Modern analog circuits are heavily dependent on inductor performance, where the poor inductor quality factor ( ) of silicon processes leads to degradation in circuit efficacy, especially at RF and microwave frequencies. Several techniques have been proposed to enhance the of integrated on-chip inductors, but the most effective method of improvement is to lower the series resistance by increasing the inductor metal thickness. This paper presents the most cost-effective method of achieving a thick metal by using a standard 0.18-m multilayer BiCMOS process. An expanded physically based model for multiple-metal stacked inductors is presented, which expands on previous research to show the effects and limitations of stacking two, three, and four metal layers in a five-metal-layer process. The excellent accuracy of this geometrical model is illustrated with respect to a range of inductor designs showing that an improvement in of more than 50% may be achieved. Due to the increased parasitics in multilayer structures, the improvement is very frequency dependent, which is clearly predicted with the expanded model. The predictive capability of the model is further used to provide detailed insight into the effectiveness of a patterned ground shield for different substrate characteristics. This predictive ability will contribute greatly to first time right inductor designs and eliminate the expensive and time-consuming fabrication iterations required to fine tune other inductor models.Index Terms-Integrated stacked inductor model, patterned ground shield (PGS), improvement, prediction.

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A clever way to simulate numerical matched loads is presented and applied in the mathematical framework of the moment method. This approach presents a lot of advantages with regard to other numerical matched load simulations, and could be used whateier the shape of the planar circuit without the help of the characteristic impedance concept. Results show that very good efficiency is obtained for the reflection coefficient of such matched loads. Typical results are exhibited for S‐parameter determination of multipart microstrip circuits. © 1994 John Wiley & Sons, Inc.

A light weight, simple design NMR apparatus consists of 24 identical magnets arranged in Halbach array was designed and built. The homogeneity of the magnetic field B0 can be improved by dividing a long magnets into several rings. The size of the useful volume depends on both the gap between each ring and some others shim magnets. Our aim is to enhance the sensitive volume and to maintain the highest magnetic static field (B0). This apparatus generates a B0 field strength of about 0.1 T. This work focuses on the magneto-static simulation of NdFeB magnets arrangement and on the comparison with the measurement of the magnetic field strength and homogeneity in three dimensions (3D). The homogeneity of the magnetic field B0 is optimized with the help of CAD and mathematical software. Our results were also validated with a Finite Element Method (FEM). The simulation results of the strength and of the homogeneity of B0 field were compared to those obtained with a digital gaussmeter. The homogeneity in the magnet longitudinal axis and the field B0 strength are similar. However, the homogeneity in transverse plane differs from simulation and measurement because of the quality of the magnets. In order to improve the homogeneity, we propose a new shim method.