AM/AM and AM/PM Distortion Generation Mechanisms in Si LDMOS and GaN HEMT Based RF Power Amplifiers

Nunes, Luís C.; Cabral, Pedro M.; Pedro, José C.

doi:10.1109/tmtt.2014.2305806

Cited by 84 publications

(39 citation statements)

References 17 publications

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“…A linearly increasing capacitance would cause quadratic nonlinearity, but here the limiting asymptotes of about 60 and 90 pF cause . In our previous studies, we have shown that has a very strong impact on the generation of AM-PM in the class-AB LDMOS PA [20], [21]. Similar results were obtained with intermodulation distortion (IMD) analysis of an LDMOS Doherty PA equipped with MRF21125, in which of the carrier PA was the main contributor to the total distortion [22].…”

Section: Distortion Contribution Analysissupporting

confidence: 81%

Extraction of a Multi-Dimensional Polynomial Device Model for an Improved Distortion Contribution Analysis Technique

Aikio

Rahkonen

Pedro

2015

IEEE Trans. Microwave Theory Techn.

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This paper presents a method to characterize a multidimensional polynomial current and charge source models needed for a distortion contribution analysis technique that can identify the dominant nonlinearities and different mixing mechanisms. A separate model characterization step with carefully chosen test signals is used to break the inherent input-output correlation that otherwise complicates the model fitting. The proposed Volterraon-top-of-harmonic-balance technique and improved polynomial fitting are then verified through the analysis of a 100-W LDMOS RF Doherty amplifier, which showed that, in this circuit, the cubic nonlinearity of the gate capacitance is the main culprit of AM-PM distortion.Index Terms-Distortion analysis, Doherty power amplifier (PA), polynomial device model, Volterra analysis.

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Section: Distortion Contribution Analysissupporting

confidence: 81%

Extraction of a Multi-Dimensional Polynomial Device Model for an Improved Distortion Contribution Analysis Technique

Aikio

Rahkonen

Pedro

2015

IEEE Trans. Microwave Theory Techn.

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“…(i) it cannot be related to the transconductance versus gatesource voltage G m (V GS ) profile [and thus drain-source current i DS (v GS ), the recognized major source of nonlinearity in FET devices], as they seem identical to the ones extracted from Si LDMOS and many other field-effect devices [4], [5];…”

Section: Introductionmentioning

confidence: 99%

Soft compression and the origins of nonlinear behavior of GaN HEMTs

Pedro

Nunes

Cabral

2014

2014 44th European Microwave Conference

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This work responds to the commonly formulated question in PA design of "Why do GaN HEMTs' nonlinear behavior seems so distinct from the one of their Si LDMOS, GaAs MESFETs or HEMTs counterparts?". Starting from some recent results on the origin of AM/AM and AM/PM distortion in power amplifiers made for these two device types, we demonstrate that there is no fundamental reason why the devices should be different, except that the formers suffer from a noticeable low-frequency dispersion. Then, we dig into this particular aspect of GaN HEMT operation, to show that this charge trapping-related phenomenon is responsible for a severe self-biasing capable of inducing soft-compression of an otherwise almost flat AM/AM gain plot -when measured with static CW tests -which, in fact, corresponds to a severe gain expansion when the AM/AM is assessed with more realistic dynamic tests performed with real communication signals. And it is this class-C PA like AM/AM that is responsible for the recognized GaN HEMT nonlinearity.

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“…The C gs nonlinearity, especially for the class-C biased peaking transistor, leads to a dependency of the input impedance (and, as a result, of the input power division ratio) on the input power. This will degrade the DPA linearity [12].…”

Section: B Parasitic Capacitancesmentioning

confidence: 99%

Breaking the Bandwidth Limit: A Review of Broadband Doherty Power Amplifier Design for 5G

2020

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AM/AM and AM/PM Distortion Generation Mechanisms in Si LDMOS and GaN HEMT Based RF Power Amplifiers

Cited by 84 publications

References 17 publications

Extraction of a Multi-Dimensional Polynomial Device Model for an Improved Distortion Contribution Analysis Technique

Extraction of a Multi-Dimensional Polynomial Device Model for an Improved Distortion Contribution Analysis Technique

Soft compression and the origins of nonlinear behavior of GaN HEMTs

Breaking the Bandwidth Limit: A Review of Broadband Doherty Power Amplifier Design for 5G

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