In this letter, a four-phase hybrid step-up/step-down dc–dc converter with a delay-based zero-current detector (ZCD) is proposed. The proposed power stage operates in step-up or step-down mode depending on the target output voltage. It utilizes hybrid switched-inductor-capacitor and dual-path topologies with multiphase operation to reduce conduction loss due to the dc resistance of the inductor by reducing the rms inductor current ( I_L ). The delay-based ZCD determines the zero-current point of I_L with a five-bit binary signal to compensate for the propagation delay between the control and the output signals of the driver. The system is fabricated using 180-nm CMOS technology. The power density is 1.838 A/mm ² , and the peak efficiency is measured at 89.49% and 86.83% in the step-down and step-up mode, respectively, with a load current range of up to 2 A.