Low-Quiescent and Reduced-Power Zero-Current Detector for a DC-DC Switched-Mode Converter Implemented in 22nm FDSOI

This paper introduces a low-quiescent and reduced-power zero current detector (ZCD) designed specifically for a DC-DC switched-mode converter operating in discontinuous current mode. The ZCD incorporates control switches strategically placed to minimize power consumption and leakage current. The ZCD operation is enabled through a ZCD controller circuit, which efficiently manages the power consumption. The controller circuit generates a voltage to control the ZCD, ensuring that the control switches are triggered only when the inductor current is about to change polarity, typically occurring when the low-side power switch of the converter is active. Once the zero current is detected, the ZCD becomes inactive after a slight delay of 1ns, as defined in this paper. The ZCD controller circuit comprises flip-flops and logic gates, managing the ZCD's activation and deactivation. Control switches are strategically placed at each branch of the ZCD circuit to optimize its efficiency. To monitor the inductor current of the DC-DC converter, the voltage polarity at one end (input side) of the inductor is sensed in relation to the ground. The ZCD is configured with transistors in reverse back gate biasing, further enhancing its performance and efficiency. The simulation results showcase impressive outcomes, with the ZCD exhibiting a quiescent current of 1.13nA and an average current of 323nA at a 0.8V supply voltage. This design is implemented using the advanced 22nm FDSOI technology, showcasing its practicality and relevance in modern circuit design.