I'm wondering if I could take an sx-Amp and hot rod it to deliver similar performance figures.
So, what is an "sx-Amp" ?
I can do 500V/us without much sweat . . . . hmmm.
Winfield's power device selection criteria, and his Figure Of Merit for ranking, are laid out in one of the attachments. I suspect these are part of his Secret Sauce that enables higher speed.
Could you get it to do 5MHz -3dB?
I am a bit busy this week (new product release) but I will look at this over the weekend.
No doubt, as Mark has alluded, the devil is in the detail, but it would be a very interesting challenge.
I have AoE (latest book). Seriously good introduction to the art.
So, what is an "sx-Amp" ?
A DIY CFA (class A) amp. There’s a thread if you do a search.
Could you get it to do 5MHz -3dB?
It's this simple: the example amp has the -3 dB point at 20 MHz - see pics.
Attachments
It's this simple: the example amp has the -3 dB point at 20 MHz - see pics.
Build?
Jan
Can you do a loop gain plot? Looks very simple - hopefully you solved Jan’s request for him.
The reason I came here was to find an amp that I can use to excite a psu regulator with DC + AC at the input, as well as DC + AC load current at the output to measure input ripple rejection, output impedance, that sort of thing.
In principle, an audio power amp fits the bill but I want to sweep the frequency to at least a few 100kHz, better to at least a Meg.
Jan
Build?
Jan
Probably not, because I also designed an amp with THD (100 W 8 ohm 20 KHz) below 30 ppb (no mistake). IMD is lowered similarly, likely even audibly so and the only extra part is a dual opamp, LM49860 plus a few RC's.
Probably not, because I also designed an amp with THD (100 W 8 ohm 20 KHz) below 30 ppb (no mistake). IMD is lowered similarly, likely even audibly so and the only extra part is a dual opamp, LM49860 plus a few RC's.
Did you build that one? Care to show?
Jan
The reason I came here was to find an amp that I can use to excite a psu regulator with DC + AC at the input, as well as DC + AC load current at the output to measure input ripple rejection, output impedance, that sort of thing.
In principle, an audio power amp fits the bill but I want to sweep the frequency to at least a few 100kHz, better to at least a Meg.
Jan
Understood.
That said, for what you are doing, would a current load (adjustable) in parallel with a pulse generator (also adjustable) do the trick?
If you are driving the PSU UT with a fast rise time pulse train, you will be exciting it to HF because of the harmonic content while the DC load will be shifting the operating point.
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"sx-Amp" is ..
Phrase "sx-Amp" will show no results on forum search, but now we know a new name for CF amplifier.
A DIY CFA (class A) amp. There’s a thread if you do a search.
Phrase "sx-Amp" will show no results on forum search, but now we know a new name for CF amplifier.
We are all talking ppb. Does it matter ?
Or over 200v/uS ? Audio only requires a paltry <20v/uS.
The only reason I go with a 200V/uS CFA is the "fat" gain margin
at 20K , so I can get my (realistic) <20ppm THD 20K.
Not for the slewrate.
Edit - I have ported "greenamp CFA " to a BJT 40W class A. 1-5ppm all the way.
But not too "green". It gets too hot here.
OS
Or over 200v/uS ? Audio only requires a paltry <20v/uS.
The only reason I go with a 200V/uS CFA is the "fat" gain margin
at 20K , so I can get my (realistic) <20ppm THD 20K.
Not for the slewrate.
Edit - I have ported "greenamp CFA " to a BJT 40W class A. 1-5ppm all the way.
But not too "green". It gets too hot here.
OS
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Understood.
That said, for what you are doing, would a current load (adjustable) in parallel with a pulse generator (also adjustable) do the trick?
If you are driving the PSU UT with a fast rise time pulse train, you will be exciting it to HF because of the harmonic content while the DC load will be shifting the operating point.
Yes, understood. But not as nice and easy to interprete as, say, a frequency sweep.
I was looking at this as well:
https://www.batronix.com/files/ITECH/IT8800.pdf
Specifically the 8812B.
Jan
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"sx-Amp" is ..
Phrase "sx-Amp" will show no results on forum search, but now we know a new name for CF amplifier.
Here sx-Amp and nx-Amp
You are right sx-Amplifier does not return any results
Yes, understood. But not as nice and easy to interprete as, say, a frequency sweep.
I was looking at this as well:
https://www.batronix.com/files/ITECH/IT8800.pdf
Specifically the 8812B.
Jan
Whew. Nice, but it looks very expensive - I can see why you rather prefer to go with a fast amp.
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