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TAS5611A Feedback loop

Dirk Seidel
Prodigy 30 points
Other Parts Discussed in Thread: TAS5611A

Hello,

Im using the the amplifier TAS5611A with AD modulation.

1. I dont understand, how the feedback loop works.On the internet I found a picture, with the principle, but I dont  know if its right.

2. If I have an input signal, like sine - I get  an amplified sine wave signal on the output. But if I change the suplly voltage, the amplitude of the output signal is the same.

Why is it constant?

Thank you

  • 0
    TI__Expert 8505 points

    Hi Dirk,

     

    Think of it as the close loop architecture takes the output voltage feeds it back through some sensor mechanism to the reference (input). The feedback signal is compared with the reference and the difference (error) is then sent to the Powerstage. Because of this, you dont increase the output signal by increasing supply voltage, instead output signal increases with increasing input voltage. The benefit of this closed-loop architecture is a superior PSRR and subsequently better THD+N compared to open-loop amps. As you can see the noise coupled to the output from the power supply can be suppressed through negative feedback.

     

    This is a good article that discusses further the advantages of closed-loop amps: http://www.planetanalog.com/document.asp?doc_id=527759

     

    Please let me know if you have further questions. Thanks!

     

    Regards,

     

    Brian Wang

     

  • 0 in reply to Brian Wang
    Prodigy 30 points

    Hi Brian,

    thank you very much for your answer.  It is very helpful.

    Yours faithfully

    Dirk Seidel