Spice-compatible nonlinear Op Amp and CFOA macro-models

This paper describes SPICE-compatible macromodels to model the nonlinear behavior of operational amplifiers (Op Amp) and current feedback operational amplifiers (CFOA). The proposed macro-models include not only those performance parameters more important of the Op Amp and CFOA like the dynamic range, slew-rate, DC gain and gain-bandwidth product, but parasitic resistors and capacitors associated to the input-output terminals are also included. To validate the proposed macro-models, non-inverting amplifiers and one nonlinear resistor called saturated nonlinear function series (SNFS) were built to be used as test vehicles. First, the UA741 and AD844AN foundry-provided macro-models were used for generating frequency-domain numerical simulations of each no-inverting amplifier. Simulation results were compared with numerical results obtained by means of the proposed macro-models, showing a good accuracy among them. Afterwards, a chaotic signal experimentally obtained was applied as excitation signal for each SNFS built with the foundry-provided macro-models and with the proposed macro-models, confirming good agreement among theoretical simulations and experimental tests. Our results indicate that the proposed macro-models can be used either frequency- or time-domain for forecasting the behavior of linear and nonlinear circuits without that the accuracy worsens and in a less time compared with the foundry-provided macro-models.