Voltage Regulators Design Through Advanced Mixed-Mode Circuit Simulation

Switching power suppliers are described through a mixed analog/digital model. The analog (nonlinear) part is represented by the power circuit and the digital one by the control driving the (MOSFET) switches. We present a general, efficient, and reliable technique to determine, versus variations of design parameters, 1) the periodic steady-state behavior of these circuits discussing stability, 2) periodic time varying transfer functions, and 3) to straightforwardly evaluate the performances of the controller. The proposed simulation approach resorts to the saltation matrix operator to define fundamental matrix for hybrid dynamical systems. This extends conventional simulation and analysis techniques such as the shooting method, the periodic linear phasor, and the Floquet multipliers evaluation to mixed analog/digital circuits. The effectiveness of the approach, representing an alternative viewpoint with respect to commonly adopted analysis strategies, is shown by designing a version of a voltage regulator module for a computer and by investigating its limits versus its output filtering capacitance.