The Kubota Reg, uh ?
Nice working reg, but it should deserve some improvements IMHO. Just have a look at this post by Jonathan Carr (and the following posts too) :
http://www.diyaudio.com/forums/showthread.php?postid=135268#post135268
I'm currently willing to implement such regs in my future preamp, and I've made some simulations, trying to improve the output impedance and the line regulation.
For the moment, I ended up replacing the emitter's resistance of the diff pairs by CCS (just a source degerated JFet for example).
Improving the voltage reference filtering with a RC network won't certainly hurt, and adding a decoupling cap for the sensing resistor bridge helps a lot.
I've attached the schematic I've used so far, but I'm sure things can be further improved, though I don't know how...
In the schematic, R2/C3/C4 provide low pass filtering for the reference. The C2 cap showed a great influence on the reg's performance (PSRR), the higher being the better...
I've added the C5-C6 caps. I found them mandatory to further reduce the output impedance below 10mOhms.
Feel free to comment/improve/flame...
Nice working reg, but it should deserve some improvements IMHO. Just have a look at this post by Jonathan Carr (and the following posts too) :
http://www.diyaudio.com/forums/showthread.php?postid=135268#post135268
I'm currently willing to implement such regs in my future preamp, and I've made some simulations, trying to improve the output impedance and the line regulation.
For the moment, I ended up replacing the emitter's resistance of the diff pairs by CCS (just a source degerated JFet for example).
Improving the voltage reference filtering with a RC network won't certainly hurt, and adding a decoupling cap for the sensing resistor bridge helps a lot.
I've attached the schematic I've used so far, but I'm sure things can be further improved, though I don't know how...
In the schematic, R2/C3/C4 provide low pass filtering for the reference. The C2 cap showed a great influence on the reg's performance (PSRR), the higher being the better...
I've added the C5-C6 caps. I found them mandatory to further reduce the output impedance below 10mOhms.
Feel free to comment/improve/flame...
Attachments
Yep, sort of...
AFAIK, they provide a lower impedance network, both for the sensing bridge and the whole output, to which it is connected. I didn't invent anything, it appears in many discrete regs, even the Walt Jung's one. Here is a plot of the output impedance, showing that (in theory), it improves the Zo by a 8 factor...
AFAIK, they provide a lower impedance network, both for the sensing bridge and the whole output, to which it is connected. I didn't invent anything, it appears in many discrete regs, even the Walt Jung's one. Here is a plot of the output impedance, showing that (in theory), it improves the Zo by a 8 factor...
Attachments
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