ADC higher nyquist zonee

Question

I know it is possible to use ADC for sampling signals with frequencies even higher than ADC first Nyquist zone (SPS/2). But how ADC's are classified to indicate this ability. And how can we understand their performance in those Nyquist region? For example LTC2253 have 125MSPS and introduced schematic for sample rates even higher than 300 MHz. But the question is how much higher? And what is the performance? It have sfdr plot for DC to 300 MHz but what about higher frequencies? How sfdr indicate performance? Is it the figure of merit? 
 Also what is cost effective of at least 10MHz bandwidth for signals between 100MHz to 2 GHz signals?

jmoreno5 · Accepted Answer

Hi mohammadsdtmnd , 
 Thank you for your patience and apologies for the delay response. 
 Unfortunately for LTC2253, it could not handle your input frequency for your target band of 1GHz to 2GHz as its Full analog input bandwidth is only up to 640MHz. Please note that the degradation of SFDR shown from the datasheet is the result of aliasing due to frequencies higher than half of the sampling rate creating spurious signals. 
 As for your application, you need to have at least analog input full power bandwidth of 2GHz or higher such as AD9690 or AD9625. 
 Thanks.)

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