Dear Jonathan,
I am directly using the schematic specified on the CN-0276 Application Note (http://www.analog.com/media/en/reference-design-documentation/reference-designs/CN0276.pdf ).
With the resolver stopped at 180 or 360 degrees the signal is stable around a single value. The problem appears when approaching these "critical" angles. If I turn the rotor by hand slowly around this angles it looks like as if AD2S1210 reads these angles some times before finally reaching them.
Best regards,