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4/9/2019 10:00:59 PM
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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!

3/18/2019 6:17:16 PM
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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!

3/17/2019 9:54:20 AM
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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. 


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