Research On On-chip Integrated Magnetic Core Transformer And Its Application In Isolated DC-DC Power Supply

In the design of modern electronic products,the volume of power modules such as DC-DC is the key to the miniaturization of electronic products.In power modules,the size of magnetic devices such as transformers is one of the bottlenecks in the miniaturization of switching power supplies.Therefore,the development of miniaturized,high-power-density integrated transformers to reduce the volume of power modules such as DC-DC is of great significance to the realization of the miniaturization of electronic products.This article first analyzes the different structures of several integrated transformers and their advantages and disadvantages.On this basis,this paper designs a "magnetic-clad copper" spiral integrated transformer.The transformer uses a silicon wafer as a substrate and has an elongated spiral copper wire,and adopts a structure in which two upper and lower closed magnetic cores wrap the copper wire.Since the structure has only one layer of wires,the use of through-holes is avoided to increase the contact resistance.At the same time,since only the straightened part of the copper wire is wrapped by the magnetic core,the high-frequency loss of the magnetic core is effectively reduced and the operating frequency of the integrated transformer is increased.In the process of theoretical analysis of the integrated transformer,using ANSYS Electronics software to perform FEA electromagnetic simulation on the integrated transformer and analyzes the key performance parameters of the integrated transformer.In the actual development process of the integrated transformer,using MEMS technology in the ultra-clean room to complete the tape out of the integrated transformer chip.And through impedance analyzer,vector network analyzer,and other equipment to complete the test of the main performance parameters of the integrated transformer.Among them,the DC resistance value of the integrated transformer is 0.276Ω,and its maximum quality factor can reach 7.83 at a frequency of 21 MHz.Finally,this article applies the integrated transformer to an isolated 30MHz-Ga N resonant flyback circuit.By building a DC-DC power supply application circuit for testing,a maximum circuit conversion efficiency of 45% was achieved under 3V input voltage/210 mW output power.