Theory and Design of Class-J Power Amplifiers With Dynamic Load Modulation

Andersson, Cristina; Gustafsson, David; Yamanaka, Koji; Kuwata, Eigo; Otsuka, Hiroshi; Nakayama, Minoru; Hirano, Y.; Angelov, I.; Fager, Christian; Rorsman, Niklas

doi:10.1109/tmtt.2012.2221140

Cited by 48 publications

(29 citation statements)

References 14 publications

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“…In [121,122], a similar theoretical analysis is applied to the Class-J solution, while, in [123], a Class-B solution is presented, which achieves dual-band operation.…”

Section: Dynamic Load Modulationmentioning

confidence: 99%

“…In continuous-type DLM, the tunability feature of the output filter is obtained by means of varactor devices, which ensures the best possible efficiency enhancement. In theory, the reactive nature of varactors makes the output losses independent of the dynamic loading control [121]. However, in practice, parasitic losses and breakdown characteristics of real varactors limit the achievable performance of the tunable filer, often requiring more than a single tunable element to provide significant efficiency improvement, which in turn impacts circuit complexity and varactors' integrability [129].…”

Section: Dynamic Load Modulationmentioning

confidence: 99%

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High Efficiency Power Amplifiers for Modern Mobile Communications: The Load-Modulation Approach

et al. 2017

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Abstract:Modern mobile communication signals require power amplifiers able to maintain very high efficiency in a wide range of output power levels, which is a major issue for classical power amplifier architectures. Following the load-modulation approach, efficiency enhancement is achieved by dynamically changing the amplifier load impedance as a function of the input power. In this paper, a review of the widely-adopted Doherty power amplifier and of the other load-modulation efficiency enhancement techniques is presented. The main theoretical aspects behind each method are introduced, and the most relevant practical implementations available in recent literature are reported and discussed.

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“…In [121,122], a similar theoretical analysis is applied to the Class-J solution, while, in [123], a Class-B solution is presented, which achieves dual-band operation.…”

Section: Dynamic Load Modulationmentioning

confidence: 99%

Section: Dynamic Load Modulationmentioning

confidence: 99%

High Efficiency Power Amplifiers for Modern Mobile Communications: The Load-Modulation Approach

et al. 2017

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“…The load impedance seen at the current generator plane ( ) is . Even though it is not the ideal Class-J load, it stays within the Class-J load region and provides the optimum performance between the output power and the efficiency, as demonstrated in [16]; slight load tuning helps to increase the output power while achieving the similar level of PAEs. In this case, one then needs to design a broadband load matching circuit to satisfy the intrinsic impedances conditions of (3) and (4) at the harmonic frequencies while hitting the optimum load condition of (2) at the fundamental frequencies.…”

Section: B Output Matching Networkmentioning

confidence: 99%

Broadband CMOS Stacked RF Power Amplifier Using Reconfigurable Interstage Network for Wideband Envelope Tracking

Park

Woo

Kim

et al. 2015

IEEE Trans. Microwave Theory Techn.

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In this paper, a two-stage broadband CMOS stacked FET RF power amplifier (PA) with a reconfigurable interstage matching network is developed for wideband envelope tracking (ET). The proposed RF PA is designed based on Class-J mode of operation, where the output matching is realized with a two-section low-pass matching network. To overcome the bandwidth (BW) limitation from the high-interstage impedance, a reconfigurable matching network is proposed, allowing a triple frequency mode of operation using two RF switches. The proposed RF PA is fabricated in a 0.32-m silicon-on-insulator CMOS process and shows continuous wave (CW) power-added efficiencies (PAEs) higher than 60% from 0.65 to 1.03 GHz with a peak PAE of 69.2% at 0.85 GHz. The complete ET PA system performance is demonstrated using the envelope amplifier fabricated on the same process. When measured using a 20-MHz BW long-term evolution signal, the overall system PAE of the ET PA is higher than 40% from 0.65 to 0.97 GHz while evolved universal terrestrial radio access adjacent channel leakage ratios are better than 33 dBc across the entire BW after memoryless digital pre-distortion. To our knowledge, this study represents the highest overall system performance in terms of PAE and BW among the published broadband ET PAs, including GaAs HBT and SiGe BiCMOS.Index Terms-Broadband, class-J, CMOS, envelope tracking (ET), high-efficiency, long-term evolution (LTE), multiband, power amplifier (PA), silicon-on-insulator (SOI), stacked FET.

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“…Most researchers have made great effect to develop various efficiency enhancement techniques for solving the PAs’ issue of transmitting high PAPR signal with poor efficiency, such as Doherty, envelope tracking, Chireix out‐phasing, pulse width modulation, and pulsed load modulation . As an alternative to above techniques, dynamic load modulation (DLM) technique was first introduced into Class‐E PAs by Rabb, and has been developed for the past few years . DLM technique can be realized by using two possible practical implementations, namely load modulated balanced type and varactor or microelectromechanical systems (MEMS) or laterally diffused metal oxide semiconductor (LDMOS) based DLM type .…”

Section: Introductionmentioning

confidence: 99%

Investigation of load modulated inverse Class-F power amplifier with extended conduction angle

You

Helaoui

et al. 2018

Int J RF Microw Comput Aided Eng

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A novel design space of load modulated (LM) inverse Class‐F power amplifiers (PAs) with extended conduction angle is proposed. The effects of the driven level factor β and the biasing operation factor ρ on the third‐harmonic generation are discussed. The harmonic generation mechanism shows that the knee voltage effects are the source of third‐harmonics for LM inverse Class‐F PAs. The definition of the inverse Class‐F mode is consistently valid under the circumstance of load modulation in a limited output power back‐off (OPBO) range. Meanwhile, the conduction angle θ0 can be extended from π/2 to a limited value (<110°) to keep the standard waveforms of inverse Class‐F mode and maintain high efficiency. After introducing the “continuous concept” and the second harmonic manipulation method, the mathematical design space of inverse Class‐F PAs with extended conduction angle is derived. Calculation shows that the purely conductive load modulation can enable high back‐off efficiency operation for LM inverse Class‐F PAs. As proof of concept, a demonstrator amplifier is fabricated and measured. The experimental results show that the power added efficiency (PAE) with optimum Vctrl is improved by 5% over an OPBO range of 6 dB compared with the same PA with fixed Vctrl.

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Theory and Design of Class-J Power Amplifiers With Dynamic Load Modulation

Cited by 48 publications

References 14 publications

High Efficiency Power Amplifiers for Modern Mobile Communications: The Load-Modulation Approach

High Efficiency Power Amplifiers for Modern Mobile Communications: The Load-Modulation Approach

Broadband CMOS Stacked RF Power Amplifier Using Reconfigurable Interstage Network for Wideband Envelope Tracking

Investigation of load modulated inverse Class-F power amplifier with extended conduction angle

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