Modeling Asymmetric Distortion in Multichannel Radio Frequency Communication Systems

Abstract

A multi-slice behavioral model is used to capture baseband memory effects in multichannel communication circuits and systems. The model is composed of two slices. Each slice includes a static nonlinear function box and linear filters. The first slice captures short-term memory effects and the second slice captures baseband memory effects. A robust extraction procedure for the model is developed with a physically realistic baseband slice. An efficient measurement method for the extraction is used. A 2.4~GHz power amplifier is modeled as an example. The performance of the extracted model is verified by showing that it captures baseband effects when the power amplifier is excited with a two-channel WCDMA signal. One of the advantages of the model is that it can be used in various established simulation schemes such as envelope transient simulation and transient (time-marching or SPICE-like) simulation. The model is shown to be compatible with both. In the transient simulation, the model supports the use of a much lower carrier frequency. This results in enhanced computational efficiency and the same results are achieved. This opens up a new contribution for RF system simulation where complex signals comprise of signals that can be of general form including signals that cannot be represented as modulated carriers. While envelope transient simulation is restricted to slowly modulated carriers, there is no restriction on the type of drive signal so that single tone, multi-tone, CDMA, chirp and noise signals can be combined.