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Wireless and Microwave Technology Conference, 2009. WAMICON '09. IEEE 10th Annual

Date 20-21 April 2009

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  • WAMICON 2009 IEEE Wireless and Microwave Technology Conference

    Publication Year: 2009 , Page(s): 1 - 5
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  • Propagation modeling — a CSP approach

    Publication Year: 2009 , Page(s): 1 - 5
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    Radio wave propagation models are extremely important in radio network planning as well as in interference planning, for the frequency range between 500 MHz and 5 GHz. This is because of the fact that an accurate propagation model enables efficient prediction of the coverage area of a cell and efficient resource reallocation in the form of better coverage prediction at the desired area. A certain model is usually applicable to limited distances and other parameter values. The simplest approach to the prediction of the field strength in urban scenarios is empirical models. The empirical models are very fast but they are not very accurate. Each of these models can also be viewed as a constraint satisfaction problem (CSP). In general, each propagation model involves a large number of variables such as frequency, base station antenna height, mobile station antenna height, distance etc. Each variable has a well-defined domain for a particular mobile environment under consideration and the constraint can be defined on the term representing the path loss. Therefore, the constraint satisfaction problem can be well utilized to model the propagation phenomenon. In the present work, the objective is to analyze the propagation modeling using CSP algorithms. There are five CSP algorithms such as backtracking, backjumping, conflicted directed backjumping, backmarking, forward checking and their hybrids. In our work backtracking CSP algorithm are used to compute the path loss against various parameters for Okumura-Hata and Walfisch-Ikegami models and analyze their behaviour at higher frequency ranges. View full abstract»

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  • A model to predict reverberant decay time in reflective spaces for wireless applications

    Publication Year: 2009 , Page(s): 1 - 5
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    A simple model for predicting the characteristic energy decay time of wireless RF emissions in confined, reflective spaces is presented. Based on this cavity decay time, accurate estimates of room quality factor, diffuse (multi-path) insertion loss, and average electric field components are possible. Spaces of interest for model applications include aircraft cabins, below-deck compartments in ships, automobile interiors and metallic building or room enclosures. Decay time predictions are shown to be in excellent agreement with measured data from two different reverberant spaces over the 1-14 GHz frequency range. View full abstract»

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  • 5-GHz low-phase noise quadrature VCO in 0.13−μm RF CMOS process technology

    Publication Year: 2009 , Page(s): 1 - 4
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (454 KB) |  | HTML iconHTML  

    In this paper, a 5 GHz low-phase noise RF CMOS quadrature voltage controlled oscillator (QVCO) is presented. The quadrature signals are generated by coupling two VCOs through pMOS coupling transistors. The tail biasing MOS current mirror is replaced with tail biasing resistor of 100 Omega multifingers gate structure of pMOS varactor (3.125 mum width of each gate finger) and source damping resistor of 40 are the techniques which are used to achieve low phase noise in proposed QVCO. The pMOS varactor releases the frequency tuning range of 5.26% from the center frequency of 5.13 GHz. The proposed QVCO core power dissipation is 3.7 mW from 1.2 V DC power supply. The QVCO exhibits the measured phase noise of -118.24 dBc/Hz at the offset frequency of 1 MHz. The calculated figure of merit is -186.7. The proposed QVCO is implemented utilizing 0.13 mum 1 poly 8 metal RF CMOS process technology. View full abstract»

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  • A high-gain high-linearity distributed amplifier for ultra-wideband-applications using a low cost SiGe BiCMOS technology

    Publication Year: 2009 , Page(s): 1 - 4
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    In this paper the analysis, design and characterization of a 1-15 GHz power distributed amplifier for ultra-wideband radar and sensing applications are presented. The amplifier is fabricated in a low cost 0.25 mum SiGe BiCMOS technology with a transit frequency ft of 25 GHz. The circuit integrates four cascode gain cells, which are capacitively coupled to the base line for power optimization and bandwidth enhancement. Up to 16.9 dBm output power have been measured at the 1 dB compression point (P1 dB) in the desired frequency range with an associated gain of 11.5 dB and a gain flatness of plusmn1 dB with total power consumption of 450 mW. The maximum third order intermodulation intercept point (OIP3) is 21.5 dBm. The chip size of the amplifier is 1.19mm2. View full abstract»

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  • Design, fabrication and measurement of a GPS-Galileo dual-passband filter

    Publication Year: 2009 , Page(s): 1 - 4
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1682 KB) |  | HTML iconHTML  

    This paper presents the design, fabrication and measurement of a GPS-Galileo dual-passband filter. The applied synthesis methodology is based on a frequency transformation of the Chebyshev low-pass prototype, and unlike most of conventional synthesis methodologies allows us to design dual-passband filters as classical coupled-resonator filters. The filter is designed and fabricated in microstrip technology which offers a very cost effective device with reduced size and weight. The measured insertion loss is about 2 dB in the lower band and 3.5 dB in the higher band. Lower insertion loss is possible using resonators with higher unloaded quality factor, for example cavity resonators, but on the other hand this type of resonators presents much higher cost, size and weight. View full abstract»

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  • Design of uplink schedulers for broadband wireless access networks

    Publication Year: 2009 , Page(s): 1 - 2
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1175 KB) |  | HTML iconHTML  

    In order to support different types of multimedia applications, the IEEE 802.16 standard defines different service classes with their associated quality of service (QoS) parameters [1]. The scheduling algorithm is the crucial point in QoS provisioning over such broadband wireless access (BWA) network and it is important that the scheduling algorithm have a multi-dimensional objective of satisfying QoS requirements of the users, maximizing system utilization and ensuring fairness among users [2], [3]. In this article we present two different scheduling algorithms for the uplink (UL) connection. One is a combination of legacy scheduling algorithms earliest deadline first (EDF) and weighted fair queuing (WFQ). The other proposed algorithm is a cross-layer algorithm that pledges fairness among admitted connections and it also supports all service classes. View full abstract»

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  • Predictive traffic estimation for uplink resource allocation in satellite communications

    Publication Year: 2009 , Page(s): 1 - 6
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (107 KB) |  | HTML iconHTML  

    In this paper, we propose a predictive traffic estimation strategy for the resource allocation to uplinks in the satellite communication. Estimating the traffic arriving during the next epoch is an important part of the dynamic bandwidth resource allocation (DBRA). Based on this estimate, the terminals request the bandwidth resources for transmission during the next epoch or next several epochs. This problem becomes critical when traffic from different quality of service (QoS) require different traffic treatments, and the constraints of the delay and jitter become crucial. This necessitates that such traffic, which are sensitive to delay & jitter, not be queued at all, with dedicated resources assigned to them. At the same time, it is also necessary that the available bandwidth be efficiently used, if such traffic is not active and the lower class traffic needs band-width. Many of the available techniques estimate the traffic requirements based on the queue occupancy and the rate requirements. Reserving precious bandwidth for the highest QoS traffic may result in wasting the bandwidth and may also result in swelling queues of lower priority classes. Furthermore, allocating the resources based on the queue size only may not be enough to give the right estimate of the arrival rates. This study explores the applicability of the predictive estimation techniques for the demand estimation in a QoS environment. View full abstract»

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  • A fault tolerant location management for MNANET

    Publication Year: 2009 , Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (185 KB) |  | HTML iconHTML  

    In an Ad-hoc network, mobile nodes disconnected intermittently. One of the biggest challenges in such network is design of routing protocols that tolerate the nodes disconnection. In this paper, we present a novel schema to perform fault tolerant location management named FTLM. With location management scheme, each source node in the network trusts a small subset of nodes, namely its location servers, and updates them with its new geographic location. Fault tolerance in our approach achieved by redundancy in number of location servers that store node's positions. Same the Octopus we employ synchronized aggregation technique to decreasing location management overhead. In this technique the location of many nodes updated at many other nodes with only a single packet. Simulation results show that FTLM is more scalable than Octopus and some other location management methods, moreover it is highly fault tolerant in failure prone environments. View full abstract»

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  • Diamond Dipole antenna optimization using a genetic Algorithm/Finite Difference Time Domain hybrid technique

    Publication Year: 2009 , Page(s): 1 - 2
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (762 KB) |  | HTML iconHTML  

    An optimized diamond dipole antenna for ultra-wideband (UWB) operation is presented in this paper. The optimization method uses a hybrid genetic algorithm (GA) and finite-difference time-domain (FDTD) technique. The method obtains a structure with increased bandwidth performance in the UWB.The radiating elements of the antenna are made out of very thin perfectly electric conducting (PEC) material and they are etched onto a substrate material with a dielectric constant (epsivr = 4.3), the thickness t of the substrate is 1.59 mm. The electromagnetic analysis is done using the XFDTDTM software, which is a commercial FDTD program by Remcom, Inc. The antenna geometry is modeled with a spatial grid of (1 times 1 times 0.4 mm3). The antenna is excited with a gap voltage source (1.0-V Gaussian derivative pulse) with a 50-Omega source resistance. FDTD grid is terminated using Liao's absorbing boundary condition. Figure 1 below shows the geometry of the diamond dipole antenna. Dimensions (mm): d = 24, h = 8, r = 12, s = 1,t = 1.59, L = 41. View full abstract»

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  • AlGaN/GaN HEMT temperature-dependent large-signal model thermal circuit extraction with verification through advanced thermal imaging

    Publication Year: 2009 , Page(s): 1 - 5
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (566 KB) |  | HTML iconHTML  

    Investigation has been done on procedure, development and verification of a large-signal, temperature-dependent model for aluminum-gallium-nitride/gallium-nitride (AlGaN-GaN) high-electron-mobility transistors (HEMTs). Procedural issues have been designed to investigate model selection based on application and operation over varying bias. Theoretical and experimental analysis has been completed on device operating point selection in measurement and modeling to account for thermal coefficient extraction and RF dispersion effects. The model has been optimized for use in power amplifier design applications that apply class AB operation. Advanced thermal imaging verification has been performed to validate thermal resistance modeling parameters. View full abstract»

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  • Design of high directivity microstrip coupler with single floating conductor on coupled edges

    Publication Year: 2009 , Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (219 KB) |  | HTML iconHTML  

    This paper presents a design of new quarter-wavelength microstrip coupler with high directivity, which consists of a single floating conductor in the slot on the inner edges. The design procedure doesn't require the prior knowledge of the physical geometry of the coupler and requires only the information of the port impedances, coupling and operational frequency. Using this new design, a 15-dB coupler is designed and a high directivity of 25 dB or more is obtained over a considerably wide bandwidth. The validity of the design concept is confirmed by EM-simulations. View full abstract»

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  • Compact, tunable large group delay line

    Publication Year: 2009 , Page(s): 1 - 3
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    In this letter, we present a compact, tunable delay line based on left-handed nonlinear transmission line (LH NLTL). The widely tunable range of the large group delay is achieved by controlling a reverse bias voltage of series varactors in the LH NLTL. The proposed tunable delay line can be made in a very compact form since its size is dominated by the cascaded varactors. Our experiment shows that the fabricated prototype exhibits tunable group delay between 1.2 ns and 2.2 ns at a frequency of 1.42 GHz with good return loss. The circuit size is merely 1.6 cm in length. View full abstract»

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  • A CMOS 434/868 MHz FSK/OOK transmitter with integrated fractional-N PLL

    Publication Year: 2009 , Page(s): 1 - 4
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    A 434/868 MHz FSK/OOK transmitter with integrated PLL is reported. Direct digital modulation of a fully integrated ¿-¿ fractional-N PLL frequency synthesizer is used to ensure fine frequency resolution and low phase noise. A wideband VCO together with an adaptive frequency calibration (AFC) is used to cover the desired bands. A differential-to-single output programmable power amplifier is integrated to make the chip low cost and low power. The measurement results show that the phase noise are -76dBc/Hz and -131dBc/Hz at 10-kHz offset and 3-MHz offset with carrier centered at 868 MHz, respectively. The peak output power of the transmitter is is 3.5 dBm on 50-¿ load and the measured adjacent channel power ratio (ACPR) for 100 kHz channel is less than -50-dBc. The chip is fabricated with 0.35-¿m RF CMOS process. The 2-mm2 transmitter IC including PLL and power amplifier (PA) consumes 87.6 mW at 3 V voltage supply. View full abstract»

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  • Compact quasi-ridged resonator for 28 GHz integrated on LCP substrate

    Publication Year: 2009 , Page(s): 1 - 3
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    In this paper an approach to design a compact substrate integrated resonator is presented. Multilayer LCP substrate integrated waveguide is loaded with a quasi-ridged structure. Component is designed with a resonant frequency of 28 GHz. Proposed structure is 4.5 times more compact by square than its conventional substrate integrated counterpart and 1.7 times than resonator designed using EBG-substrate. Chebyshev filter with proposed resonator is designed; its layout and characteristics are presented. View full abstract»

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  • An adaptive fuzzy logic based vertical handoff decision algorithm for wireless heterogeneous networks

    Publication Year: 2009 , Page(s): 1 - 9
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (8592 KB) |  | HTML iconHTML  

    Handoff decision making is one of the most challenging issues in wireless heterogeneous networks designs since there are many parameters which have to be considered when triggering handoff and choosing the best candidate access point. Various parameters such as data rate, monetary cost, remaining battery, mobile speed, etc., must be exploited in handoff process of wireless overlapped networks along with the RSSI information which is already utilized widely in traditional networks. Beside these parameters, an effective handoff decision algorithm must be developed to combine and process them as well. In this study, an adaptive fuzzy logic based handoff decision algorithm is introduced for wireless heterogeneous networks. The parameters data rate, monetary cost, RSSI, and mobile speed are considered as inputs of the proposed fuzzy based system. According to these parameters, an output value, which varies between one and ten, is produced. This output describes the candidacy level of the available access points in the vicinity of smart terminal and is utilized in the access point selection algorithm. This algorithm decides whether a handoff is necessary or not, by using the handoff resolution value. The results show that, compared to the traditional RSSI based algorithms the performance is significantly enhanced for both user and network by the method proposed. View full abstract»

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  • A novel design procedure for tunable low noise amplifiers

    Publication Year: 2009 , Page(s): 1 - 5
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4324 KB) |  | HTML iconHTML  

    A novel design methodology for tunable low noise amplifiers with the associated circuit topology will be presented. The procedure steps based on low noise design essentials are given as the main results of their mathematical analysis using the circuit and noise theory. After the methodology is demonstrated at narrowband by the simulation graphs, the tunability aspect of the design using the series matching at the input and output will be verified. If a tunable capacitor is inserted to the base of the heterojunction bipolar transistor (HBT) at the input, simulation outcomes reveal that for the range of 3.5- 6.5 GHz, input and output return ratios (S11 and S22) can be ensured to be below -10 dB and the difference between noise figure (NF) and minimum noise figure (NFMIN) to be below 0.5 dB. View full abstract»

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  • Experimental investigation of WCDMA uplink transmit power for practical usage scenarios

    Publication Year: 2009 , Page(s): 1 - 4
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (311 KB) |  | HTML iconHTML  

    This paper presents an empirical investigation into WCDMA uplink (UL) transmit power for various indoor/outdoor locations. Specifically, the statistics of UL transmit power measured in different locations over a commercial UMTS network are provided and compared. Similar locations are then grouped to form four practical mobile usage scenarios, and their empirical probability distribution functions are analyzed. Further, we investigate the impact of typical handset positions (next to the ear and using a Bluetooth headset) on the UL transmit power levels. The results presented in this paper can be useful for not only optimizing a WCDMA handset design for the UMTS network, but also predicting battery life and examining WCDMA coverage. View full abstract»

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  • An analysis of uplink transmit power in WCDMA networks

    Publication Year: 2009 , Page(s): 1 - 4
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4926 KB) |  | HTML iconHTML  

    In this paper, we present an experimental analysis of uplink (UL) transmit power in WCDMA networks based on measurement data over a commercial UMTS network. In particular, three factors which may influence the transmit power profiles in practical mobile usage scenarios are examined: (a) handset position, (b) channel effects, and (c) network loading. First, a handset under test is placed at different positions relative to the body or nearby objects during peak and off-peak hours. Second, we study the relationship between the UL transmit power and received signal code power (RSCP) via a linear regression model. Then, the effect of network loading during three times of the day is examined for different areas and handset positions. Throughout this paper, measurement results of mean UL transmit power and RSCP along with their scatter plots are presented. View full abstract»

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  • Design of a variable gain and phase amplifier using double resonance and current conveyor circuits

    Publication Year: 2009 , Page(s): 1 - 5
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    Some radiofrequency applications require control of magnitude and phase of narrowband signals, such as beamforming networks for antenna arrays. An amplifier capable of varying magnitude and phase of a signal through control signals can be called a variable gain and phase amplifier (VGPA). In this paper a VGPA circuit is proposed which utilizes two double resonance circuits, each one with a voltage variable capacitor to produce magnitude and phase variations. To avoid excessive reflections at the output port, and to establish high impedance in certain parts of the circuit, two current conveyor circuits connected as voltage follower are used. Analysis of each stage as well as design methodology is presented. A design example is carried out and graphics for the properties of gain and phase are obtained using simulation tools. Although control of these characteristics is not independent, the advantage is that it can be done by a single circuit. View full abstract»

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  • Ultrawideband EH shaped stack patch antenna for wireless communications

    Publication Year: 2009 , Page(s): 1 - 4
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    A broadband folded patch feed antenna for ultrawideband (UWB) application is proposed and designed. The antenna consists of a folded patch feed and a shorting wall attached to E and H shaped stack patch. Bandwidth broadening is achieved by an H shaped patch fed by a folded patch feed and the size reduction is realized through the use of shorting wall. Electromagnetic coupling in between E and H shaped stack patch further enhance the impedance bandwidth in this design. The proposed antenna has a small electrical size of 19 times 15 times 10 mm3 and an impedance bandwidth of 102.36% ranging from 3.42 to 10.59 GHz. Relatively stable radiation patterns with gain greater than 4.5 dBi is obtained over the entire bandwidth. View full abstract»

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  • A noise-optimized LC-VCO and DTC

    Publication Year: 2009 , Page(s): 1 - 10
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    This paper presents a phase noise analysis for all-PMOS Voltage-Controlled Oscillators (VCOs) in 1/f2 region. A closed-form equation for VCO phase noise is derived as an auxiliary optimization tool for designers. The maximum operating frequency of divide-by-two circuit (DTC) is predicted to help reduce the phase noise introduced by the DTC. Based on the derived formulas, size optimization for noise performance of VCO and DTC is possible. Also, the DTC can generate IQ signal. In order to reduce the noise arose from the upconversion of flicker noise and thermal noise in current tail, a parallel LC circuit resonating at twice the VCO frequency is inserted between the cross-coupled pair and PMOS tail. The simulation results show that the VCO has a phase noise of -131 dBc@1 MHz offset with 2-GHz center frequency when consuming 4 mA from a 3.3-V voltage supply. The DTC output improves the phase noise by 6 dB while taking 500 uA. The simulations are done with 0.35 um CMOS models. View full abstract»

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  • Distortion improvement of power amplifiers with digital predistortion

    Publication Year: 2009 , Page(s): 1 - 2
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (234 KB) |  | HTML iconHTML  

    This paper presents an optimized digital predistortion (DPD) technique based on iterative injecting of distortion components into the baseband signal. The ratio of computation complexity to linearization degree can be regulated by choosing the appropriate number of injections. The proposed DPD technique allows achieving a significant increase in linearization degree and overcoming the distortion compensation limit. Experimental results for a 21-dB gain GaAs power amplifier fed with a 5-MHz digitally modulated signal show significant improvement in spectral regrowth. View full abstract»

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  • Compact microstrip pseudo-interdigital stepped impedance bandpass filters with improved stopband performance

    Publication Year: 2009 , Page(s): 1 - 2
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    In this paper we present design of a compact microstrip pseudo-interdigital stepped impedance bandpass filter with improved stopband performance. Stepped-impedance resonators are used to maximise the ratio between higher order and fundamental resonances. The improved stopband performance is realized using additional spur line and open-stub sections used for creation of transmission zeros. Total size of the filter is 30.1times7.2 mm. The stopband extension up to 5.7f0 has been achieved. View full abstract»

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  • A Study of memory effects of RF power LDMOS before and after digital predistortion

    Publication Year: 2009 , Page(s): 1 - 5
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (285 KB) |  | HTML iconHTML  

    Sideband asymmetries in distortion products are created due to electrical and thermal memory effects and this can be difficult to correct for in a digital predistortion algorithm. In this study, sideband asymmetries in third-order intermodulation distortion products before and after digital predistortion were investigated using 2-tone and 2-carrier WCDMA signals. The parallel Hammerstein (PH) model was used in the digital predistortion algorithm. The sign of the asymmetries before correction were found to depend on power level. Memoryless correction lead to an increase in asymmetries for some power ranges whereas using a PH model of order 13 with only one order of memory length lead to good correction over a large power range. View full abstract»

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