So for some reason I need to add an offset of 3.6 V to a sinusoidal signal. I have set up a circuit according to this schematic:
I know that there are probably easier ways to do this but it should work and give the following results (red is output, green excitation):
For some reason however the output of the summing amplifier is a 1 MHz signal which I do not understand. Can anyone here explain this behavior?
Some additional information:
- the IC used is an OPA4134 in a SO package
- the schematic is actually only a small part of a larger circuit, that's why the voltage buffers are there
- the excitation in the actual circuit is the output of a XR2206 function generator
- there are vias under the IC, could that be a problem (stray capacitance)?
- V+ and V- are bypassed vs. GND with 100nF capacitors on the actual board
I would appreciate every piece of advice or idea you can give me!