PCM5102A: THD+N test performance...

Hello Peter,

The very first thing I would do is to monitor the output of DAC, it is a constructed sinewave ,just to be sure your are looking at the right signal. 

Also make sure you are really plotting THD .

If we want to plot THD vs Freq, simply select X-Y  and for Data 2 select “None” . For Source1  select DGen  freq  and set start and stop freq. The plot will be TDH vs frequency for the given amplitude that you have given  in Digital generator( in your case -1dBFS)

Regards,

Arash

Dear Sir,

I measured the signal of Lout/Rout of the PCM5102A, I think that is the right signal we talk about.

For the setting you mentioned, I just test again and got the picture as below.

The values were closed from the setting panel and the plot.

May I have a question that, if the test method is the same for dynamic range testing?

And, how to improve the performance(value) compared with datasheet value?

Thanks.

I am glad you get the correct measurements for THD. 

In order to calculate dynamic range, I usually get into  FFT function.

• In digital analyzer panel, select FFT spectrum analyzer. Set other parameters as shown below.
• Set the amplitude of Digital generator to -3.141 ( the 1% THD that was measured in previous step. 
• Hit F4, it writes this value in dBr A in Analog analyzer as a reference.
• Now change the amplitude of your signal to -60dB in digital Analyzer and turn on the outputs again. 
• Change the amplitude to Band Reject in Analog analyzer so it removes the -60db tone; the value you read is  Noise level for -60dB input.
• Add the reference (dBr A) to this value and this is your dynamic range, 
• 

The datasheet specs the typical ( and max min of the device). if you are not getting the values close to expected values usually you have check your design and layout.

AP website sometimes has very good tutorials that you can refer to them for various topics.

Regards,

Arash

Hi Sir,

As the test result below, please help to review the setting if there is anything wrong with it?

For the start point is -44dB due to it is the min. value that I can adjust the from full scale of 2.1Vrms.

As the measured data, the DR should be -99db + 6dB= -93dB, right?

The dymanic range we got is lower than datasheet spec.

Below is the schematics and layout file, may I have your suggestion for it to improve the performance?

Thanks.

PCM5102A.pdf.pdflayout.pdf.pdf

Hi Peter,

I am not clear about the -44dB, as originally you had it started at around 0db. Also the 6 dB that you are subtracting, is it -6dB ( input level that yields 1% THD)?

I don't see anything out of ordinary in your schematic, although I am not sure if AZ5325-01F (the TVS Diode ,  ESD / transient protection of high-speed) has any contribution to this. From layout point of view, I cannot make any comment but I don't see anything that pops out immediately. Check your cables and  wires as well, my only suggestions is to repeat the test with different cables and see if it has any noticeable effect. Overall you are in the right ballpark of measurement..

Regards,

Arash