
Home  Forums  Rules  Articles  The diyAudio Store  Gallery  Blogs  Register  Donations  FAQ  Calendar  Search  Today's Posts  Mark Forums Read  Search 
Parts Where to get, and how to make the best bits. PCB's, caps, transformers, etc. 

Please consider donating to help us continue to serve you.
Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving 

Thread Tools  Search this Thread 
22nd April 2004, 12:15 PM  #31 
diyAudio Member

I think I'll get the picture now, using SPICE. The last element is a resistor which will be conveted into a capacitor. It's OK to have a cap as load up to a finite frequency. Highpass fillter has a cap to "unlimited frequency => unrealistic current demands.
I'll guess that it's true that highpass filters can't be made by FDNR. In theory it will but not in real life.
__________________
/PerAnders (my first name) or PA as my friends call me PA03 LM4780 amplifier group buy, SIGN UP HERE 52 boards so far. Paid (28) 
26th April 2004, 05:46 PM  #32  
diyAudio Member

Quote:
http://www.kemt.fei.tuke.sk/Predmety...ialy/ch029.pdf it's in part 29.3 of the article: 

27th April 2004, 02:06 PM  #33 
diyAudio Member

FDNR's are impossible to use a highpass filter but I can use the same style simulated inductor instead.
jackinnj, please note that your example is a simple negative resistance, not frequency dependent.
__________________
/PerAnders (my first name) or PA as my friends call me PA03 LM4780 amplifier group buy, SIGN UP HERE 52 boards so far. Paid (28) 
27th April 2004, 02:27 PM  #34 
diyAudio Member

Per  no, the bottom figure is reactive.

27th April 2004, 02:34 PM  #35 
diyAudio Member

Yes, as L, inductance. I know how a GIC inductance looks like, just use one cap.
__________________
/PerAnders (my first name) or PA as my friends call me PA03 LM4780 amplifier group buy, SIGN UP HERE 52 boards so far. Paid (28) 
14th July 2005, 07:42 AM  #36 
diyAudio Member

Why not use a gyrator circuit to simulate an inductor?
I do that in my own active filter one The manual has all equations needed \Jens 
14th July 2005, 07:55 AM  #37 
diyAudio Member

I know about the gyrator circuit with one or two opamps but a GIC looks cooler. I have no idea if it has any hidden good properties.
Jens, how come you found this old thread? Searched for FDNR?
__________________
/PerAnders (my first name) or PA as my friends call me PA03 LM4780 amplifier group buy, SIGN UP HERE 52 boards so far. Paid (28) 
14th July 2005, 08:07 AM  #38 
diyAudio Member

Nope,
I just clicked your link in the bottom of your post \Jens 
22nd October 2010, 03:42 PM  #39 
diyAudio Member
Join Date: Oct 2010

HP FDNR
I know this thread is old and dead. But in case anyone was curious you can get a FDNR HP using something like the attached image. If you want LP just switch all the R's and C's

19th February 2011, 05:42 PM  #40 
diyAudio Member
Join Date: Dec 2009

I started investigating FDNR's again.
I used a 1 opamp grounded FDNR on my crossover page, and also a 1 opamp grounded gyrator (inductor simulator). Oneendisgrounded oneopamp FDNR's and gyrators use 1 opamp instead of 2, which is very useful for shunt legs on filters; its downside is it has a parasitic shunt R (in the case of the FDNR, series R in the case of the gyrator), which, with careful design, can be rendered insignificant. I used it to great effect, reducing my opamp count, over the 2 opamp gyrator/FDNR, and it is far less sensitive to component tolerance than the biquad type of zeropair implementation (according to Spice Monte Carlo analysis). With 2 opamps I achieved a 4th order elliptic filter (4 poles, 2 imaginary zero pairs). By configuring the opamp as a unity gain follower, open loop gain isn't that much of an issue, depending on the exact topology (e.g. if the impedance you need doesn't need to go very high); what you have to watch out for is the load presented to the opamp and the opamp input impedance (you usually need FET input opamps). The effect of open loop gain is apparent if you simulate gain = 0.99 (which is with open loop gain = 40 dB). (Ditto for effect of input impedance, on circuit's required max impedance). I wrote the page back in 2000: Jason Cuadra: Elliptic Crossovers Scroll to the bottom. Last edited by jasoncsbb; 19th February 2011 at 05:50 PM. 
Thread Tools  Search this Thread 


Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
Audio Gate Circuit / frequency filters, too?  junktl  Everything Else  0  23rd January 2009 07:36 PM 
Number of taps vs. frequency resolution for fir filters  Dan_E10  Digital Source  3  20th June 2008 09:09 PM 
FDNR Deluxe Active filter  peranders  Parts  17  31st August 2005 07:55 AM 
Technical Discussion about Frequency Dependent Terminal Impedance  dkemppai  Full Range  22  18th August 2005 02:32 AM 
where to place active filters?  AndrewT  MultiWay  1  22nd October 2004 01:14 AM 
New To Site?  Need Help? 