can I use the AD8138 to add two differential signals?
Bandwidth is approx. 10 MHz.
Thanks in advance!
As opposed to my first answer due to my misunderstanding, AD8138 can be used as a summing amplifier. You just have to configure it as inverting summer by applying each differential signal to the summing nodes through the Rg. Its gain can be determined by Rf/Rg. Also, you have to consider that if ever your gain configurations are unequal due to mismatched resistors, your output will still remain balanced due to the internal common-mode feedback loop.
If you may, can you share with us your schematic so we can help you better? Or you can download ADI's free Multisim for your simulation.
Hope this helps. Apology for the late response.
Differential amplifiers, like AD8138, can't be used to add two differential signals. They are called differential amps not only due to their input configuration but also by its output voltage which is the "difference" between the two different input voltage signals. Thus making these amplifiers a "subtractor".
If you're in need of a summing amplifier, you may use an operational amplifier like OP777 a micropower op amp or you may want to try AD830 a resistorless summing amplifier.
You may also want to read this mini tutorial MT-214 regarding inverting summing amplifier.
Hope this helps.
thanks for your comment.
I was not exact enough.
I want to "combine" the powers of two uncorrelated (noise like) differential signal sources with an equivalent bandwidth of about 10 MHz and feed them to a common differential ADC.
Retrieving data ...