Linearization of large-signal scattering functions

Large-signal output characteristic investigation of the MOSFETs in the breakdown region based on X-parameters

“…The increased X s 2121 becomes larger than X T 2121 at V DS higher than 2.6 V, causing another intercept point as shown in Figure 3. When compared with the intercept point analysis of X s 2121 and X T 2121 for HEMT in the linear region, [5,7] the presented investigation further extends to X s 2121 and X T 2121 intercept behavior for the MOSFETs operating in the breakdown region. It is found that X T 2121 can be significant in the breakdown region and should be taken into account to characterize realistic output large-signal characteristics.…”

“…This modified large-signal model is obtained by fitting the measured X-parameters where the large-signal spectral components (X F terms) and probing information (X S and X T terms) under the condition of large-signal excitations are included. Compared with the conventional industry standard hot-S parameters, [4] X T terms of the X-parameters which can be significant at high input power [5,7] are further considered in model establishment. Therefore, realistic output characteristics of MOSFETs under large-signal drive can be investigated.…”

“…However, a output reflected wave of a device can be influenced by an X T term under large-signal operation which can lead to a decrease of the output signal phase. [5] This pronounced X T term under large-signal excitation in the X-parameter measurements should be taken into account to characterize the output characteristics of a device. Our measurement results show that the X T term can be obvious for the MOSFET operating in the breakdown region.…”

Nonlinear behavioral models of HEMTs using response surface methodology

“…As a result, simple tabular models may take several hundreds of MB, which is usually unacceptable when one wants to distribute the model. Therefore, one may consider limiting the model size by introducing linearization assumptions as in X-parameters [4], but at the same time one loses some amount of information. Another approach is to model a nonlinear device with an arbitrary global function like in Artificial Neural Networks (ANN), Radial Basis Function (RBF) or State Space models.…”

An analytical approach to obtain optimum load impedance using X-parameters^®

“…An alternative to formulating a large signal model is to use a measurement based behavioral approach such as the X-parameter model. X-parameters are the mathematically correct supersets of S parameters valid for nonlinear (and linear) components under large-signal (and small-signal) conditions [5,6].…”