Download or read book Broadband High Efficiency RF Power Amplifier Design for Cellular Base Stations in Wireless Communications written by Mengsu Yang and published by . This book was released on 2016 with total page 144 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Push pull Based High Efficiency and High Power Broadband Power Amplifiers for Wireless Base Stations written by Ayman Jundi and published by . This book was released on 2019 with total page 109 pages. Available in PDF, EPUB and Kindle. Book excerpt: The monthly data throughput by 2021 is forecasted to be ten times that of December 2015. As a result of the on going dramatic increase in demand, service providers are assigned new frequency bands to accommodate more channels to carry more data. However, the usable part of the spectrum is a limited resource so modern communication signals were designed to be more spectrally efficient to send more bits over the same channel bandwidth. However, these spectrally efficient signals have high PAPR. The immediate reaction to these changes was to add additional RF front-end branches to accommodate the new frequency bands. Initially, the PAs used at the time were not optimized for back-off efficiency and where operating at low efficiency which caused significant increase in heat generation for the same average power produced which in turn increased cooling costs and reduced the life time of the PA. After the introduction of back-off efficiency enhancement techniques the PAs became more efficient however they were limited in bandwidth which is typically 10-15%. This work focuses on reducing the redundancy of power amplifiers in communication base stations while maintaining high back-off efficiency. After exploring the literature to understand the limitations of current implementations, it was found that the push-pull topology is often used at low frequency in broadband high power PAs. In the absence of a complimentary transistor pairs the push-pull implantation requires the use of balanced to unbalanced (balun) transformers. Various balun implantations were hence investigated to identify the most suitable option for broadband planar implementation. As a result, a methodology was proposed to co-design the balun and the matching network in order to have better control over the harmonic impedance. An 85 W push-pull PA was then designed based on the proposed methodology with a multi-octave bandwidth as a demonstration of the broadband potential of push-pull PAs at RF frequencies. Next, the two most popular techniques for back-off efficiency enhancement, i.e., ET and load modulation, were studied and the principle of load modulation was found to be more suitable for broadband signal transmission. The Doherty architecture is the most common implementation of load modulation and it comes in two basic variations, the PCL and SCL DPAs. The original architecture concepts are not only band limited but also ill-suited for high frequency designs where the transistors' parasitics introduce significant effect. However, later literature expanded on the original concept of the PCL variation which provided the needed flexibility for wider bandwidth implementations at a higher frequency. Using the broadband implementation and the co-design methodology two push-pull amplifiers were used in a PCL DPA topology and demonstrated that the push-pull utilization doesn't have a significant impact on the bandwidth of the output combiner as an octave bandwidth was achieved with the use of digital Doherty. Lastly, the thesis proposes a new approach for designing high power DPAs with extended bandwidth. It starts with a generic SCL DPA architecture to derive the equations that relate its underlying combiner's ABCD parameters to the transistor's optimum impedance and load impedance. These equations featured the possibility of significantly increasing the load impedance in SCL DPA compared to the one of the popular PCL DPA architecture. This is particularly beneficial when targeting very high power DPAs for macro-cell base stations and broadcast applications where very low load impedance can seriously complicate the design and limit the achievable bandwidth. To further maximize the load impedance increase, the proposed SCL DPA uses a push-pull topology for the main and peaking amplifier stages. A low-loss planar balanced to unbalanced transformer (balun) combiner network is then utilized to realize the SCL DPA combining. The proposed approach was finally applied to design a proof-of-concept 350 W SCL DPA which operates over the band spanning from 720 to 980 MHz. The prototype demonstrated a peak output power of about 55 dBm over a 30% FBW with a 6 dB back-off efficiency, measured using pulsed signal, between 46.6% and 54.6%. Furthermore, the modulated signal based measurement results confirmed the linearizability of the SCL DPA prototype while maintaining a back-off efficiency over 50% for a 7.1 dB peak to average power ratio signal.

Download or read book High Efficiency Load Modulation Power Amplifiers for Wireless Communications written by Zhancang Wang and published by Artech House. This book was released on 2017-06-30 with total page 389 pages. Available in PDF, EPUB and Kindle. Book excerpt: This cutting-edge resource presents a complete and systematic overview of the practical design considerations of radio frequency (RF) high efficiency load modulation power amplifiers (PA) for modern wireless communications for 4G and beyond. It provides comprehensive insight into all aspects of load modulation PA design and optimization not only covering design approaches specifically for passive and active load modulation operation but also hybrid with dynamic supply modulation and digital signal processing algorithms required for performance enhancement. Passive load impedance tuner design, dynamic load modulation PA, active load modulation PA and Doherty PA design for efficiently enhancement are explained. Readers find practical guidance into load modulation PA design for bandwidth extension, including video bandwidth enhancement techniques, broadband dynamic load amplifiers, topology selection, design procedures, and network output. This book presents the evolution and integration of classical load modulation PA topologies in order to meet new challenges in the field.

Download or read book Bandwidth and Efficiency Enhancement in Radio Frequency Power Amplifiers for Wireless Transmitters written by Karun Rawat and published by Springer Nature. This book was released on 2020-03-05 with total page 390 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book focuses on broadband power amplifier design for wireless communication. Nonlinear model embedding is described as a powerful tool for designing broadband continuous Class-J and continuous class F power amplifiers. The authors also discuss various techniques for extending bandwidth of load modulation based power amplifiers, such as Doherty power amplifier and Chireix outphasing amplifiers. The book also covers recent trends on digital as well as analog techniques to enhance bandwidth and linearity in wireless transmitters. Presents latest trends in designing broadband power amplifiers; Covers latest techniques for using nonlinear model embedding in designing power amplifiers based on waveform engineering; Describes the latest techniques for extending bandwidth of load modulation based power amplifiers such as Doherty power amplifier and Chireix outphasing amplifiers; Includes coverage of hybrid analog/digital predistortion as wideband solution for wireless transmitters; Discusses recent trends on on-chip power amplifier design with GaN /GaAs MMICs for high frequency applications.

Download or read book RF and Microwave Power Amplifier Design written by Andrei Grebennikov and published by McGraw Hill Professional. This book was released on 2004-09-15 with total page 433 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is a rigorous tutorial on radio frequency and microwave power amplifier design, teaching the circuit design techniques that form the microelectronic backbones of modern wireless communications systems. Suitable for self-study, corporate training, or Senior/Graduate classroom use, the book combines analytical calculations and computer-aided design techniques to arm electronic engineers with every possible method to improve their designs and shorten their design time cycles.

Download or read book Advances in Analog and RF IC Design for Wireless Communication Systems written by Mustafa Acar and published by Elsevier Inc. Chapters. This book was released on 2013-05-13 with total page 51 pages. Available in PDF, EPUB and Kindle. Book excerpt: This chapter presents high-efficiency power amplifiers (PAs) for wireless infrastructure. It starts by stating the importance of high efficiency and the historical evolution in base station PA concepts. It then introduces the current solution, the Doherty PA. After explaining the fundamentals of the Doherty PA, a novel implementation achieving more than 35% drain efficiency across a 6dB power back-off range and up to 20W peak power between 1.7 and 2.3GHz is given. Afterwards, a future PA concept, switch-mode outphasing PA, is introduced. Theory and implementation details of a class-E outphasing PA achieving more than 60% drain efficiency across a 6dB power back-off range and up to 19W peak power between 1800 and 2050MHz is explained. By the end of the chapter, an essential part of switch-mode PAs, high voltage (up to 10V) and high frequency (up to 4GHz) drivers are presented.

Download or read book RF Power Amplifiers for Wireless Communications written by Steve C. Cripps and published by Artech House Publishers. This book was released on 2006-01-01 with total page 456 pages. Available in PDF, EPUB and Kindle. Book excerpt: This extensively revised edition offers a comprehensive, practical, up-to-date understanding of how to tackle a power amplifier design with confidence and quickly determine the cause of malfunctioning hardware.

Download or read book Digitally Controlled Microwave Power Amplifier Design Techniques for Wireless Communications written by Varish Diddi and published by . This book was released on 2017 with total page 153 pages. Available in PDF, EPUB and Kindle. Book excerpt: In order to meet the increasing demand of high data rate mobile broadband communication, newer standards increasingly employ spectrally efficient high order modulation schemes, which lead to large peak-to-average ratio (PAPR) of transmitted signals. To drive down the cost and form factor, a significant portion of the active circuitry in today's commercial handsets is implemented in silicon CMOS technology--except for the power amplifier (PA). Silicon technology comes with low breakdown voltage, however, limiting the output power of the PA. Recent work has shown that series-connection of Si FETs (the "Stacked-FET" technique) can overcome the breakdown issue of silicon CMOS FETs to implement high power PAs. This can enable the use of scaled CMOS technology nodes which are optimized for digital logic circuits, to implement high performance PAs. The PAs, moreover, can make use of the digital circuits available to produce compact integrated circuits that are less dependent on microwave matching techniques than their counterparts. This work investigates the design and implementation of high output power, digitally-intensive PA CMOS architectures and their extensions for wireless transmitters that are highly efficient, even for signals with high peak-to-average ratio. In the first part of this work, a digitally modulated PA (DPA) is implemented in polar architecture on 180 nm CMOS SOI technology. The amplitude modulation input signal is a 10-bit digital word controlling the number of active unit cells--each unit cell being a stacked FET PA. The DPA is also driven by a constant amplitude phase modulated (PM) signal centered at RF. The demonstrated DPA provides output power of 1.45 W at 900 MHz with drain efficiency of 65.9%. The power and efficiency are adequate for use in cellular handsets for 3G and 4G standards. The DPA can transmit WCDMA and LTE signals at 900 MHz and is functional from 800 MHz to 2.4 GHz with different matching networks. This DPA is a multi-band, multi-standard PA and is used as a building block for additional designs in this work. The back-off efficiency enhancement of PA is critical to efficiently transmit signals of high PAPR from hand-sets. In the second part of the work, two identical DPAs are used to implement a digitally modulated Doherty power amplifier (DDPA). This part of the work investigates the challenges and develops the techniques for achieving strong efficiency peaking in output power back-off for CMOS Doherty PAs at microwave frequencies. The output combiner needed within the Doherty architecture is realized using surface-mount components on a printed circuit board (PCB). Digital AM signals to both DPAs are independently provided as inputs. The phase difference between RF PM inputs of main and peaking DPAs can also be varied. The peak output power of CMOS DDPA at 900 MHz is >2 W (highest reported in the literature) with drain efficiency of 55.5%, while at 6 dB back-off the drain efficiency is 52.6%. The back-off efficiency and its improvement relative to class-B is highest reported in the literature for any CMOS Doherty implementation. The DDPA is demonstrated to transmit 5 MHz 64-QAM OFDM signal with very good linearity of ACPR better than -35.9 dB and EVM of 3.8%. For applications like femto-cell base-stations, where the power needed is large, technologies like Gallium Nitride (GaN) work better than silicon because of superior voltage handling. The challenge here lies in efficiently driving the GaN FETs. The DPA developed in this work can provide large enough voltage to directly drive the input of GaN FET, thanks to the use of FET stacking. A novel architecture is demonstrated in which the CMOS DPA drives the GaN FET, which is connected as a common gate stage, with no inter-stage matching. The GaN FET in turn drives a 50 [omega] load directly. The absence of any impedance matching network (with its associated bandwidth limitation) makes this PA wideband. Key design aspects of this architecture, including bandwidth limitation caused by circuit parasitics, are discussed in this work. A digitally controlled PA with a combination of CMOS and GaN (Mitsubishi Electric 0.75 [mu]m process) is demonstrated. The CMOS-GaN PA operates over a 2.4:1 frequency range for 1dB output power variation (500 MHz to 1.2 GHz); output power varies from 2.4 W to 3 W with efficiency between 48% to 74%. This PA is demonstrated to transmit 5 MHz, 64 QAM signal at various frequencies. These characteristics make this amplifier a candidate for application in femtocells and microcells.

Download or read book Design and Control of RF Power Amplifiers written by Alireza Shirvani and published by Springer Science & Business Media. This book was released on 2013-04-18 with total page 157 pages. Available in PDF, EPUB and Kindle. Book excerpt: Design and Control of RF Power Amplifiers investigates various architectures and concepts for the design and control of radio-frequency (RF) power amplifiers. This book covers merits and challenges of integrating RF power amplifiers in various technologies, and introduces a number of RF power amplifier performance metrics. It provides a thorough review of various power amplifier topologies, followed by a description of approaches and architectures for the control and linearization of these amplifiers. A novel parallel amplifier architecture introduced in this book offers a breakthrough solution to enhancing efficiency in systems using power control. Design and Control of RF Power Amplifiers is a valuable resource for designers, researchers and students in the field of RF integrated circuit design. Detailed and thorough coverage of various concepts in RF power amplifier design makes this book an invaluable guide for both beginners and professionals.

Download or read book High Efficiency Wideband Envelope Tracking Power Amplifier for Next generation Wireless Communications written by Myoungbo Kwak and published by . This book was released on 2011 with total page 109 pages. Available in PDF, EPUB and Kindle. Book excerpt: The latest generation of smart devices deployed in cellular networks has created explosive growth in network data traffic, and the increasing demand for broadband services with higher data rates, require higher peak to average power ratio (PAPR) with wider bandwidth. One of the challenges in the conventional power amplifiers (PAs) with fixed supply voltage, is the degraded efficiency and generated heats at a large back-off to meet tight linearity requirements. This dissertation presents high efficiency wideband envelope tracking power amplifiers for 2.1 GHz micro base-stations and 2.5 GHz wireless mobile applications. By superimposing the envelope signal at the drain such that the RF amplifier operates consistently closer to saturation, the overall efficiency is improved and the generated heat is reduced dramatically. In the first part of the dissertation, a high performance BiCMOS DMOS monolithic envelope amplifier for micro-base station power amplifiers is presented. Due to the low breakdown voltage of the CMOS transistors, the high voltage envelope amplifier has been implemented with discrete components with high voltage process. Compared to these discrete solutions, an integrated circuits implementation for the envelope amplifier brings many benefits. The design of monolithic envelope amplifiers for high voltage (VDD = 15 V) envelope tracking applications, and the design techniques to solve the reliability issues with thin gate oxide is described. The overall envelope tracking system employing a GaN-HEMT RF transistor, and fully integrated high voltage envelope amplifier with a 0.35[mu]m BiCMOS DMOS process, is demonstrated. In the second part, a high-efficiency wideband envelope tracking power amplifier for mobile LTE applications will be presented. The CMOS envelope amplifier with hybrid linear and switcher is designed in a 150 nm CMOS process. The envelope amplifier employs direct sensing of the linear stage current to reduce the propagation delay in the switcher. The strategy is demonstrated to improve the efficiency of the complete envelope tracking power amplifier system. The resulting performance of envelope tracking system employing a GaAs HBT-based RF PA with a 5 MHz LTE signal input demonstrated state-of-the-art efficiency while meet the linearity requirement.

Download or read book Modeling and Design Techniques for RF Power Amplifiers written by Arvind Raghavan and published by John Wiley & Sons. This book was released on 2008-02-04 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt: Achieve higher levels of performance, integration, compactness, and cost-effectiveness in the design and modeling of radio-frequency (RF) power amplifiers RF power amplifiers are important components of any wireless transmitter, but are often the limiting factors in achieving better performance and lower cost in a wireless communication system—presenting the RF IC design community with many challenges. The next-generation technological advances presented in this book are the result of cutting-edge research in the area of large-signal device modeling and RF power amplifier design at the Georgia Institute of Technology, and have the potential to significantly address issues of performance and cost-effectiveness in this area. Richly complemented with hundreds of figures and equations, Modeling and Design Techniques for RF Power Amplifiers introduces and explores the most important topics related to RF power amplifier design under one concise cover. With a focus on efficiency enhancement techniques and the latest advances in the field, coverage includes: Device modeling for CAD Empirical modeling of bipolar devices Scalable modeling of RF MOSFETs Power amplifier IC design Power amplifier design in silicon Efficiency enhancement of RF power amplifiers The description of state-of-the-art techniques makes this book a valuable and handy reference for practicing engineers and researchers, while the breadth of coverage makes it an ideal text for graduate- and advanced undergraduate-level courses in the area of RF power amplifier design and modeling.

Download or read book RF Power Amplifiers for Mobile Communications written by Patrick Reynaert and published by Springer Science & Business Media. This book was released on 2006-11-18 with total page 259 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book tackles both high efficiency and high linearity power amplifier (PA) design in low-voltage CMOS. With its emphasis on theory, design and implementation, the book offers a guide for those actively involved in the design of fully integrated CMOS wireless transceivers. Offering mathematical background, as well as intuitive insight, the book is essential reading for RF design engineers and researchers and is also suitable as a text book.

Download or read book High Linearity Broadband RF Vector Multiplier for Analog RF Pre distortion written by Yiling Xu and published by . This book was released on 2016 with total page 66 pages. Available in PDF, EPUB and Kindle. Book excerpt: Wireless communication systems are moving towards a heterogeneous solution, where small-cell base stations such as pico-cells and femto-cells are used concurrently with macro- cell base stations in high data traffic areas. Small-cell networks are expected to provide much larger wireless data rates and capacity in small areas while only consuming a fraction of the power. However, power amplifier nonlinearity does not scale down with the size of the base station; a similar degree of nonlinearity correction is required in both small-cell and macro-cell base stations, meaning that the power consumed by the signal linearization circuits is the same. An analog-radio frequency pre-distortion (ARF-PD) solution, operating at a fraction of a conventional digital pre-distortion's power consumption, has been proposed to support the unrestrained growth of wireless communication. This thesis forms part of an ongoing research project aimed at developing a fully integrated ARF-PD solution - a promising, low-power alternative to digital pre-distortion for future wireless communications. Specifically, it focuses on delivering an integrated design of a low-power high-linearity broadband radio frequency (RF) vector multiplier, which can be used as part of the ARF-PD solution. An RF vector multiplier is considered one of the major function blocks in analog pre-distortion solutions, as it allows the analog pre-distorter to interface with the undistorted signal in the RF domain. In the thesis, two RF vector multiplier designs are proposed and implemented in integrated circuits. In the first implementation, the RF vector multiplier is designed to directly apply pre-distortion to the RF signal. This architecture imposes a need for high gain in the RF vector multiplier, which results in large transistor size and high power consumption in the output stage. The design is able to achieve promising simulation results, however, performance limitations and disadvantages are also clearly exposed compared to commercial products. To resolve the issues discovered, an alternative ARF-PD architecture is adopted to relax the output power level needed from the RF vector multiplier. In addition, a self-linearized variable gain amplifier topology is proposed to improve system linearity. Overall, the second design shows significant improvement in bandwidth, linearity and output noise level, while only consuming half of the power consumed by the first design. Ultimately, simulation results have shown satisfying performance for both RF vector multipliers as part of an ARF-PD system. However, both of the proposed integrated circuit designs should be validated by measurement.

Download or read book Linear CMOS RF Power Amplifiers for Wireless Applications written by Paulo Augusto Dal Fabbro and published by Springer Science & Business Media. This book was released on 2010-06-22 with total page 171 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advances in electronics have pushed mankind to create devices, ranging from - credible gadgets to medical equipment to spacecraft instruments. More than that, modern society is getting used to—if not dependent on—the comfort, solutions, and astonishing amount of information brought by these devices. One ?eld that has continuously bene?tted from those advances is the radio frequency integrated c- cuit (RFIC) design, which in its turn has promoted countless bene?ts to the mankind as a payback. Wireless communications is one prominent example of what the - vances in electronics have enabled and their consequences to our daily life. How could anyone back in the eighties think of the possibilities opened by the wireless local area networks (WLANs) that can be found today in a host of places, such as public libraries, coffee shops, trains, to name just a few? How can a youngster, who lives this true WLAN experience nowadays, imagine a world without it? This book dealswith the design oflinearCMOS RF PowerAmpli?ers(PAs). The RF PA is a very important part of the RF transceiver, the device that enables wireless communications. Two important aspects that are key to keep the advances in RF PA design at an accelerate pace are treated: ef?ciency enhancement and frequen- tunable capability. For this purpose, the design of two different integrated circuits realizedina0. 11μmtechnologyispresented,eachoneaddressingadifferentaspect. With respect to ef?ciency enhancement, the design of a dynamic supply RF power ampli?er is treated, making up the material of Chaps. 2 to 4.

Download or read book Envelope Amplifier Design for Wireless Base station Power Amplifiers written by Chin Hsia and published by . This book was released on 2010 with total page 128 pages. Available in PDF, EPUB and Kindle. Book excerpt: In order to deliver high data rates, modern wireless communication systems transmit complex modulated signals with high peak-to-average ratio, which demands wide bandwidth and stringent linearity performance for power amplifiers. To satisfy spectral mask regulations and achieve adequate error vector magnitude, power amplifiers typically operate at 6 to 10 dB back-off from the maximum output power, leading to low efficiency. To overcome the low efficiency problem, the envelope tracking power amplifier architecture has been proposed for this type of application due to its feature of high efficiency over a wide power range. The overall efficiency of an envelope tracking system relies not only on performance of the RF power amplifier but also on that of an envelope amplifier that provides a dynamically varying power supply voltage. This dissertation focuses on envelope amplifier design for efficiency enhancement of envelope tracking power amplifiers. First, the envelope tracking power amplifier architecture is analyzed, and the efficiency of a RF transistor in the envelope tracking technique is described. Then envelope amplifier behavior is investigated and a general purpose simulator is developed for analyzing and designing an envelope amplifier. Power loss and efficiency of the envelope amplifier is analyzed and compared with experimental results. The design of envelope amplifiers for high voltage (> 30 V) envelope tracking applications is described. A high voltage envelope amplifier is designed, implemented and verified. The overall envelope tracking system employing a GaN-HEMT RF transistor is demonstrated. Finally, a new architecture is developed for the efficiency enhancement of envelope amplifiers, using a digitally assisted controller design. Digital control is utilized to mitigate delay in the control loop inside the envelope amplifier, leading to lower overall power dissipation. A novel envelope amplifier architecture with dual-switcher stages based on the digitally-assisted control strategy is proposed, designed and implemented. The strategy is demonstrated to improve the efficiency of envelope amplifier as well as the system overall efficiency. The resulting performance of envelope tracking system employing a GaAs high voltage HBT with a single carrier W-CDMA input demonstrated state-of-the-art efficiency with good linearity performance.

Download or read book Fundamentals of RF and Microwave Transistor Amplifiers written by Inder Bahl and published by John Wiley & Sons. This book was released on 2009-06-17 with total page 696 pages. Available in PDF, EPUB and Kindle. Book excerpt: A Comprehensive and Up-to-Date Treatment of RF and Microwave Transistor Amplifiers This book provides state-of-the-art coverage of RF and microwave transistor amplifiers, including low-noise, narrowband, broadband, linear, high-power, high-efficiency, and high-voltage. Topics covered include modeling, analysis, design, packaging, and thermal and fabrication considerations. Through a unique integration of theory and practice, readers will learn to solve amplifier-related design problems ranging from matching networks to biasing and stability. More than 240 problems are included to help readers test their basic amplifier and circuit design skills-and more than half of the problems feature fully worked-out solutions. With an emphasis on theory, design, and everyday applications, this book is geared toward students, teachers, scientists, and practicing engineers who are interested in broadening their knowledge of RF and microwave transistor amplifier circuit design.

Download or read book Envelope Assisted RF Digital Predistortion for Broadband Radio over Fiber Systems with RF Power Amplifiers written by Weijie Tang and published by . This book was released on 2017 with total page 114 pages. Available in PDF, EPUB and Kindle. Book excerpt: Wireless communications play an extremely important role in our daily life. The ubiquitous cellphones and smartphones can provide not only voice service but also data service when they are connected to cellular network. With the enormous amount of mobile applications available to smartphones, people can listen to music, watch movies, check emails, update and share information on social media anytime and anywhere on their smartphones. All of these activities are possible because of the fast development of the wireless communication technology. Nowadays many people are enjoying the entertainments brought by 4G technology. In the meantime, companies and engineers in telecommunication industry have already been developing the 5G technology. To support the high data transmission rate of 4G or 5G technology, a complex and robust infrastructure is essential. Radio-over-Fiber (RoF) technology is a good solution to build such an infrastructure. RoF transmission can provide extremely high capacity with very low attenuation. Besides, RoF transmission system is much cheaper compared to the traditional way of transmission such as microwave coaxial cable or digital optical fiber transmission. However, like other analog systems, RoF system suffers from signal distortion induced by nonlinearities.RF power amplifier is needed to transmit the signal from a base station to the handsets because the attenuation of RF signal in the air is very high. Although many new types of RF power amplifiers have been designed to improve the power efficiency and the linearity, nonlinearity is still a big problem.To reduce the distortion of an RoF system, as well as that induced by an RF power amplifier, a new digital predistortion (DPD) technique, envelope-assisted RF digital predistortion, is presented in this thesis. This DPD model is evolved from the memory polynomial, and composed of an RF memory polynomial and a baseband memory polynomial. Therefore, this model takes both the RF signal and the baseband envelope as inputs to realize the digital predistortion. The RF polynomial is aimed to suppress the in-band nonlinearity, out-of-band nonlinearity and short-term memory effect, while the baseband polynomial is aimed to weaken the in-band nonlinearity and long-term memory effect. The indirect learning architecture is adopted and the least squares method is used to calculate the coefficients of the model. The validity of the proposed DPD has been proved by simulation and experiment. In the simulation system, an RoF model is built which can induce both short-term and long-term memory effects, as well as the in-band and out-of-band nonlinearities. The optimal RF and baseband memory depths of the proposed DPD adopted in the simulation system have been found in terms of error vector magnitude (EVM) improvement and complexity. After the establishment of the memory depths, three simulation cases have been run to evaluate the performance of the proposed DPD. The first case is a normal two-band test, where two 20 MHz LTE signals are located at 800 MHz and 900 MHz. Simulation results show that EVM is improved by 14.6 dB, adjacent channel power ratio (ACPR) is suppressed by 13.5 dB, and third order intermodulation distortion (IMD3) is weakened by 19.5 dB. In the second case, two LTE signals are closely located at 800 MHz and 840 MHz. Simulation results show that EVM is improved by 16.3 dB, ACPR is suppressed by 15.5 dB, and IMD3 is weakened by 27.5 dB. In the third case, three LTE signals are located at 800 MHz, 850 MHz and 900 MHz. EVM is improved by 15.7 dB, ACPR is suppressed by 15.2 dB and IMD3 is weakened by 14.1 dB. The performance of the proposed DPD has also been compared to that of a baseband 2D DPD. Comparison results show that 2D DPD is only better at improving the EVM and ACPR in the first case, and the proposed DPD is superior to the 2D DPD on all the other aspects. Especially, the proposed DPD is not limited by the number of signal bands, while the 2D DPD is limited to two-band scenarios.Experimentation has been conducted to further prove the effectiveness of the proposed DPD in a real RoF system. A similar test flow is adopted as in the simulation work. Firstly the optimal RF and baseband memory depths have been found. Then three test cases have been done. In the first case, EVM is improved by 6.9 dB, ACPR is suppressed by 14.8 dB, and IMD3 is weakened by 12.2 dB. In the second case, EVM is improved by 4.8 dB, ACPR is suppressed by 8.6 dB, and IMD3 is weakened by 9.5 dB. In the third case, EVM is improved by 8.9 dB, ACPR is suppressed by 16 dB, and IMD3 is weakened by 13.6 dB. Comparison with the 2D DPD shows the same result as in the simulation that the 2D DPD is only better at improving the EVM and ACPR in the first case. Influence of input power on EVM improvement has been studied. Experiment results show that the EVM improvement can be optimized at specific input power level. Sampling bandwidth has been reduced by down-converting the RF signal and sampling it at an intermediate frequency. Therefore, the implementation cost of the proposed DPD could be greatly reduced. In the two-band test, experiment results show that the performance of the proposed DPD with down conversion is even better than that of without down conversion. Influence of sampling bandwidth on EVM improvement has also been studied and the experiment results show that after down conversion, higher sampling bandwidth does not lead to significant EVM improvement.