Simple? op-amp problem...

[jrz126]

I am working on a project for work that involves retrofitting a sigma-delta converter onto an existing design. The problem is that the sigma-delta converter has a 0-5V input, but the current circuit has a signal range of -5 to +5.

So I need to add another stage to convert this signal to 0-5V. I figure I could just use a gain of 0.5 for the scaling, but I dont know how to offset it.

 

[ericgibbs]

hi,
This is a circuit for +/-2.5V input, you could easily modify for +/-5V input.

 

[Roff]

hi,
This is a circuit for +/-2.5V input, you could easily modify for +/-5V input.

That circuit inverts the input. This may not be a problem. If it is, you could add another inverter, with appropriate offsetting.
Another way is to use an R-R attenuator (gain=0.5), but instead of returning the other end of the attenuator to GND, return it to a 5.0V reference. You could follow that with a unity gain buffer (op amp with gain=+1), or you might not need one, depending on your source and load resistances.
EDIT: Note that this won't work if your source is AC-coupled.