Cycle-by-Cycle Digital Control of a Multi-Megahertz Variable-Frequency Boost Converter for Automatic Power Control of LiDAR

Dynamic voltage scaling is needed to support efficient operation despite rapidly fluctuating power demand, which is exemplified in the automatic power control of LiDAR (Light Detection and Ranging) for autonomous ground and airborne vehicles. This is especially challenging in boost converters because of more complicated dynamics. A current-mode boost converter using constant-off-time (variable-frequency) is particularly advantageous because inductor current settles in one switching cycle. Digital control is needed for programmable flexibility over a wide operating range. However, variable frequency power conversion and high speed digital control are difficult to combine in a traditional digital control framework. In this paper, we apply and demonstrate in hardware a recently published theoretical framework for cycle-by-cycle digital control of variable frequency power converters. The prototype variable-frequency boost converter with a 3 MHz peak switching frequency shows an exceptionally fast dynamic response over a wide operating range.