I am using AD9257 in my design, i connect the ADC driver opamp input to ground to find the ENOB, i get the variation count from -45 to -15 in the digital side, that mean the variation count is 30,it reduces my ENOB and SNR.
ADC Clock and jitter details attached here.
Where i loose my SNR ?? My expected ENOB is 11.5 bit and SNR 70dB.
Kindly suggest the solution.
The AGND and DGND is shorted on signle point at one place of my board.