AbstractThe origin of the slew rate asymmetry found experimentally in FET‐input LF355 op amps is analysed in order to explain why macromodels based on a strict build‐up technique can fail when used to simulate the behaviour of amplifiers driven by out‐of‐band large voltage signals. These simulations may be very important in predicting the effects of electromagnetic interferences conveyed to the circuit input port. Other performances of op amp macromodels designed either by build‐up techniques or by simplification/build‐up techniques are also compared an