differential to single ended signal convertor

[Ian_Ren]

Any body know if I can buy an off-the-shelf conversion box that converts differential signals to sigle-ended signals?

Thanks.

Ian

[duncan carter]

Ian - we've discussed making such a device before. I'm not working as I'm ill so I searched quite a bit but was unsuccessful in finding a commercail device. I did find some example circuits from Maxim and from Linear Technologies that might be suitable and give better accuracy than what we discussed previously but I don't know/remember enough about your application to say.

Duncan

[preston_johnson]

What you are working to do, is to get all the signals to share the same ground. You can use the NI SCC series signal conditioning, or 5B style signal conditioning to bring in inputs, isolate them, and then host them to a single ended input. This idea may be of use to you.

[duncan carter]

Preston - unless there's been a change, Ian is working with existing 447x series hardware.

[Ian_Ren]

Duncan

You are right, we are working with 447X. I just wish that there will be a new version that has a pseudo-differential and real differential selection.

Thanks for your suggestions in your previous reply. I will have a look at the circuits from Maxim and from Linear Technologies.

We actually have made a box using op-amp, resistors and capacitors based on a circuits from text book. It worked in the sense that the outputs from the box are now single ended, but the response curve is not as flat as I wanted. If we spend more time on it, we can probably make the box work better, but this excecise can become very costly, particularly we only need one or two of such boxes.

Preston:

Which NI SCC or 5B do you suggest and what is the typical response curve? I have never used SCC or 5B products before.

Thanks.

Ian

[Marni]

Dear Ian,

Thank you for contacting National Instruments! There is a KnowledgeBase posted on ni.com that explains how to input a differential signal into a PCI 447x.

http://digital.ni.com/public.nsf/websearch/581574D9C2AEC19B86256E59000CFEDB?OpenDocument

Take a look at this and let me know if you have any questions. Have a great day!

Marni S.
National Instruments

[Dilbert]

I need a conversor that does a conversion of differential to single ended and single ended to diferential. This conversion is for 10BASE-T and 100BASE-T to fiber converter. I had already  though in some solutions such as using operational amplifiers but as i have read here it will be hard. Is there any solution in a single one IC?

I will thank you a lot if you have any suggestion because ive never done this kind of conversion.

Regards.

[MickeyD]

Hello,

Using an Op Amp would not be that difficult to set up.  The main problem would be keeping the signal flat.  I have looked for a simple integrated circuit but have not seen a simple cheap turn key solution on the web.  If I knew a little more about your application we might find a way or think of a different strategy to get the functionality you want.  What kind of singals are coming in over the 100 or 10 BASE-T lines and why do you need to convert them to single ended and fiber cable.  What are you going to do with the signal?  Please let me know if you need any further help and get back to me with that information.

Have a great day,

Michael D
Applications Engineer
National Instruments

[Dilbert]

Hello

I was trying to implement a cheap 10/100 BASE-TX to 100-BASE-FX but i realized that it will not be that simple as i had thought, i mean simple like: convert the differential ethernet signal to logical signal and then input it on the fiber transmiter (which accepts logical signals). Probably it will need one more IC like IP113A making the circuit more complex...

thanks.