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Design of Power Combining Amplifiers for Mobile CommunicationsZhao, Jinshu 04 June 2024 (has links)
This work explores the application of various power amplifier design techniques for mobile communications. Several circuit configurations including class A amplifier, Doherty amplifier and power combining amplifier have been developed, which are to improve the performance of power amplifiers in terms of power added efficiency transmission power and bandwidth.
In chapter 2, the cascode PA adopting tuning capacitor structure is proposed and implemented to enhance the efficiency. In chapter 3, a novel Doherty amplifier configuration using a 3-stage polyphase filter as power splitter is introduced. Moreover, the second harmonic cancellation function of balun combining PA is analysed and verified with experimental results in chapter 4.
The fully integrated cascode class A amplifier adopts RC negative feedback, which is to enhance bandwidth and input/output matching. The integrated choke inductor compensating the parasitic capacitor of transistors has very low quality factor, which decreases the efficiency of the power amplifier. To reduce the inductance value of the choke inductor, a tuning capacitor is connected in parallel with the choke inductor. As a result, the inductor resistance is reduced as well, which diminishes the power consumption induced by the resistance of the choke inductor. This proposed PA configuration is validated by simulation results with the PAE improved by 3 % at the 1 dB compression point compared to the topology without tuning capacitor. The experimental results demonstrate a PA which delivers an output power of 21.3 dBm with PAE of 21 % at the 1 dB compression point.
The Doherty amplifier with 2-way Wilkinson power splitter is integrated in a 0.9 mm×1.8 mm chip. The main and peak amplifier adopt cascode configuration to improve the stability of the Doherty amplifier. To minimize the chip size, the quarter wave transmission line in the topology is replaced by π-type lumped element equivalent network.
To increase the operating bandwidth, the Doherty amplifier configuration using a 3-stage polyphase filter as power splitter is proposed. The topology consists of 3-stage RC polyphase filter, drive amplifiers, main amplifier, peak amplifier, and impedance inverter. By employing the polyphase filter, the quarter-wave transmission line at the input of the peak amplifier for compensating the phase shift of the impedance inverter is eliminated. According to the analysis of the polyphase filter prototype, the 3-stage polyphase filter is selected, and the component parameters are determined. The main amplifier and peak amplifier are using differential cascode configuration. The drive amplifier is to increase the power gain and provide proper impedance matching for the Doherty amplifier. The results demonstrate an outstanding broadband Doherty amplifier with a bandwidth of 1.8 GHz.
The chip temperature rises dramatically due to the high power consumption of power amplifier. Consequently, the collector currents of the SiGe transistors are varying with the changing temperature, which deteriorates the PA performance. In the improved 3-stage PPF Doherty design, the bias voltages of the transistors in the first version 3-stage PPF Doherty amplifier are replaced by reference currents feeding through bias circuits. With current sources providing bias current to the transistors, the performance of the improved Doherty amplifier is enhanced.
The power combining PAs are constructed on FR-4 PCB boards using discrete components. The single ended power amplifier in the power combining PA is built with high linearity HEMT transistor. The balun combining PA has an advantage of second harmonic cancellation, which is validated by both analysis and measurements. Moreover, power combining PAs with 2-way transmission line and lumped element Wilkinson power divider are designed. The transmission lines in these designs are analyzed using EM simulation tool and verified with testing structures on PCB boards.
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Gate Bias Control and Harmonic Load Modulation for a Doherty AmplifierSmith, Karla Jenny Isabella January 2009 (has links)
Linearity and efficiency are both critical parameters for radio frequency transmitter applications. In theory, a Doherty amplifier is a linear amplifier that is significantly more efficient than comparable conventional linear amplifiers. It comprises two amplifiers, connected at their outputs by a quarter-wave transformer. The main amplifier is always on, while the peaking amplifier is off during low power levels. Load modulation of the main amplifier occurs when the peaking amplifier is on due to the quarter-wave transformer, ensuring the main amplifier never enters saturation. This results in an efficiency characteristic that increases with respect to input power at twice the normal rate at low power levels, and plateaus to a high value at high power levels. However, in much of the research that has been done to-date, less-than-ideal results have been achieved (although efficiency was better than a conventional amplifier). It was decided to investigate the cause of the discrepancy between theoretical and practical results, and devise a method to counteract the problem.
It was discovered that the main cause of the discrepancy was non-ideal transistor gate-voltage to drain-current characteristics. The implementation of a gate bias control scheme based upon measured transistor transfer characteristics, and the desired main and peaking amplifier output currents, resulted in a robust method to ensure near-ideal results. A prototype amplifier was constructed to test the control scheme, and theoretical, simulated and measured results were well matched. The amplifier had a region of high efficiency in the high power levels (over 34% for the last 6 dB of input power), and the gain was nearly constant with respect to input power (between 4 and 5 dB over the dynamic range).
Furthermore, it was decided to investigate the role harmonics play within the Doherty amplifier. A classical implementation shunts unwanted harmonics to ground within the main and peaking amplifiers. However, odd harmonics generated by the peaking amplifier can be used to operate the main amplifier like a class F amplifier. This means its supply voltage can be lowered, without the amplifier entering saturation, and the efficiency of the Doherty amplifier can be increased without a detrimental effect on the its linearity. A prototype amplifier was constructed to test this theory, and gave good results, with better efficiency than that of a conventional amplifier, and a constant gain with respect to input power (between 6.4 dB and 6.5 dB over the dynamic range).
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A Doherty Power Amplifier with Extended Bandwidth and Reconfigurable Back-off LevelWu, Yu-Ting David 03 1900 (has links)
Emerging wireless standards are designed to be spectrally efficient to address the high cost of licensing wireless spectra. Unfortunately, the resulting signals have a high peak-to-average ratio that reduces the base station power amplifier efficiency at the back-off power level. The wasted energy is converted to heat that degrades the device reliability and increases the base-station’s carbon footprint and cooling requirements. In addition, these new standards place stringent re- quirements on the amplifier output power, linearity, efficiency, and bandwidth.
To improve the back-off efficiency, a Doherty amplifier, which uses two device in parallel for back-off efficiency enhancement, is deployed in a typical base station. Unfortunately, the conventional Doherty amplifier is narrowband and thus cannot satisfy the bandwidth requirement of the modern base station that needs to support multiple standards and backward compatibility.
In this thesis, we begin by studying the class F/F−1 high efficiency mode of operation. To this end, we designed a narrowband, harmonically-tuned 3.3 GHz, 10 W GaN high efficiency amplifier. Next, we investigate how to simultaneously achieve high efficiency and broad bandwidth by harnessing the simplified real frequency technique for the broadband matching network design. A 2 to 3 GHz, 45 W GaN amplifier and a 650 to 1050 MHz, 45 W LDMOS amplifier were designed. Finally, we analyze the conventional Doherty amplifier to determine the cause of its narrow bandwidth. We find that the narrow bandwidth can be attributed to the band-limited quarter-wave transformer as well as the widely adopted traditional design technique.
As an original contribution to knowledge, we propose a novel Doherty amplifier configuration with intrinsically broadband characteristics by analyzing the load modulation concept and the conventional Doherty amplifier. The proposed amplifier uses asymmetrical drain voltage biases and symmetrical devices and it does not require a complex mixed-signal setup. To demonstrate the proposed concept in practice, we designed a 700 to 1000 MHz, 90 W GaN broadband Doherty amplifier. Moreover, to show that the proposed concept is applicable to high power designs, we designed a 200 W GaN broadband Doherty amplifier in the same band. In addition, to show that the technique is independent of the device technology, we designed a 700 to 900 MHz, 60 W LDMOS broadband Doherty amplifier. Using digital pre-distortion, the three prototypes were shown to be highly linearizable when driven with wideband 20 MHz LTE and WCDMA modulated signals and achieved excellent back-off efficiency.
Lastly, using the insights from the previous analyses, we propose a novel mixed-technology Doherty amplifier with an extended and reconfigurable back-off level as well as an improved power utilization factor. The reconfigurability of the proposed amplifier makes it possible to customize the back-off level to achieve the highest average efficiency for a given modulated signal without redesigning the matching networks. A 790 to 960 MHz, 180 W LDMOS/GaN Doherty amplifier demonstrated the extended bandwidth and reconfigurability of the back-off level. The proposed amplifier addresses the shortcomings of the conventional Doherty amplifier and satisfies the many requirements of a modern base station power amplifier.
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A Doherty Power Amplifier with Extended Bandwidth and Reconfigurable Back-off LevelWu, Yu-Ting David 03 1900 (has links)
Emerging wireless standards are designed to be spectrally efficient to address the high cost of licensing wireless spectra. Unfortunately, the resulting signals have a high peak-to-average ratio that reduces the base station power amplifier efficiency at the back-off power level. The wasted energy is converted to heat that degrades the device reliability and increases the base-station’s carbon footprint and cooling requirements. In addition, these new standards place stringent re- quirements on the amplifier output power, linearity, efficiency, and bandwidth.
To improve the back-off efficiency, a Doherty amplifier, which uses two device in parallel for back-off efficiency enhancement, is deployed in a typical base station. Unfortunately, the conventional Doherty amplifier is narrowband and thus cannot satisfy the bandwidth requirement of the modern base station that needs to support multiple standards and backward compatibility.
In this thesis, we begin by studying the class F/F−1 high efficiency mode of operation. To this end, we designed a narrowband, harmonically-tuned 3.3 GHz, 10 W GaN high efficiency amplifier. Next, we investigate how to simultaneously achieve high efficiency and broad bandwidth by harnessing the simplified real frequency technique for the broadband matching network design. A 2 to 3 GHz, 45 W GaN amplifier and a 650 to 1050 MHz, 45 W LDMOS amplifier were designed. Finally, we analyze the conventional Doherty amplifier to determine the cause of its narrow bandwidth. We find that the narrow bandwidth can be attributed to the band-limited quarter-wave transformer as well as the widely adopted traditional design technique.
As an original contribution to knowledge, we propose a novel Doherty amplifier configuration with intrinsically broadband characteristics by analyzing the load modulation concept and the conventional Doherty amplifier. The proposed amplifier uses asymmetrical drain voltage biases and symmetrical devices and it does not require a complex mixed-signal setup. To demonstrate the proposed concept in practice, we designed a 700 to 1000 MHz, 90 W GaN broadband Doherty amplifier. Moreover, to show that the proposed concept is applicable to high power designs, we designed a 200 W GaN broadband Doherty amplifier in the same band. In addition, to show that the technique is independent of the device technology, we designed a 700 to 900 MHz, 60 W LDMOS broadband Doherty amplifier. Using digital pre-distortion, the three prototypes were shown to be highly linearizable when driven with wideband 20 MHz LTE and WCDMA modulated signals and achieved excellent back-off efficiency.
Lastly, using the insights from the previous analyses, we propose a novel mixed-technology Doherty amplifier with an extended and reconfigurable back-off level as well as an improved power utilization factor. The reconfigurability of the proposed amplifier makes it possible to customize the back-off level to achieve the highest average efficiency for a given modulated signal without redesigning the matching networks. A 790 to 960 MHz, 180 W LDMOS/GaN Doherty amplifier demonstrated the extended bandwidth and reconfigurability of the back-off level. The proposed amplifier addresses the shortcomings of the conventional Doherty amplifier and satisfies the many requirements of a modern base station power amplifier.
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Etude et Conception d’amplificateurs DOHERTY GaN en technologie Quasi - MMIC en bande C / Study and conception of GaN Doherty amplifiers in Quasi - MMIC technology on C bandAyad, Mohammed 30 June 2017 (has links)
Ce travail répond à un besoin industriel accru en termes d’amplification des signaux sur porteuses à enveloppes variables utilisés par les systèmes de télécommunications actuels. Ces signaux disposent d’un fort PAPR et d’une distribution statistique d’enveloppe centrée en-deçà de la valeur crête d’enveloppe. La raison pour laquelle les industriels télécoms requièrent alors des amplificateurs de très fortes puissances de sortie, robustes, fiables et ayant une dépense énergétique optimale le long de la dynamique d’enveloppe associée à un niveau de linéarité acceptable. Ce document expose les résultats d’étude et de réalisation de deux Amplificateurs de Puissance Doherty (APD) à haut rendement encapsulés en boîtiers plastiques QFN. Le premier est un amplificateur Doherty symétrique classique (APD-SE) et le second est un amplificateur à deux entrées RF (APD-DE). Ces démonstrateurs fonctionnant en bande C sont fondés sur l’utilisation de la technologie Quasi-MMIC associant des barrettes de puissance à base des transistors HEMTs AlGaN/GaN sur SiC à des circuits d’adaptation en technologie ULRC. L’approche Quasi-MMIC associée à la solution d’encapsulation plastique QFN permettant une meilleure gestion des comportements thermiques offre des performances électriques similaires à celles de la technologie MMIC avec des coûts et des cycles de fabrication très attractifs. Durant ces travaux, une nouvelle méthode d’évaluation des transistors dédiés à la conception d’amplificateurs Doherty a été développée et mise en oeuvre. L’utilisation intensive des simulations électromagnétiques 2.5D et 3D a permis de bien prendre en compte les effets de couplages entre les différents circuits dans l’environnement du boîtier QFN. Les résultats des tests des amplificateurs réalisés fonctionnant sur une bande de 1GHz ont permis de valider la méthode de conception et ont montré que les concepts avancés associés à l’approche Quasi-MMIC ainsi qu’à des technologies d’encapsulation plastique, peuvent générer des fonctions micro-ondes innovantes. Les caractérisations de l’APD-DE ont relevé l’intérêt inhérent à la préformation des signaux d’excitation et des points de polarisation de chaque étage de l’amplificateur. / This work responds to an increased industrial need for on carrier signals with variable envelope amplification used by current telecommunications systems. These signals have a strong PAPR and an envelope statistical distribution centred below the envelope peak value, the reason why the telecom industrialists then require a robust and reliable high power amplifiers having an energy expenditure along of the envelope dynamics associated with an acceptable level of linearity. This document presents the results of the study and realization of two, high efficiency, Doherty Power Amplifiers (DPA) encapsulated in QFN plastic packages. The first is a conventional Doherty power Amplifier (DPA-SE) and the second is a dual-input Doherty power amplifier (DPA-DE). These C-band demonstrators are based on the use of Quasi-MMIC technology combining power bars based on the AlGaN/GaN transistors on SiC to matching circuits in ULRC technology. The Quasi-MMIC approach combined with Quasi-MMIC approach combined with QFN plastic package solution for better thermal behaviour management offers electrical performances similar to those of MMIC technology with very attractive coasts and manufacturing cycles. During this work, a new evaluation method for the transistors dedicated to the design of DPA was developed and implemented. The intensive use of 2.5D and 3D electromagnetic simulations made it possible to take into account the coupling effects existing between the different circuits in the QFN package environment. The results of the tests of the amplifiers realised and operating on 1GHz bandwidth validated the design method and showed that the advanced concepts associated with the Quasi-MMIC approach as well as plastic encapsulation technologies can generate innovative microwave functions. The characterizations of the DPA-DE have noted the interest inherent in the preformation of the excitation signals and the bias points of each stage of the amplifier.
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Design of a Broadband Doherty Power Amplifier with a Graphical User Interface ToolGong, Pingzhu 27 October 2022 (has links)
No description available.
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Advanced Power Amplifiers Design for Modern Wireless CommunicationShao, Jin 08 1900 (has links)
Modern wireless communication systems use spectrally efficient modulation schemes to reach high data rate transmission. These schemes are generally involved with signals with high peak-to-average power ratio (PAPR). Moreover, the development of next generation wireless communication systems requires the power amplifiers to operate over a wide frequency band or multiple frequency bands to support different applications. These wide-band and multi-band solutions will lead to reductions in both the size and cost of the whole system. This dissertation presents several advanced power amplifier solutions to provide wide-band and multi-band operations with efficiency improvement at power back-offs.
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Leistungsverstärker für den Einsatz in energiesparsamer Informations- und KommunikationstechnikSeidel, Andres 23 October 2023 (has links)
Thematisch eingebettet in das Forschungsgebiet der energiesparsamen Informations- und Kommunikationstechnik (IKT), beschäftigt sich diese Dissertation mit dem Entwurf und der Analyse von Leistungsverstärkern (LV) für drahtlose Übertragungssysteme. Die Arbeit konzentriert sich einerseits auf den asymmetrischen Doherty-Leistungsverstärker (DPA), welcher in einem Ausgangsleistungs-Backoff (OBO) von mehr als 6 dB einen zusätzlichen Ef fizienzhochpunkt aufweist. Andererseits wird die Topologie des geschalteten inversen Klasse-E Verstärkers beleuchtet, der sich durch einen theoretischen Wirkungsgrad von 100 % auszeichnet und daher für den Einsatz in energiesparsamer IKT von besonderem Interesse ist.
Das Breitbandverhalten des DPA wird zur Optimierung der Leistungseffizienz (PAE) theoretisch analysiert. Hierbei wird der Einfluss der charakteristischen Impedanz des Impedanzinverters (IT) im Main-Pfad untersucht. Daran anknüpfend werden drei asymmetrische Sub-6 GHz DPA mit unterschiedlichen IT entworfen. Labormessung ergeben eine maximale PAE zwischen 52 % und 63 % bei einer Ausgangsleistung von 41 dBm bis 42 dBm, was für einen derartigen LV mit einer Mittenfrequenz oberhalb von 3 GHz den höchsten Wert im Vergleich zum Stand der Technik darstellt. Neben diesem diskreten Aufbau werden zwei weitere integrierte asymmetrische DPA-Designs in Galliumnitrid (GaN) bzw. Siliziumgermanium (SiGe) vorgestellt. Für den GaN-DPA mit Chebyshev-Anpassnetzwerk wird in der Messung eine abweichende Phasenlage zwischen Peak- und Main-Pfad detektiert, die nachträglich durch Bonddrahtmodifikation auf dem Chip verbessert wird.
Der Schaltkreis erreicht eine hohe PAE im OBO von 34 % bis 54 %. Der dritte Entwurf untersucht einen zweistufigen asymmetrischen DPA in SiGe, der auf einer Analyse des WLAN-Standards bei 60 GHz basiert. Diese Analyse ergibt ein Verhältnis von maximaler zu mittlerer Ausgangsleistung (PAPR) von 8 dB. Der LV erreicht im Frequenzbereich von 59 GHz bis 67 GHz den vergleichsweise höchsten Leistungsgewinn von 22 dB.
Die inverse Klasse-E Topologie wird als Ausgangsstufe in einem polaren Vektormodulator mit niedriger Versorgungsspannung verwendet. Eine theoretische Analyse der Topologie zeigt, dass die für einen effizienten Betrieb erforderlichen Induktivitäten geringer sind als beim klassischen Klasse-E Verstärker. Der daraus resultierende geringere Bedarf an Chipfläche macht diese Topologie besonders für stark skalierte CMOS-Prozesse interessant. Es werden zwei integrierte Schaltkreise (IC) in 45 nm bzw. 22 nm CMOS entworfen. Das Prinzip des Vektormodulators wird mit dem in 45 nm gefertigten IC getestet. Zur Steigerung der Ausgangsleistung auf bis zu 19,3 dBm wird die Topologie in eine neuartige inverse Klasse-E Gegentaktstufe überführt. Die kompakte Schaltung zeichnet sich durch eine hohe relative Bandbreite von 70,5 % aus. Neben den rein schaltungstechnischen Inhalten der Arbeit wird in einer kollaborativen Studie das Reduktionspotential von Treibhausgasemissionen durch IKT untersucht. Ziel ist der interdisziplinäre Brückenschlag zwischen Umwelt- und Ingenieurwissenschaften, um die ganzheitliche Sichtweise auf das Thema energieeffizienter IKT zu erweitern. Am Beispiel deutscher Konferenzreisen für das Jahr 2030 wird anhand einer Szenarioanalyse gezeigt, dass die deutschen CO2-Emissionen durch den Einsatz neuartiger 2D/3D-Videokonferenzsysteme jährlich um bis zu 20, 51 MtCO2e gesenkt werden könnten. Dies entspräche rund 2,7 % der gesamtdeutschen Emissionen. In diesem Teil der Arbeit werden mögliche Chancen des IKT-Beitrags zur Erreichung der Klimaziele deutlich. Unklar bleibt allerdings, ob es zu Rebound-Effekten kommt und wie Ressourcenbedarf und Recycling der Technologie in Zukunft nachhaltig gestaltet werden können.
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Optimum Design of Doherty RFPA for Mobile WiMAX Base StationsGhazaany, Tahereh S., Abd-Alhameed, Raed, Child, Mark B., Ali, N.T., Rodriguez, Jonathan, Hussaini, Abubakar S. 09 June 2010 (has links)
Yes / RF power amplifiers in mobile WiMAX transceivers operate in an inherently nonlinear manner. It is possible to amplify the signal in the linear region, and avoid distortion, using output power back-off; however, this approach may suffer significant reduction in efficiency and power output. This paper investigates the use of Doherty techniques instead of back-off, to simultaneously achieve good efficiency and acceptable linearity. A 3.5 GHz Doherty RFPA has been designed and optimized using a large signal model simulation of the active device, and performance analysis under different drive levels. However, the Doherty EVM is generally poor for mobile WiMAX. Linearity may be improved by further digital pre-distortion, and a simple pre-distortion method using forward and reverse AM-AM and AM-PM modeling. Measurements on the realized amplifier show that this approach satisfies the EVM requirements for WiMAX base stations. It exhibits a PAE over 60%, and increases the maximum linear output power to 43 dBm, whilst improving the EVM.
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DESIGN OF CLASS F-BASED DOHERTY POWER AMPLIFIER FOR S-BAND APPLICATIONSChang, Kyle 01 June 2023 (has links) (PDF)
Modern RF and millimeter-wave communication links call for high-efficiency front end systems with high output power and high linearity to meet minimum transmission requirements. Advanced modulation techniques, such as orthogonal frequency-division multiplexing (OFDM) require a large power amplifier (PA) dynamic range due to the high peak-to-average power ratio (PAPR). This thesis provides the analysis, design, and experimental verification of a high-efficiency, high-linearity S-band Doherty power amplifier (DPA) based on the Class F PA. Traditional Class F PAs use harmonically tuned output matching networks to obtain up to 88.4% power-added efficiency (PAE) theoretically, however the amplifier experiences poor linearity performance due to switched mode operation, typically yielding less than 30dB C/I ratio [1]. The DPA overcomes this linearity limitation by using an auxiliary amplifier to boost output power when the amplifier is subject to a high input power due to its limited conduction cycle. The DPA also provides improved saturated output power back-off performance to maintain high PAE during operation.
The DPA presented in this thesis optimizes PAE while maintaining linearity by employing harmonically tuned Class F amplifier topology on a primary and an auxiliary amplifier. A Class F PA is first designed and fabricated to optimize output network linearity – this is followed by a DPA design based on the fabricated Class F PA. A GaN HEMT Class F PA and DPA operating at 2.2GHz are implemented with the PAs measuring 40% and 45% PAE respectively while maintaining a 30dB carrier-to-intermodulation (C/I) ratio on a two-tone test. The PAE is characterized at maximum 21dBm input power per tone and 20MHz tone spacing. When subject to a single 24dBm continuous wave input tone, the Class F PA and DPA output 37dBm and 35.5dBm respectively. The PAs presented in the thesis provide over 30dB C/I ratio up to 21dBm input tones while maintaining over 40% PAE suitable for base station applications.
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