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 audio_tony 23rd October 2009 03:28 PM

Spice simulation of balanced circuit

I'm trying to simulate a balanced opamp circuit in Tina.

Now this might sound like a stupid question but...

Should I provide the voltage source with a reference to gnd like this..

http://www.gtkc.net/forum-images/with-gnd-ref.png

Or without gnd reference like this...

http://www.gtkc.net/forum-images/without-gnd-ref.png

Thanks.

 stinius 23rd October 2009 03:42 PM

Hi Tony

I知 not familiar with TINA, I知 using PSpice, but what I do when I知 simulating a balanced circuit is that I use 2 voltage sources, both connected to ground, and have one of them 180 degrees out of phase. You put ｽ the voltage in each of them.

Cheers

 Frank Berry 23rd October 2009 04:00 PM

Number 2 is correct. The + input is referenced to ground through R5.

 audio_tony 23rd October 2009 04:05 PM

Quote:
 Originally Posted by stinius (http://www.diyaudio.com/forums/software-tools/153819-spice-simulation-balanced-circuit-post1958518.html#post1958518) Hi Tony I知 not familiar with TINA, I知 using PSpice, but what I do when I知 simulating a balanced circuit is that I use 2 voltage sources, both connected to ground, and have one of them 180 degrees out of phase. You put ｽ the voltage in each of them. Cheers
Hi Stinius, I tried that, unfortunately Tina gives an error message "Only one input is allowed".

Thanks for the suggestion though!

 audio_tony 23rd October 2009 04:06 PM

Quote:
 Originally Posted by Frank Berry (http://www.diyaudio.com/forums/software-tools/153819-spice-simulation-balanced-circuit-post1958535.html#post1958535) Number 2 is correct. The + input is referenced to ground through R5.
Hi Frank, surely you meant the + input is referenced to gnd through R4 and not R5? (which doesn't exist!)

Thanks,
Tony.

 tiefbassuebertr 23rd October 2009 11:58 PM

The input source don't need referenced to ground at my simulations of bal. circuits in "circuitmaker". But the output load need this one. So I must use number 2 of your schematic. I think, at your software it must be the same behaivour. If you see error messages nevertheless, please try to sketch leads between all points of GND and remove the earth symbols except one pieces.
By simulate of a circlotron topology (output also balanced) I must still differentiate between an real GND and GND only for simulate at the negative output

 Ouroboros 30th October 2009 09:14 AM

1 Attachment(s)
This is how I do it for a quick check. This circuit is for a high CMRR differential amp with both a differential input and a common-mode input.

 Ouroboros 30th October 2009 09:17 AM

Of course, for the Bose plots, you need to remove and short-circuit the ac voltage source that is not needed for the plot, as only one ac signal source can be used when performing gain/phase analysis.

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