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Wireless and Microwave Technology Conference, 2006. WAMICON '06. IEEE Annual

Date 4-5 Dec. 2006

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Displaying Results 1 - 25 of 73
  • Ranging in the IEEE 802.15.4a Standard

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (6098 KB) |  | HTML iconHTML  

    The emerging IEEE 802.15.4a standard is the first international standard that specifies a wireless physical layer to enable precision ranging. In this article, ranging signal waveforms and ranging protocols adopted into the standard are discussed in a tutorial manner View full abstract»

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  • Geolocation for UWB Networks in underground mines

    Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3680 KB) |  | HTML iconHTML  

    Ultra wideband technology is regarded by many as one of the future key technologies in communications and positioning. Even though the basic principles of UWB have been studied for decades, there is still a great demand for research, especially in the field of precise local positioning. Techniques have to be further developed to cope with for example varying line of sight (LOS)/non line of sight (NLOS) or severe multipath conditions. In this paper we give an experimental measurement and modeling of ultra wideband radio propagation in underground mines for indoor geolocation. This work has been carried out by the underground communications research laboratory LRCS and the experimental mine CANMET (Canadian Center for Minerals and Energy Technology) in Val-d'Or, Canada. View full abstract»

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  • Precise Wireless Indoor Localization with Trilateration Based on Microwave Backscatter

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4966 KB) |  | HTML iconHTML  

    We present two techniques for estimating accurately the position of a mobile base station in industrial environment with trilateration. By eliminating the need to measure angles, trilateration uses only distance measurements to estimate position, which facilitate the implementation of real-time positioning systems like the global positioning system (GPS). Iterative linear least squares and nonlinear least squares estimators are implemented through simulation. We consider the minimization of the squares of errors, where the main difference depends on the linearity of the measurement equation which relates the coordinates to be estimated to the measured distance. The results obtained show that the nonlinear squares technique results in more accurate position estimates than linear least squares. Error distribution functions and histograms in both cases are derived and analysed View full abstract»

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  • Impact of Building Environment on the Performance of Dynamic Indoor Localization

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (6516 KB) |  | HTML iconHTML  

    Location determination of mobile users within a building is challenging due to the complexities of the indoor radio propagation characteristics. For a RF based indoor system, a common practice is to construct a signal strength map table showing the radio signal strength at different known locations in the building. A mobile user's location at an arbitrary point in the building is then determined by measuring the signal strength at the location in question and determining the location by referring to the above map table using a LMSE (least mean square error) criterion. Much work has been done lately in the indoor radio propagation in order to automatically generate the signal strength map table according to the changing environment. This research is based on the ARIADNE indoor localization system with the purpose to analyze the impact of building structures and indoor furniture on the performance of the indoor localization. We provide a simple strategy to model these indoor structures, and we verify the methodology using a complex basement building. Experimental results indicate that up to 15% improvement in location estimation is achievable from the proposed method View full abstract»

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  • Application of Ad-hoc sensor networks for localization in underground mines

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4266 KB) |  | HTML iconHTML  

    Underground mining is a hazardous industrial activity. The harsh physical environment and distinct topology that make mining dangerous act as a hindrance or constraint to the very techniques and technologies that could improve safety and productivity. Workers safety is of paramount importance and is certainly a moral obligation for any business! Wireless sensor networks monitoring is an application that is very crucial for the safety of mine workers. These sensors can monitor vital life signs of workers which may be very useful during emergency situations. Localization and tracking of moving objects is an essential capacity for a sensor network in many applications. This paper studies the problem of localization in underground mines using ad-hoc sensor networks. We use the DV-hop algorithm to estimate the distance between a mobile node and a fixed anchor and we apply the bounding box technique to estimate the location View full abstract»

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  • An Optimum Ultra-Wideband (UWB) Bandpass Filter with Spurious Response Suppression

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4158 KB) |  | HTML iconHTML  

    A high selectivity ultra-wideband (UWB) bandpass filter (BPF) with a fractional bandwidth (FBW) of about 110% is presented using a microstrip structure. The filter is based on a circuit model for an optimum distributed highpass filter consisting of only 5 short-circuited stubs separated by non-redundant connecting lines. As a result, the filter in a compact structure exhibited a selective filtering characteristic equivalent to a 9-pole Chebyshev filter. In addition, an optimum bandstop filter was added in order to suppress the second spurious harmonic. The design was successfully realized in theory and verified by full-wave EM simulation of the full layout and the experiment. The proposed filter had low insertion loss, sharp rejection, and a group delay of about 0.2 ns over the most center band. The filter also demonstrated an UWB reject band from 11.4 GHz to more than 20 GHz at -30 dB View full abstract»

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  • Modeling of 3.1-10.6 GHz CMOS Filter-Based Low Noise Amplifier for Ultra-Wideband Receivers

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (223 KB) |  | HTML iconHTML  

    In this paper, the authors present a complete modeling methodology for fully integrated filter-based ultra-wideband low noise amplifiers (LNA). The accurate analytical models capture the impact of device and passive component parasitics and transistor short channel effects to closely match circuit simulation results. Utilizing the method, the authors are able to accurately generate an ultrawideband LNA in the 3.1 to 10.6 GHz band that achieves a power gain greater than 10dB, input and output impedance matching less than -10dB, and a noise figure from 2.2dB to 3.3dB when using a TSMC 0.18mum mixed-signal/RF model. These performance parameters exceed the results reported from previous ultra-wideband designs. Our modeling methodology provides a new means for accurate modeling and efficient design of high performance ultrawideband amplifiers in wireless front-end RF systems View full abstract»

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  • Characterization of Indoor Ultra-wide Band NLOS channel

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4568 KB) |  | HTML iconHTML  

    Characterization of indoor UWB non-line-of-sight (NLOS) channel is done by using new algorithm manipulate of Win's experimental data. A statistical model is then proposed based on these new characteristics. The model has the flexibility to deal with the "soft NLOS" and the "hard NLOS" environment, which is shown in measurements, by defining the polarity of a particular model parameter. Therefore, the channel impulse responses (CIR) generated by the proposed mode "resemble" the measured channel impulse responses better than SV/IEEE 802.15.3a model in terms of the cumulative distribution functions (CDFs) of the small-scale statistics, instead of just the average values View full abstract»

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  • Wireless IPTV over WiMAX: Challenges and Applications

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (7069 KB) |  | HTML iconHTML  

    Internet protocol television (IPTV) is gaining recognition as a viable alternative for the delivery of video by telecommunications and cable companies. It features bandwidth efficiencies, and management; therefore, it is ideally suited for broadcast, multicast, unicast interactive and multimedia services (IMS - IP multimedia). Core networks are packet-based, however, access networks are not always packet-based. Furthermore, they are wired as either fiber-coax or fiber-twisted pair topologies. Design, construction, and maintenance costs of such topologies are exorbitant, making the IPTV deployment economically unviable, especially in underdeveloped countries and rural areas. Worldwide interoperability for microwave access (WiMAX) offers a wireless solution in the access networks that can support IPTV services. WiMAX is capable of very high data rates, longer reach, and operates in non-line of sight (NLOS) modes in licensed and license exempt frequencies. Bandwidth is scalable and managed. Contents are encrypted for secured transmission and mobility is supported at vehicular speeds. Installation and maintenance costs of WiMAX systems are at a fraction of the costs of wired access networks. Taking advantage of these features, IPTV services can be designed, delivered, and managed cost effectively without compromising the video and audio quality. In this paper, the authors present IPTV over WiMAX implementation in such scenarios. The authors identify challenges and discuss ways to overcome them, especially those in medium access control (MAC), physical layer (PHY) and radio sub-systems. Despite of these challenges, it is observed that IPTV over WiMAX is very feasible. View full abstract»

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  • Hardware Architecture Study for NASA's Space Software Defined Radios

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (5521 KB) |  | HTML iconHTML  

    This study defines a hardware architecture approach for software defined radios to enable commonality among NASA space missions. The architecture accommodates a range of reconfigurable processing technologies including general purpose processors, digital signal processors, field programmable date arrays (FPGAs), and application specific integrated circuits (ASICs) in addition to flexible and tunable radio frequency (RF) front ends to satisfy varying mission requirements. The hardware architecture consists of modules, radio functions, and interfaces. The modules are a logical division of common radio functions that comprise a typical communication radio. This paper describes the architecture details, module definitions, the typical functions on each module and the module interfaces. Trade-offs between component-based, custom architecture and a functional-based, open architecture are described. The architecture does not specify a physical implementation internally on each module, nor does the architecture mandate the standards or ratings of the hardware used to construct the radios View full abstract»

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  • A Medium Range Low-Cost Monopulse Radar System for Azimuth and Range Detection at 24GHz

    Page(s): 1 - 3
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2257 KB) |  | HTML iconHTML  

    The paper presents details and results on a high-performance, medium-range monopulse radar system designed for various automotive applications, with a particular emphasis on the implementation and accuracy of the azimuth detection functionality. Whilst, by comparison, front-end radar systems for range and/or speed detection are relatively straightforward to implement, the addition of the azimuth functionality, indispensable in most automotive applications, is in fact an extremely difficult task. This task is even more challenging when such a system has to be low-cost. The system that we have developed is based on a compact low-cost Tx/Rx front-end design at 24GHz. A brief overview of the system and sub-system design details and their performances are outlined. Very reliable and accurate azimuth detection functionality has been implemented by employing a variant of the phase/amplitude comparison monopulse solution, using a high-performance patch-array antenna. Some of the main performance parameters achieved with the system described here include: range/speed detection of more than 50 meters, an azimuth range of plusmn 40deg with azimuth accuracy better than 1deg in the very important low-azimuth angle range. The paper includes some of the final system test results, showing the measured azimuth performance, for the antenna itself as well as for the entire front end system. View full abstract»

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  • Emerging Commercial Applications Using the 60 GHz Unlicensed Band: Opportunities and Challenges

    Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3502 KB)  

    The 60 GHz band has emerged as an international spectrum opportunity for short-range wireless communication networks. In this paper, opportunities that may leverage 60 GHz and the technology trends that will impact the commercial deployment of systems utilizing the 60 GHz frequency band are discussed. Millimeter-wave frequency bands have historically been costly to utilize and traditionally used almost exclusively for government and non-consumer products. Recent and ongoing advances in semiconductor technology and low cost high frequency packaging can be leveraged for low cost solutions that enable widespread deployment. An example of such a system operating in the millimeter-wave spectrum where bandwidths of ~3 GHz have been achieved. Multi-gigabit data transmission and reception over significant distances has also been realized to demonstrate the potential throughput of such a broadband wireless system. View full abstract»

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  • An Analog Mixed Signal Fourier Transform Pre-Processor for OFDM Receivers

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (5138 KB) |  | HTML iconHTML  

    An FFT pre-processing architecture that reduces the constraints on the analog-to-digital converter in broadband orthogonal-frequency-division-multiplexing receivers is presented. System simulations demonstrate that the proposed approach has an improved dynamic range over the conventional approach. The proposed pre-processor replaces the typically 6-bit ADC and digital FFT processor in the broadband OFDM receiver with a more power efficient, wider dynamic range architecture. The new architecture is based on sequential sampling of the OFDM symbol and an analog-mixed-signal FFT preprocessor that transforms the OFDM symbols prior to digitization. This reduces the information conversion burden on the ADC, allowing the requisite six bits of ADC resolution to be reduced to two, thereby significantly lowering system power consumption. The increased dynamic range allows sensitivity to be improved as weak sub-channels are amplified before quantization and not subjected to the limitations of the conventional 6-bit ADC. A proof-of-concept 1-GigaSample per second IC in currently being fabricated in 130nm CMOS. View full abstract»

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  • Multi-Cell Coordinated Radio Resource Management Scheme Using a Cell-Specific Sequence in OFDMA Cellular Systems

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (5809 KB) |  | HTML iconHTML  

    In this paper, we propose a multi-cell coordinated radio resource management scheme in OFDMA cellular systems, in which each cell has its own sequence for allocating radio subchannels. We first divide a given radio resource into a set of subchannels in each cell. Here, we assume an identical set of subchannels in all cells considered. Then, we choose a set of cell-specific subchannel allocation sequences, so that they can avoid maximally inter-cell interference (ICI) and also minimize the probability of major collisions from neighbor cells in a mobile cellular environment. Finally, each cell allocates a subset of pre-defined subchannels to a requested user. In addition, prior to resource scheduling, each base station (BS) determines the total number of subchannels requested by all users in the cell, and allocates subchannels corresponding to the requested number according to its own cell-specific sequence. Through simulation results, we show that the proposed scheme can achieve a greater spectral efficiency or much higher loading under system outages as compared to the conventional schemes. We consider both the omni-cell and 3-sector cell View full abstract»

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  • Tactical AD HOC Scenarios Generator Coupled with Channel Modeling

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4252 KB) |  | HTML iconHTML  

    Simulation tools are very helpful for cost-effective design of wireless networks and useful to have better understanding of many phenomena. Ad hoc networks are one of the complex wireless systems because of the difficult to have good prediction in their topology changing. Our contribution in this paper is to provide as well as possible the best description of ad hoc scenarios in order to have a better analysis of the physical layer, and finally to improve performances of the whole network. We have created a scenarios generator to be able to generate a large number of scenarios with the same set of parameters or various scenarios. To meet some requirements of military use (which is our main application) we have proposed improvements of some classic mobility models. Many figures are depicted to illustrate our approach. And finally, we present the results in term of channel behaviour while coupling the generator with a semi-deterministic propagation model. View full abstract»

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  • Impedance Anomalies and RF Performance Limitations in AlGaN/GaN HFET's

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3381 KB) |  | HTML iconHTML  

    AlGaN/GaN HFET's have demonstrated excellent RF performance. The use of these devices in WiMAX system is of particular interest due to their inherent broadband capability. However, these devices experience physical phenomena that degrade RF performance and limit the high frequency application of these devices. In particular, these devices often demonstrate Cgs variations with input power drive that are opposite to classical FET behavior. The transconductance also decreases with input RF drive. The behavior affects the frequency performance and linearity of the device. In this work these effects are investigated using the commercial ATLAS simulator. It is demonstrated that these effects result from space-charge limited current transport, and a corresponding increase in gate-source channel resistance. Simulation results are verified by comparison to experimental data, and excellent agreement is obtained. The physical operation of the device, including effects that limit RF performance and frequency response are explained and discussed. View full abstract»

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  • Development of a New Physics-Based RF Model for AlGaN/GaN HFETs

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    A physics-based analytic model is built based on the discovery of a new zone in AlGaN/GaN HFETs that is observed in 2D device simulations, especially at high drain bias. The zone is located in the drain access region and is named the "charge deficit zone" after its particular property of a partially filled quantum well. This zone plays an important role when the HFET is under high drain bias because most of the drain voltage is dropped across it and a high lateral electric field exists within it. Good agreement is achieved in comparisons between the model and corresponding simulation results from the commercial ATLAS simulator. View full abstract»

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  • Linearity Limitations of AlGaN/GaN HFET's

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4258 KB) |  | HTML iconHTML  

    Due to high mobility (1000-1500 cm/V2), high sheet charge density (~1013 cm-2), and high electron saturation velocity (~2.0times105 cm/s), AlGaN/GaN HFET's were shown to have great potential for linear operation in high dynamic range module. However, significant linearity degradation was found in practical devices compared to that predicted from theoretic derivation. In this work it is demonstrated that nonlinear source resistance that varies in magnitude with the channel conduction current limits these device's RF performance by suppressing the channel IMAX value and introducing nonlinearity under large signal operation. The nonlinear source resistance can be affected by changing the length of the gate-source access region. RF performance is improved by minimizing the nonlinearity in the source resistance. View full abstract»

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  • Parasitic-Aware Analytical Modeling of Fully Integrated Switchable Narrow-Band CMOS Low Noise Amplifiers

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (247 KB) |  | HTML iconHTML  

    In this paper, we present an accurate and efficient analytical modeling methodology for fully integrated switchable narrow-band CMOS low noise amplifiers (LNA) in multi-band wireless systems. We employ this modeling methodology to choose the most suitable values for specific passive elements. These passive elements were chosen based on sensitivity analysis study to tune the circuit over the different frequency bands. In order to accurately predict both the impedance matching and the noise figure, the modeling methodology captures the impact of parasitics on passive components, ESD-protection structures, and devices. Our design example is a tri-band switchable narrow-band LNA that operates at 900MHz, 2.4GHz and 5.2GHz, representing the GSM, Bluetooth and WLAN standards. Based on our sensitivity analysis, we defined the most effective passive elements that can be used to tune the circuit over the three frequency bands while achieving the required performance and minimizing the number of the switchable elements. Simulation results demonstrate that our automated design methodology achieves the required LNA specifications over the tri-band while providing five orders of magnitude improvement in design space exploration speed over circuit-level based methodology. View full abstract»

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  • Mitigating the Impact of Component Variations on Narrow-Band Low Noise Amplifiers for System-on-Chip Applications

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (288 KB) |  | HTML iconHTML  

    Given the increasing demand for integrated wireless systems in system-on-chip technology, narrow-band low noise amplifier (LNA) designs must be robust against variations in device parameters and passive component values to improve manufacturing yield for high volume applications. In this paper, we develop two design techniques for reducing the impact of component variations on narrow-band LNA performance. The results demonstrate that by increasing the bandwidth of the narrow-band LNA and applying more conservative design constraints, we can mitigate the reliability implications of process variations on impedance matching, gain, and power consumption to significantly increase yield in integrated wireless applications. View full abstract»

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  • An Overview of Volterra Series Based Behavioral Modeling of RF/Microwave Power Amplifiers

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    This paper presents an overview of recently-developed, simplified Volterra series based, behavioral modeling approaches for radio frequency and microwave power amplifiers. Various model topologies and model pruning strategies are discussed, together a presentation of their comparative advantages and limitations. View full abstract»

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  • A Fast Sequential Load-Pull Algorithm Implemented to Find Maximum Output Power

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3565 KB) |  | HTML iconHTML  

    In power amplifier design, it is often desired to determine the maximum output power of a transistor through a small number of measurements or simulations. A sequential search algorithm has been implemented in MATLAB to conduct a search for the load reflection coefficient providing maximum output power, performing a sequence of simulations in Agilent advanced design system (ADS). This paper describes the results and features of the co-simulation with ADS and MATLAB. It is found that excellent agreement is obtained with traditional load-pull simulations; however, the sequential search uses only a small number of simulated points to find the optimum reflection coefficient. View full abstract»

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  • AlGaN/GaN 120W WCDMA Doherty Amplifier with Digital Pre-Distortion Correction

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    The design of a 120W 2.1GHz AlGaN/GaN Doherty amplifier optimized for maximum efficiency is reported. Compared with a class AB PA using the same device technology, the gallium nitride (GaN) Doherty amplifier provides up to 7% improvement in drain efficiency at 3dB back-off (BO) from maximum power. Using digital pre-distortion (DPD) with crest reduction, 45% drain efficiency at 47dbm output power at -45dBcACLR was observed for a single carrier 64 DPCH WCDMA signal. View full abstract»

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  • A Linearized Cascode CMOS Power Amplifier

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3416 KB) |  | HTML iconHTML  

    In this paper, an RF predistorter linearizer compatible with a CMOS process is proposed. The predistorter uses a diode connected MOSFET as a nonlinearity generation circuit. A negative or positive AM-PM characteristic is obtained from the predistorter by inserting a capacitor or an inductor in parallel with the predistorter. A 5.8 GHz cascode CMOS power amplifier was designed using a 0.18-mum 1P6M mixed-mode CMOS process and a predistorter was customized for the cascode power amplifier and integrated with it. The gain and phase distortion of the power amplifier were compensated and the simulation result of the cascode power amplifier shows a 29.3-dB improvement in the third order inter-modulation distortion when the predistorter is turned on. View full abstract»

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  • Achievements of European Research Cooperation on Microwave Amplifiers in the TARGET Network

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (220 KB) |  | HTML iconHTML  

    A remarkably extensive cooperation involving most of the major organizations involved in microwave amplifier research in Europe reaches its third birthday at the end of 2006. This "network of excellence" called TARGET is co-funded by the European Commission and aims to create a new culture of cooperation and synergy within the power amplifier domain in Europe. The expected benefits include greater efficiency, efficiencies of scale through avoiding duplication and the achievement of a large critical mass. This paper reviews the achievements of TARGET and the extent to which it is fulfilling its initial objectives. View full abstract»

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