A Mixed-Signal Synchronous/Asynchronous Control for High-Frequency DC-DC Boost Converters

This paper investigates the application of a mixed-signal synchronous/asynchronous digital controller to DC-DC boost converters. The digital control synchronously generates current and voltage ramps by using two low-resolution digital-to-analog converters. The switch turn-on and turn-off are determined asynchronously by comparing the converter-state variables and the digitally generated current and voltage ramps. The control features high dynamic performance, frequency modulation during transients, small quantization effects, and low complexity. In order to evaluate the dynamic performance and compare the proposed solution with conventional analog peak-current-mode control, a small-signal model of the synchronous/asynchronous modulation is derived. Even if aimed to an integrated digital controller, experimental investigation has been performed by using discrete components, implementing the digital control in a field-programmable gate array by using a VHDL. The simulation and experimental results on 100-W DC-DC boost converter confirm the proposed analysis and show that the proposed solution enables a dynamic performance that is comparable with that of analog peak-current- mode control.