SINAD, ENOB, and to a lesser degree SNR, all degrade as the analog input frequency to the ADC is increased. This is due to increased distortion and nonlinearities which occur at higher slew rates. Some ADCs are designed to maintain good SINAD over the baseband Nyquist bandwidth. Other ADCs that are suitable for IF sampling maintain good SINAD in higher Nyquist zones. This slide shows a plot for SINAD and ENOB for the AD9226 12-bit, 65MSPS ADC as a function of input frequency and input full-scale span. Values are given for differential and single-ended input spans of 2V and 1V. Note that the AD9226 with a 2V differential input span maintains good SINAD for input frequencies up to 100MHz. This graph also illustrates the answer to a common question about ADCs with differential input. Many customers will ask if they have to drive the input differentially or if they can use a single-ended input. As shown here, the performance at higher frequencies will degrade if a single-ended input is used with a differential input ADC. It is important to know how SNR, SINAD, and ENOB will change over the bandwidth of the application.