This thesis consists of two parts. Part 1 introduces the characteristics of Class E power amplifier. Part 2 is focused on the implementation of Class E power amplifier for 2.4GHz Bluetooth applications. The design procedure follows the theory of class E power amplifier, and is implemented in MMICs and modules. For MMICs, the GaAs HBT foundry services are provided by the GCTC Ltd. and WIN Ltd.. Under single supply voltage of 3.3V and the output power of 20dBm, two designed MMICs have gain 23dB and 11dB, and power added efficiency (PAE) 57% and 72%, respectively. For Hybrid modules, RF transistors are provided by the Filtronic Ltd.. Under the same supply voltage of 3.3V, the measured output power, gain, and power added efficiency are 20 dBm, 25dB, and 75% respectively. Compared with the other types of power amplifiers on the market, Class E power amplifier has higher power added efficiency, and thus can increase the using time of communication system.

Abstract¡G This thesis studies the memory effect due to bias perturbation on digital predistortion technique, and employs multi-tone continuous wave signal and digital modulation signals with different bandwidth to discuss the performance of digital predistortion technique. Memory effect makes a great impact on the digital predistortion technique, and bias perturbation is one of the major causes. Lowering the bias perturbation can improve the effectiveness of digital predistortion technique. Another focus of this thesis is to design a Class E power amplifier in 0.18 £gm CMOS process. The power amplifier uses cascode structure to alleviate the breakdown voltage problem and employs power combining technique to achieve impedance transformation on chip for the purpose of increasing the output power and efficiency.

Modern day wireless communication systems are constantly facing increasing bandwidth demands due to a growing consumer base. To cope up with it, they are required to have a better power vs performance from the RF devices. The amount of data being exchanged over wireless links has tremendously increased and simultaneously, there is a need to switch to portable RF devices and this has in turn forced the issue of low-power RF system design. Therefore, what we need is an RF transceiver that operates at high data rates and over adverse channels with a low power consumption. A major portion of the power is utilized by the RF front end of the wireless system. Many methods like controlled positive feedback, re-utilizing bias current, etc have been employed to reduce the power consumption of the RF front end. The most modern wireless systems adapt to the channel quality by adjusting the data transmission rates and by adjusting the output power of the RF Power Amplifier. However, each of these methods concentrates on working for the worst case channel and giving the highest data rate. What needs to be known is that the channel conditions are not always worst. Even for a normal channel, the system is going to utilize a lot of power and give the highest possible data rate which may or may not be necessary. And thus, for the most part, the system is going to use up more power than necessary. What we need instead, is a system which works nominally for a normal channel and exhaustively for a harsh channel condition. This requires the system to adapt to the channel conditions. Also another major factor causing fluctuations in the performance is the process variations. This calls for a channel-dependent dynamic transceiver with adequate power management and tuning. In our work, we try to devise a method to dynamically minimize the power considering the varying channel conditions and process variations. We first use companding to reduce the dynamic range of the signal so that it can be used on facilities with smaller dynamic range. This brings down the transmitted power. We also create multiple instances of the Power Amplifier to simulate process variations. After finding the optimum tuning knob settings for one instance of the PA, we try to use it to obtain the optimum settings for another instance. This requires the use of some heuristics and in our work, we have supplemented it with Simulated Annealing. Using SA, we can dynamically tune the power of a system for changing channel conditions and existing process variations. Towards the end, we have also proved that the slower the cooling rate of the experiment, the more elaborate the search space is and the more accurate the result is.

ITC/USA 2012 Conference Proceedings / The Forty-Eighth Annual International Telemetering Conference and Technical Exhibition / October 22-25, 2012 / Town and Country Resort & Convention Center, San Diego, California / This paper details design, development and test of the Low Cost OFDM Transceiver (LCOT) LCT2-040-2200 module at S band. The goal of the project is to provide a low cost transmit and receive unit for demonstrating OFDM communication on a flight platform. The LCOT module is built to transmit and receive OFDM signals. It transmits OFDM signals at 10W power out through a custom built high power amplifier and conforms to the IEEE 802.11.g spectral emissions mask.

The FREIA laboratory is a Facility for REsearch Instrumentation and Acceleratior development at Uppsala University, Sweden, constructed recently to test and develop superconducting accelerating cavities and their high power RF sources. FREIA's activity target initially the European Spallation Source (ESS) requirements for testing spoke cavities and RF power stations, typically 400 kW per cavity. Different power stations will be installed at the FREIA laboratory. The first one is based on vacuum tubes and the second on a combination of solid state modules. In this context, we investigate different related aspects, such as power generation and power combination. For the characterization of solid state amplifier modules in pulsed mode, at ESS specifications, we implement a Hot Sparameter measurement set-up, allowing in addition the measurement of different parameters such as gain and efficiency. Two new solid state amplifier modules are designed, constructed and measured at 352 MHz, using commercially available LDMOS transistors. Preliminary results show a drain efficiency of 71 % at 1300 W pulsed output power. The effects of changing quiescent current (IDq) and drain voltage are investigated, aswell as the possibilities to combine several modules together.

No description available.

Modern wireless communication systems transmit complex modulated signals with high peak to average ratio in order to deliver high data rates. It demands wide bandwidth and rigorous efficiency performance for power amplifiers. Today’s conventional RF power amplifiers have relatively poor operating efficiency and require more power and area for operation. Therefore, more research on high efficiency power amplifier is crucial to the growth of the wireless industry. Until recent days, WiMAX systems are using technology processes such as Gallium Arsenide (GaAs) and Si LDMOSFET to obtain the performance. Although they are providing the required functional performance, they do not optimize cost and/or size. The primary focus of this thesis is to enhance the efficiency and output power of a compact microwave Power Amplifier suitable for a WiMAX base station. To achieve this goal, this thesis explores the highly efficient switched mode Class E microwave power amplifier using the Gallium Nitride on Silicon Carbide HFET (GaN-on-SiC) technology. The smallest gate length (0.15 µm) device recently released by NRC is used in this design. It provides higher performance at lower cost and area than the alternative Gallium Arsenide (GaAs) technology. Importance is given in designing the bias network of the device. The biasing network has a great impact on efficiency of power amplifiers. Many new techniques of Class E design have been presented to date, but there is not significant improvement related to the biasing network. A highly efficient Class E power amplifier for WiMAX base station transmitter was developed in this thesis for 2.5 GHz application. An improved bias network was introduced for biasing the active device. This successful design shows acceptable simulated performance with a gain of 10.12 dB, an output power of 34.12 dB, and a power added efficiency of 41.7 % at the peak output power.

In this research, an innovative phased array antenna module is proposed to implement a high-power, high-efficient and compact C-band radio transmitter. The module configuration, which can be integrated into front-end circuits, was designed as planar layers stacked up together to form a metallic cube. The layers were fabricated by using a Computer Numerical Control (CNC) milling machine and screwed together. The antenna parts and the amplifier units were designed at two opposite sides of the cube to spread the dissipated heat produced by the amplifiers and act as a heat sink. Merging the antenna parts with the amplifier circuits offers additional advantages such as decreasing the total power loss, mass, and volume of the transmitter modules by removing the extra power divider and combiner networks and connectors between them as well as reducing the total signal path. To achieve both a maximum possible radiation efficiency and high directivity, the aperture waveguide antenna was selected as the array element. Four antenna elements have been located in a cavity to be excited equally and the cavity is excited through a slot on its underside so a compact subarray is formed. Antenna measurements demonstrated a 15.5 dBi gain and 20 dB return loss at 10 % fractional bandwidth centered around 5.8 GHz and with more than 98% radiation efficiency. The total dimensions of the subarray are approximately 8*12*4 cm3. The outcoming signal from the amplifiers is transferred into the slot exciting the subarray through a microstrip-to-waveguide transition (MWT). A novel and robust MWT structure was designed for the presented application. The MWT was also integrated with a microstrip coupler to monitor the power from the amplifier output. The measured insertion loss of the MWT along with the microstrip coupler was less than 0.25 dB along with more than 20 dB return loss within the same bandwidth of the subarray. The microstrip coupler shows 38 dB of coupling and more than 48 dB of isolation with negligible effects on the amplifier output signal and the insertion/return loss of the MWT. The amplifier subcomponents consist of power combiners/dividers (PCDs), high power amplifiers (HPAs) and bias circuitry. A Monolithic Microwave Integrated Circuit (MMIC) three-stage HPA was designed in a commercially available 0.15 um AlGaN/GaN HEMT technology provided by National Research Council Canada (NRC) and occupies an area of 4.7*3.7 mm2. To stabilize the HPA, a novel inductive degeneration technique was successfully used. To the best of the author’s knowledge, this is the first time this technique has been used to stabilize HPAs. Careful considerations on input/output impedances of all HEMTs were taken into account to prevent parametric oscillations. Other instability sources, i.e. odd-mode, even-mode, and low frequency (bias circuit) oscillations were also prevented by designing the required stabilization circuits. The electromagnetic simulation of the HPA shows 35 W (45.5 dBm) of saturated output power, 26 dB large signal gain and 29% power added efficiency within the same operating bandwidth as the subarray. The output distortion is less than 27 dB, indicating that the HPA is highly linear. The PCD was designed by utilizing a novel, enhanced configuration of a Gysel structure implemented on Rogers RT-Duroid5880. The insertion loss of the Gysel is less than 0.2 dB while return loss and isolation are greater than 20 dB over the entire bandwidth. The same subarray area (8*12 cm2) has been used for the amplifier circuits and up to eight HPAs can be included in each module. All the above parts of the transmitter module were fabricated and measured, except the MMIC-HPA.

Power amplifiers (PA) are typically the most power-consuming building blocks of RF transceivers. Therefore, the design of a high-efficiency radio frequency power amplifier is the most obvious solution to overcoming the battery lifetime limitation in the portable communication systems. A power amplifier's classes (A, AB, B, C, F, E, etc), and design techniques (Load-pull and large-signal S-parameters techniques) are presented. The design accuracy of class-A power amplifier based on the small-signal S-parameters was investigated, where compression in the power gain was used as an indicator for design accuracy. The effect of drain voltage variation on the power gain compression has been studied in this research. The class-E amplifier has a maximum theoretical efficiency of 100%. It consists of a single transistor that is driven as a switch and a passive load network. The passive load network is designed to minimize drain (collector) voltage and current waveforms overlapping, which minimize the output power dissipation. Two L-band class-E amplifiers are implemented in section 5.3. One of them is a lumped elements based circuit and the other is a transmission lines based circuit. Both circuits show good performance (60% PAD) over a wide bandwidth (1.0 GHz). In section 5.4, lumped elements and transmission lines based X-band class-E amplifiers are presented. Both circuits show good performance (62% PAD) over wide bandwidth (4.8 GHz). A new technique to improve the drain efficiency of the class-E amplifier has been proposed. This technique uses two passive networks. One of them is in a series with the shunt capacitor CS and the other is in a series with the transistor's source terminal. This technique shows improvement in the drain efficiency, which jumps from 62% to 82%. Last few years have seen an increase in the popularity of the wireless communication systems. As a result, the demand for compact, low-cost, and low power portable (Single-chip) transceivers has increased dramatically. Among the transceiver's building blocks is the power amplifier. Thus, there is a need for a low-cost power amplifier. A 900 MHz CMOS RF PA with one-watt output power and a high power added efficiency (68%) is presented in chapter 6. This PA can be used in the European standard for mobile communications (GSM) handset transmitter. / Ph. D.

The power amplifiers are typically the most power-consuming block in wireless communication systems. Spectrum is expensive, and newer technologies demand transmission of maximum amount of data with minimum spectrum usage. This requires sophisticated modulation techniques, leading to wide, dynamic signals that require linear amplification. Although linear amplification is achievable, it always comes at the expense of efficiency. Most of the modern wireless applications such as WCDMA use non-constant envelope modulation techniques with a high peak to average ratio. Linearity being a critical issue, power amplifiers implemented in such applications are forced to operate at a backed off region from saturation. Therefore, in order to overcome the battery lifetime limitation, a design of a high efficiency power amplifier that can maintain the efficiency for a wider range of radio frequency input signal is the obvious solution. A new technique that improves the drain efficiency of a linear power amplifier such as Class A or AB, for a wider range of output power, has been investigated in this research. The Doherty technique consists of two amplifiers in parallel; in such a way that the combination enhances the power added efficiency of the main amplifier at 6dB back off from the maximum output power. The classes of operation of power amplifier (A, AB, B, C etc), and the design techniques are presented. Design of a 2.14 GHz Doherty power amplifier has been provided in chapter 4. This technique shows a 15% increase in power added efficiency at 6 dB back off from the compression point. This PA can be implemented in WCDMA base station transmitter. / Master of Science