Matej,
JuergenK is right!
You need to lift your reference voltages, I'd suggest TL431 shunt regulators set up to give 5 volts. You can run the OpAmps as straight followers then (and I'd suggest 5534 for the opamps).
Do you still need the sim files? I use PSpiceAD, which program do you use? (might be incompatible regarding the various file types).
I have attached a screen shot of an AC-sweep analysis (injecting 10mV AC at the reference voltage), using the same circuit you have posted. The peaking is obvoius, sim was done with 5 ESR values from 1 milliohms to 10 ohms, in x10 steps. The blue line is for 0.1 ohms, for example. With too high an ESR, like 10 ohms, things get worse again, because the emitter follower transistor steals phase margin from the OpAmp and that now comes into play.
Note: Obviously the sim-model of the op amp didn't show the common mode problem... I checked with a 4V Vref, same curves
Regards, Klaus
JuergenK is right!
You need to lift your reference voltages, I'd suggest TL431 shunt regulators set up to give 5 volts. You can run the OpAmps as straight followers then (and I'd suggest 5534 for the opamps).
Do you still need the sim files? I use PSpiceAD, which program do you use? (might be incompatible regarding the various file types).
I have attached a screen shot of an AC-sweep analysis (injecting 10mV AC at the reference voltage), using the same circuit you have posted. The peaking is obvoius, sim was done with 5 ESR values from 1 milliohms to 10 ohms, in x10 steps. The blue line is for 0.1 ohms, for example. With too high an ESR, like 10 ohms, things get worse again, because the emitter follower transistor steals phase margin from the OpAmp and that now comes into play.
Note: Obviously the sim-model of the op amp didn't show the common mode problem... I checked with a 4V Vref, same curves
Regards, Klaus
Attachments
I've tried similar opamp based series regulator, also +/- dual supply, but with transformer.
http://www.diyaudio.com/forums/showthread.php?s=&threadid=94731
To me it looks like the -ve regulator is reversed in the spice schematic.....
Q2 PNP collector should be connected to -12V input but not ground. V3 battery +ve terminal should be connected to ground instead
http://www.diyaudio.com/forums/showthread.php?s=&threadid=94731
To me it looks like the -ve regulator is reversed in the spice schematic.....
Q2 PNP collector should be connected to -12V input but not ground. V3 battery +ve terminal should be connected to ground instead
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