HOME  |  NEWS  |  BLOGS  |  MESSAGES  |  FEATURES  |  VIDEOS  |  WEBINARS  |  INDUSTRIES  |  FOCUS ON FUNDAMENTALS
  |  REGISTER  |  LOGIN  |  HELP
AnandY
User Rank
Gold
Silicon area
AnandY   6/12/2013 5:22:50 AM
NO RATINGS
In a SCF, capacitors and switches take the place of resistors...

High-value resistors can be implemented in very little silicon area. For example, a 1-Mohm resistor can be realized with a 1-pF capacitor switched at a clock rate of 1-MHz.

AnandY
User Rank
Gold
Capacitor ratios
AnandY   6/12/2013 5:16:08 AM
NO RATINGS
So, for an SCF, the frequency response depends solely on the ratio of two capacitors, C and C1, and the switching-clock frequency, fclk.

@Jon, thanks for the very informative post. Capacitor ratios can take advantage of the superior matching of capacitances fabricated on silicon. Especially in monolithic form capacitor ratios are very robust against changes in temperature.

Jon Titus
User Rank
Blogger
Switched-Cap Filter Applications?
Jon Titus   6/11/2013 5:41:48 PM
NO RATINGS
You will find switched-capacitor filters (SCFs) in audio circuits, in anti-aliasing filters, and in tracking filters. The latter type of filter can track a signal by adjusting the filter's clock frequency to "tune" filter characteristics as a sampled signal changes frequency. You also can use SCFs in tone-detection circuits. Unlike a PLL circuit that requires external passive components (and trimming) to detect a tone, an SCF requires only a clock signal. SCFs also serve as notch filters.

Because the filtering occurs based on a "master" clock signal's frequency, you might consider an SCF is you want to scan a given bandwidth to obtain information within it at certain frequencies.  The SCFs would act like the front end of a spectrum analyzer.

Cabe Atwell
User Rank
Blogger
app
Cabe Atwell   6/11/2013 5:20:43 PM
NO RATINGS
Jon,

Can you suggest some applications for the filter you describe?

C



Partner Zone
Latest Analysis
We shared our list, now Design News readers tell us which artificial intelligence movies they watch again and again.
Researchers have been working on a number of alternative chemistries to lithium-ion for next-gen batteries, silicon-air among them. However, while the technology has been viewed as promising and cost-effective, to date researchers haven’t managed to develop a battery of this chemistry with a viable running time -- until now.
Norway-based additive manufacturing company Norsk Titanium is building what it says is the first industrial-scale 3D printing plant in the world for making aerospace-grade metal components. The New York state plant will produce 400 metric tons each year of aerospace-grade, structural titanium parts.
Researchers have simplified the fabrication of the geometric requirements for fluid motion in microrobots for in vivo medical applications.
The National Aeronautics and Space Administration’s recently announced plan to put an electric airplane in the air by 2018 is forward-looking, but hardly unique.
More:Blogs|News
Quick Poll
The Continuing Education Center offers engineers an entirely new way to get the education they need to formulate next-generation solutions.
Jul 11 - 15, Embedded System Design Techniques™ - Debugging Real-time Embedded Software – Hands on
SEMESTERS: 1  |  2  |  3  |  4  |  5  |  6 |  7 | 8 | 9 | 10


Focus on Fundamentals consists of 45-minute on-line classes that cover a host of technologies. You learn without leaving the comfort of your desk. All classes are taught by subject-matter experts and all are archived. So if you can't attend live, attend at your convenience.
Learn More   |   Login   |   Archived Classes
Twitter Feed
Design News Twitter Feed
Like Us on Facebook

Technology Marketplace

Copyright © 2016 UBM Canon, A UBM company, All rights reserved. Privacy Policy | Terms of Service