I have downloaded the SPICE model file for the OP177 but found that it actually contains the model for the OP1177.
Where can I get the proper SPICE model file for the OP177 ?
I knew the AD629 but not the newer AD8479.
In fact my 2nd version is modelled after the AD629, which however has only +(-)270V common mode range. So for 350V with some headroom additional series resistors woud have to be used, reducing the overall gain correspondingly.
Yes the noise gain would be 50 which is comparable to the AD629's behavior. Actually it is somewhat more, but that is due to a generous common mode range setting of roughly 700 V at supply voltages of -9 & +18 V, assuming a maximum common mode voltage of ~15V at the OpAmp inputs. It might be reduced to a lower value between 25...30.
The AD8479 looks very interesting with its +-600 V common mode range and still quite high bandwidth, but I can't use the SOIC-8 package, can only handle the old DIL-8 stuff.