Design and Optimization of Magnetic-core Solenoid Inductor for Multi-phase Buck Converter

Due to heterogeneous integration, there is an increased demand for on-chip voltage regulators to provide many voltage domains for efficient operation of the system. Towards this, planar magnetic-core based inductors gained popularity due to their increased inductance density for on-chip buck converter realization. To ensure proper operation of the converter, the magnetic-core should not saturate, and over-design of the inductor decreases the efficiency of the converter significantly. Also, the magnetic-core area budget allocated to the converter implementation will be limited. This paper details the design and analysis of magnetic-core solenoid inductor based multi-phase buck converter. Also, an optimization framework to design an efficient multi-phase buck converter for the given specifications with the magnetic-core solenoid inductor is proposed. Full-wave simulations on commercial tool show that the multi-phase buck converter designed with our optimization framework achieves 92.8% efficiency and 0.5mV voltage ripple for the load current of 500 mA with the solenoid inductor is implemented with 0.397 mm2 magnetic-core area for the given specifications.

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