Check out the Tamagawa app note for a more in-depth explanation of the situation. This is what actually needs to be done for an automotive environment.
What I've found from actually building these things is that on one hand, you can build something that just works in the lab. It can be very simple. Now put it in a noisy environment (and an electric motor is the definition of a noisy environment) and see how the simple circuit works. Remember, at high frequencies, the wires to the resolver are excellent antennas. Also, the PWM power supply that's supplying that +/- 7 volts for the op-amp (plan on SOME signal loss) can also be a very significant noise source. Attempting to do precise instrumentation of subtle voltages with no filtration or shielding will lead to lots of grey hair.