The LT1056 improved JFET operational amplifier macromodel, which addresses slew rate asymmetry, is described.
slew rate asymmetry
SPICE macromodels for op amps have been available for some time for both bipolar [1,2] and JFET  input stage device types. Interestingly, however, not much attention has been given to the models available to controlled slewing asymmetry. Dependent upon a given amplifier design topology, the large signal characteristics can have various degrees of slew rate (SR) asymmetry. It therefore makes sense to have models which emulate real IC parts in this regard.
A case in point is ...