Hi

Regarding data sheet of AD9161/9162, I can see the difference between Page4 and Page78 about DAC clock input as follows.

You can see the common-mode voltage is 0.6V and the input impedance is 90ohm on below table.

But you can see 5k ohm and 1.25V on Figure 185 of Page 78 below.

In addition, there is a comment in page 78 that " the input is self biased with a nominal impedance of 90 Ω, it is recommended that the clock source be ac-coupled to the CLK± input pins."

Our customer is confused about the impedance and about the voltage.

Which is correct 90 ohm or 5k+5k=10k ohm? Which is correct 0.6V or 1.25V?

Regards

Hiroyuki

To answer your question regarding the input impedance, AC differential input impedance might be confused with DC differential input impedance. These two numbers are different and the 90Ω impedance is measured at 3GHz as mentioned in the table and it is AC differential impedance.

Regarding the second question about input common mode (ICM) voltage, you are right; in the block diagram we've made a mistake. Thank you for bringing this to our attention!

As is mentioned in the table the ICM voltage is 0.6v. If we forgot about 1.25V shown in the block diagram, the 16uA current sinking into the 40KΩ gives a 0.64V of ICM voltage which is the correct ICM voltage and is reflected in the characterization table, as well.