The K-model: RF IC modelling for communication systems simulation

A new technique for modelling the entire analogue front-end of an RF IC for fast simulation and analysis in a DSP design environment is described. The designer´s objective is to see if an existing analogue front-end circuit design will work in the target end-to-end system before the RF IC is fabricated. Accurate full system simulation might save the need for chip redesign, mask generation and refabrication. A wireless receiver´s analogue front-end circuitry introduces varying levels of distortion dependent on carrier bias. To simulate the RF front-end in a system simulation, time-domain based behavioural models, K-models, are used to represent the receiver´s nonlinear effects. With SpectreRF´s periodic AC and periodic noise analyses the receiver´s nonlinear frequency translating and noise effects are accurately characterized. A scripting language called OCEAN^TM is used to write an extraction program to run SpectreRFM simulations and save the necessary base-band to base-band frequency response and power spectral density data files. K-models reside in the signal processing work system (SPW^TM) as block diagram symbols. The K-model uses the SpectreRFM data from the extraction simulation to define its nonlinear performance. Full end to end system simulations are then analyzed within SPW^TM. The K-model behavioural simulation approach is found to be extremely fast when compared with full circuit transistor level simulation techniques