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ADA4937 input impedance - 1k or 50R?

Question asked by DavidE on Dec 7, 2011
Latest reply on Dec 16, 2011 by Zoltan

I'm using the ADA4937 as a buffer/driver for the AD9649BCPZ-40 ADC.


My system is required to have 1k input impedance.  The current line-up is: input -> anti-alias LPF -> ADA4937 -> differential RLC LPF -> AD9649BCPZ-40.


Would it be better to design the ADA4937 with 50 ohm input impedance and design the anti-alias LPF to transform from 1k to 50 ohm, or should I just design everything at 1k?  Required bandwidth is less than 10 MHz but I need it to be low noise.