The AD9684 has programmable input terminations. This termination can be
SPI register 0x016. Available options are 400Ù, 200Ù, 100Ù or 50Ù
The programmable input termination enables better filter integration and eases
the filter design. For low frequencies, the input termination can be set to a
high value. For higher input frequencies, an input termination of 100Ù or 50Ù
differential is recommended.