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ltspice simulation model LTC6362

Category: Software
Product Number: LTC6362
Software Version: LTspice 17.0.34.0

HI,

I have been trying to simulate the noise of the LTC6362 and I would like to compare the results with the datasheet of the component.

from the datasheet I can see that the common mode noise is 14.3nV/rtHz.

HOwever, if I measure the noise from one of the output of the FDA in buffer configuration I do not get this value at 100kHz. HEre below my simulation :

Simulation results show that the common mode noise at 100kHz is 55nV/rtHz, am I right? or am i interpreting the results in a wrong way?

Unfortunately the LTC6362 spice model is built in in LTSPICE and the sub file is encripted, so i cannot check the implementation. 

Any tips?

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  • Hi,

    It seems that you have not connected anything to the Vocm input, which is causing the additional noise. If you look closely at the datasheet, you can see a voltage divider on the block diagram.

    The resultant resistance is 170 kOhm, which causes thermal noise:

    The noise of 55nV/rtHz measured in the simulation corresponds to the sum of the common mode noise (given in the datasheet) and the thermal noise from the voltage divider. You can solve this problem by connecting a 100 nF capacitor. This, together with the resistors, creates a low-pass filter so that the noise is significantly reduced at 100 kHz.

Reply
  • Hi,

    It seems that you have not connected anything to the Vocm input, which is causing the additional noise. If you look closely at the datasheet, you can see a voltage divider on the block diagram.

    The resultant resistance is 170 kOhm, which causes thermal noise:

    The noise of 55nV/rtHz measured in the simulation corresponds to the sum of the common mode noise (given in the datasheet) and the thermal noise from the voltage divider. You can solve this problem by connecting a 100 nF capacitor. This, together with the resistors, creates a low-pass filter so that the noise is significantly reduced at 100 kHz.

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