I'm using LTspice to simulate a LPF using the AD8605. I'm expecting this circuit to attenuate high frequency signals but the output I'm getting is attenuation at any frequency, more so at low frequencies. As a sanity check I've made sure I have the most up-to-date SPICE model and have tried swapping in similar opamps I'm familiar with, but I see this behavior only with the AD8604-8606 series. Does this seem like an issue with the circuit or with the SPICE model? Thanks!