Digital controller for high-performance multiphase vrm with current balancing and near-ideal transient response

Abstract

A mixed-signal controller for controlling a multiphase average-current-mode voltage regulator having an output connected to a load, which comprises a digital voltage-sampling ADC for converting the output voltage signal from analog to digital representation; a digital current-sampling ADC, for converting the inductor current from analog to digital representation; a digital compensator for generating a current reference signal, based on a digital voltage error signal and for generating a duty-ratio command signal, based on a digital current error signal; a multiphase Digital Pulse Width Modulator (DPWM), for generating a pulse-width-modulated signal (per-phase), to thereby control the per-phase currents and output voltage supplied to the load; an analog front-end, in which single-ended signals are used for steady-state control via ADC measurement and the single-ended output voltage is used for transient detection and output voltage extremum detection during transient; a Transient Suppression Unit (TSU), for generating gating signals being fed to the gates of the converter's transistors during a transient event; a Phase Count Optimizer (PCO) unit generating an enable/disable control signal to each phase PWM output tri-state buffer; an Active Voltage Positioning (AVP) unit for generating the voltage loop compensator voltage reference signal.