No description available.

The availability of low-cost wireless devices has enabled wide-scale connectivity over recent years. Today’s wireless devices provide services including voice communication, GPS location, and internet connectivity. With a larger number of supported wireless standards within a single device, new wireless radio techniques are required in order to implement flexible and programmable broadband receivers to replace the standard specific receivers often seen today. The continual growth in the use of the wireless spectrum has led to an increasingly hostile interference environment for such receivers. While interferers may be located out of the signal band of interest, they may still reside within the large band of operation of the broadband receiver, making removal of the interference by filtering difficult. The requirement for small form-factor and cost minimization has made an increased level of integration highly desirable to minimize the number of external filter components required to reject interferers. A key consideration in the design of broadband receivers is the spurious response of the downconversion mixers, where local oscillator (LO) harmonics can lead to downconversion of unfiltered interferers to baseband, along with the desired signal, thus degrading the signal-to-noise ratio. Recent broadband receivers utilize a harmonic rejection mixer to reject LO harmonics within the downconversion mixer and prevent interferers from being downconverted to baseband. This report details the cause of harmonic mixing within CMOS mixers and provides a survey of published circuit techniques robust to device mismatch to remove LO harmonic response. A description of frequency translation and the effect of harmonic mixing on the translation is presented. The theoretical background of the operation of harmonic rejection mixers is described, including the effect of gain and phase errors on the achievable level of harmonic rejection. An overview of published harmonic rejection mixer techniques including the first harmonic rejection mixer and techniques to limit the effects of phase and gain mismatch on harmonic rejection is discussed. The report concludes with the introduction of a novel method for effective synthesis of multiple downconversion local oscillator frequencies within a harmonic rejection mixer. The proposed method reduces the tuning range required of the downconversion oscillator in broadband applications. Based on Monte Carlo simulations, while considering device mismatches over a 3σ spread, harmonic rejection better than 63 dB is observed for all selectable LO frequencies. / text

There exists a need for a new class of underwater vehicle that can perform both close control tasks, as well as long-range exploration, without manual reconfiguration. A tetherless underwater vehicle (TUV) with acoustic communications to an operator station has potential to fulfill this need, while also removing much of the operating costs associated with tether management. The problem with TUVs is the limited communications bandwidth and time lag increasing with range from the transmitter. This thesis introduces a new class of controller for TUV vehicles that isolates the operator from the time-varying delay. This isolation is achieved through the formation of a continuum of control comprised of existing control paradigms, such as predictive and autonomous control. A smooth evolution through the continuum is formulated based on the time delay. The resulting controller permits operator close control for extended ranges without manual reconfiguration of the vehicle or controller.

No description available.

In this thesis, three broadband low-noise mixing circuits which use CMOS 130 nm technology are presented. As one of the first few stages in a receiving front-end, stringent requirements are posted on mixer performance. The Gilbert cell mixers have presented excellent properties and achieved wide applications. However, the noise of a conventional active Gilbert cell mixer is high. This thesis demonstrates both passive and active mixing circuits with improved noise performance while maintaining the advantages of the Gilbert cell-based mixing core. Furthermore, wide bandwidth and variable gain are implemented, making the designed mixers multi-functional, yet with compact sizes and low power consumptions. The first circuit is a passive 2x subharmonic mixer that works from 4.5 GHz to 8.5 GHz. The subharmonic mixing core is a two-stage passive Gilbert cell driven by a quadrature LO signal. Together with a noise-cancelling transconductor and an inverter-based TIA, this subharmonic mixer possesses an excellent broadband conversion gain and a low noise figure. Measurement results show a high conversion gain of 16 dB and a low average DSB NF of 9 dB. The second design is a broadband low-noise variable gain mixer which operates between 1 and 6 GHz. The transconductor stage is implemented with noise cancellation and current bleeding techniques. Series inductive peaking is used to extend the bandwidth. Gain variation is achieved by a current-steering IF stage. Measurements show a wide gain control range of 13 dB and a low noise performance over the entire frequency and gain range. The lowest DSB NF is 3.8 dB and the highest DSB NF is 14.2 dB. The Third design is a broadband low-noise mixer with linear-in-dB gain control scheme. Using the same transconductance stage with the second circuit, this design also works from 1 to 6 GHz. A 10 dB linear-in-dB gain control range is achieved using an R-r load network with a linear-in-dB error less than $\pm$ 0.5 dB. Low noise performance is achieved. For different frequencies and conversion gains, the lowest DSB NF is 3.8 dB and the highest DSB NF is 12 dB. / Thesis (Master, Electrical & Computer Engineering) -- Queen's University, 2013-10-02 04:37:31.606

<p>In this thesis work, a design of RF down-conversion mixer for WLAN standard, such as Wi-Fi or Bluetooth is presented. The target technology is 0.35um CMOS process. Several mixer topologies are analyzed and simulated at the schematic level using the Cadence Spectre-RF software. The active double balanced mixer is chosen for the ultimate implementation. For this mixer simulation results from schematic level to layout level are presented and discussed in detail. </p><p>To build an RF front-end, the complete mixer is integrated with an available LNA block. The performance of the front-end is evaluated as well. The obtained simulation results satisfy the specification for Wi-Fi standard. </p><p>Since the RF front-end is designed for testability, the fault simulation is incorporated as well. So the performance of the front end is also evaluated for so called “spot defects”, typical of CMOS technology. They are modeled using resistive shorts or opens in the circuit.</p>

The IEEE 802.11a has become the mainstream protocol used in modern wireless communication system due to its high propagation rate of data (54 Mb/s). To meet high propagation rates, the communication devices used in IEEE 802.11a protocol usually present a high conversion gain and a high linearity (denoted as third order intercept point, IIP3). The IIP3 of conventional up- and down-conversion mixers are only about 0 dBm and -5 dBm, which fail to achieve a high propagation rate of data. This thesis utilizes the TSMC 0.18 &#x00B5;m CMOS technology to design and fabrication up- and down-conversion mixers with very high linearity for IEEE 802.11a application. The proposed high-linearity up-conversion mixer with 1.01 mm ¡Ñ 0.85 mm chip size and its wide bandwidth (5~6 GHz) is well suited for IEEE 802.11a application. To enhance the linearity and bandwidth, a transconductor stage with gm-boosted structure, a switch stgae with LO-body grounded structure and a load stage with shunt peaking structure are adopted in this research. Under 5.2/5.4/5.8 GHz operating frequencies, the implemented up-conversion mixer demonstrates a high conversion gain of 6.8/7.1/6.3 dB and a high linearity of 8.9/9/13.2 dBm, respectivly. In addition, a moderate consuming power (6.86 mW) of such mixer can be achieved at 1.2 V supply voltage. On the other hand, this thesis also designed and fabricated a high-linearity down-conversion mixer with chip size of 1.02 mm ¡Ñ 0.86 mm and 5.2 GHz center frequency. To improve the linearity and isolation and reduce the high-order noise, a transconductor stage with dual-gate structure and a load stage with RC-tank structure are adopted in this research. According to the EM-simulation resutls, the proposed down-conversion mixer presents a moderate conversion gain of 6 dB and a high linearity of 0.8 dBm. Additionly, a moderate consuming power (6.75 mW) of such mixer can be achieved at 1.8 V supply voltage.

Noise is a major environmental pollutant, which can inict physical and psychologicalinjury. An important noise contribution stems from aeroacousticsources, which are found in e.g., ventilation ducts, engine exhaust systems andairplane engines.In this thesis, research methods for low Mach number aeroacoustic sourcesin ducts are developed. The basis of the methods is the ability to describe theintrinsic linear properties of the source as an N-port (multiport), where theoutput sound eld is related to the input sound eld and the generated soundeld, all consisting of plane waves. The methods presented are both numericaland experimental. The numerical method treats the passive properties, i.e.,scattering, attenuation and amplication of incident sound, while the experimentalmethod treats the active part (intrinsic sound generation) as well. Themethods are applied in the study of noise generation by a vortex mixer plate,placed in an airow of Mach 0.2, and in the study of acoustic-hydrodynamicinteraction in a T-junction of rectangular ducts.It is found that the accuracy of the experimental methods is signicantly increasedwhen the equations are over-determined, which is achieved by addingadditional microphones to the test rig. In the frequency range studied, themixer plate is found to generate less sound when made exible, without disturbingthe mixing quality.For the numerical method { based on the linearized Navier-Stokes equations,a model of the oscillation of the Reynolds stress (\turbulent damping")due to the acoustic eld is introduced. By comparing with experimental results,it is found that not using this model results in an over-prediction of theamplication at higher frequencies with several factors in magnitude, whileimplementing the model results in a much better agreement. / <p>QC 20121123</p>

Hydrogenated nitrile butadiene rubber (HNBR) which is known for its excellent elastomeric properties and mechanical retention properties after long time exposure to heat, oil and air is produced by the catalytic hydrogenation of nitrile butadiene rubber (NBR). Hydrogenation of NBR is carried out preferably in solution via homogeneous catalysis. As yet, it is being commercially produced in a semi-batch process where gaseous hydrogen continuously flows into a batch of reactant polymer. Several catalysts have been exploited successfully for the hydrogenation of NBR in organic solvents, which include palladium, rhodium, ruthenium, iridium and osmium complexes. Owing to the drawbacks of batch production (such as time taken for charging and discharging the reactants/products, heating and cooling, reactor clean up), and the huge demand for HNBR, a continuous process is proposed where potential time saving is possible in addition to the high turn over of the product. Numerical investigation of the HNBR production in a plug flow reactor and a continuous stirred tank reactor showed that a reactor with plug flow behavior would be economical and efficient. A static mixer (SM) reactor with open-curve blade internal geometry is designed based on the simulation and hydrodynamic results. The SM reactor was designed with 24 mixing elements, 3.81 cm ID and 90 cm length. The reactor has a jacket in which steam is used to heat the polymer solution. The hydrodynamics in the SM reactor (open-flat blade structure) with air-water system showed that plug flow could be achieved even under laminar flow conditions (Reh < 20). For a constant mean residence time, the Peclet number was varying such that it is 4.7 times the number of mixing elements (ne) used in the SM reactor. Empirical correlations were developed for gas hold up (εG) and overall mass transfer coefficient (KLa). The mass transfer experiments showed that high KLa, 4 to 6 times compared to that of the conventional reactors could be achieved in the SM reactor at particular operating conditions. Very important information on the Peclet number, liquid hold were obtained from the hydrodynamic experiments conducted with the actual working fluids (hydrogen, polymer solutions) in the SM reactor. The superficial gas velocity had an adverse effect on both Peclet number and liquid hold up. The viscosity of the polymer solution also had a marginal negative effect on the Peclet number while a positive effect on the liquid hold up. The hydrogenation performance with the homogeneous catalyst OsHCl(CO)(O2)(PCy3)2 was performed in the continuous process with SM reactor. Complete hydrogenation of NBR was possible in a single pass. The effect of mean residence time, catalyst and polymer concentration on the final degree of hydrogenation was studied. The minimum catalyst required to achieve degree of hydrogenation over 97% was empirically found and an empirical correlation was developed for degree of hydrogenation as a function of operating conditions and parameters. Hydrogenation in the SM reactor is modeled by using plug flow with axial dispersion model that is coupled with the concentrations of carbon-carbon double bond, hydrogen and osmium catalyst. The model involves coupled, non-linear partial differential equations with different dimensionless parameters. The proposed model was verified with the experimental results obtained from the hydrogenation and hydrodynamic experiments. The model could satisfactorily predict the degree of hydrogenation obtained from experimental results at various operating conditions. In general, the designed continuous process with SM reactor performed well and was an effective method of manufacturing HNBR on a continuous basis. The designed system is amicable to the industrial operating conditions and promises to be highly efficient and economic process for production of HNBR.

Hydrogenated nitrile butadiene rubber (HNBR) which is known for its excellent elastomeric properties and mechanical retention properties after long time exposure to heat, oil and air is produced by the catalytic hydrogenation of nitrile butadiene rubber (NBR). Hydrogenation of NBR is carried out preferably in solution via homogeneous catalysis. As yet, it is being commercially produced in a semi-batch process where gaseous hydrogen continuously flows into a batch of reactant polymer. Several catalysts have been exploited successfully for the hydrogenation of NBR in organic solvents, which include palladium, rhodium, ruthenium, iridium and osmium complexes. Owing to the drawbacks of batch production (such as time taken for charging and discharging the reactants/products, heating and cooling, reactor clean up), and the huge demand for HNBR, a continuous process is proposed where potential time saving is possible in addition to the high turn over of the product. Numerical investigation of the HNBR production in a plug flow reactor and a continuous stirred tank reactor showed that a reactor with plug flow behavior would be economical and efficient. A static mixer (SM) reactor with open-curve blade internal geometry is designed based on the simulation and hydrodynamic results. The SM reactor was designed with 24 mixing elements, 3.81 cm ID and 90 cm length. The reactor has a jacket in which steam is used to heat the polymer solution. The hydrodynamics in the SM reactor (open-flat blade structure) with air-water system showed that plug flow could be achieved even under laminar flow conditions (Reh < 20). For a constant mean residence time, the Peclet number was varying such that it is 4.7 times the number of mixing elements (ne) used in the SM reactor. Empirical correlations were developed for gas hold up (εG) and overall mass transfer coefficient (KLa). The mass transfer experiments showed that high KLa, 4 to 6 times compared to that of the conventional reactors could be achieved in the SM reactor at particular operating conditions. Very important information on the Peclet number, liquid hold were obtained from the hydrodynamic experiments conducted with the actual working fluids (hydrogen, polymer solutions) in the SM reactor. The superficial gas velocity had an adverse effect on both Peclet number and liquid hold up. The viscosity of the polymer solution also had a marginal negative effect on the Peclet number while a positive effect on the liquid hold up. The hydrogenation performance with the homogeneous catalyst OsHCl(CO)(O2)(PCy3)2 was performed in the continuous process with SM reactor. Complete hydrogenation of NBR was possible in a single pass. The effect of mean residence time, catalyst and polymer concentration on the final degree of hydrogenation was studied. The minimum catalyst required to achieve degree of hydrogenation over 97% was empirically found and an empirical correlation was developed for degree of hydrogenation as a function of operating conditions and parameters. Hydrogenation in the SM reactor is modeled by using plug flow with axial dispersion model that is coupled with the concentrations of carbon-carbon double bond, hydrogen and osmium catalyst. The model involves coupled, non-linear partial differential equations with different dimensionless parameters. The proposed model was verified with the experimental results obtained from the hydrogenation and hydrodynamic experiments. The model could satisfactorily predict the degree of hydrogenation obtained from experimental results at various operating conditions. In general, the designed continuous process with SM reactor performed well and was an effective method of manufacturing HNBR on a continuous basis. The designed system is amicable to the industrial operating conditions and promises to be highly efficient and economic process for production of HNBR.