Hi, in my design I am measuring a THD+N hump at 6KHz at lower power levels. I have tried a number of things to fix or at least help identify why this is happening but with no success.
At around 200mW the THD+N is up at 0.8%THD+N, at higher power levels it drops to 0.3<04% until we reach the supply rail limit - please see power vs THD+N sweep below.
The noise is harmonic, I can see the third harmonic is fairly high compared to the fundamental - see 6KHz harmonic sweep attached.
I do not have a TPA3126EVM for direct measurement comparison. I do have a TPA3116EVM and this measures as per datasheet figures.
I have compared all components in my design against the BOM in TPA3126EVM app note and they mostly compare. Where they did not exactly (cap dielectric for example), I have changed them to match the TPA3126EVM BOM but this made no improvement. Note: we are using the Wurth 7447709100 output inductors. Schematic for my design attached for your reference.
The have checked the layout and compared against the reference design/guidelines. I think it looks sensible but have attached gerbers for your reference.
If anyone can help it would be greatly appreciated.
Thanks
Rob
