I am using a AD215 two port isolator from analog devices to obtain an isolated output from a NI DAQ channel output. I made a test circuit on a breadboard with unity gain as described in the datasheet. I am powering AD215 in the same manner as in the datasheet and other connections are also made as such (2k resistor at V_signal at the IN+, e.g.). For some reason, I am seeing a spikes at 1 MHz repetition rate at the output, the amplitude of the spikes is about 20 to 40 mV. Just to check that it is not with the specific AD215 I had, I made another test circuit with a different AD215, but the same result. I am using a floating scope for looking at the signal, but it looks same on non-floating scope.
Please can anyone tell me what is wrong, or if others have also come across something like this?