GaN power amplifiers with supply modulation

Popović, Zoya

doi:10.1109/mwsym.2015.7167057

Cited by 21 publications

(11 citation statements)

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“…Structure with negative group delay (NGD) characteristics has been used to enhance the efficiency of feed-forward amplifiers [6]. Usually, the time mismatch between the envelope and the RF paths in supply-modulated power amplifiers will decrease linearity [7] and cause instability [8]. NGD power dividers can be used to compensate the group delay through different transmission paths in the supply-modulated power amplifier.…”

Section: Introductionmentioning

confidence: 99%

Novel Gysel Power Dividers with Negative Group Delay Characteristics

Zhu

Wang

Zhou

et al. 2019

International Journal of Antennas and Propagation

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A novel Gysel power divider with negative group delay (NGD), good matching, and low insertion loss is proposed. Resistors connected with short-circuited coupled lines (RCSCL) are shunted at output ports of the Gysel power divider to obtain NGD characteristics, and another resistor is shunted at the input port to realize perfect input and output matching. To verify the proposed structure, an NGD Gysel power divider is designed and fabricated. At the center frequency of 1.0 GHz, the measured NGD times for different output ports are −1.94 ns and −1.97 ns, the input/output port return loss is greater than 38 dB, the insertion loss is less than 8.3 dB, and the isolation between output ports is higher than 41 dB. To enhance the NGD bandwidth, two RCSCL networks having slightly different center frequencies are connected in parallel, which provides wider bandwidth with good input matching characteristics.

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Section: Introductionmentioning

confidence: 99%

Novel Gysel Power Dividers with Negative Group Delay Characteristics

Zhu

Wang

Zhou

et al. 2019

International Journal of Antennas and Propagation

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“…This dynamic variation in power distribution requires the conventional RFPA to operate under power back-off conditions, avoiding compression, which presents technical challenges in terms of achieving high linearity and back-off efficiency simultaneously [2]. To satisfy these requirements, several PA architectures have been proposed to improve the PA efficiency, such as and the Doherty PA [3] and envelope tracking [4], [5]. ET is a strong contender for both base transceiver station and user equipment applications due to its potential to support multimode and multiband operation.…”

Section: Introductionmentioning

confidence: 99%

Supply Modulator Ripple in Envelope Tracking Systems - Effects and Countermeasures

Alsahali

Alt

Chen

et al. 2019

2019 49th European Microwave Conference (EuMC)

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Envelope tracking power amplifiers (ET PAs) are one of the promising architectures to provide high efficiency amplification for future wireless communication systems. This is due to their ability to offer high efficiency over a wide output power range, by modulating the supply voltage applied to the PA. Generating this dynamic supply voltage with switching-mode modulators is highly efficient, but filtering the output remains a challenge, resulting in a residual 'ripple' on the supply voltage. This paper presents an experimental investigation into the interaction between a PA and a supply modulator in the presence of this ripple. By adding a varying ripple magnitude to the modulated drain voltage of a 2.14 GHz GaN ET PA with a 10 MHz LTE signal, the effects on the linearity of the RFPA can be observed and analysed to allow the system designer an insight into the amount of ripple that is tolerable, while still being able to achieve linearity and efficiency targets. The mixing products of the ripple and RF signal are shown to be a potential issue in ET PAs. This paper shows, for the first time, the full impact of the ripple voltage magnitude on the output spectrum.Further more, the ripple sensitivity of two different ET PA linearisation approaches are explored; firstly applying a generic memory polynomial digital pre-distortion (DPD) and secondly optimising the ET tracking signal shaping function to improve linearity. Measurements show that for the case where the ripple and RF are not synchronized, neither approach is able to significantly mitigate the ripple effect on the PA linearity.

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“…Power amplifiers developed for modern LTE-A base stations are thus mostly operating around the average power level with infrequent operation around peak power levels. Special PA architectures such as the Doherty, 1,2 Chireix, 3 and envelope tracking 4 are then used to provide a high power-efficiency at both peak and backoff power while maintaining a reasonably good linearity. In this study, a 17 Watts dual-input Chireix PA operating in class F and realized with two GaN high-electron-mobility transistors (HEMTs) is considered.…”

Section: Introductionmentioning

confidence: 99%

“…Compact dual-band reconfigurable antennas have also been proposed in refs. [4,5], which targets mobile phone application with omni-directional patterns.…”

Section: Introductionmentioning

confidence: 99%