PCM1792A: I/V for differential output high thd on TINA

Briquel Florian

Part Number: PCM1792A
Other Parts Discussed in Thread: PGA4311, OPA1611

Hello,

I'm working on a I/V stage for PCM1792A with differential ouput.

I'm simulating on TINA (.tsc file below) and the level of THD calculated by TINA is very high (about 0.28%), when simulating with LTSpice the THD is as expected (in the range of 1m).

Is there something wrong with my implementation?

The following I/V stage is sourcing a PGA4311 volume controler and after a differential power amp.

DAC.TSC

over 4 years ago

0 Briquel Florian over 4 years ago

Intellectual 280 points

Hello,

If I remove capacitor the THD is as expected, didn't understand why.. the I guess my design is fine.

With capacitor:

And without:

0 Paul_Frost over 4 years ago in reply to Briquel Florian

TI__Guru 52803 points

Hi Briquel,

There are two main things to note:

1. The model for the OPA1611 and 1632 do not list THD as a modeled specification, so it probably does not model it correctly.

2. The settings for the THD configuration are critical. Can you try some of the steps my colleague recommends in this post:

https://e2e.ti.com/support/tools/sim-hw-system-design/f/234/t/697941

Thanks,

Paul

0 Briquel Florian over 4 years ago in reply to Paul_Frost

Intellectual 280 points

Hi Paul,

Finally I will stay on the results I own today (lack of time to investigate more).

Here a fft run with LTSpice, results seems good with caution if the THD is not modeled in spice model of components.

Regards,

Florian

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PCM1792A: I/V for differential output high thd on TINA