TLV320DAC3101 Measurement Condition of THD+N

Hi Matt-san,

Thank you for your reply.
The operation conditions are shown as below.

<Operation Conditions>
Measurement Object    : TLV320DAC3101 EVM
Measurement Points    : Headphone Output
Load Impedance        : 16ohm
Input Signal          : 0dBFS(DAC Playback)
Input Frequency Range : 20Hz to 20kHz

Is the characteristics of THD+N defined by the input of 0dBFS@1kHz in the data sheet of TLV320DAC3101 although I could not find it?
Could you please send the results which you evaluated to me if possible?

Best Regards,
Kato

Hi Kato-san,

You are correct, the THD+N defined listed in the datasheet is 0dBFS @ 1KHz even if the frequency it is not specified. 1KHz testing is a standard in audio.

I will test the EVM and get back to you.

Regards,
Matt

Hi Matt-san,

Thank you for explaining so politely.
I am looking forward to hearing additional information from you.

Best Regards,
Kato

Hi Matt-san,

I have one more request for you as below.
Could you please send me the measurement data which you evaluated regarding the analog volume control since I would like to compare my measurement data with your measurement data?

http://e2e.ti.com/support/data_converters/audio_converters/f/64/t/355472.aspx
http://e2e.ti.com/support/data_converters/audio_converters/f/64/p/353447/1243445.aspx#1243445

Best Regards,
Kato

Hi Kato,

As Don pointed out in the pother post, where you are noticing a deviation is at such small gains (around -60db) that it is: 1. very insignificant, and 2. will be due to very small variations in the component. At those levels, it doesn’t take much to have a huge change in gain. The measuring process used could also induce error.

For example, measuring 1mV vs 2mV is a change in gain of ½. You need to have a very low noise, calibrated, high quality multitier in order to have confidence in a measurement difference of 1mV. In contrast the difference between 1V and 2V is easy for most millimeters to detect. So an error of 1mV for this measurment is negligible because it is orders of magnitude smaller than the desired accuracy.

Why are you worried about this?

Do you plan to use the volume at exclusively a -60dB gain and below?

Regards,

Matt

Hi Matt-san,

Thank you for explaining so politely.
As you said, I am concerned whether my measurement result is correct although I understand that the gain error will be occurred easily when setting the VERY low gain.
Thus, I believe that I will compare my measurement data with your measurement data just in case and would like to probe it.
Probably, I will not use below -60dB as the gain settings.

Best Regards,
Kato

Hi Matt-san,

Do you have any updates for the evaluation result of "THD+N vs Frequency" ?
Could you please send it for 20Hz to 20kHz @ 0dBFS to me since I would like to compare THD+N ?
I would appreciate your prompt response.

Best Regards,
Kato

Hi Matt-san,

Could you please send the AP screen capture of "THD+N vs Frequency" to me if you have ?
Of course, you do not need to guarantee it.

Best Regards,
Kato