50 Ohm impedance matching circuit for the 7852R PXI DAQ analog and digital channels

[Sharpie]

I am using the 7852R PXI DAQ card to provide AM, FM, and Pulse modulation to the RF source I am using. The RF Source has a 50 Ohm input impedance while the DAQ has a 0.5 Ohm output impedance on its analog channels. Is there a commonly known or commercially available circuit out there to save time or do I have to design my own impedance matching circuit? 

[rpursley8]

You can just put a 50 ohm resistor in series with the output.  This will cut down your voltage, but it would be matched.  If the frequencies you are outputting are low enough and/or the cables are not too long, I don't think you would have too much of a problem even without matching.

Are you sure that is the problem?  The analog outputs max out at 2.5 amps.  This can only generate a 0.125 V signal into 50 ohms.  Maybe you should buffer the outputs with op-amps.

[AnalogKid2DigitalMan]

Randall:

I think you meant 2.5m amps (2.5mA), not 2.5 amps (2.5A) 🙂

-AK2DM

[rpursley8]

Thanks for the correction.

[Sharpie]

You are correct in everything you said rpursley8. My problem really is that the FPGA card does not have the current to drive my RF Sources because of the difference in impedance. I am looking into using an op amp right now that looks like it can drive my RF Sources. Simply putting a resistor inline would not work for me because for my Pulse Mod I am using a DIO 3.3V Line and cutting this voltage in half will not work. I was really just wishing that there was a commercially available PCB with all the circuitry on it that I could just plug and play and move on. Thank you for all the help.

[Juan G]

Randall is correct.

You can just put a 50 ohm resistor in series with the output. Op-amps will be the solution to buffer the outputs

 Regards,