Research And Design Based On Mems Planar Transformer Spiral Inductors

The main function of the transformer is the conversion between the signal and theenergy. The modern scientific information technology makes the transformer be ofsmall size, low loss, high reliability, integration and automation of production. Alongwith the development of information science and technology, the plane transformer hasthe advantages of small size, light weight and high transformer ratio. It plays an anextremely important role in the military, aviation, communication and so on. In the lastten years, with the developmentment of the bonding techniques, the further developmentof surface micromachining and bulk micro-machining technology in MEMS, the chipspiral inductance and plane transformers have a great progress.This subject requires the transformer’volume be of no larger than3×3cm2andit’s input voltage is27V, output voltage is2000V. Because this transformer’ratio is veryhigh, it needs three small transformers to combine into a whole transformer. Thispaper’s studies is only for the first transformer, its transformation ratio is1:5.This paper researches the inductance of the three main performance index:inductance L, quality factor Q and the resonance frequency f. Some imulation of thetransformer on the silicon has done by the software of Ansoft Maxwell. The result isthat the specific value of the coil width and center hole width is no more than1.5, themagnetic flux caused by ring current is big. Combined with the MEMS technologyprocessing technology, plane transformer takes the S-P-S laminated structure and thecoil needs the help of the EI ferrite magnetic cores. Each layer coil based on a siliconwafer, then superimpose the three silicon chip to be a transformer with the EI ferritemagnetic cores. At last, do some imulation about the transformer on the silicon by thesoftware of Ansoft Maxwell.This paper is based on the planar transformer structure, taking advantage of themicromachining process micromachining, surface micromachining and bondingtechniques. It ues the silicon as a substrate, with sputting masking layer to reduce thesubstrate loss. Because the lane transformer’s plane is too large, the pervasive of themagnetic is very serious. The EI miniature magnetic cores can effectively reduce the severity of the pervasive. This solution can improve the working efficiency of the planetransformer. At the same time, the insulation of the material is a important problem ofthe transformer, the micromachining process micromachining and the surfacemicromachining can sputter great insulating materials to protect the micro-wires. TheMEMS can stack the three silicon chip to be a complete transformer to meet the designrequirements. After all, such transformer is of light weight, small volume and goodperformance.