Comparing FET Technologies in Terms of Their Suitability for Broadband Envelope Tracking Power Amplifiers

Alt, Alexander; Chen, Peng; Alsahali, Sattam; Quaglia, Roberto; Tasker, P.J.; Lees, Jonathan

doi:10.1109/inmmic.2018.8430025

Cited by 5 publications

(5 citation statements)

References 14 publications

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“…The bias point for the large signal measurements in the previous figures (1,2,4,5) has been chosen to give a somewhat flat gain at the lowest supply voltage, V GG = -5.4 V. Fig. 10 shows that in this case, the g m values are grouped closely between 15 V and 30 V. The measurements show therefore that the gain changes significantly, see Fig.…”

Section: On the Origin Of Small-signal Gain Variationmentioning

confidence: 91%

“…As a result of this, the transistor is not operated at a fixed supply voltage as in a conventional PA, but over a range of supply voltages. The implications of this have been explored [4], [5] where transistor technologies are compared in terms of suitability for ET. One issue that has been identified is the variation of the transistor's gain, both small-signal and large signal, with a changing supply voltage.…”

mentioning

confidence: 99%

“…One issue that has been identified is the variation of the transistor's gain, both small-signal and large signal, with a changing supply voltage. Although GaN HEMTs are generally accepted as one of the most promising transistor technologies for broadband power amplifiers in most established and emerging communication frequency bands, it has been shown [5] that, depending on the technology, they can exhibit different and significant degrees of gain variation. While [5] compares device technologies and mentions a wide range of gain variation in different devices, this paper will focus on the characterisation, impact and origins of gain variation itself.…”

mentioning

confidence: 99%

“…Although GaN HEMTs are generally accepted as one of the most promising transistor technologies for broadband power amplifiers in most established and emerging communication frequency bands, it has been shown [5] that, depending on the technology, they can exhibit different and significant degrees of gain variation. While [5] compares device technologies and mentions a wide range of gain variation in different devices, this paper will focus on the characterisation, impact and origins of gain variation itself. For clarity, while a transistor's gain depends on many factors, such as applied voltages, temperature and bias, for this paper, the term gain variation is used to describe only the supply voltage dependent gain variation.…”

mentioning

confidence: 99%

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Analysis of Gain Variation With Changing Supply Voltages in GaN HEMTs for Envelope Tracking Power Amplifiers

Alt

Hirshy

Jiang

et al. 2019

IEEE Trans. Microwave Theory Techn.

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Envelope tracking (ET) is a promising power amplifier (PA) architecture for current and future communications systems, that uses dynamic modulation of the supply voltage to provide high efficiency and potentially very wide bandwidth over a large dynamic range of output power. The dynamic nature of the supply voltage can lead to a problematic variation in transistor gain however, particularly in GaN HEMTs. This paper describes and analyses this behaviour and the detrimental effect it can have on ET PAs. Contributing factors and origins of gain variation are described in detail along with how, for the first time, meaningful comparisons can be made between different devices. Using these guidelines, gain variation is shown to be a widespread issue effecting most GaN HEMTs presented in literature. To allow an analysis of the intrinsic device behaviour, an extended transistor model is developed that takes the effect of gate and source field plates into account. This model is refined using measurement data and used to demonstrate the fact that the parasitic gate-drain capacitance (C GD ) is the main contributor to the small-signal gain variation; a significant part of the overall gain variation. Based on this knowledge, possible strategies to reduce gain variation at the transistor technology level are proposed, allowing the optimisation of GaN HEMTs specifically for ET PAs. One identified strategy involves reducing the length of the gate field plate, and is shown to be a viable approach to reduce the gain variation in GaN HEMTs, albeit at an increased RF/dc dispersion.

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Section: On the Origin Of Small-signal Gain Variationmentioning

confidence: 91%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Analysis of Gain Variation With Changing Supply Voltages in GaN HEMTs for Envelope Tracking Power Amplifiers

Alt

Hirshy

Jiang

et al. 2019

IEEE Trans. Microwave Theory Techn.

Self Cite

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“…Since in practical devices, output or input capacitances can change with input voltage, change in supply voltage will lead to change in capacitances, and hence, design of matching circuit will be difficult. A comparison of Si LDMOS, GaAs pHEMT, and GaN HEMTs was undertaken in Alt et al 37 GaN HEMT was found to be the best candidate for ET amplifier design because of smaller intrinsic capacitances and moderate gain variation.…”

Section: Efficiency Enhancement Techniquesmentioning

confidence: 99%

Review of efficiency enhancement techniques and linearization techniques for power amplifier

Singh

Malik

2021

Circuit Theory & Apps

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Summary Power amplifier is one of the most important module of transceiver design. Linearity and efficiency are the two main areas of improvement in power amplifier design. Fifth generation (5G) mobile communication is one of the most important application of power amplifier, which require power amplifiers that are extremely linear and efficient. In this paper, review of different efficiency enhancement and linearization techniques has been undertaken. Basic architecture, advantages, and challenges of efficiency enhancement techniques—outphasing, Doherty, and envelope tracking—have been discussed. Linearization techniques—feedback, feedforward, and predistortion—have also been discussed in this paper.

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TCAD Simulation of Novel Recess Gate Common Drain Dual Channel AlGaN/GaN HEMT for Small Signal Performance

Pal,

Pratap,

Kabra

2024

IETE Technical Review

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Comparing FET Technologies in Terms of Their Suitability for Broadband Envelope Tracking Power Amplifiers

Cited by 5 publications

References 14 publications

Analysis of Gain Variation With Changing Supply Voltages in GaN HEMTs for Envelope Tracking Power Amplifiers

Analysis of Gain Variation With Changing Supply Voltages in GaN HEMTs for Envelope Tracking Power Amplifiers

Review of efficiency enhancement techniques and linearization techniques for power amplifier

TCAD Simulation of Novel Recess Gate Common Drain Dual Channel AlGaN/GaN HEMT for Small Signal Performance

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