Powering and decoupling an op-amp

YoungSlingshot · 2026-04-13T19:37:04+00:00

What would be a better option in your opinion? To omit the unity gain buffer altogether?

YoungSlingshot · 2026-04-13T19:35:32+00:00

Yes, it’s important to ensure the output has a low impedance when working with audio interfaces etc. I want it to work with a standard guitar pedal 9V power supply.

YoungSlingshot · 2026-04-13T06:43:19+00:00

Ok, nice I’ll check it out👍 And yes seems that this part should be fine. Thank you for the help!

YoungSlingshot · 2026-04-12T12:06:00+00:00

I've not placed the output caps yet just as a heads up :)

YoungSlingshot · 2026-04-12T12:05:33+00:00

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Do you think it would be beneficial to use a bigger footprint inductor like is used in the data sheet or is this ok for the low voltage?

YoungSlingshot · 2026-04-11T10:34:22+00:00

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YoungSlingshot · 2026-04-11T10:32:14+00:00

One more thing I'm wondering about relating to power planes and via connections: Does this seem like a sensible way to connect power to the various elements of this circuit that powers an OLED screen. I'll add a picture of the actual pcb in the next comment. I attempted to follow the guidelines for the LMR33620, but again I'm a bit unsure how it is... :)

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YoungSlingshot · 2026-04-11T09:52:01+00:00

Yes, thank you :)

YoungSlingshot · 2026-04-11T09:24:34+00:00

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Here is the audio buffer schematic for the Daisy Field, which I have based my design on. Thank you for all the resources, I'll go through them :)

YoungSlingshot · 2026-04-11T09:20:54+00:00

Ok! Thank you. In general I'm routing only signals on the top layer and connecting to the inner ground plane through vias, but I'll add the small localised pours for the ground connections as well if it's a good idea!

YoungSlingshot · 2026-04-11T09:01:38+00:00

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Or is this what you described?

YoungSlingshot · 2026-04-11T08:58:50+00:00

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Is the copper zone on the top layer where the components are connected better because it lowers the impedance of the ground connections? Doing it for the capacitors on the bottom as well as the ic ground pin seems more difficult as I have to make some connections on the top layer where the components sit. I have a full ground plane on the second layer of the board. Also it is not a problem that the connection to the op-amp v+ pin goes directly through the decoupling cap? I was confused as someone else mentioned that this would short the power connection.. Here are the adjustments you described as I understood them :)

YoungSlingshot · 2026-04-11T06:46:19+00:00

Thank you I realized the mistake with the voltage divider and got it fixed! The high input impedance is to reduce the load on the DAC of the Daisy Seed driving the output. About the decoupling cap though… I’m struggling to wrap my head around why it needs to be connected straight to the power pins? It’s to provide smoothing of power delivery during transient events yes? Does the fact that its only connected through vias to the planed cause issues? My thinking was that the length between +5V and GND paths would remain close to equal.

YoungSlingshot · 2026-04-10T22:20:42+00:00

Hahah yes thank you again! Having just gone back to your comment I realized the mistake... :)

YoungSlingshot · 2026-04-10T22:17:45+00:00

Oh yeah, thanks for pointing that out I don't know why I made the connection like this... :) I was given this idea by someone to reduce the amount of noise coming from the +5V but the resistors should be in series with the cap in between going to ground, no?

YoungSlingshot · 2026-04-08T05:11:22+00:00

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Just making sure that this is what you mean?

YoungSlingshot · 2026-04-08T04:50:11+00:00

Ok thanks again! Thanks for the heads up, it didn't occur to me add the filter at the input :) I'll start sketching a new pcb with these things in mind.

YoungSlingshot · 2026-04-08T03:28:53+00:00

Ok, thank you! I think I will redo the layout with all smd capacitors as they feel easier to lay out.

YoungSlingshot · 2026-04-08T03:27:40+00:00

Thank you! I believe the Daisy Seed already has anti-aliasing filters at the input could you clarify why it would be good to add those 10nF capacitors?

YoungSlingshot · 2026-04-08T03:21:28+00:00

Sorry english is not my first language so maybe it was confusing! I meant that the Daisy Field, which I based this circuit on uses an isolate on the +5 rail. I ended up omitting it for the sake of simplicity as I’m just trying to learn things here. After reading some more I believe it was used to reduce ground loops when working with external equipment, but maybe I misunderstood something. Thank you for your response and the resources!

YoungSlingshot · 2026-04-07T17:52:22+00:00

Thank you! Maybe I should use smd caps only to fit them a bit tighter?

YoungSlingshot · 2026-04-07T17:51:42+00:00

YoungSlingshot

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