X-Parameters

X-parameters are a mathematical superset of S-parameters and are used for characterizing the amplitudes & relative phase of harmonics generated by nonlinear components under large input power levels.

Description

Agilent’s X-parameters* represent a new category of nonlinear network parameters for high-frequency design. X-parameters:

Are applicable to both large-signal and small-signal conditions, and for linear and nonlinear components.
Characterize the amplitudes and relative phase of harmonics generated by components under large input power levels at all ports.
Correctly characterize impedance mismatches and frequency mixing behavior to allow accurate simulation of cascaded nonlinear X-parameter blocks, such as amplifiers and mixers in wireless design.
Functionality was included in the Nonlinear Vector Network Analyzer (NVNA), and the Advanced Design System in 2008.
X-parameter model support was added to the SystemVue environment in 2010. SystemVue connects X-parameter models into RF system-level analysis, as well as full physical layer baseband/DSP simulations

X-parameters can help you overcome a key challenge in RF engineering, namely that of nonlinear impedance differences, harmonic mixing, and nonlinear reflection effects that occur when components are cascaded under large signal operating conditions. X-parameters help solve this complex cascading problem: if you measure the X-parameters of a set of components individually, you can calculate the X-parameters and hence the nonlinear transfer function of any cascade made from them. Calculations based on X-parameters are usually performed within a harmonic balance simulator environment.

* "X-parameters" is a trademark of Agilent Technologies, Inc. The X-parameter format and underlying equations are open and documented. For more information click here.