AD7768 AND ADA4922-1

Hi All,

 I am working one of my project called 8 Channel Receiver.

In this project, I have 8 Channel of differential Analog input.

I will get the all the 8 Channel input from external source with the range of 10Vpp as Max .

I have mentioned my design block diagram for your reference.


This differential signal is fed to the PGA AD8253 with selectable range of gain.

After this PGA I am going to remove high frequency components and allowable range of 0 -30khz Band and remove other range of signals. Hence the Output of PGA will be 20Vpp.

 Due to the Input Constraints of AD7768  (AD7768 – allow only Differential or pseudo- differential Input with maximum allowable Common mode range is 5Vpp).

 I am going to attenuate this signal 20Vpp to 10Vpp using LT1678. Then ,I convert this single ended bipolar 10Vpp to the differential bipolar signal 5Vpp using ADA4922-1.

 And also level shift the output signal 2.5V by given REF pin of ADA4922-1.

 Hence finally I will get the differential unipolar signal range of 0 to 5V. and fed to the AD7768 ADC.

 My questions are below: 

  1. Using AD4922-1: Is it ok for single end to differential Convert?

           In this datasheet mentioned, AD4992-1 is Differential 18 bit ADC Driver.

           my ADC is 24 bit, Is this AD4922-1 have capable to drive my differential signal ? 

  1. By level shifting of signal of AD4922-1 by Appling 2.5V at the REF pin, Is this right way?
  2. Is there any part which is equivalent or better than ADA4922-1 please let me know.

 Please leave your comments as soon . we are going to release the Schematic design to PCB design.

Thanks and Regards,

Mohamed Sidiq.H