Analysis And Design Of Power Level High Frequency Coupled Thin Film Micro-inductors

The frequency of processor has been continuously improved with the rapidly development of internet information technology,and a new requirement about the capacitive,power density and dynamic reaction of processor power supply is proposed.It has attempting to integrate the processor and its power supply,and to realize the power supply on-chip so as to further enhance the charging quality of processor power supply and cut down the parasitic influence of leads.But it shall improve the operation frequency up to megahertz or even hundreds of megahertz to reduce the bulk of power to with a size of processor.And with the development of semiconductor,footprint,and high density of capacitor integration technology,the most bottleneck of limitation for power on-chip is the integration of inductor.The thin film micro-inductors are featured by the small size,light weight,and high density of inductor,which are the key point for power on-chip to make breakthrough.This paper have researched the racetrack-shaped thin film micro-inductor of two way coupling,and mainly focus on magnetic circuit model,the analytical algorithm of winding loss and the optimization design of structural parameters,which could make a difference on theory research and engineering practicability.This paper firstly introduced the necessity of coupling schemes for high frequency thin film micro-inductors and analyze the changes of magnetic reluctance.According to the distribution of the magnetic field,a conventional magnetic circuit model of the two-way coupled racetrack-shaped thin film micro-inductors is established,which is used to guide the preliminary design of the thin film micro-inductors.Based on the conventional magnetic circuit model,an improved magnetic circuit model is established to well reflect the non-linear changes of the thin film micro-inductors performance parameter in the frequency domain.The magnetic field distribution has obvious two-dimensional characteristics in the window space of thin film micro-inductors with closed cores.One-dimensional analytical calculation methods are no longer applicable to calculate the winding ac losses for this kind of inductors.The magnetic field distribution characteristics of thin film micro-inductors with closed cores are analyzed in detail,and the magnetic field intensity of winding boundaries are calculated in this paper.The two dimensional magnetic field in the winding window space is decomposed to vertical field and horizontal field.A two-dimensional analytical calculation method is developed to evaluate the winding ac losses of thin film micro-inductors.The high accuracy of this new analytical calculation method is verified,and its calculation error can be controlled within 6%.Coupled thin film micro-inductors can improve the performance of power supply,but the phase shift between coupled winding currents in coupled thin film micro-inductors causes variation of the winding loss significantly due to the changes of the magnetic field distribution.This paper analysed the magnetic field distribution of coupled racetrack-shaped thin film micro-inductors at different phase shift angles.A detailed analytical calculation method of winding loss considering arbitrary phase shift is presented by a derivation of the resistance matrix.The high accuracy and wide applicability of this analytical calculation method are verified by comparing the calculated results with simulated results of finite element method.At the end of this paper,the influence of geometry parameters on the performance of coupled racetrack-shaped thin film micro-inductors is analyzed in detail.The influence of different structure parameters on the performance of the thin film micro-inductors,which are related to each other.In order to obtain the optimal design scheme for coupled thin film micro-inductors,the multivariable analysis method are adopted in this paper.Ansoft Maxwell is integrated by the multi-disciplinary optimization design platform iSIGHT to reach the optimal design target.And the frequency-domain characteristic curves of the coupled thin film micro-inductor after optimization are proposed.