Class D Amplifier Delay

Dear Team,

Its been a while since I heard from you. Can you please provide insights to my queries above. 

Regards,

Hermione

  Please support in this.

Regards,

Hermione

Hi Hermione, I have reached out to the product applications engineer. Thank you for your patience here.

Dear emassa,

Thank you so much for your support.

Looking forward to any response from the engineer side.

Regards,

Hermione

Hello Hermoine,

Patrick did answer your questions. The delay is mostly due to the sampling rate. Any IIR or analog filters will also create a phase shift and add some latency based on frequency of the audio. Any FIR filters will just add a fixed latency for all frequencies. So your total latency will depend s little on your processing. 

Notice the numbers from Patrick. At 48kHz it was 60us. The switching amplifier filter that is used to filter out the out of band noise is an analog filter and you see it adds another 5.7us of latency. 

So depending on your processing there may be a small change in latency based on signal input frequency but it usually is not a lot. If you were running at 192kHz fs then it can become more significant. 

As far as a procedure to share. Our procedure is simple with the test equipment we have. We use the Audio Precision APx system. We have the serial digital output option and the analog input option. We go out of the digital serial port directly into the amp using I2S. Then the output of the amp goes to the switching filter and the filter output goes into the analog input of the Audio Precision. Then we setup the test equipment to use the correct inputs and outputs and you can then measure the latency. It will read it on the computer screen for you. It is very easy. 

If you do not have that then it is a little more difficult. You would need to use an oscilloscope and the best signal to use is a tone burst. This way you will know you are not one or more full wavelengths off. Then measure the time on the scope. 

I hope this helps.

Dave T