Hi Jignesh,
I think the best thing to do at this point is to replace R5 and R6 (4.7k resistors) with 0 ohm (direct short). There should be a low impedance connection between the AGND and DGND of the ADS1234. Also, you will starve the analog portion of the device by restricting the current to AVDD. If you want to add some filtering, try 10 ohms at AVDD, but in no way should you add any resistance between the grounds.
Best regards,
Bob B