I am a novice and I don’t know why an ADA4945 is connected behind the LTC6373 in the case AN-2555.

Hi mangostar ,

Good day. May I know if the differential signal you're asking is the input to the LTC6373 or is it the differential input to ADA4945? Thank you.

Regards,
Gilbeys

Hi mangostar ,

In AN-2555, the ADC driver (ADA4945) is used to scale and shift the output of LTC6373 to fit the requirements of the ADC (LTC2387-18). In the article, the input requirement is a +/-10V differential signal. While LTC6373 can accept the +/-10V as is, its output doesn't quite fit the requirements of the ADC. Hence, additional attenuation was done in ADA4945 to maximize the dynamic range and performance of the ADC.

For your requirement, LTC6373 alone can modify +/-5V differential input into a 0-2.5V Vout. Set the gain of LTC6373 to 0.25 and Vocm pin to 1.25V. Unfortunately, we do not have SNR and THD data for LTC6373 + LTC2387 combination, but if you still want to pursue the AN-2555 design, you can set the gain of ADA4945 to G=1 and achieve the Vout that you want.

Hope this helps.

Regards,

Kristine