AnsweredAssumed Answered

Single Ended - Differential conversion phase shift issue

Question asked by MustafaERD on Jun 28, 2018
Latest reply on Jun 28, 2018 by JinoL

Hi,

I am trying to drive 14 bit ADC( LTM9007-14) using two op-amps.( What I do is converting single ended signal to differential signal) I have two different configurations that seem to work for me. But when I run a simulation in LT Spice I see slight differences in the results of two configurations.

My first configuration is below.Config1

The result is as follows;

Result_config1

Single ended to differential conversion seems to work well. But the problem I recognized is that the line in turquoise color which represents the sum of two differential signals is not straight. There is an oscillation of around 10mVp-p.

 

The second configuration that I mentioned is below.

Config2

The result is as follows;

Result_config2

The turquoise line again stands for sum of two differential signals. It's not straight again. But this time the oscillation is about 5mVp-p.

 

I suppose that this oscillation is caused by the phase difference between two differential signals. Does such an oscillation cause a problem for A/D conversion?

 

Which configuration for single ended to differential conversion is recommended when considering all cons and pros I mentioned or not?

Thanks,

Mustafa

Outcomes