Some background on why I care about this: NASA GSFC launched a mission (ASTRO-H) a while back, and the front-end amplifier designs incorporated the OP470 in virtually all of the bias control. However, the engineer at the time claimed that the OP470 spice model was not available, so he ran worst case analyses using the OPO-27 since they seem to be very close in performance to each other. We are very interested in the low noise performance of this device for our application.
I am reviewing these analyses and managed to find a SPICE model for the 470. When I run a noise analysis, I am seeing some different behavior between the OP27 and OP470.
I've attached a brief write-up on what I've done with some results. Are these results consistent with how the device actually works, or am I seeing a model issue here?
Thank you very much for your time, please contact me if you have any questions on how I've done the analysis. (I welcome all darts thrown my way...)