Efficiency Of Power Amplifier Research Articles

A low-complexity crest factor reduction design for 5G NR sub-6 GHz digital front-end with restricted peak regrowth

In recent years, orthogonal frequency division multiplexing (OFDM) has gained widespread adoption in communication technologies, exemplified by long-term evolution (LTE), 5th generation new radio (5G NR sub-6 GHz), and others. These technologies are instrumental in meeting the increasing demands for high data rates, throughput, and reliable downlink network access. However, a notable challenge associated with OFDM is the high peak-to-average power ratio (PAPR), imposing limitations on the efficiency of power amplifiers that often operate with significant back-offs. To mitigate this issue, the widely employed crest factor reduction (CFR) technique aims to enhance efficiency. This paper introduces a novel CFR methodology utilizing mixed and multi-iterative signal distortion-based techniques. Our approach is versatile, demonstrating effectiveness for low-bandwidth signals like LTE, as well as large-bandwidth signals reaching up to 100 MHz, as seen in 5G NR FR1. Also, digital up-sampling used to achieve the required high sample rate causes the issue of peak regrowth even after the required PAPR reduction achieved by CFR processing, which defeats the purpose of CFR. Our proposed design offers a solution to this challenge, enabling operation at a low data rate before digital up-sampling while effectively mitigating peak regrowth. Importantly, the implementation significantly reduces FPGA resource utilization, alleviating the complexity associated with multiple-input multiple-output (MIMO) radio systems. Demonstrating compliance with 3rd generation partnership project (3GPP) specifications for 5G NR on a real-time testbed, our approach stands as a practical and efficient solution for contemporary communication systems.

Design of a wideband, highly efficient FPA using an asymmetrical open-circuit coupled-lines-based filtering matching network

This study introduces a novel approach to designing a broadband, highly efficient filtering power amplifier (FPA) characterized by unique integrated filtering capabilities. Central to the proposed technique is the utilization of an asymmetrical open-circuit coupled-lines bandpass filter (BPF), serving dual functions as both an input matching network and an output matching network. Notably, this filter design not only enhances the bandpass filtering response but also significantly improves second harmonic rejection performance. To validate this methodology, a broadband FPA is implemented, employing the Cree 10 W GaN HEMT. The proposed FPA, operating between 2.0–3.0 GHz, achieves a peak drain efficiency of 45.9 %-73.26 %, corresponding to a peak output power of 38.5–41.95 dBm at saturation. This marks a notable efficiency enhancement compared to recent research findings. It is believed that the FPA solution is custom-tailored to meet the demanding requirements of modern base stations, striking the balance between improved power-efficiency and good filtering performance.

A symmetrical fully-integrated CMOS doherty power amplifier

This paper presents a new method to enhance the efficiency of a symmetrical doherty power amplifier (DPA) by fully utilizing the current driving capability of a class-C biased peaking amplifier. In this method, with utilization of the passive voltage gain concept, the input matching networks are designed in a way that the peaking path experiences a higher voltage gain than the carrier path, at high powers. As a result, the higher drive voltage of the peaking amplifier compensates for its lower gate bias and identical peak output currents for both amplifiers can be achieved. For demonstration purpose, a two-stage symmetrical DPA with a power utilization factor (PUF) of about unity is designed and fabricated in a standard 0.18-μm CMOS technology. The measurement results at 2.6 GHz show a power gain of 21 dB and an 1 dB compression point of 21.3 dBm. The peak power added efficiency (PAE) is 35% and the PAE at 6 dB power back-off (PBO) is better than 23%.

E-band telecom-compatible 40 dB gain high-power bismuth-doped fiber amplifier with record power conversion efficiency

Multi-band transmission is one of the key practical solutions to cope with the continuously growing demand on the capacity of optical communication networks without changing the huge existing fiber base. However, ultra-broadband communication requires the development of novel power efficient optical amplifiers operating beyond C- and L-bands, and this is a major research and technical challenge comparable to the introduction of the seminal erbium-doped fiber amplifiers that dramatically changed the optical communication sector. There are several types of optical fibers operating beyond C- and L-bands that can be used for the development of such amplifiers, specifically the fibers doped with neodymium, praseodymium, thulium, and bismuth. However, among these, Bi-doped fibers are of special interest as the most promising amplification medium because, unlike the others, different Bi-associated active centers allow amplification in an enormous band of overall width of 700 nm (1100–1800 nm). Such spectral coverage can be obtained by using different host materials, such as aluminosilicate, phosphosilicate, silica, and germanosilicate glasses. Here, we report a novel Bi-doped fiber amplifier with record characteristics for E-band amplification, including the highest power conversion efficiency among telecom-compatible E-band amplifiers reported to date. This bismuth-doped fiber amplifier (BDFA) features a maximum gain of 39.8 dB and a minimal noise figure of 4.6 dB enabled by 173 m Bi-doped fiber length. The maximum achieved power conversion efficiency of 38% is higher than that of L-band Er-doped fiber amplifiers. This performance demonstrates the high potential of BDFA for becoming the amplifier of choice in modern multi-band optical communication networks.

A 1.8–5.4-GHz GaN MMIC Distributed Efficient Power Amplifier With Reactance Compensation and Adaptive Biasing

A 1.8–5.4-GHz GaN MMIC Distributed Efficient Power Amplifier With Reactance Compensation and Adaptive Biasing

1.2 kW, 20 kHz Nanosecond Nd:YAG Slab Laser System

In this paper, we develop a kW-level high-repetition-rate nanosecond master oscillator power amplifier (MOPA) laser system, employing a structure of fiber, Nd:YVO4, and Nd:YAG hybrid amplification. A tunable fiber seed source is used for adjustable pulse repetition frequency and pulse width. The Nd:YVO4 pre-amplifier, which is dual-end-pumped, achieves high gain while maintaining good beam quality, and the high-power side-pumped Nd:YAG slab main-amplifier enables efficient power amplification. The repetition rate of the output laser can be adjusted within the range of 1~20 kHz, and the pulse width can be tuned within the range of 10~300 ns. The seed output is 6 mW at a repetition frequency of 20 kHz; we achieve an average output power of 1240 W with a total power extraction efficiency of 39.1% and single-pulse energy of 62 mJ at a pulse width of 301 ns. This parameter-controllable high-power laser holds promise for applications in the laser cleaning of complex surface contaminants.

High efficiency GaN power amplifier with compact harmonic tuning network

AbstractOne high efficiency second harmonic tuned (2HT) power amplifier (PA) with a compact multi‐harmonic tuning network is presented. The proposed design method can drive the third harmonic impedance to short‐circuit condition to achieve an ideal 2HT PA operation. Then the second harmonic impedance is controlled to proper position to improve the PA efficiency. Meanwhile, the fundamental impedance is also transferred to 50 Ω load by making the most of this tuning network. Consequently, the proposed output network can be designed to a compact size and is suitable for high frequency PA applications. For demonstration, a PA using Cree CGH40010 GaN high‐electron‐mobility transistor is designed and fabricated at 3.5 GHz. The measured results show that the PA achieves peak power added efficiency of 72.8%, output power of 41.3 dBm and drain efficiency of 80.2% at 3.3 GHz.

Modified Error Function Companding for reduction of PAPR in GFDM signals

Generalized Frequency Division Multiplexing (GFDM) is a multicarrier modulation technique, nevertheless, it provides high peak to average power ratio (PAPR) which affects the power amplifier (PA) efficiency. In this work, the modified error function companding is proposed for reducing PAPR in GFDM signals. The power scaling parameter (η) and companding parameter (a) are used to reduce the peak power. The average power is not altered in the proposed method, so there is no need to adjust the dynamic gain of PA. The theoretical expressions for the transform gain, achievable PAPR reduction and closed form expression of attenuation factor are derived. Moreover, the transform gain, attenuation factor, power spectral density, PAPR and bit error rate (BER) performance of the proposed method is analysed for different values of companding parameter. The results ensure that the proposed mEFC method at a=1 provides significant PAPR reduction than existing companding methods.

Design of a hybrid continuous mode broadband high efficiency power amplifier based on reconfigurable devices

AbstractThis letter presents a design method of resistance reactance hybrid continuous power amplifier based on reconfigurable devices and CG2H40010F. The power amplifier combines resistive‐reactive inverse F‐class power amplifier (RRIFPA), resistive‐reactive J‐class power amplifier (RRJPA), and resistive‐reactive F class power amplifier (RRFPA). We utilize the principle of low‐pass filters to control the impedance of multi‐frequency harmonics, and use the reconfigurable device SMP1345‐079LF to expand the bandwidth of the power amplifier. This article designs and produces a 1–4 GHz broadband power amplifier. The simulation and measurement results show that within the entire frequency range of 1–4 GHz, the Drain efficiency is between 53.6 and 72.1, the output power is between 40.1 and 42.6 dBm, the gain is between 10.1 and 12.6 dB, and the relative bandwidth is up to 120.

Optimizing Power Losses and Efficiency of Broadband Parallel-Circuit Class-E Power Amplifier

Optimizing Power Losses and Efficiency of Broadband Parallel-Circuit Class-E Power Amplifier

A Generic Multidimensional Design Methodology for Highly Efficient RF Power Amplifier with Improved Linearity

A Generic Multidimensional Design Methodology for Highly Efficient RF Power Amplifier with Improved Linearity

EFFICIENCY ANALYSIS OF SWITCHING CONVERTER-MODULATOR

The article discusses methods of highly efficient linear RF power amplifier and transmitter design for future 5G/6G networks. Based on a consideration of various known methods for constructing high-efficiency power amplifiers, the prospects of developments using the envelope elimination and restoration (EER, or Kahn method) and envelope tracking (ET) method are substantiated. The prospects for implementing PWM switching converter-modulator for these methods are assessed. Based on the evaluation calculations performed, it is shown that this structure can potentially be used as an EEP/ET modulator for a number of 5G/6G applications and will have advantages over structures using class AB amplification.

Design of High Efficient Power Amplifier with Wide-Band Input Matching Technique for UWB Wireless Applications

Design of High Efficient Power Amplifier with Wide-Band Input Matching Technique for UWB Wireless Applications

Development Review of Highly Efficient Sequential Power Amplifier with Extended Back-Off Range for Broadband Application

Similar to a Doherty power amplifier (DPA), a sequential power amplifier (SPA) is mainly composed of a main amplifier, an auxiliary amplifier and a combiner. However, SPA breaks the bandwidth limitation of the impedance inverter in the DPA, and also simplifies the design procedure. Since the main amplifier has no load modulation, it is easy for the SPA to realize broadband operation and improve the output back-off (OBO) power range. Therefore, SPA has great advantages and potential in expanding bandwidth, improving drain efficiency and expanding the back-off range of a power amplifier simultaneously. This paper describes the evolution and classification of the SPA. First, the basic theory of the SPA is reviewed. Then, some two-way SPAs using coupler and circulator as a power combiner are discussed. Thirdly, the latest popular sequential load modulated balanced amplifier is overviewed.

Power Amplifier Optimization for M2M Node using DPD and Hybrid DFT-s-OFDM with CFR

Power Amplifiers (PAs) play a vital role in mobile communication. However, their inherent nonlinearity can lead to issues such as unwanted radiation, interference with neighboring channels, and distortion within the desired frequency range. To address these problems, PAs are typically operated at a lower power level than their saturation point, sacrificing power efficiency to improve Error Vector Magnitude (EVM) performance. Consequently, more than 70-80% of the DC power is wasted as heat. This inefficiency necessitates the exploration of techniques to enhance PA efficiency while maintaining acceptable linearity and performance. Digital Pre-Distortion (DPD) is a useful technique to linearize PAs. DPD allows affordable nonlinear PAs to function with minimal distortion in their nonlinear operating regions. This results in amplified signals with increased power output and improved power efficiency. Using nonlinear functions, the output signal of the PA can be linearized, mitigate distortions, and be effectively optimized. When using various operating channels and varying time, temperature, and PA nonlinearity, the DPD must adjust. In order to increase the power efficiency of 5G systems, DPD-enabled systems are inculcating with adaptive DFT-s-OFDM employed 5G physical layer along with the Crest Factor Reduction (CFR) algorithm.

Design of a Highly Efficient Class-F GaN MMIC Power Amplifier Using a Multi-Function Bias Network and a Harmonic-Isolation L-C Resonator

Design of a Highly Efficient Class-F GaN MMIC Power Amplifier Using a Multi-Function Bias Network and a Harmonic-Isolation L-C Resonator

DFT-Spread Orthogonal Time Frequency Space System With Superimposed Pilots for Terahertz Integrated Sensing and Communication

Terahertz (THz) integrated sensing and communication (ISAC) is a promising interdisciplinary technology that realizes simultaneously transmitting Terabit-per-second (Tbps) and millimeter-level accurate environment or human activity sensing. However, both communication performance and sensing accuracy are influenced by the Doppler effects, which are especially severe in the THz band. Moreover, peak-to-average power ratio (PAPR) degrades the THz power amplifier (PA) efficiency. In this paper, a discrete Fourier transform spread orthogonal time frequency space (DFT-s-OTFS) system with superimposed pilots is proposed to improve the robustness to Doppler effects and reduce PAPR for THz ISAC. Then, a two-phase sensing parameter estimation algorithm is developed to integrate sensing functionality into the DFT-s-OTFS waveform. Meanwhile, a low-complexity iterative channel estimation and data detection method with a conjugate gradient based equalizer is proposed to recover the data symbols of DFT-s-OTFS. The proposed DFT-s-OTFS waveform can improve the PA efficiency by 10% on average compared to OTFS. Simulation results demonstrate that the proposed two-phase sensing estimation algorithm for THz DFT-s-OTFS systems is able to realize millimeter-level range estimation accuracy and decimeter-per-second-level velocity estimation accuracy. Moreover, the effectiveness of the iterative method for data detection aided by superimposed pilots in DFT-s-OTFS systems is validated by the simulations and the bit error rate performance is not degraded by the Doppler effects.

Strategic Optimization and Application Analysis of Orthogonal Frequency Division Multiplexing Index Modulation Systems

Orthogonal Frequency Division Multiplexing (OFDM) is a type of Multi-Carrier Modulation that operates by dividing a single channel into numerous orthogonal subchannels. By doing this, it facilitates the transformation of high-speed digital signals into parallel subdata streams. These streams are then modulated onto the subchannels, thereby enabling efficient transmission. OFDM with Index Modulation (OFDM-IM) further enhances this process by combining the benefits of OFDM with the high spectral efficiency of spatial modulation techniques, leading to significant improvements in the bit-error rate performance of the system. Despite the advantages of OFDM-IM systems, several challenges exist. For instance, the presence of inconsistent sampling rates can result in amplitude distortion. Furthermore, a high peak-to-average power ratio can adversely impact the efficiency of the RF power amplifier. These problems necessitate the exploration of diverse solutions to improve the performance of OFDM-IM systems. The focus of this thesis is to investigate and assess different strategies aimed at addressing these issues within OFDM-IM systems. We will explore these strategies, compare their effectiveness, and offer comprehensive recommendations on their optimal applications based on specific system requirements and scenarios. In doing so, the goal is to pave the way for more effective and efficient implementation of OFDM-IM systems in diverse contexts.

Design of High-efficiency Continuous Class F Doherty Power Amplifier

The high efficiency of the saturation state and rollback state is an important part of the front end of modern wireless communication systems. Improving the efficiency of RF power amplifiers is of great significance for energy saving and amplifier performance. Based on the traditional Doherty power amplifier, the harmonic suppression network is introduced before the fundamental frequency matching, so that the second harmonic impedance and third harmonic impedance can achieve continuous class F impedance matching conditions, and then the saturation efficiency and regression efficiency can be improved without affecting the fundamental wave matching. The results of the simulation show that the saturation efficiency of the Doherty amplifier reaches 73.94%~77.22%. The drain efficiency of back-off 6 dB reaches 61.80%~62.92%. The average saturation drain efficiency is 75.58%, and the average back-off 6 dB drain efficiency is 62.36%.

Improved Linearity and Efficiency of 5-GHz HBT Power Amplifier Using Transformer-Based Second Harmonic Trap Network

Improved Linearity and Efficiency of 5-GHz HBT Power Amplifier Using Transformer-Based Second Harmonic Trap Network