Offset Analysis in CMOS Magnetotransistors by Numerical Simulation


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Signal offset in magnetotransistors is for the first time analyzed by numerical simulation. Offset needs to be mini-mized to improve the accuracy of low cost CMOS contact-less angle detection systems. The offset is an unwanted relative imbalance of two collector currents on the order of 1%. To single out this small effect, an accurate device model and an absolutely symmetrical mesh are required. The effect of metal contact misalignment, which is a dominant offset cause, is simulated in excellent agreement with experimental results. This kind of offset is explained by asymmetric ohmic voltage drops within the emitter. It is reduced by a factor of 3 to 4 by an improved emitter layout, which is shown experimentally and by simulation. The effect of emitter layout is studied systematically. The favorable emitter shape is long and narrow having long metal contacts not placed directly opposite the collectors with a minimal margin to the diffusion.

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Journal: TechConnect Briefs
Volume: Technical Proceedings of the 1999 International Conference on Modeling and Simulation of Microsystems
Published: April 19, 1999
Pages: 403 - 406
Industry sector: Sensors, MEMS, Electronics
Topic: Modeling & Simulation of Microsystems
ISBN: 0-9666135-4-6