Hello

I am confused and I don't what to do, so I decided to ask the experts: what topology sholud I use to drive the inputs of a differential line driver

(in particular AD8132)?

Here are some details: I have a single-ended signal source which enters a differential buffer made out of AD8039 (two op amps in one package).

The the differential signal goes into a line driver. And here's the tricky part that I am stucked on. I don't know whether I should termite the line driver

inputs, which topology should I use etc.

I will appreciate your help and competence.

Hi, Martin.

To terminate a single-ended source, you have to follow three steps.

1. Calculate the input impedance of the differential amplifier. To calculate it, please see below formula (only for single-ended input).

2. Match your souce resistance by calculating the termination resistance. You may download for free our DiffAmpCalc for an easy calculation.

3. Compensate the imbalances of the gain resistors by adding a correction resistor.

For a more detailed procedure you may look at page 19 of ADA4927 datasheet under "terminating a single-ended input" section.

You may also want to read this application note AN-584 on how to use AD813X.

Hope this helps.

Good luck!

Anna