LPF with differential input - diyAudio
Go Back   Home > Forums > Source & Line > Digital Line Level

Digital Line Level DACs, Digital Crossovers, Equalizers, 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
Reply
 
Thread Tools Search this Thread
Old 6th March 2015, 04:08 PM   #1
Toshen is offline Toshen  Ukraine
diyAudio Member
 
Join Date: Jul 2014
Default LPF with differential input

Hi. Can anybody tell me how to design LPF that has differential input?
There is Sallen-Key topology for example with one OP. Are both of signals will flow into this OP or there is additional OP is needed(comparer)?
Click the image to open in full size.
  Reply With Quote
Old 6th March 2015, 04:16 PM   #2
rayma is offline rayma  United States
diyAudio Member
 
Join Date: Apr 2011
Location: Upper midwest
Quote:
Originally Posted by Toshen View Post
Hi. Can anybody tell me how to design LPF that has differential input? There is Sallen-Key topology
A balanced input/balanced output version of this circuit would have a second identical circuit,
with the Z4 components connected together instead of being grounded.

If you want a single ended output, connect the balanced outputs to a diff amp circuit.

Last edited by rayma; 6th March 2015 at 04:20 PM.
  Reply With Quote
Old 6th March 2015, 05:18 PM   #3
Toshen is offline Toshen  Ukraine
diyAudio Member
 
Join Date: Jul 2014
Did you mean something like this for the second case?
Click the image to open in full size.
PS. not Vin, means Vout(right cannel +-)

Last edited by Toshen; 6th March 2015 at 05:21 PM. Reason: mistake
  Reply With Quote
Old 6th March 2015, 05:22 PM   #4
rayma is offline rayma  United States
diyAudio Member
 
Join Date: Apr 2011
Location: Upper midwest
Quote:
Originally Posted by Toshen View Post
Did you mean something like this for the second case?
Yes, that looks ok. The impedances connecting the two circuits (R4 and R8) can be combined into just one part.
This will likely be a capacitor (of half the value for a single circuit, since they're in series) for a LPF.

Last edited by rayma; 6th March 2015 at 05:28 PM.
  Reply With Quote
Old 6th March 2015, 05:26 PM   #5
Toshen is offline Toshen  Ukraine
diyAudio Member
 
Join Date: Jul 2014
Thanks a lot!
  Reply With Quote
Old 9th March 2015, 07:44 PM   #6
diyAudio Member
 
Join Date: Aug 2008
When you combine Z4, you need to double resistors and inductors, halve capacitors that are part of Z4.

You don't have to take Z4 to the other half though, you can leave them to ground.
__________________
Tyler
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
My differential input 49830 Phil Olson Solid State 6 6th May 2012 11:38 PM
Adding a third input to a differential input stage? maudio Solid State 15 11th October 2006 02:16 AM
please advise.. ext. LPF summing differential outputs by an opamp ASSaBeong Digital Source 0 17th May 2006 11:15 AM


New To Site? Need Help?

All times are GMT. The time now is 09:59 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2015 DragonByte Technologies Ltd.
Copyright 1999-2015 diyAudio

Content Relevant URLs by vBSEO 3.3.2