I've done some MC stepups recently in which I fine-tuned the pullup resistor in a folded cascode to reduce 2nd. I am listening to it now, for a change.
For very simple material, like a solo voice, not much. For IM, significant concern IMO. Where there is 2nd there is sum and difference frequency IM.
The one proof that we have landed on the moon should be having hubble focus
on the areas where we have been on the moon and publish photos.
Forgive my ignorance, but it might be kinda nice to see. So where are
the pics of the moon landing sites from earth or orbital eyes in the sky?
How many men really know Neil Armstrong?
I"ve looked I can't figure it out either. So where are the pics showning the
moon and people on it from earth, or landings images. Wasn't Neil only
a qkuiet guy after he walked on the moon?
I am not sure if a really effective low noise current source is practical in this design, IF noise is to be minimum. Look at the simple equivalent circuit that I put up. Can you see that if everything is equal, then we will lose 3dB from the current source alone. Could be worse, much worse. A resistor should give better noise performance.
Attachments
250 mill trace width 2 oz copper 125 mill hole not a via. Not exactly the kind of layouts you seem to be doing.
Power supply rejection ratio is often specified at line frequencies rather than the critical audio frequencies around 6000 Hz. In addition there are lots of other paths for power supply noise to couple to the output. So a clean power supply is a really good first step.
So magically high PSSR often has no benefit.
Yes, especially if the ccs is used as a gain stage load application....... So, what is your next step in development?
-RNM
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I have never considered it art such even when I was doing tape ups... Maybe that's why I have always been in demand as a PCB designer, because I consider it an engineering discipline, study all aspects of it and don't have an arty f.... attitude to layout.
I think part of the art is that the final output is often referred to as an artwork... That's just my boring view, but a PCB is just a physical representation of a circuit diagram.
Without getting into too much theory, I believe the above is true and why it almost always makes me prefer a wide bandwidth low GNFB amp to the traditional high gain, high GNFB designs. Of course, that's just one part of the whole, but I firmly believe it is a crucial part.
Such amplifiers seem to be subjectively faster, almost instaneous in situations where the music is dense so to speak, with a sound stage full of participants. There is an air of immediacy and vigour I rarely find in traditional designs. The penalty are poorer specs, greater THD measurements, but also usually better phase response. It simply usually sounds better (usually - not guaranteed).
Just to be clear, neither did I, but was just trying to remind everyone of the good old days. Rubylith anyone?
Exactly which type of CCS? Some time ago, we exchanged some words about them, and looking over my documentation I was quite surprised to find an outstanding choice of possible designs used today. Probably the most frequently used type in the industry is a zener diode preceeded and followed by resistors, possibly in parallel with a cap ranging in value from 0.1 to 47 uF meant to filter out the zener noise.
Some manufacturers of commercial amps, like Harman/Cardon, by default pay much attention to them, and use rather complex ciruits (e.g. PA 2400), built around BJTs and using 9 transistors. Obviously, they believe that the CCS is a very important matter deserving such uncommon attention.
Just as an idea, in his research, perhaps John could take a closer look at the common types of CCS in view of his requirements.
Some examples are shown below. Not a complete list, I need to update it.
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