### Document Brief

PAGE 34 OCTOBER 2004...

FEATURE ARTICLE...

MICROWAVE PRODUCT DIGEST...

Black-Box Modeling of RFIC Amplifiers for Linear and Non-linear Simulations...

by W. Clausen, J. Capwell, L. Dunleavy & T. Weller, Modelithics, Inc. J. Verspecht, Jan Verspecht bvba & J. Liu and H. Arslan, University of South Florida...

ehavioral modeling of RFIC amplifiers is presented, based on a novel approach that fits complex impedance dependent data for power compression, and Third Order Intercept (TOI) performance. An example, implemented in Agilent ADS, is shown for a commercially available RFIC amplifier operating in the 136 to 174 MHz range. Simulated to measured results are presented that demonstrate the ability to reliably re-create S-parameters, noise parameters, power compression, and intermodulation distortion behavior. The model also predicts noise and non-linear performance variation under source/load pull tuning....

the gain compression and phase compression under different source/load conditions to be able to accurately predict the harmonic and intermodulation performance. It is not trivial to obtain those datasets. This limitation can be overcome by the use of Sinusoidal Input Describing Functions (SIDFs). SIDFs are used to model nonlinear system behavior under periodic excitation. This is achieved by relating the distortion signals to the fundamental input signals through linear descriptor functions or DFs 6 . Eq. 4 presents a simple representation of the DF for the IM products under two-tone input stimulus signals ...

Eq. 4 Figure 1 Small-signal and large-signal S-parameter comparison....

Introduction...

Behavioral (black box) models are widely used in system design and evaluation, because they simplify the modeling complexity of the sub-systems (mixers, amplifiers, etc) and cut short the simulation time. This is because behavioral models only considers the input/output relationship of the system under study and use mathematical expressions or data file based models to describe the observation of the system response. In this paper, a behavioral amplifier model will be introduced that characterizes compression and load pull performance using functions that describe large-signal S-parameters. The concept of large-signal s-parameters was introduced in late 1990s 1 , 2 , 3 . Large-signal sparameter is an extension of the small-signal scattering-parameters 4 for the purpose of representing the nonlinear performance of a system that is under large-signal excitation. Figure 1 il...

### Document Keywords

Black - Box Modeling of RFIC Amplifiers for Linear and Non - linear Simulations paper 238