High-Throughput Signal Component Separator for Asymmetric Multi-Level Outphasing Power

Abstract—This paper presents an energy-efficient highthroughput and high-precision signal component separator (SCS) chip design for the asymmetric-multilevel-outphasing (AMO) power amplifier. It uses a fixed-point piece-wise linearfunctional approximation developed to improve the hardware efficiency of the outphasing signal processing functions. The chip is fabricated in 45 nm SOI CMOS process and the SCS consumes an active area of 1.5 mm. The new algorithm enables the SCS to run at a throughput of 3.4 GSamples/s producing the phases with 12-bit accuracy. Compared to traditional low-throughput AMO SCS implementations, at 0.8 GSamples/s this design improves the area efficiency by 25 and the energy-efficiency by 2.Thisfastest high-precision SCS to date enables a new class of high-throughput mm-wave and base station transmitters that can operate at high area, energy and spectral efficiency. Index Terms—Application specific integrated circuits (ASIC), asymmetric multi-level outphasing (AMO) power amplifier, baseband, energy efficiency, linear amplification by nonlinear component (LINC), Signal component separator (SCS), throughput. I

Linearity of Outphasing Radio Transmitters

The outphasing transmitter is a promising technique, which can simultaneously achieve high linearity and power efficiency, thereby addressing the major design requirements of next generation transmitters. It employs highly non-linear power amplifier (PA) classes in a linear manner, in principle transmitting a distortion-free signal. Due to symmetric nature of the outphasing architecture, its linearity performance is constrained by any mismatches and non-linear effects encountered in the RF paths. This thesis analyzes the linearity performance of outphasing transmitters (in terms of ACLR specification) for LTE base station applications, under the non-linear effects and tolerances present in practical implementations. The system-level model, built in Matlab software, investigates the important non-linear effects present in outphasing transmitters, including gain and phase imbalance, IQ modulator mismatches, delay imbalance, and the non-linear effects of PAs and Chireix combiners. The path and delay mismatches result in only partial cancellation of the wideband quadrature signal, and thus create interference in both the in-band and out-of-band frequency regions. The misalignment in IQ modulators, such as gain/phase imbalance and carrier leakage, introduces amplitude and phase modulation in the outphased signals. The quadrature modulator mismatches, in conjunction with amplifier nonlinearity, result in spectral regrowth around the carrier frequency. The transmitter linearity performance is also affected by mismatches in the non-linear characteristics of the PAs. Realistic square-wave signals, exhibiting finite rise- and fall- time, also create spectral leakage for distinct rise/fall times in each outphasing branch. Furthermore, the Chireix combiner severely degrades the linearity of outphasing transmitters; it produces ACLR well below the specified limit for LTE base stations. This makes mandatory the compensation of Chireix combiner induced non-linearity in outphasing transmitters. The strict linearity requirements (for LTE downlink applications) present a small tolerance window for mismatches experienced in practical circuits. The relatively small tolerance margin indicates the need of linearization and compensation techniques in outphasing transmitters

Optimization Of 5.7 Ghz Class E Power Amplifier For The Application Of Envelope Elimination And Restoration

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2007Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2007Rekabetin yoğun olduğu günümüzde tasarımcılar hafif, boyutları daha küçük ve düşük güçle çalışan yüksek performanslı ürün geliştirmenin yollarını aramaktadırlar. RF alıcı uygulamalarında güç kuvvetlendiricileri en fazla güç sarfiyatının olduğu bölümdür. Kablosuz iletişim sistemlerinde güç küvvetlendiricisi verimi maliyeti direkt olarak etkilemektedir. Teorik olarak %100 verim elde edilebilen E-sınıfı güç kuvvetlendiricileri transistorların açık/kapalı durum geçişlerinde güç sarfiyatını minimize edebilmektedir. Ayrıca çıkış gerilimi kaynak gerilimi ile doğrusal değişmektedir. Bu çalışmada E sınıfı güç kuvvetlendiricilerinin tasarım metodları ele alınmıştır. 5.7 GHz de çalışan birinde toplu devre elemanları, diğerinde transmisyon hattı elemanları kullanımış E sınıfı güç kuvvetlendiricileri tasarlanmıştır. Her iki devrede de %50 güç ekli verim (GEV) ve 500mW çıkış gücü elde edilmiştir. Sinyaldeki bozulmayı azaltmak için başvurulan doğrusallaştırma yöntemi Zarf Yoketme ve Tekrar Oluşturma metodudur. E sınıfı kuvvetlendiricinin Zarf Yoketme ve Tekrar Oluşturma yöntemi kullanılarak doğrusallaştırılmasıyla IMD bileşenlerinde 7.5 dB azalmış olup seviyesi gerçek işaretin 20dB altındadır.In today’s competitive, manufactures and product developers are seeking ways to build high performance devices that are lighter in weight, smaller in size and operating at lower power. In transceiver applications one module is responsible for a large portion of the power consumption - the power amplifier. The efficiency of the power amplifier has a direct impact on the cost of the wireless communication system. The class-E amplifier has a maximum theoretical efficiency of 100%. Class E power amplifiers have the ability to minimize power loss during on/off transitions of the transistor. Also, the output voltage varies linearly with the supply voltage. This thesis describes the design and the linearization methodology of the Class E amplifiers. Two class-E amplifiers operating at 5.7 GHz are presented. One of them is a lumped elements based circuit and the other is a transmission lines based circuit. Both circuit show good performance with 50% PAE and have 500mW output power. Envelope elimination and restoration is the linearization method chosen to achieve reduction of signal distortion. Linearization Class E PA using EER system provides an additional 7.5 dB reduction in intermodulation distortion products, achieving a minimum distortion level of 20 dB below the fundamental signals.Yüksek LisansM.Sc

Theory and Implementation of RF-Input Outphasing Power Amplification

Conventional outphasing power amplifier systems require both a radio frequency (RF) carrier input and a separate baseband input to synthesize a modulated RF output. This work presents an RF-input/RF-output outphasing power amplifier that directly amplifies a modulated RF input, eliminating the need for multiple costly IQ modulators and baseband signal component separation as in previous outphasing systems. An RF signal decomposition network directly synthesizes the phase- and amplitude-modulated signals used to drive the branch power amplifiers (PAs). With this approach, a modulated RF signal including zero-crossings can be applied to the single RF input port of the outphasing RF amplifier system. The proposed technique is demonstrated at 2.14 GHz in a four-way lossless outphasing amplifier with transmission-line power combiner. The RF decomposition network is implemented using a transmission-line resistance compression network with nonlinear loads designed to provide the necessary amplitude and phase decomposition. The resulting proof-of-concept outphasing power amplifier has a peak CW output power of 93 W, peak drain efficiency of 70%, and performance on par with a previously-demonstrated outphasing and power combining system requiring four IQ modulators and a digital signal component separator

Phase manipulation for efficient radio frequency transmission

Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2012.Cataloged from PDF version of thesis.Includes bibliographical references (p. 109-112).Power amplifiers (PAs) for microwave communications are generally the most power-hungry element of a transmitter. High linearity is required for modern digital communications standards, and often is achieved at the expense of efficiency. Outphasing architectures, which combine multiple nonlinear but efficient switching PAs into a system with an overall linear response, represent a promising strategy for breaking the efficiency/linearity tradeoff inherent to conventional PAs. This work explores methods for efficient PA design using outphasing techniques. Two aspects of outphasing design are considered. First, a wide-band phase modulator is introduced that uses a single current-steering digital to analog converter (DAC) structure and discrete clock prerotation. This topology takes advantage of specifications particular to outphasing architectures to reduce matching requirements as compared to a two-DAC phase modulator while providing wideband capability. The phase modulator is demonstrated in 65-nm CMOS, operates over a carrier frequency range of 1.2-4.2 GHz and has a 12-bit phase resolution and sample rate of 160 MSamples/second. The second technique is a novel four-way lossless power combiner and outphasing system which provides ideally lossless power combining along with resistive loading of switching power amplifiers over a wide output range. This work presents the first-ever demonstration of this system at microwave frequencies. Particular attention is paid to the microwave-specific aspects of implementation. A 60-W GaN prototype demonstrates the outphasing and dynamic performance, which closely matches the expected performance despite the challenges of operating at microwave frequencies.by Taylor Wallis Barton.Sc.D

An Octave-Range, Watt-Level, Fully-Integrated CMOS Switching Power Mixer Array for Linearization and Back-Off-Efficiency Improvement

The power mixer array is presented as a novel power generation approach for non-constant envelope signals. It comprises several power mixer units that are dynamically turned on and off to improve the linearity and back-off efficiency. At the circuit level, the power mixer unit can operate as a switching amplifier to achieve high peak power efficiency. Additional circuit level linearization and back-off efficiency improvement techniques are also proposed. To demonstrate the feasibility of this idea, a fully-integrated octave-range CMOS power mixer array is implemented in a 130 nm CMOS process. It is operational between 1.2 GHz and 2.4 GHz and can generate an output power of +31.3 dBm into an external 50 Ω load with a PAE of 42% and a gain compression of only 0.4 dB at 1.8 GHz. It achieves a PAE of 25%, at an average output power of +26.4 dBm, and an EVM of 4.6% with a non-constant-envelope 16 QAM signal. It can also produce arbitrary signal levels down to -70 dBm of output power with the 16 QAM-modulated signal without any RF gain control circuit

Design and Construction of a Liquid-Cooled Solid-State Digital Television Transmitter

With the advent of terrestrial digital broadcasting, new and improved digital transmitter technologies are required since existing analog transmitter technology is, for the most part, unable to adequately transmit a decodable digital television signal. This study focuses on the design and construction of a solid-state, liquid-cooled UHF digital television transmitter. Emphasis is placed on the design of the amplifier module including the amplifier card, Wilkinson splitter and combiner, input and output matching circuits, DC bias network and the system mask filter. The results of this research are also presented for two television transmitters that are installed and continue to be in use today, including analyses of specific failures that have occurred while in the field. The overall objective of this study is not only to document the research that is behind the design of this system, but also to document the construction of the transmitter for reference in system maintenance and repair as well as a basis for future design

Design and Construction of a Liquid-Cooled Solid-State Digital Television Transmitter

With the advent of terrestrial digital broadcasting, new and improved digital transmitter technologies are required since existing analog transmitter technology is, for the most part, unable to adequately transmit a decodable digital television signal. This study focuses on the design and construction of a solid-state, liquid-cooled UHF digital television transmitter. Emphasis is placed on the design of the amplifier module including the amplifier card, Wilkinson splitter and combiner, input and output matching circuits, DC bias network and the system mask filter. The results of this research are also presented for two television transmitters that are installed and continue to be in use today, including analyses of specific failures that have occurred while in the field. The overall objective of this study is not only to document the research that is behind the design of this system, but also to document the construction of the transmitter for reference in system maintenance and repair as well as a basis for future design