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
Some humanoid walking robots are also good at running, balancing, and coordinated movements in group settings. Several of our sports robots have won regional or worldwide acclaim in the RoboCup soccer World Cup, or FIRST Robotics competitions. Others include the world's first hockey-playing robot and a trash-talking Scrabble player.
Sherlock Ohms highlights stories told by engineers who have used their deductive reasoning and technical prowess to troubleshoot and solve the most perplexing engineering mysteries.
Melissa Cavanagh of 3DP Unlimited talked to Design News about the company’s large format 3D printer, during Medical Design and Manufacturing Midwest.
The DDV-IP is a two-wheeled self-balancing robot that can deliver cold beverages to thirsty folks on hot summer days. A wireless RF remote enables manual control of the device beyond the act of self-balancing. All of the features of the DDV-IP result in an effective delivery vehicle while providing entertainment to the user.
Eric Doster of iFixit talks about the most surprising aspect of the Microsoft Surface Pro 3 teardown. In a presentation at Medical Design & Manufacturing Midwest, iFixit gave the Surface Pro 3 a score of one (out of a possible 10) for repairability.
More:Blogs|News
Design News Webinar Series
10/7/2014 8:00 a.m. California / 11:00 a.m. New York
9/25/2014 11:00 a.m. California / 2:00 p.m. New York
9/10/2014 11:00 a.m. California / 2:00 p.m. New York
7/23/2014 11:00 a.m. California / 2:00 p.m. New York
Quick Poll
The Continuing Education Center offers engineers an entirely new way to get the education they need to formulate next-generation solutions.
Oct 20 - 24, How to Design & Build an Embedded Web Server: An Embedded TCP/IP Tutorial
SEMESTERS: 1  |  2  |  3  |  4  |  5  |  6


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.
Next Class: 10/28-10/30 11:00 AM
Sponsored by Stratasys
Next Class: 10/28-10/30 2:00 PM
Sponsored by Gates Corporation
Learn More   |   Login   |   Archived Classes
Twitter Feed
Design News Twitter Feed
Like Us on Facebook

Sponsored Content

Technology Marketplace

Copyright © 2014 UBM Canon, A UBM company, All rights reserved. Privacy Policy | Terms of Service