Maxim high pass filters

Optical · 20th November 2002, 11:47 AM

I just found out about these!
has anyone tried them out? ive ordered some samples, im not sure that they have a spectacular noise figure or anything, but they look very useable..

Are there any competition I.C's to these around?
Would an 8th order sullen-key filter be better?

http://www.maxim-ic.com/quick_view2.cfm/qv_pk/1370

jackinnj · 20th November 2002, 02:40 PM

As you increase the order of an analog filter the tolerances of the components required get tighter and tighter, that is, with a 12dB/8vo filter you can probably get away with 1%, with 24dB/8vo it's more like 0.1%. OTOH, there are other problems to consider with switched cap filters:

With switched cap filters you have to post-filter to remove the clocking noise. Maxim doesn't state this in their PDF.

Note the noise figure and distortion -- -70dB -- well at least you will be able to measure it.

Fred Dieckmann · 20th November 2002, 03:35 PM

For what?

high distortion
high noise
Extremly! low power supply rejection.

These filter types are maginal for all but the lowest fidelity uses.
I have even had trouble with them in voice frequency low end telcom applications.

Not even worth trying,
Fred

Its Sallen-Key, not sullen-key, by the way. Sullen is what you will be after reading this post.

http://www.bartleby.com/61/68/S0876800.html

Sallen-Key
http://www.altavista.com/web/results...ls=1&avkw=qtrp

jackinnj · 20th November 2002, 04:17 PM

on Sallen-Key filters. It is well worth downloading.

Optical · 20th November 2002, 11:24 PM

So i forgot how it was spelt... Sullen im not.

Optical · 20th November 2002, 11:26 PM

Ive been checking out other manufacturers, seems LT make an ultralow noise model.. Ive got samples on the way, thanks for the input!

20th November 2002, 11:47 AM	#1
Optical diyAudio Member Join Date: Nov 2002 Location: Auckland, New Zealand	Maxim high pass filters I just found out about these! has anyone tried them out? ive ordered some samples, im not sure that they have a spectacular noise figure or anything, but they look very useable.. Are there any competition I.C's to these around? Would an 8th order sullen-key filter be better? http://www.maxim-ic.com/quick_view2.cfm/qv_pk/1370

20th November 2002, 03:35 PM	#3
Fred Dieckmann diyAudio Retiree Join Date: Oct 2002 Location: Spain or the pueblo of Los Angeles	but they look very useable.. For what? high distortion high noise Extremly! low power supply rejection. These filter types are maginal for all but the lowest fidelity uses. I have even had trouble with them in voice frequency low end telcom applications. Not even worth trying, Fred Its Sallen-Key, not sullen-key, by the way. Sullen is what you will be after reading this post. http://www.bartleby.com/61/68/S0876800.html Sallen-Key http://www.altavista.com/web/results...ls=1&avkw=qtrp

20th November 2002, 04:17 PM	#4
jackinnj diyAudio Member Join Date: Apr 2002 Location: Llanddewi Brefi, NJ	TI has a big ap note on Sallen-Key filters. It is well worth downloading.

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20th November 2002, 02:40 PM	#2
jackinnj diyAudio Member Join Date: Apr 2002 Location: Llanddewi Brefi, NJ	As you increase the order of an analog filter the tolerances of the components required get tighter and tighter, that is, with a 12dB/8vo filter you can probably get away with 1%, with 24dB/8vo it's more like 0.1%. OTOH, there are other problems to consider with switched cap filters: With switched cap filters you have to post-filter to remove the clocking noise. Maxim doesn't state this in their PDF. Note the noise figure and distortion -- -70dB -- well at least you will be able to measure it.

20th November 2002, 11:24 PM	#5
Optical diyAudio Member Join Date: Nov 2002 Location: Auckland, New Zealand	So i forgot how it was spelt... Sullen im not.

20th November 2002, 11:26 PM	#6
Optical diyAudio Member Join Date: Nov 2002 Location: Auckland, New Zealand	Ive been checking out other manufacturers, seems LT make an ultralow noise model.. Ive got samples on the way, thanks for the input!

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