Inductance Calculation,Design Application Of On-Chip Solenoid Magnetic Core Inductors

Full integrated voltage regulator has the characteristic of high response speed,high power density,and high integration,attracting more and more people’s attention,with the trend towards miniaturization of electronic devices,nowdays.Howerver,the on-chip magnetic components such as inductors and transformers is the challenge for implement fully integrated voltage regulator,which is extensively studied by academia and industry.So far,the most potential on-chip power inductors is the on-chip solenoid magnetic core inductor,which has a higher inductance density compared to air core inductors and easier manufacturing process,as it only requires one layer of magnetic core compared to other magnetic core inductors,attracting the attention and research of many top companies in the industry such as TSMC,Global Foundries and Huawei.As a result,this thesis mainly focuses on the inductance calculation,inductor design and applications to circuits.Due to the small size of the on-chip integrated magnetic core,there are non ideal factors such as demagnetization effect and large magnetic resistance in the inductor,leading to the large error of the inductance calculation based on traditional formula and binging difficulties to design and optimization of on-chip solenoid magnetic inductors.As a result,this thesis explored the influence of various structure parameters on inductance and proposed two new analytic empirical inductance formula reducing the average calculation error of inductance by 3-5 times,through the massive three-dimensional simulations of on-chip solenoid magnetic inductors.Based on the new analytic empirical inductance formula,this thesis derived the formula for the structure parameters of on-chip solenoid magnetic inductors with the given performance parameters of inductors.Through the application of a new empirical analysis formula,this article had completed the design research of an on chip solenoid magnetic core inductor for optimizing the inductance/DC resistance ratio,greatly saving the inductance modeling and simulation time required for simulation based optimization design.As a circuit application of on chip solenoid magnetic core inductor,this thesis also designed a fully integrated 1.8V-0.9V single-phase buck DC-DC converter with a switching frequency of 100MHz and designed a on chip solenoid magnetic core inductor use in this converter by utilizing the new analytic empirical inductance formula and reported magnetic material and process in literature.The inductance of the designed on chip solenoid magnetic core inductor is 25.47n H,L/R_dc is 472n H/Ωand efficiency in this converter reached 91.5%,and the overall efficiency of the converter reached 82.7%.