A nonlinear S-parameters behavioral model for RF LNAs

A nonlinear behavioral model for radio frequency low noise amplifiers (LNA´s) is presented. The model captures effects of nonlinearity, output power saturation, noise figure and port impedance mismatch. A high-level S-parameters approach is adopted during the model derivation. Consequently, the model inherits the S-parameters dual ability to characterize the transfer function between ports while including their impedances. The model derivation is thoroughly discussed showing how the effects of intermodulation as well as output power saturation can be included within the S-parameters representation for the block. Furthermore, in order to minimize the calibration effort, the model generics are made such that they map directly to typical LNA specifications. It follows that the model as implemented is not topology specific and can be easily calibrated to serve within top-down or bottom-up verification flows. Finally, the model accuracy is validated against reference transistor level simulations. Results comparison shows good agreement is attained.