• State Resolved
  • Locked Locked
  • Replies 2 replies
  • Subscribers 30 subscribers
  • Views 136 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Original question:

TPA6138A2: How can we achieve Low THD+N < 0.01% at 10 mW Into 32 Ω?

TPA6138A2: Two peaks on THD+N

Mochi
Genius 3925 points
Part Number: TPA6138A2

Hello,

We have seen strange THD+N characteristics at Vdd=3.3V RL=33ohm SE input configuration on own PCB, not EVM.

There is two peaks before Voltage clipping as attached image, we also observed switching noise at positive signal peak.

(Horizontal output power of AP graph is not calibrated)

 

 

At no load condition this noise is disappeared. It seems charge pump noise related phenomena but it positive side.

Could you give us check point of PCB layout or another critical GND connection etc.

 

Regards,

Mochizuki

  • 0
    TI__Guru** 100965 points

    Hi Mochizuki-san,

    I have some questions/suggestions for debugging:

    • Is it only at higher load impedance?
    • If you use lower impedance like 16-Ohm, is it different?
    • Is it possible to test with a different power supply? Preferably directly at VDD (want to rule out any LDO or converter supplying the device)
    • Could you please also try different frequencies for the sweep? Is it any different?

    Best regards,
    -Ivan Salazar
    Applications Engineer

  • 0 in reply to Ivan Salazar
    Genius 3925 points

    Hello Ivan-san,

     

    Thank you for your prompt suggestions.

    We have confirmed EMC RF bypass cap is in place directly to output node.

    So, it was heavy capacitive load to TPA6138A2, it was solved by changing cap location.

    I appreciate for your kindly support as usual.

     

    Regards,

    Mochizuki