Team,
The ADC16DX370 has a Nominal resistance of 100 Ohms at the sampling port Vin+, and Vin-.
What is the tolerance of that 100 Ohms Resistance? At ambient and at temperature.
I need to build an Anti-alias filter. In the application Notes on page 50 an external load resistance RL is used, and in 49 a 33 ohms is used.
Thank you.
Hi Go,
The analog input resistance of the ADC is 100ohm differential and is part of the IC process, these resistors can have a wider range of tolerance, even at ambient temperature. See the S11 plot in figure 39.
If you plan to design an anti-aliasing filter with an amplifier, I would use the 200ohm differential load specified in the datasheet for the filter design. I would also leave an option to back terminate to help "stiffen" the impedance for what is actually needed.
The entire input network, when using an amplifier, will need to reflect the optimum impedance or Rload the amplifier was characterized under. For example, on the THS4521, the Rload is 1kohm differential.
Regards,
Rob
