Phase shifters play a crucial role in radar, satellite communications, and 5G networks. Recently, the idea of using filters as phase shifters have attracted much interest due to providing many benefits such as smaller area, lower noise figure, easier fabrication method as compared with other technologies, reduced cost, and the ability to work as multi-functioning device. This work focuses on the implementation of bandstop-based and bandpass-based filtering phase shifters. For the bandstop-based approach, some of the resonating structures that were examined are stubs, LC tanks, L-shaped/U-shaped half wavelength resonators and many others. Periodic stub loading filter design method was compared against traditional filter synthesis method in order to determine which approach can provide better insertion loss range, higher phase range, and wider bandwidth. Optimization of stub impedance and the size of the device was presented. With regards to bandpass-based filtering phase shifters, microstrip-based and substrate integrated waveguide-based designs were investigated. The benefits of microstrip technology include low profile, low cost, ease of fabrication and integration. Microstrip-based designs were implemented using square shaped and octagon shaped split ring resonators. Then, substrate integrated waveguide (SIW) cavity-based designs were proposed and realized using hexagon resonators. The advantages of SIW-based filters are low insertion loss, high power handling, high immunity to external noise and crosstalk. A novel SIW-based filtering phase shifter with tunable transmission zero and tunable center frequency was developed aimed at maximizing device performance.

This thesis presents distributed MEMS transmission line (DMTL) phase shifters, emphasizing the circuit modeling and design as well as the performance improvement. A novel modeling methodology is introduced for DMTL unit sections, with bridge widths larger than 50 &amp / #956 / m. The introduced model is compared with EM simulation results and the CLR modeling results. For structures with bridge widths larger than 50 &amp / #956 / m, the introduced model fits the simulation results much better than the CLR model. The simulated structures are fabricated in METU micro-electronics facilities on glass substrates using gold structural layers. 1-20 GHz S-parameter measurement results of various DMTL structures are compared with the introduced model. It is observed that the S-parameters match except for a scaling need in the insertion loss. The measurement results give 2 dB insertion and 15 dB isolation at 20 GHz. The ABCD parameters of the introduced model are converted into S-parameters. Loss and the phase shift of the DMTL structures are expressed in terms of these S-parameters. These expressions are re-written as MATLAB code, from which the phase shift/loss (degree/dB) performance is evaluated. Therefore degree/dB plots with respect to bridge widths and center CPW conductor widths are obtained. From these plots the optimum DMTL phase shifters, which give maximum phase shift for minimum loss are determined for a pre-defined DMTL structure. To increase the degree/dB performance of a DMTL phase shifter, a change in the geometry of the DMTL phase shifters is proposed. The geometry change is based on inserting an open-ended stub through the signal line and connecting one side of the stub to the bridge. By this way, the stub capacitance is added to the shunt capacitance of the bridge satisfying a larger phase shift. The simulations point out a performance of 217 degree/dB at 20 GHz with a 15 % change in the 25 &amp / #956 / m wide bridge height ratio.

No description available.

No description available.

<p>This thesis considers integration of antennas and active electronics manufactured on the same substrate. The main topic is on-chip antennas for commercial silicon processes, but hybrid integration using printed circuit board technology is also addressed.</p><p>The possible use of micromachining techniques as a means of reducing substrate losses of antennas manufactured on low resistivity silicon wafers is investigated. Compact dipole, loop, and inverted-F antennas for the 20-40 GHz frequency range are designed, implemented, and characterized. The results show significantly improved antenna efficiency when micromachining is used as a post-processing step for on-chip antennas manufactured in silicon technology.</p><p>High resistivity wafers are used in a commercial silicon germanium technology to improve the efficiency of dipole antennas realized using the available circuit metal layers in the process. Monolithically integrated 24 GHz receivers with on-chip antennas are designed and evaluated with regard to antenna and system performance. No noticeable degradation of the receiver performance caused by cross talk between the antenna and the integrated circuit is observed.</p><p>For low frequency antenna arrays, such as base station antennas, hybrid integration of active devices within the antenna aperture is treated. A compact varactor based phase shifter for traveling wave antenna applications is proposed and evaluated. Electrically steerable traveling wave patch antenna arrays, with the phase shifters implemented in the same conductor layer as the radiating elements, are designed and manufactured in microstrip technology. It is experimentally verified that the radiation from the feed network and phase shifters in the proposed antenna configuration is small.</p>

This thesis considers integration of antennas and active electronics manufactured on the same substrate. The main topic is on-chip antennas for commercial silicon processes, but hybrid integration using printed circuit board technology is also addressed. The possible use of micromachining techniques as a means of reducing substrate losses of antennas manufactured on low resistivity silicon wafers is investigated. Compact dipole, loop, and inverted-F antennas for the 20-40 GHz frequency range are designed, implemented, and characterized. The results show significantly improved antenna efficiency when micromachining is used as a post-processing step for on-chip antennas manufactured in silicon technology. High resistivity wafers are used in a commercial silicon germanium technology to improve the efficiency of dipole antennas realized using the available circuit metal layers in the process. Monolithically integrated 24 GHz receivers with on-chip antennas are designed and evaluated with regard to antenna and system performance. No noticeable degradation of the receiver performance caused by cross talk between the antenna and the integrated circuit is observed. For low frequency antenna arrays, such as base station antennas, hybrid integration of active devices within the antenna aperture is treated. A compact varactor based phase shifter for traveling wave antenna applications is proposed and evaluated. Electrically steerable traveling wave patch antenna arrays, with the phase shifters implemented in the same conductor layer as the radiating elements, are designed and manufactured in microstrip technology. It is experimentally verified that the radiation from the feed network and phase shifters in the proposed antenna configuration is small.

A comprehensive study of the High-pass/Low-pass topology has been performed, increasing the understanding of error sources arising from bit layout issues and fabrication tolerances. This included a detailed analysis of error sources in monolithic microwave phase shifters due to device size limitations, inductor parasitics, loading effects, and non-ideal switches. Each component utilized in the implementation of a monolithic high-low pass phase shifter was analyzed, with its influence on phase behavior shown in detail. An emphasis was placed on the net impact on absolute phase variation, which is critical to the system performance of a phased array radar system. The design of the individual phase shifter filter sections, and the influence of bit ordering on overall performance was also addressed. A variety of X-band four- and five-bit phase shifters were fabricated in a 200 GHz SiGe HBT BiCMOS technology platform, and further served to validate the analysis and design methodology. The SiGe phase shifter can be successfully incorporated into a single-chip T/R module forming a system-on-a-chip (SoC). Reduction in the physical size of transmission lines was shown to be a possibility with spinel magnetic nanoparticle films. The signal transmission properties of phase lines treated with nanoparticle thin films were examined, showing the potential for significant size reduction in both delay line and High-pass/Low-pass phase topologies. Wide-band, low-loss, and near-hermetic packaging techniques for RF MEMS devices were presented. A thermal compression bonding technique compatible with standard IC fabrication techniques was shown, that uses a low temperature thermal compression bonding method that avoids plastic deformations of the MEMS membrane. Ultimately, a system-on-a-package (SoP) approach was demonstrated that utilized packaged RF MEMS switches to maintain the performance of the SiGe phase shifter with much lower loss. The extremely competitive performance of the MEMS-based High-pass/Low-pass phase shifter, despite the lack of the extensive toolkits and commercial fabrication facilities employed with the active-based SiGe phase shifters, confirms both the effectiveness of the detailed phase error analysis presented in this work and the robust nature of the High-pass/Low-pass topology.

The area of deterministic noise cancellation in mobile radio communication systems is investigated and analyzed. Several interoperation problems in the mobile wireless radio space are identified and interference concerns for the Bluetooth - WLAN networks are characterized and quantified in the physical layer. A mathematical framework has been created for describing interference in the 2.4 GHz band. An adaptive noise suppression system has been developed that is able to alleviate the encroachment of the aggressor signal on the victim without sacrificing any of the original signal. This system is demonstrated to improve the victim SNR in a spread spectrum communication scenario. The research is extended to construct an interference canceller that is easy to assimilate into existing RF front-ends. A low-power small form-factor analog active canceller has been designed in 0.18-ìm Si-CMOS IC technology that delivers adequate noise suppression performance while operating in the RF domain. This includes novel implementations of phase rotator circuits based on delay interpolation and an integrated low-current quadrature modulator-based continuously variable analog phase shifter. This canceller is capable of up to 30 dB of in-band cancellation for the Bluetooth - WLAN problem. Other versions of the canceller are configured to protect GPS and DVB-H receivers from unintentional radiators transmitting in the vicinity. These demonstrate noise mitigation of at least 15 dB in their respective bands while generating very low broadband noise at the output. A simple low-power mixed-signal automatic control mechanism is also developed to operate the canceller adaptively. The work described in this dissertation advances the state-of-the-art in the area of mobile wireless radio coexistence.

<p>Most of today’s microwave circuits are designed for specific function and specialneed. There is a growing trend to have flexible and reconfigurable circuits. Circuitsthat can be digitally programmed to achieve various functions based on specific needs. Realization of high frequency circuit blocks that can be dynamically reconfigured toachieve the desired performance seems to be challenging. However, with recentadvances in many areas of technology these demands can now be met.</p><p>Two concepts have been investigated in this thesis. The initial part presents thefeasibility of a flexible and programmable circuit (PROMFA) that can be utilized formultifunctional systems operating at microwave frequencies. Design details andPROMFA implementation is presented. This concept is based on an array of genericcells, which consists of a matrix of analog building blocks that can be dynamicallyreconfigured. Either each matrix element can be programmed independently or severalelements can be programmed collectively to achieve a specific function. The PROMFA circuit can therefore realize more complex functions, such as filters oroscillators. Realization of a flexible RF circuit based on generic cells is a new concept.In order to validate the idea, a test chip has been fabricated in a 0.2μm GaAs process, ED02AH from OMMIC^TM. Simulated and measured results are presented along withsome key applications like implementation of a widely tunable band pass filter and anactive corporate feed network.</p><p>The later part of the thesis covers the design and implementation of tunable andwideband highly linear LNAs that can be very useful for multistandard terminals suchas software defined radio (SDR). One of the key components in the design of a flexibleradio is low noise amplifier (LNA). Considering a multimode and multiband radiofront end, the LNA must provide adequate performance within a large frequency band.Optimization of LNA performance for a single frequency band is not suitable for thisapplication. There are two possible solutions for multiband and multimode radio frontends (a) Narrowband tunable LNAs (b) Wideband highly linear LNAs. A dual bandtunable LNA MMIC has been fabricated in 0.2μm GaAs process. A self tuningtechnique has also been proposed for the optimization of this LNA. This thesis alsopresents the design of a novel highly linear current mode LNA that can be used forwideband RF front ends for multistandard applications. Technology process for thiscircuit is 90nm CMOS.</p>

Thesis (M.Eng.(Microelectronic Engineering))--University of Pretoria, 2009. / Includes summaries in Afrikaans and English. Includes bibliographical references (leaves [74]-78). Mode of access: World Wide Web.