I'm designing a differential amplifier to remove noise from a signal, and I'm trying to verify my design by simulating a noisy input, but I'm not sure how to do this. The diagram below is roughly what I'm trying to achieve. Signal 1 and 2 have different frequencies. Signal 1 is present on both inputs of the amplifier, while signal 2 is only present on one. The amplifier should isolate signal 2, and amplify it at the output Vo.
I've already designed the amplifier, but I'm just not sure what the combining circuit should be? What's the best way to combine the two signals, making sure that they are both still present in the input V2?