With the penalty of an extra pole in the feedback loop but with the advantage of being able to use a higher impedance feedback network.
I prefer to not buffer and suffer higher heat losses in the feedback resistors.
Paul
I proposed Low Impedance Inverting Input op-amp, LiiiOp last wenesday :
La contre-reaction en courant n'est plus ce qu'elle etait
Heat in the FB R is not my fav.
I guess you will need a so called "DC-Servo" as well? Or *** forbid using an output C.
Cheers
S
Heat in the FB R is not my fav.
I guess you will need a so called "DC-Servo" as well? Or *** forbid using an output C.
Cheers
S
Trade offs
- heat is ok for me and in my current design saves having to match 4 jfets.You guessed right but I connect my DC servos in a unconventional way. Don't like to connect to the feedback network.
No output C for me either or in the feedback network.
Paul
TBH I don't think Mr. Didden is interested in a tech. discussion. IMO his only interested is to stir the pot.
Cheers
S
When saying VFA is a buffered CFA, you point something very important where disagreements about the way CFAs really works do not matter.
What you say implies that the job of the transistors in charge of the subtraction process of feedback is the same in CFAs and VFAs.
How about making this discussion even more nonsensical by taking it one abstraction level higher?
According to the definitions used in this thread, a voltage feedback amplifier is one with shunt feedback at the output, series feedback at the input and a high open-loop input impedance of the negative input. Similarly, a current feedback amplifier is one with shunt feedback at the output, series feedback at the input and a low open-loop input impedance of the negative input.
If you want to think about feedback concepts without worrying about implementation details, it is often useful to start with a nullor (two-port consisting of a nullator and a norator) instead of a real physical amplifier implementation. By definition, the voltage across and current through a nullor output port (norator) can have any value, while the input port of a nullor (the nullator) by definition has an input current and an input voltage of 0. Its impedance is therefore 0 V/0 A, or undefined.
How should you call an amplifier consisting of a nullor and a feedback network with shunt feedback at the output and series feedback at the input? An undefined feedback amplifier because the nullator impedance is undefined, or a 0 feedback amplifier because the error signal is 0 (which implies infinite loopgain)?
According to the definitions used in this thread, a voltage feedback amplifier is one with shunt feedback at the output, series feedback at the input and a high open-loop input impedance of the negative input. Similarly, a current feedback amplifier is one with shunt feedback at the output, series feedback at the input and a low open-loop input impedance of the negative input.
If you want to think about feedback concepts without worrying about implementation details, it is often useful to start with a nullor (two-port consisting of a nullator and a norator) instead of a real physical amplifier implementation. By definition, the voltage across and current through a nullor output port (norator) can have any value, while the input port of a nullor (the nullator) by definition has an input current and an input voltage of 0. Its impedance is therefore 0 V/0 A, or undefined.
How should you call an amplifier consisting of a nullor and a feedback network with shunt feedback at the output and series feedback at the input? An undefined feedback amplifier because the nullator impedance is undefined, or a 0 feedback amplifier because the error signal is 0 (which implies infinite loopgain)?
I give up. You posts are too full of content for me, and you are getting good at it.
Ignore list? No why would that be? Lots of useful and interesting posts from you, where I don't feel the need to comment. It's just when you switch to your pi$$-off/personal mode that it gets useless and content-free. Just wanted to make you aware in case you weren't. But I can handle it
Jan
Ignore list? No why would that be? Lots of useful and interesting posts from you, where I don't feel the need to comment. It's just when you switch to your pi$$-off/personal mode that it gets useless and content-free. Just wanted to make you aware in case you weren't. But I can handle it
Jan
I am not sure what all the hubbub is about. Originally, the topology was referred to as Current-Mode Operation as opposed to Voltage-Mode operation. The internal workings are of current transfers, low Z and thus fast stray/device C charge and therefore high BW and SR. etc.
I put up early publications on the subject from conferences. Simply read a new book from Springer publications called - Current Feedback Operational Amplifiers and their Applications. ACSP - Analog Circuits and Signal processing. By Raj Senani et al 2013. Add it to your library.
No need to argue about what it is or isn't.... just read the book and know. Done.
BTW Waly - Dadod's Current-Mode PA is not only a simulation... but built and tested and is as the SIM indicates.
THx-RNMarsh
I put up early publications on the subject from conferences. Simply read a new book from Springer publications called - Current Feedback Operational Amplifiers and their Applications. ACSP - Analog Circuits and Signal processing. By Raj Senani et al 2013. Add it to your library.
No need to argue about what it is or isn't.... just read the book and know. Done.
BTW Waly - Dadod's Current-Mode PA is not only a simulation... but built and tested and is as the SIM indicates.
THx-RNMarsh
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As does Bonsai amps and many others. I pointed out before that most of the well known (Marantz etc) and High End have Current-Mode power amps for their top tier products and Volt Mode below them. I haven't talked to their engineers but might guess because they produce the best results and seems buyers agree. It is what it is.
THx-RNMarsh
My V4 amplifier too, and I did it because of the sound quality. If I can go beyond with different topology, I will forget it...
Sajti
That’s perfectly fine, do what you think you have to do.
I'm just onthe sideline and am admiring Michael Kiwanuka as well as some here in the task to bring forward the technology of analog amplification by bitching over semantics.
All this invested time surely will result in something tangible at the end.
The others maybe have better things to do, eg. taking care for traction when transferring their brain-HP to the wheels.
Back to your regular program, gents.