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Show us your square wave
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magic:
What's the frequency of this ringing, 300MHz or so? Note the slow timebase of 50ns. I think it's too slow for filter artifact on a 600MHz DSO.

It should be genuine ringing and I have seen enough of it in similar generators that I'm surprised this one performs so well, despite being built with THT components. What chip is this? You expect there to be ringing because the chip is a capacitor connected to the power supply through inductors and it draws sharp pulses of current which excite the resonance.

The "pre-ringing" is probably ringing caused by the oscillator gate switching, and then you see the edge one tpd later followed by more violent ringing caused by the line driving gate(s) switching.

These generators perform better if built with SMD components.

edit
case in point: SOT23 package and a 400MHz analog scope:
https://www.mikrocontroller.net/topic/217945#2205244
David Hess:

--- Quote from: magic on June 09, 2024, 08:37:04 am ---What's the frequency of this ringing, 300MHz or so? Note the slow timebase of 50ns. I think it's too slow for filter artifact on a 600MHz DSO.
--- End quote ---

Both examples are at 2 GS/s, which apparently is the limit for this DSO despite the high claimed bandwidth.  It looks like the number of listed points is correct for the time/div setting, if that is what points means.  I am dubious about the bandwidth claim until I see it measured at different sensitivities with different amplitudes because this may be another case of a modern DSO variable full power bandwidth limited by slew rate.

It would help to see both measurements made at the same time/div.  Could the DSO filtering be executed on the display record, so changing the time/div would do all kinds of weird things with a fast transition time edge?


--- Quote ---It should be genuine ringing and I have seen enough of it in similar generators that I'm surprised this one performs so well, despite being built with THT components. What chip is this? You expect there to be ringing because the chip is a capacitor connected to the power supply through inductors and it draws sharp pulses of current which excite the resonance.

The "pre-ringing" is probably ringing caused by the oscillator gate switching, and then you see the edge one tpd later followed by more violent ringing caused by the line driving gate(s) switching.
--- End quote ---

Expanding the display of the preshoot should help.  If the preshoot starts by a gate delay, then maybe it is the ringing of the first stage coupled into the supply of the output buffer?  I do not see any output series resistors but they could be on the other side of the printed circuit board.


--- Quote ---These generators perform better if built with SMD components.
--- End quote ---

The construction looks pretty good, but I agree.  I would not use that circuit at all if I did not want ringing, although it does fine with slower parts like HC, AS, and FAST.  AS and FAST have the advantage over CMOS of faster operation with slower edge rates so they had fewer problems with construction.
BillyO:
Okay, here are some more shots of the home made pulser.

I have used the same channel are with the Bodnar to eliminate that as a variable.


Same as the pink trace




Same as the Bodnar




Detail.  Seems the oscillation is @ approximately 400MHz


BillyO:
A few slides from the sweep used to determine BW.  The generator is not mine, so I can't easily do this at multiple sensitivities.  However, I am not the only one that has found this.  The scope itself is spec'd to be 500MHz, but like most of these goes a little beyond that.  Sweep started @ 600mV  (6 divisions).

These results are supported by the risetime found using the Bodnar.



BillyO:
Here are some more picture of the home made pulser, the schematic and the board layout.

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