AD6645: Selection of resistor values

Q

In the EVM you use two banks of resistor before and after the latches. Does the
board work with values between 33 and 47 ohm for RN1 and RN3?

A

The board will be functional with all values of resistors up to the 470ohms.
The higher resistance limits the current / voltage transient, and its timing.
The 2 devices..the AD6644 and the AD6645 were characterized with different
values of resistors to find optimum values for dynamic performance (SNR /
SFDR). The T/H on the front end can be very sensitive to transients and their
timing in relation to the sampling instant, and this is different for the 2
devices (AD6645 has faster front end).