitors and high switching frequency. The focus of the present paper is the small-signal modeling for control loop design using the AVP<formula formulatype="inline"><tex>$+$</tex> </formula> scheme which was never analyzed before. And the comparisons were made between AVP<formula formulatype="inline"><tex>$+$</tex></formula> and AVP<formula formulatype="inline"><tex>$-$</tex></formula> on the stability and output impedance performance. </para>