A 95% efficiency Buck-Boost Converter with Full-Cycle Continuous Current Sensing and Adaptive Mode Control

In battery-powered devices, power-efficient power management systems, such as high-power-efficiency buck-boost converters, are critical. In this paper, we propose a novel digital-input average current mode high-power-efficiency buck-boost converter. The proposed buck-boost converter embodies a novel full-cycle continuous current sensing circuit, which eliminates the need for a current selection circuit by continuously sensing the inductor current throughout the entire switching cycle. Unlike conventional approaches which rely on non-continuous sensing, this method improves current sensing accuracy and eliminates false switching, leading to reduced output noise, increased power efficiency, and improved circuit robustness. The proposed buck-boost converter further embodies a PWM controller with novel adaptive mode control, which dynamically adjusts the pulse width of the power transistors in buck-boost operation - this is to avoid narrow pulses hence preventing false switching. This further enhances the power efficiency and the robustness of the buck-boost converter. Both the proposed full-cycle continuous current sensing circuit and the adaptive mode control circuit are simple, with little hardware or power dissipation overheads. The proposed buck-boost converter is designed and fabricated in a 55nm BCD process with an IC area of 2.4mm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>. Based on measurements, the proposed buck-boost converter features a high peak power efficiency of 95% and maintains a high efficiency of >90% across a wide output range (0.3W to 4.3 W) with a supply voltage of 2.5 V to 5.5 V