Extension of X-parameters to include long-term dynamic memory effects

-Static X-parameter (XP) models for RF power amplifiers (PAs), derived from both simulations and nonlinear vector network analyzer (NVNA) measurements, are investigated for the prediction of PA performance under dynamic signal conditions such as in envelope tracking (ET). The instantaneous AM-AM, AM-PM and PAE predictions of XP models extracted from simulation are compared under ET dynamic signal conditions to two types of circuit models using envelope simulation. An XP PA model is extracted for a peak 8W GaN class-F -1 ET PA from NVNA measurements with automated bias control. By applying a constant gain shaping table derived from the XP model to the drain supply voltage, the average PAE is improved from 40% to 57% for 3.84 MHz WCDMA signals at 2.14 GHz compared to fixed drain bias operation.

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“…Another approach would use the dynamic extensions of X-parameters [9] applied to both the RF and the supply ports. …”

Section: Discussionmentioning

confidence: 99%

Simulation and measurement-based X-parameter models for power amplifiers with envelope tracking

Jang

Zai

Reveyrand

et al. 2013

2013 IEEE MTT-S International Microwave Symposium Digest (MTT)

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“…File size can become large if sweeping all independent variables densely. Memory effects are not yet included (but see [15]). A simplified comparison of the two approaches is summarized and presented in Table 1.…”

Section: Discussion and Comparisonmentioning

confidence: 99%

Device modeling with NVNAs and X-parameters

Root

Horn

et al. 2010

2010 Workshop on Integrated Nonlinear Microwave and Millimeter-Wave Circuits

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This paper reviews and contrasts two complementary device modeling approaches based on data readily obtainable from a nonlinear vector network analyzer (NVNA) [1]. The first approach extends the application of waveform data to improve the characterization, parameter extraction, and validation methodologies for "compact" transistor models. NVNA data is used to train artificial neural network -based constitutive relations depending on multiple coupled dynamic variables, including temperature and trap states for an advanced compact model suitable for GaAs and GaN transistors. The second approach is based on loaddependent X-parameters* [2], [3], [5], [6], measured using an output tuner working with the NVNA. It is demonstrated that Xparameters measured versus load at the fundamental frequency predict well the independent effects of harmonic load tuning on a 10W GaN packaged transistor without having to independently control harmonic loads during characterization. A comparison of the respective merits of the two approaches is presented.

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“…We now show that experiments for a single sine and cosine stimulus suffice to completely specify all HCWs for a memoryless nonlinearity. Let (23) where is a memoryless nonlinearity. Using the expression for the Fourier series coefficient of the response results in and differentiating gives (24) where (25) Then the HCW series in (12) becomes a discrete convolution.…”

Section: Memoryless Nonlinearitiesmentioning

confidence: 99%

Evaluation of Harmonic Coupling Weights in Nonlinear Periodicity Preservation Systems

Baylis

Marks

2012

IEEE Trans. Circuits Syst. I

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When stimulated by a periodic stimulus, every component of a possibly nonlinear periodicity preservation system oscillates periodically with the same period as the stimulus. Changes in the harmonic structure of the the stimulus couples each input harmonic to, in general, every response harmonic. Knowledge of harmonic coupling weights (HCWs) allows model free characterization of effects of all small stimulus perturbation. This paper develops foundational methodology for experimentally measuring the HCWs. The on-frequency method uses small tickle tones at harmonic frequencies to do this. The off-frequency method places tickle tones adjacent to harmonic frequencies and is applicable to PP systems that are locally frequency invariant. Memoryless nonlinear PP systems are an example where the approach works exactly. The off-frequency method also requires fewer experiments. In some cases, the off-frequency method can be extended to measure numerous HCWs in a single experiment. Some system types such as the memoryless nonlinearity, require fewer experiments than general PP systems. Methods to experimentally measure the Hessian are also presented.

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Extension of X-parameters to include long-term dynamic memory effects

Cited by 52 publications

References 9 publications

Simulation and measurement-based X-parameter models for power amplifiers with envelope tracking

Simulation and measurement-based X-parameter models for power amplifiers with envelope tracking

Device modeling with NVNAs and X-parameters

Evaluation of Harmonic Coupling Weights in Nonlinear Periodicity Preservation Systems

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