Quality-Factor Improvment Designs for Spiral Inductors

• Main Authors: Hui-Ching Sung, 宋惠卿
• Other Authors: Hao-Hui Chen
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/37376433106176642331

碩士 === 華梵大學 === 電子工程學系碩士班 === 95 === Among the wireless communication circuits, the spiral inductor is play an important elements in radio frequency integrated circuits (RFICs). Improvement of the quality factor (Q-factor) of inductors is important issue. Since the Q-factor is the main determine that the loss of the metal strip and substrate, much research has been devoted to improve the Q-factor by reducing the metal or substrate loss. In this work, by reducing the metal loss improved the Q-factor.We will make use of an analytical formula is developed to efficiently determine the line width in the variable line-width inductor design. the formula can characterized by an equivalent series resistance Rs, an analytical formula expression of the series resistance for a spiral inductor is first derived. Nevertheless, Rs can be decomposed into the ohmic resistance Rohm and the eddy-current resistance Reddy. By minimizing Rs, an analytical formula for determining the proper line width (Wopt) of the n-th coil is then formulated. One method approach is the variable line width layout design. this technique modifies a conventional spiral inductor with fixed line width that is decreasing from the outer to the inner turns. By narrowing the width of the inner coils, can be alleviated the loss due to induced current by the time-varying magnetic flux passing through the metal lines in the inner coils. Although this technique is effective and can be easily implemented Q-factor by original technologies, it is generally difficult to find the proper line width of each metal coil. With the obtained analytical formula, the variable line width design can be a very efficient and user-friendly method for improving the inductor performance. We have been make use of several spiral inductors tested,by EM numerical and measurement shows that the conspicuous can improve Q-factor .