SWITCH MODE RF POWER AMPLIFIER DESIGN, ANALYSIS AND IMPLEMENTATION

With the high interest in digital modulation techniques which are very sensitive to the PA nonlinearity, modern wireless communication systems require the usage of linearization techniques to improve the linear behavior of the RF power amplifier. The powerful and cheap digital processing technology makes the digital predistortion (DPD) a competitive candidate for the linearization of the PA. This thesis introduces the basic principle of DPD, its implementation on FPGA and the adaptive DPD system. The linearization of 4 PAs with DPD technique has been introduced: for the hybrid class AB PA operating at 2.6 GHz with a WiMAX testing signal, 33.7 dBm average power, 29.6 % drain efficiency, 13 dB ACPR and 9 dB NMSE improvement have been obtained; for the hybrid Doherty PA operating at 3.4 GHz with an I/Q testing signal, 35.0 dBm average power, 36.8 % drain efficiency, 12 dB ACPR and 13 dB NMSE improvement have been obtained; for the MMIC class AB PA operating at 7 GHz with an I/Q testing signal, 29.4 dBm average power, 25.7 % drain efficiency, 12 dB ACPR and 12 dB NMSE improvement have been obtained; for the two-stage PA operating at 24 GHz with an I/Q testing signal, 23.5 dBm average power, more than 14.0 % drain efficiency, 11 dB ACPR and 11 dB NMSE improvement have been obtained. The DPD algorithm has been implemented on FPGA with two methods based on LUT and a direct structure with only adders and multipliers. The block RAM on the FPGA board is chosen as the table in the LUT methods. The linearization performance for these three methods is similar. The test PA is the hybrid Doherty PA mentioned above and the test signal is the I/Q signal with 7.4 dB PAPR. 35.1 dBm average power, 36.8 % efficiency, 11 dB ACPR and 11 dB NMSE improvement have been obtained. The cost of logic resources for the direct structure method is the largest with 1,172 flip-flops, while the number of flip-flops for the two LUT methods are 263 and 583, respectively. A new adaptive algorithm has been proposed in this thesis for the adaptive DPD system. This new algorithm improves the performance in extracting the model parameters in complex number domain. With the experimental data from a combined class AB PA, the final accuracy of the model extracted by the new algorithm has been improved from -20 dB to about -40 dB and the converge speed is faster

This bachelor thesis covers the realization and thermal properties optimization of a broadband radio frequency power amplifier in the Reader of Radio Frequency Identification applications in the Super High Frequency band from 5.725 to 5.875 GHz. Based on the preceding internship at the Fraunhofer Institute for Microelectronic Circuits and Systems, a number of different designs are developed in simulation to improve the thermal properties from some cost-effective aspects. Furthermore, some designs with the area of 4 cmx4 cm are selected for production and verification. Through measurement, their electrical characteristics and thermal properties are compared and evaluated respectively. Through the thermal simulation results and measurement results, it can be concluded that the AC ground and DC ground on the PCB of the RF-power amplifier have a great influence on the electrical characteristics and thermal properties. When AC ground and DC ground are separated from each other, the gain and impedance matching of transmission line is good. However, the heat on the PCB cannot be conducted well in the practical application, so the temperature of the chip might be too high, thereby degrading the electrical characteristics of the chip or even damaging the chip. On the contrary, the electrical characteristics of the PCB are slightly worse, while the thermal characteristics are greatly improved. Therefore, the design requirements need to be specifically considered in practice. In addition, increasing the density of the vias (reducing the via-to-via spacing) around the chip or reducing the thickness of the PCB can slightly improve the electrical characteristics and thermal properties of the PCB. Based on the consistency of the measurement results and the simulation results, it can be inferred that if the area is increased, the thermal performance will be significantly improved. Therefore, in the practical application, if the front end of the RFID reader has more space left for the RF-power amplifier, it can also be considered to separate the AC ground from the DC ground on the PCB with larger area, such as 5 cmx5 cm.

Most existing behavioral models of the radio frequency (RF) power amplifiers assume that power amplifiers are memoryless devices. But in broadband communication systems, memory effects of the RF power amplifiers are significantly observed. The traditional memoryless models can no longer accurately depict the input-output relationship of power amplifiers. This paper investigates power amplifiers memory effects and a pre-distortion method is proposed for linearizing RF power amplifiers with memory effects. A valid behavioral model based on the Volterra series is suggested to treat memory effects. Since the characteristics of amplifiers change during transmission time, a recursive least squares algorithm with size- fixed observation matrices is developed to update the parameters of the proposed power amplifiers model. The identification algorithm can decrease computational complexity and data storage space and facilitate real-time online identification. Simultaneously, the pre-distortion model is constructed to simulate. Simulation results show that the proposed method can effectively compensate for the nonlinear distortion and memory effects of RF power amplifiers. The model's accuracy is used to evaluate power amplifiers memory effects by the enormalized mean square error (NMSE). In the end, simulation and evaluation of this pre-distortion system proceeded, and the power spectral density estimation was also applied to calculate the adjacent channel power ratio.

The nonlinearity of power amplifiers is one of the principal reasons degrading the transmission quality in the wireless communication systems comprising the single-carrier frequency-division multiple access (SC-FDMA) utilised for the up-link in the LTE system. In this letter, we analysed and predicted the nonlinearity of SC-FDMA signals in spectrum respect. Owing to the nonlinearity of radio frequency (RF) power amplifiers, an analytic model is established on the basis of a third-order intercept point (), which is fit for weakly nonlinear systems and devices. The research results confirm that the spectrum regrowth with RF power amplifier is specified and measured efficiently. This sort of design inherits the advantages of orthogonal frequency division multiplexing (OFDM) and is of great help for both designing RF power amplifiers and further improving the spectrum regrowth with pre-distortion outside channels, extended to other wireless systems based on SC-FDMA modulation.

Preface. About the Authors. Acknowledgments. 1 Power Amplifier Fundamentals. 1.1 Introduction. 1.2 Definition of Power Amplifier Parameters. 1.3 Distortion Parameters. 1.4 Power Match Condition. 1.5 Class of Operation. 1.6 Overview of Semiconductors for PAs. 1.7 Devices for PA. 1.8 Appendix: Demonstration of Useful Relationships. 1.9 References. 2 Power Amplifier Design. 2.1 Introduction. 2.2 Design Flow. 2.3 Simplified Approaches. 2.4 The Tuned Load Amplifier. 2.5 Sample Design of a Tuned Load PA. 2.6 References. 3 Nonlinear Analysis for Power Amplifiers. 3.1 Introduction. 3.2 Linear vs. Nonlinear Circuits. 3.3 Time Domain Integration. 3.4 Example. 3.5 Solution by Series Expansion. 3.6 The Volterra Series. 3.7 The Fourier Series. 3.8 The Harmonic Balance. 3.9 Envelope Analysis. 3.10 Spectral Balance. 3.11 Large Signal Stability Issue. 3.12 References. 4 Load Pull. 4.1 Introduction. 4.2 Passive Source/Load Pull Measurement Systems. 4.3 Active Source/Load Pull Measurement Systems. 4.4 Measurement Test-sets. 4.5 Advanced Load Pull Measurements. 4.6 Source/Load Pull Characterization. 4.7 Determination of Optimum Load Condition. 4.8 Appendix: Construction of Simplified Load Pull Contours through Linear Simulations. 4.9 References. 5 High Efficiency PA Design Theory. 5.1 Introduction. 5.2 Power Balance in a PA. 5.3 Ideal Approaches. 5.4 High Frequency Harmonic Tuning Approaches. 5.5 High Frequency Third Harmonic Tuned (Class F). 5.6 High Frequency Second Harmonic Tuned. 5.7 High Frequency Second and Third Harmonic Tuned. 5.8 Design by Harmonic Tuning. 5.9 Final Remarks. 5.10 References. 6 Switched Amplifiers. 6.1 Introduction. 6.2 The Ideal Class E Amplifier. 6.3 Class E Behavioural Analysis. 6.4 Low Frequency Class E Amplifier Design. 6.5 Class E Amplifier Design with 50# Duty-cycle. 6.6 Examples of High Frequency Class E Amplifiers. 6.7 Class E vs. Harmonic Tuned. 6.8 Class E Final Remarks. 6.9 Appendix: Demonstration of Useful Relationships. 6.10 References. 7 High Frequency Class F Power Amplifiers. 7.1 Introduction. 7.2 Class F Description Based on Voltage Wave-shaping. 7.3 High Frequency Class F Amplifiers. 7.4 Bias Level Selection. 7.5 Class F Output Matching Network Design. 7.6 Class F Design Examples. 7.7 References. 8 High Frequency Harmonic Tuned Power Amplifiers. 8.1 Introduction. 8.2 Theory of Harmonic Tuned PA Design. 8.3 Input Device Nonlinear Phenomena: Theoretical Analysis. 8.4 Input Device Nonlinear Phenomena: Experimental Results. 8.5 Output Device Nonlinear Phenomena. 8.6 Design of a Second HT Power Amplifier. 8.7 Design of a Second and Third HT Power Amplifier. 8.8 Example of 2nd HT GaN PA. 8.9 Final Remarks. 8.10 References. 9 High Linearity in Efficient Power Amplifiers. 9.1 Introduction. 9.2 Systems Classification. 9.3 Linearity Issue. 9.4 Bias Point Influence on IMD. 9.5 Harmonic Loading Effects on IMD. 9.6 Appendix: Volterra Analysis Example. 9.7 References. 10 Power Combining. 10.1 Introduction. 10.2 Device Scaling Properties. 10.3 Power Budget. 10.4 Power Combiner Classification. 10.5 The T-junction Power Divider. 10.6 Wilkinson Combiner. 10.7 The Quadrature (90 ) Hybrid. 10.8 The 180 Hybrid (Ring Coupler or Rat-race). 10.9 Bus-bar Combiner. 10.10 Other Planar Combiners. 10.11 Corporate Combiners. 10.12 Resonating Planar Combiners. 10.13 Graceful Degradation. 10.14 Matching Properties of Combined PAs. 10.15 Unbalance Issue in Hybrid Combiners. 10.16 Appendix: Basic Properties of Three-port Networks. 10.17 References. 11 The Doherty Power Amplifier. 11.1 Introduction. 11.2 Doherty's Idea. 11.3 The Classical Doherty Configuration. 11.4 The 'AB-C' Doherty Amplifier Analysis. 11.5 Power Splitter Sizing. 11.6 Evaluation of the Gain in a Doherty Amplifier. 11.7 Design Example. 11.8 Advanced Solutions. 11.9 References. Index.

The rapid evolution of telecommunication systems has strongly influenced our lives, and the way we communicate and exchange information. Nevertheless, much progress is expected to happen in the next years with the introduction of new generations of wireless communications standards, which require signals with large bandwidth and very high Peak-to-Average Power Ratio (PAPR) in order to enhance the spectral efficiency and maximize the data rate. However, such developments can only take place through the evolution of Radio-Frequency (RF) which should be capable of working at higher frequencies, higher bandwidth and with higher efficiencies than before. In order to meet these demanding specifications, transmitter architectures have to evolve from a single linear RF Power-Amplifier (PA) into more complex architectures. Envelope Tracking (ET) is one of the most promising solutions for the efficiency-enhancement of next generation transmitters. The research described in this thesis aims to provide solutions to enhance the efficiency of the RF PA by means of an ET architecture. To this purpose, a novel discrete level supply modulator is investigated, which is based on a direct digital-to-analog power conversion. This supply modulator is capable of synthesizing eight voltage steps by means of three isolated voltage sources, thus behaving like a Power Digital-to-Analog Converter (Power-DAC). A hybrid version of the Power-DAC exploiting very fast GaN devices is developed and tested with an L-band PA achieving efficiency improvement up to 13% with 10 MHz of bandwidth. Furthermore, a monolithic GaN version of the Power-DAC is prototyped and tested with an X-band PA achieving efficiency improvement up to 20% and bandwidth of 20 MHz. This supply modulator is tested with outphasing PAs showing promising results with modulated signals and efficiency improvement up to 9%. Finally, dispersive phenomena, which affect PAs and switches in supply modulators, are investigated, characterized and modeled.

Turkish accelerator and radiation laboratory (TARLA) is an accelerator based oscillator mode free electronlaser (FEL) facility under construction. The acceleration beamline includes a fundamental buncher (FB) in order to confine the electron beam into a compressed bunch. In this study, we demonstrate the commissioning tests of 500 W RF amplifier powering FB and present the phase stability dependence on the pressure and temperature of the water cooling line under long time run conditions.As the disturbing effects break down the synchronization between the particle and RF power during acceleration, the reasons disquieting the stability of the RF amplifier are investigated. One reason which causes disturbance in the stability is the variation in the phase of the output power. Phase variation of the output power of the RF amplifier which was measured as $\sim$10 deg/$^{\circ}$C in average initially, which was beyond permitted variation levels by the controller electronics, namely the low level RF system (LLRF), is decreased to less than $\sim$0.45 deg/$^{\circ}$C by incorporating a phase shifter. In addition, this phase variation reduction is accompanied with a reflected power at the output of the RF amplifier decline from 4.3 W (~36.33 dBm) down to 3 mW (~4.7 dBm) by utilizing a circulator, which is also important and desirable in terms of protection of the electronics in the long term run. As ensuring phase stability in the output power is very important, this work may serve as a guide since the documentation regarding the output power dependence of the water cooling line for long term run is very limited.

Theoretically, memoryless nonlinear effect is the main concern for RF power amplifier (PA) modelling and analysis. However, the latest generation wireless communication systems, such as Wi-Fi, WiMAX and LTE, using wider bandwidth, add new problems for the analysis of RF PAs, which is the memory effect associated with the bandwidth. The memory effect causes additional distortion to the PA and affects the performance of digital predistortion (DPD) design. Previously, we predicted the memoryless spectrum regrowth of a PA related to its intercept points up to arbitrary high order for a few of wireless communication signals, such as TDMA, CMDA and OFDM. In this letter, we propose a simplified Hammerstein structure-based method to consider the memory effect as well in order to analyse the nonlinear characteristic of PAs more precisely and completely. The simplification greatly reduced the complexity of classic Hammerstein system identification for PAs. The result will be useful in the analysis of RF PAs with memory effect and the proposed PA model is intended to be used in predistorter design for modern wideband wireless communication systems.

Two differential radio frequency (RF) power amplifier (PA) architectures are presented in this paper both of which can be used to implement a wideband Doherty PA. Classic PA architecture is compared to a SB (SB) PA in order to determine an architecture that offers the widest input impedance match without external component tuning. Both amplifiers presented in this paper have been designed to output an average of 10.5 dBm of continuous wave (CW) power with 1.8 V supply. The classic PA architecture is tuned to 1.9 GHz central frequency by external components and has a bandwidth of 500 MHz at S11=−10 dB. The SB PA architecture has an operating range spanning from 0.8 GHz to 2.2 GHz at S11=−10 dB. SB PA has a higher power added efficiency (PAE) at output compression point (OR-P1dB) in the whole 1.2 GHz–2.4 GHz range by 3 %–7 % with a peak efficiency of 31 %. The presented results indicate that a SB RF PA architecture can be implemented designing a wideband Doherty PA.

To satisfy the continuously increasing demand for high data rates and mobility required by new wireless applications, the 5G has gained much attention recently. Radio frequency power amplifiers (RF-PAs), as one of critical components of 5G transmitter system, are becoming a hot issue. In this paper, the statistical analysis on RF PA papers shows the research on RF-PAs in Asia-Pacific and cooperation between different affiliations and countries are gradually becoming more prominent, showing the globalization trend of RF PA research and the 5G technologies. The decreased research cycle of RF PA shows the processes of research on PA and 5G technologies are speeding up. Some promising RF-PA technologies for 5G wireless communication system are also been discussed.

Turkish Accelerator and Radiation Laboratory in Ankara (TARLA) is an oscillator mode IR-FEL facility which is under construction since 2011. ELBE licensed superconducting modules housing TESLA RF cavities have been manufacturing for one year and the first module will be delivered in 2015. He Cryogenic System has also started to be manufacturing at similar time with the accelerator structures. It will be delivered in 2014. High Power RF amplifiers are started to tender procedures and delivery time is planning as 2015. The installation of high power transmission lines have to be completed at the same time with the delivery date of HPRF amplifiers to test the cavities and amplifiers. In this study, the final structural design of high power RF transmission lines and design parameters of RF amplifiers for TARLA is discussed.

This paper presents an adaptive predistortion RF power amplifier for repeater systems with a spectrum monitor. For adaptive control of cancellation, we implement a spectrum monitor that improves the adjacent channel leakage ratio (ACLR) characteristics of the power amplifier by analyzing the output spectrums of RF power amplifiers directly and simultaneously. For experimental validation, we also implement a class-AB RF power amplifier that adopts a predistortion linearizer with the spectrum monitor and measure the characteristics for the wide-band code division multiple access (WCDMA) band. With an optimum gate bias voltage of the power amplifier, ACLRs of 22 and 20.5 dB are improved for the cases of one- and four-carrier WCDMA applications, respectively. The predistortion power amplifier with the spectrum monitor delivers a P <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">out</sub> of 37.5 dBm with an ACLR of -45 dBc for four-carrier WCDMA applications. Furthermore, excellent ACLR characteristics are consistently maintained with the minimization algorithm by adaptively controlling the vector modulator in the predistorter under various environments that include varying input power levels, temperatures, and operating frequencies

RF power amplifiers are one of challenging blocks in designing radio frequency transceivers, this is due to non-linearity behavior of power amplifiers that leads to inter-modulation distortion. This paper presents the design of wide-band power amplifier which combined with parallel coupled line band pass filter at the input and output of power amplifier to allow the only required frequency band to pass through the power amplifier. Class-A topology and ATF-511P8 transistor are used in this design. Advanced Design System software used as a simulation tool to simulate the designed wide-band power amplifier. The simulation results showed an input return loss (S11) which less than -10dB, and gain (S21) is higher than 10 dB over the entire frequency band and considers as flat as well. The designed amplifier is stable over the bandwidth (K&amp;gt;1). Inter-modulation distortion is -56.919dBc which is less than -50dBc with 10dBm input power. The designed amplifier can be used for the microwave applications which include weather radar, satellite communication, wireless networking, mobile, and TV.

RF transistors can be found in several present day electronics including mobile radio and telecommunication applications, TV & radio broadcast, avionics, radar and defense communications as well as industrial, scientific, medical (ISM) and broadcast applications. The increasing demands for data anywhere/anytime (mobile internet) requires increased deployment of wireless communication infrastructure. This has pushed upwards across the supply chain (suppliers and customers alike). At the core are RF power amplifiers (PA) with a very costly design, hence important to get it right as rework may not be possible. The assembly of RF power transistors in PA modules is the back-bone of these applications. Such modules are usually generating high power (> 100 watts) with different package outlines and lead configuration. The high power demands excellent thermal management, else product performance and lifetime (reliability) are compromised. As a consequence, the transistors are often packaged in "chunky" S OT outlines, with a cerami c/plastic body and a metal flange. Packaging such RF power modules (or PA) has historically been achieved with bolt down devices, where only the leads of the components were soldered (more akin to manual assembly operations). A thermal compound was used underneath the transistor. High volume assembly is a basic capability (with automation a necessity) to meet industry demand. There are a variety of issues to consider module assembly since there are strong interplay between design, materials and process in order to achieve the desired performance (electrical, thermal, mechanical, and reliability). Due to thermal management requirement, the transistors are normally soldered directly onto the pallet (laminate bonded onto a heat sink) with the leads and SMDs on to the laminate on the pallet. Base on the SOT outline (i.e. gull wing), a cavity or pedestal is required in the pallet with a cut-out in the laminate. Each PA module will be different in i.e. size, weight, materials, number of transistors, board construction with no two modules the same. With such spectra of possibilities in the module design and permutations on assembly processes, the paper outlines and addresses the key issues to consider and approach to achieve robust PA modules assembly. It includes but not limited to substrates, solders, heat sinks, plating, board design and reflow soldering (assembly process flow). Key to achieving the robust assembly process is an iterative approach with feedback at each step in the process including a modeled reflow profiling. In addition, a novel use of Rth (thermal impedance) in combination to acoustic microscopy / x-rays to assess the quality of the soldered interface is presented. The solder volume is key to accommodate manufacturing tolerances and solder joint reliability. Additionally, the issues presented constitute a "toll-box" for PA module assembly, including microwave pallet modules with matched input/output impedance.

A novel backgate modulation technique alleviating limitations associated with supply-regulated polar transmitters is proposed. The backgate of a partially depleted silicon-on-insulator metal-semiconductor field-effect transistor with a breakdown voltage of 15 V is used to modulate the gain and output power of an RF power amplifier (PA). The high-impedance backgate provides high-efficiency and wide-dynamic-range modulation of PA gain. Measured results at 1.8 GHz demonstrate 16% power-added efficiency improvement at 6-dB backed-off output power, compared with the same RF PA without backgate modulation.