Inverter Oscillator Ground Return

[longlivetheDee]

Hello technical folks! I have a PCB design for a guitar pedal with a DSP chip processing some audio signals that would normally run off a 32768 Hz crystal, but part of the effect allows the user to change the clock speed using a slide potentiometer. To do so, I am using the Schmitt trigger oscillator circuit shown in the Falstad schematic. My question is regarding ground return paths and shielding of the audio trace from the oscillator.

As shown in the PCB layout image, the oscillator circuit is entirely contained within a ground pour on the top layer. There is a solid ground pour on the bottom layer below the oscillator. There is an audio trace to the left and top (highlighted in yellow) and some audio traces off to the right (not shown). Additionally the DC power supply is off-screen to the right (also not shown). Given the design of the oscillator circuit, am I correct in thinking that there should be no high frequency ground return path from the oscillator that induces noise in the audio traces, and only the DC will have a ground return path off to the right? Should I include some via fencing to further shield the audio?

[jonpaul]

Bonjour, no idea what is "Falsted"

At ~ 37kHz the grd pl an layout of little concern.
 
 
 
j

[Zero999]

Falstad is a web based simulator. It's great for demonstrating many electrical principles but is rather limited, compared to a proper SPICE simulator.

The circuit attached to the original post doesn't appear to be a Schmitt trigger oscillator.

Here's how to make a Schmitt trigger. I would recommend the 74HC14, as the 40106 isn't ideal at 3.3V.

A2 can be all the unused sections in parallel, to lower the output impedance.