REGISTER | LOGIN
Home    Bloggers    Blogs    Article Archives    Messages    About Us   
Tw  |  Fb  |  In  |  Rss
The Filter Wizard Remastered

An E96 formula: How Can You Resist It?

Kendall Castor-Perry
michaelmaloney
michaelmaloney
4/9/2019 10:00:59 PM
User Rank
Newbie
Cheers!
It's frustrating to have to try and work out things across different platforms, but I guess it's good to be able to learn all sorts of different systems to make your ability to work more flexible across the board. Glad to have this all laid out on the table though. Perhaps it might help the next time I'm trying to crunch some fingers so thank you very much for sharing all of this information!

50%
50%
Sfinx
Sfinx
3/20/2019 2:52:01 PM
User Rank
Newbie
Re: Precision C0G caps are much lower price now
I certainly agree that exact design pays off for single amplifier biquads.  I've found that cell-based suvvessive design works better for tunable state-variables for apex legends free coins ...

50%
50%
kendallcp
kendallcp
3/18/2019 6:17:16 PM
User Rank
Artist
Re: Precision C0G caps are much lower price now
Thanks for that, Mike!  I guess my incessant moaning (and that of others with larger production runs <g>) about the lapse in cap supply must have paid off some time in the last decade!  The radio guys certainly need plenty of steps in the sup-100pF range, for RF matching networks and filters.

I certainly agree that exact design pays off for single amplifier biquads.  I've found that cell-based suvvessive design works better for tunable state-variables.  And as for FDNR ladder derived designs, they are generally so insensitive that you can convert everything to E96 in one go and still get something that's almost indistinguishable from the prototype.

Good to hear from you, keep in touch!

50%
50%
TucsonMike
TucsonMike
3/17/2019 9:54:20 AM
User Rank
Blogger
Precision C0G caps are much lower price now
I am going to try and paste in a word document with a snip showing some recent prices - snip might not come across, No it didn't, darn - oh well I found some <$0.01 in 100s even in 1% C0G, 0201, E24 steps, 25V MLCC caps from Murata. Full part number for the 100pF 1% tolerance was GRM0335C1E1010FA01D. 

Hey Kendall,

 

Nice to have that E96 equations, but I think some of your comments apply more to some years back. Oddly, on another discussion doing MFB filters I went back and checked again for e24 values in finer tolerance than 5%. Wow, they have really come down. I found 2% and 1% both under $0.01 in 100s at Mouser (Murata, GRM series)

 

 

I don't see why we should not use 1% C0G caps now – but since the E24 are in such large steps, what I do it kind of iterate to some standard C values first (in the LP MFB), then solve exactly for the 3 R's then go on from there for E96 selections for best fit. 

50%
50%
More Blogs from The Filter Wizard Remastered
There’s a further cool thing you can do with a spreadsheet that most SPICEs can’t. That’s to use the spreadsheet ‘solver’ functionality to adjust component values in the search for a better-fitting circuit – or even to find a set of component values for a circuit you can’t otherwise design.
You now need to adjust component values to achieve some system goal, such as predefined frequency response or time behaviour, and there’s no closed method for working out those values.
In previous posts I’ve talked about transferring spreadsheet-based circuit design “directly” to the lovely LTspice simulator, and a reader of The Filter Wizard was keen to understand exactly what “directly” actually meant, and to get some practical information on how to do it.
The required selectivity of a customer design implied four-pole filters with about 10% bandwidth (passband width about 10% of the centre frequency). There was a catch---a tight power budget
Now, our customer doesn’t want to buy big, expensive, high quality capacitors to build an active filter with this response. So, having established the principle of optimizing in the analogue domain, let’s look at whether need to make any changes in order to use it to create a digital filter – which we’ll be able to implement on the Cypress PSoC 3
flash poll
educational resources
 
follow Planet Analog on Twitter
Planet Analog Twitter Feed
like us on facebook
our partners
Planet Analog
About Us     Contact Us     Help     Register     Twitter     Facebook     RSS