[pt] A busca constante pela melhoria dos meios de comunicação em banda larga demandou o surgimento de novas tecnologias visando atender a real necessidade de seus usuários. O uso de mobilidade no acesso à internet banda larga como propõem os padrões WiMAX e LTE, impõe a necessidade de se estudar com mais profundidade os parâmetros que caracterizam um canal rádio móvel. Este trabalho objetiva apresentar os resultados experimentais que permitem caracterizar em banda estreita o comportamento do canal de radiopropagação num ambiente urbano. Como resultado das campanhas de medições, são identificados modelos do canal que possibilita ao projetista definir os melhores critérios para a implantação de uma rede móvel de acesso sem fio. Desta forma, são apresentadas duas campanhas de medições, operando nas frequências de 2,5 GHz e 3,5 GHz, destinadas para novos serviços móveis banda larga. / [en] The constant search for improvement of broadband communication systems requires new technologies to attend the increasing needs of the users. The use of mobility in broadband Internet access as proposed in WiMAX and LTE standards, imposes the need to further understand the parameters that characterize a channel mobile radio. This dissertation presents experimental results that allow characterizing the narrow band channel behavior of radio propagation in an urban environment. As a result of measurement campaigns, channel models are identified which allow the designer to define the best criteria to implement a mobile wireless network. The work presents results of two measurement campaigns, at the frequencies of 2.5 GHz and 3.5 GHz, designed for new mobile broadband services.

The 5 GHz Wireless LAN (802.11a) is a popular standard for wireless indoor communications providing moderate range and speed. Combined with the emerging ultra Wideband standard (UWB) for short range and high speed communications, the two standards promise to fulfil all areas of wireless application needs. However, due to the overlapping of the two spectrums, the stronger 802.11a signals tend to interfere causing degradation to the UWB receiver. This presents one of the main technical challenges preventing the wide acceptance of UWB. The research work presented in this thesis is to propose a low cost RF receiver front-end filter topology that would resolve the narrowband (NB) interference to UWB receiver while being operable in both 802.11a mode and UWB mode. The goal of the dual mode filter design is to reduce cost and complexity by developing a fully integrated front-end filter. The filter design utilizes high Q passive devices and Q-enhancement technique to provide front-end channel-selection in NB mode and NB interference rejection in UWB mode. In the 802.11a NB mode, the filter has a tunable gain of 4 dB to 25 dB, NF of 8 dB and an IIP3 between -47 dBm and -18 dBm. The input impedance is matched at -16 dB. The frequency of operation can be tuned from 5.15 GHz to 5.35 GHz. In the UWB mode, the filter has a gain of 0 dB to 8 dB across 3.1 GHz to 9 GHz. The filter can reject the NB interference between 5.15 GHz to 5.35 GHz at up to 60 dB. The Q of the filter is tunable up to a 250 while consuming a maximum of 23.4 mW of power. The fully integrated dual mode filter occupies a die area of 1.1 mm2.

The 5 GHz Wireless LAN (802.11a) is a popular standard for wireless indoor communications providing moderate range and speed. Combined with the emerging ultra Wideband standard (UWB) for short range and high speed communications, the two standards promise to fulfil all areas of wireless application needs. However, due to the overlapping of the two spectrums, the stronger 802.11a signals tend to interfere causing degradation to the UWB receiver. This presents one of the main technical challenges preventing the wide acceptance of UWB. The research work presented in this thesis is to propose a low cost RF receiver front-end filter topology that would resolve the narrowband (NB) interference to UWB receiver while being operable in both 802.11a mode and UWB mode. The goal of the dual mode filter design is to reduce cost and complexity by developing a fully integrated front-end filter. The filter design utilizes high Q passive devices and Q-enhancement technique to provide front-end channel-selection in NB mode and NB interference rejection in UWB mode. In the 802.11a NB mode, the filter has a tunable gain of 4 dB to 25 dB, NF of 8 dB and an IIP3 between -47 dBm and -18 dBm. The input impedance is matched at -16 dB. The frequency of operation can be tuned from 5.15 GHz to 5.35 GHz. In the UWB mode, the filter has a gain of 0 dB to 8 dB across 3.1 GHz to 9 GHz. The filter can reject the NB interference between 5.15 GHz to 5.35 GHz at up to 60 dB. The Q of the filter is tunable up to a 250 while consuming a maximum of 23.4 mW of power. The fully integrated dual mode filter occupies a die area of 1.1 mm2.

No description available.

No description available.

No description available.

In 1997 the Federal Communications Commission (FCC) released 300 MHz of spectrum between 5-6 GHz designated the unlicensed national information infrastructure (U-NII) band. The intention of the FCC was to provide an unlicensed band of frequencies that would enable high-speed wireless local area networks (WLANs) and facilitate wireless access to the national information infrastructure with a minimum interference to other devices. Currently, there is a lack of cost-effective technologies for developing U-NII band components. With the commercial market placing emphasis on low cost, low power, and highly integrated implementations of RF circuitry, alternatives to the large and expensive distributed element components historically used at these frequencies are needed. Silicon Germanium (SiGe) BiCMOS technology represents one possible solution to this problem. The SiGe BiCMOS process has the potential for low cost since it leverages mature Si process technologies and can use existing Si fabrication infrastructure. In addition, SiGe BiCMOS processes offer excellent high frequency performance through the use of SiGe heterojunction bipolar transistors (HBTs), while coexisting Si CMOS offers compatibility with digital circuitry for high level 'system-on-a-chip' integration. The work presented in this thesis focuses on the development of a SiGe RFIC front-end for operation in the U-NII bands. Specifically, three variants of a packaged low noise amplifier (LNA) and a packaged active x2 sub-harmonic mixer (SHM) have been designed, simulated and measured. The fabrication of the Rifts was through the IBM SiGe foundry; the packaging was performed by RF Micro devices. The mixer and LNA designs were fabricated on separate die, packaged individually, and on-chip matched to a 50 ohm system so they could be fully characterized. Measurements were facilitated in a coaxial system using standard FR4 printed circuit boards. The LNA designs use a single stage, cascoded topology. The input ports are impedance matched using inductive emitter degeneration through bondwires to ground. One version of the LNA uses an shunt inductor/series capacitor output match while the other two variation use a series inductor output match. Gain, isolation, match, linearity and noise figure (NF) were used to characterize the performance of the LNAs in the 5 - 6 GHz frequency band. The best LNA design has a maximum gain of 9 dB, an input VSWR between 1.6:1 and 2:1, an output match between 1.7:1 and 3.6:1, a NF better than 3.9 dB and an input intercept point (IIP3) greater than 5.4 dBm. The LNA operates from a 3.3 V supply voltage and consumes 4 mA of current. The SHM is an active, double-balance mixer that achieves x2 sub-harmonic mixing through two quadrature (I/Q) driven, stacked Gilbert-cell switching stages. Single-ended-to-differential conversion, buffering and I/Q phase separation of the LO signal are integrated on-chip. Measurements were performed to find the optimal operating range for the mixer, and the mixer was characterized under these sets of conditions. It was found that the optimal performance of the mixer occurs at an IF of 250-450 MHz and an LO power of -5 dBm. Under these conditions, the mixer has a measured conversion gain of 9.3 dB, a P_1-dB of -15.7 dBm and an 2LO/RF isolation greater than 35 dB at 5.25 GHz. At 5.775 GHz, the conversion gain is 7.7 dB, the P_1-dB is -15.0 dBm, and the isolation is greater than 35 dB. The mixer core consumes 9.5 mA from a 5.0 V supply voltage. This work is sponsored by RF Microdevices (RFMD)through the CWT affiliate program.The author was supported under a Bradley Foundation fellowship. / Master of Science

In this master´s thesis an issue of broadband planar antennas was analyzed. Firstly, the basic elements that affect bandwidth, such as the influence of the dieletric substrate, suitable shape or feeding network, were described. Furthermore technics that can be used to widen the band of the planar antennas were described. These technics were applied to a chosen type of a planar antenna. This antenna was modeled and simulated for desired dielectric substrate in CST STUDIO SUITE 2010 software. Feeding network with power dividers was designed for the antenna array. In order to obtain a higher gain, the antenna was implemented into the 2x2 element array. The results of the simulation are evaluated in the conclusion.

In-phase and quadrature (I/Q) signal generation is often required in modern transceiver architectures, such as direct conversion or low-IF, either for vector modulation and demodulation, negative frequency recovery in direct conversion receivers, or image rejection. If imbalance between the I and Q channels exists, the bit-error-rate (BER) of the transceiver and/or the image rejection ratio (IRR) will quickly deteriorate. Methods for correcting I/Q imbalance are desirable and necessary to improve the performance of quadrature transceiver architectures and modulation schemes. This thesis presents the design and characterization of a monolithic 5-6 GHz Silicon Germanium (SiGe) inductor-capacitor (LC) tank voltage controlled oscillator (VCO) with tunable polyphase outputs. Circuits were designed and fabricated using the Motorola 0.4 ìm CDR1 SiGe BiCMOS process, which has four interconnect metal layers and a thick copper uppermost bump layer for high-quality radio frequency (RF) passives. The VCO design includes full-wave electromagnetic characterization of an electrically symmetric differential inductor and a traditional dual inductor. Differential effective inductance and Q factor are extracted and compared for simulated and measured inductors. At 5.25 GHz, the measured Q factors of the electrically symmetric and dual inductors are 15.4 and 10.4, respectively. The electrically symmetric inductor provides a measured 48% percent improvement in Q factor over the traditional dual inductor. Two VCOs were designed and fabricated; one uses the electrically symmetric inductor in the LC tank circuit while the other uses the dual inductor. Both VCOs are based on an identical cross-coupled, differential pair negative transconductance -GM oscillator topology. Analysis and design considerations of this topology are presented with a particular emphasis on designing for low phase noise and low-power consumption. The fabricated VCO with an electrically symmetric inductor in the tank circuit tunes from 4.19 to 5.45 GHz (26% tuning range) for control voltages from 1.7 to 4.0 V. This circuit consumes 3.81 mA from a 3.3 V supply for the VCO core and 14.1 mA from a 2.5 V supply for the output buffer. The measured phase noise is -115.5 dBc/Hz at a 1 MHz offset and a tank varactor control voltage of 1.0 V. The VCO figure-of-merit (FOM) for the symmetric inductor VCO is -179.2 dBc/Hz, which is within 4 dBc/Hz of the best reported VCO in the 5 GHz frequency regime. The die area including pads for the symmetric inductor VCO is 1 mm x 0.76 mm. In comparison, the dual inductor VCO tunes from 3.50 to 4.58 GHz (27% tuning range) for control voltages from 1.7 to 4.0 V. DC power consumption of this circuit consists of 3.75 mA from a 3.3 V supply for the VCO and 13.3 mA from a 2.5 V supply for the buffer. At 1 MHz from the carrier and a control voltage of 0 V, the dual inductor VCO has a phase noise of -104 dBc/Hz. The advantage of the higher Q symmetric inductor is apparent by comparing the FOM of the two VCO designs at the same varactor control voltage of 0 V. At this tuning voltage, the dual inductor VCO FOM is -166.3 dBc/Hz compared to -175.7 dBc/Hz for the symmetric inductor VCO -- an improvement of about 10 dBc/Hz. The die area including pads for the dual inductor VCO is 1.2 mm x 0.76 mm. In addition to these VCOs, a tunable polyphase filter with integrated input and output buffers was designed and fabricated for a bandwidth of 5.15 to 5.825 GHz. Series tunable capacitors (varactors) provide phase tunability for the quadrature outputs of the polyphase filter. The die area of the tunable polyphase with pads is 920 ìm x 755 ìm. The stand-alone polyphase filter consumes 13.74 mA in the input buffer and 6.29 mA in the two output buffers from a 2.5 V supply. Based on measurements, approximately 15° of I/Q phase imbalance can be tuned out using the fabricated polyphase filter, proving the concept of tunable phase. The output varactor control voltages can be used to achieve a potential ±5° phase flatness bandwidth of 700 MHz. To the author's knowledge, this is the first reported I/Q balance tunable polyphase network. The tunable polyphase filter can be integrated with the VCO designs described above to yield a quadrature VCO with phase tunable outputs. Based on the above designs I/Q tunability can be added to VCO at the expense of about 6 mA. Future work includes testing of a fabricated version of this combined polyphase VCO circuit. / Master of Science

<p>Rapporten är en jämförande studie av täckningsgrad och bandbredd i trådlösa nätverk av typ hot-spot med IEEE 802.11A/G respektive IEEE 802.11N Draft 2.0. Studien är gjord i tre olika scenarion på Kvarnholmen i Kalmar under april och maj månad 2008.</p>