Hi.
I'm mostly addressing what I perceive as weaknesses in this article from the perspective of someone who really has little idea of the math or what this phase and magnitude stuff actually means. I am specifically not addressing the factual content. If I have worded something in a way which changes the meaning, that is inadvertent.
In closed loop gain, you have "Aol /1+A
β" Did you mean "Aol / (1+A
β)"?
In gain bandwidth, you have "where the gain is 1". I think it might be sensible to say "where the gain is 1 (i.e. the output is the same as the input)", and I'm not sure if you should also say "where the voltage gain is 1...".
In Noise gain, you say: "NG= R1/R2+1". I'm not sure if you mean "NG = (R1/R2)+1", or "NG = R1 / (R2+1)". It's a very easy mistake to make, and I would probably include parentheses even where the rules of precedence mean they are not strictly required.
It might be useful at least once to note how you get from a voltage gain of 1, or 800,000 to a gain in dB of 0 or 118). Perhaps you can place this in your definitions.
I might reword the following:
"Well that’s not far off. Unity gain at approx 800KHz and a gain of approx 118dB and a phase of -45˚.
Now if we look at the slope we see a nice gradual slope down to 0dB. This is the classic single pole response and is the same as the same as a single RC low pass filter.
Note: The solid line on the plot is the magnitude of the output and the dashed line is the phase."
as
"The convention in this document, unless otherwise noted, is that the solid red line on a plot is the magnitude of the output and the dashed red line is the phase difference between the input and the output -- we shall simply call this phase.
Well that’s not far off! Unity gain (0db on the magnitude line) is at approx 800KHz and a gain of approx 118dB. The black dotted lines highlight 0db and approximately 800kHz. The phase at this point (800kHz) is -45˚.
If we look at the magnitude line we see a nice gradual slope down to 0dB. This is the classic single pole response and is the same as the same as a single RC low pass filter."
The technical details I'll leave up to you, but I think it's important that the reader is totally aware of what you're talking about. As you go further, you can drop the parenthetical comments unless the meaning of the lines on the graphs change.
A little later you say:
"What would cause this to come up over the line and be within our unity gain bandwidth? Well in some cases all it needs it a bit of capacitance."
And this sounds like a dire and terrible thing!!! However I'm not sure exactly where to look on the graph, and you haven't told me what terrible thing is going to happen.
Much later you say:
"Why 0.707, I don’t really know where this came from but I think it was derived from Butterworth’s original calculations"
I think it's worth noting to the reader that 0.707 is 1/Sqrt(2). It's not like it's a number that was pulled out of thin air. So we know where it comes from, not necessarily why this particular value was chosen.
I also think you need to add some white space as I have done in one of my examples above.
