Seems like a missed opportunity to try adding a capacitor dead-bug style onto the board to see if it cleans it up.
That being said, I'm not 100% convinced this is a 20MHz++ noise issue.
Use a small amount of glue from a hot glue gun to fixate it when done, or epoxy if that's your thing. Avoid cyanoacrylate. Not always needed but I imagine a drone moves around alot.
Bodge wiring is a good skill to acquire - PCBs will not always be perfect. Maybe practice on something else first?
I have a bunch of through-hole parts for these sorts of situations. There are plenty of small through-hole ceramics that have leads if you really want to go there.
https://www.digikey.com/en/products/detail/vishay-beyschlag-...
Like this or something similar.
In general you can just liberally dump 100nF caps all over your pcb power traces and quash most problems like this before even knowing they exist. I joke that you make a circuit then take out your 100nF salt shaker to make it just right.
Through hole parts cap out at maybe low MHz. Many electrolytic caps frankly cannot effectively decouple signals above 100s of kHz even. Above that value, capacitors become inductors due to lead lengths, parasitic resistance, and other details.
To make capacitors work faster, we make them smaller and smaller. Surface Mount Caps are the only way to reach 20MHz++ decoupling speeds, and you need crazier tricks if you need additional decoupling beyond that frequency.
We're not building a precision filter, were cutting the paws off of a paper tiger. No need to let perfect be the enemy of good.
So from my perspective, increasing the capacitance from 22uF on that output line to 22.1uF with a 100nF cap will likely do jack diddly shit.
It is far more likely that, ex, the author of this post screwed up the regulator design. Ex: did the author mistakenly think that more capacitance is better-er and stick a 100uF cap there, blowing out the phase margin of the feedback of the switching regulator?
Was the inductor properly sized? Not just inductance but also saturation current and internal resistance?
Capacitance value is essentially irrelevant to inductance. The thing that dictates inductance of a decoupling capacitor is essentially only the package size. The way to fix that is to use smaller (physical) sized components. The only reason it may be related is that some larger values of capacitance physically can't fit into tiny package sizes. For 100nF, you have essentially no restrictions though. 0201(i) are easy to find in that value.
That's always worked well enough in the past.
Hobbyists are not dealing with 20MHz noise issues. Period. And if you are actually crazy enough to deal with high frequency circuits like that, you would well know that the land of through hole designs is simply insufficient, and that you are probably somewhere with some 0402 capacitors and some tweezers right now.
It happens. Not often, but it does happen and it depends on the hobbyist and what they're up to (but you won't be sticking that together on a breadboard). Also: if you start using HCT, AHC or even G parts where you don't really need them it can happen to you in places where you don't normally expect it. Those things have crazy fast rise times.
So yeah. Hobbyists can go here. But here be dragons!!
Nonetheless, I continue to assert that typical hobbyists are making mistakes at 100kHz region rather than the 100MHz region.
And in many of those cases their skills are hard capped by their budget for test gear and simulation software rather than by their actual ability. Keep in mind that until not that long ago anything above 1 G was fair game because 'nobody does anything there anyway' and so HAMs and radio astronomers were pretty much the only ones with experience in that region.
MCP6002 jellybean is GBP of 1MHz. Most "jellybean" OpAmps I know cap out at 10MHz GBWP (aka: a useless 10x gain at 1 MHz).
LM358B is 1.2 MHz GBWP or even 700kHz depending on the design. Magnitudes away from 20MHz especially when you want more than 1.0x gain.
If you want even 10x gain (aka around 10% error), you might suffice with 200MHz GBWP at 20MHz. Or maybe get a nice ADC and just go all digital given today's equipment...
Come on man. Typical "high speed" OpAmps are like 100MHz GBWP or less... correlating to only 5x gain at 20MHz. This sort of stuff is well outside "jellybean" amps. And I'm not even sure if a 100MHz amp is very effective at 20MHz.
They cost pennies.
Looks like they're closer to $3+? Like this is more expensive than a lot of microcontrollers for just one OpAmp.
I wouldn't call any Analog Devices / Linear Technologies parts to be a jellybean. Jellybean means matching common specs that any manufacturer can do.
But at $3 per chip, that's very far away from jellybean status. And AD / LT devices are known for high quality that no one else replicates.
> although THD is getting a little rough up there
Yeah, because a 100MHz high speed OpAmps only has 5x gain at 20MHz. So your error is now well in excess of like 20% (best case) or probably way way worse errors in practice.
As I said earlier: Im not even convinced that 100MHz OpAmps have the GBWP to effectively operate on 20MHz signals. You need more GBWP than that to be comfortable.
That is just straight up not correct
What makes you think that?
Edit: FWIW I consider 20MHz to be basically audio.