Embedded Systems Design Europe - May 2008 - (Page 35)

analog ENDNOTES: 1. Huelsman, L.P. and Allen, P.E. Introduction to the Theory and Design of Active Filters. McGraw-Hill, New York, 1980. Budak, Aram. Passive and Active Network Analysis and Synthesis. Houghton Mifﬂin Company, Boston, 1974. Ghausi, M.S. and Laker, K.R. Modern ﬁlter Design: Active RC and Switched Capacitor. Prentice-Hall, Englewood Cliffs, N.J., 1981. Sallen, R.P. and Key, E.L. “A Practical Method of Designing Active Filters,” IRE Transactions on Circuit Theory, vol. CT-2, pp.74-85, March 1955. 2. 3. 4. be smaller than the denominators. All the terms are the same but, while a difference is taken in the numerator, a sum is taken in the denominator. The half term out front means that Q sensitivities to R and R are actually less than 0.5. As discussed, having all sensitivities with magnitudes of one or less is as good as it usually gets. Does this mean that the MFB ﬁlter is always less sensitive than the Sallen-Key? In many instances 2 3 it does. Digging deeper into the math, however, we may ﬁnd some surprises. In Part 2, which will be posted online at www.embedded.com, we will delve deeper into the mathematics of the Sallen-Key ﬁlter, and ﬁnd that we can implement highly insensitive ﬁlters with this topology. We will also look at the effects of op amp bandwidth, as well as how to use Monte Carlo analysis in determining how much a ﬁlter’s transfer function will vary in production. FURTHER READING: Fortunato, M. “Circuit Sensitivity; With Emphasis On Analog Filters,” Texas Instruments Developer Conference 2007, March 2007: http://focus.ti.com/general/docs/tidc/ general.tsp?templateId=6180&navigationI d=12622&path=templatedata/cm/tidcgeneral/data/am_landing/ww_07 presentations. Mark Fortunato is an analog ﬁeld applications manager for Texas Instruments. Design Line INDUSTRIAL CONTROL The AUTHORITY in Industrial Control & Automation Design THE INDUSTRIAL CONTROL DESIGNER’S ULTIMATE RESOURCE ON EU-RELATED ISSUES How-to Information & IN-DEPTH ARTICLES ON THE FOLLOWING: Motor Control/Sensors Industrial Instrumentation Process Control Networking Robotics PRODUCTS INFORMATION Product reviews and announcements to inform your design choices LIBRARY Technical references, standards & certiﬁcations and industrial resources NEWS The latest industrial control industry news and updates ELEARNING aimed at helping engineers solve their design challenges Visit Us Online at: www.Industrial-europe.com SPONSORS www.embedded.com/europe | embedded systems design europe | MAY 2008 35 http://www.embedded.com http://focus.ti.com/general/docs/tidc/general.tsp?templateId=6180&navigationId=12622&path=templatedata/cm/tidcgeneral/data/am_landing/ww_07 presentations http://focus.ti.com/general/docs/tidc/general.tsp?templateId=6180&navigationId=12622&path=templatedata/cm/tidcgeneral/data/am_landing/ww_07 presentations http://www.Industrial-europe.com http://www.mpl.ch http://www.Industrial-europe.com http://www.mpl.ch http://www.embedded.com/europe

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Embedded Systems Design Europe - May 2008 Contents Microsoft Provides Embedded Roadmap Enea Buys Developers Irish Start-Up Raises Funds for Telecom FPGAs Kontron Promotes COM Express Nano Mentor Nucleus Platform Provides UI for Atmel Small Form Factor Boards Head for the SUMIT Proffibus Advances IO-Link Integration Embedded Developers Cautious on Multicore Auto Cooperation Improves Test Altera Launches DO-254 Partner Network Building an ‘Instant-Up’ Real-Time Operating Systems An Architecture for Reusable Embedded Systems Software Free up Bandwidth in PCI Express Evaluating Software in Medical Devices Circuit Sensitivity in Analog Circuits Choosing Flash Memory New Products Advertising Contacts

Embedded Systems Design Europe - May 2008

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