Hi, I have two schemas, one in Sapwin and other in LTSpice, they have exactly the same components and values, but when I run the AC simulation, GAIN magnitude differs a lot between them, does anyone knows why? I've analysed the circuit symbolically in Matlab and I get the same freq. response graph (and equation) that in Sapwin.

Here are Sapwin and LTSpice schemas, and their respective freq. response graph

<snip> Moderator edit: link deleted owing to image host opened a page with pornographic material. Please try a differ image hosting site.

Thanks in advance!

PD: This amplifier is the Amp stage for a Vackar VCO, but that's just a tip.

 

The difference should probably be: the 2 simulators work differently, until you put it on a board and test it with an osciloscope it will never be certain.

There is probably some setting or like in orcad (the resistors change the polarity if you put pin "2" first).

 

Here's the image again. Guess it was a not so welcome image source before.