Thesis (M. App. Sc.)--Carleton University, 2003. / Includes bibliographical references (p. 99-102). Also available in electronic format on the Internet.

Travelling-wave distributed amplifiers are providing gain over broad frequency ranges for microwave applications. Similar concepts are applicable to distributed mixers and, with the use of controlled feedback, to a multifunction component simultaneously emulating a mixer, amplifier and an oscillator. The concept of this new travelling-wave frequency converter is introduced and data for a discrete component test circuit is presented. To facilitate the converter operation a new three-port travelling-wave mixer is introduced and characterized. Four-port scattering and wave scattering transformations are derived as a method of analysis of the four-port distributed structure. This enables sequential circuit analysis on a small computer. Practical applications unique to the advanced automatic network analyser, including time domain measurements, are presented to characterize test circuits as well as to develop ancillary equipment such as a transistor test fixture. Automated error corrected transistor measurements and de-embedding are also discussed. A piecewise linear quantum mechanical method of modelling the conduction channel of a short gate field effect transistor is given to aid the extrapolation of the distributed frequency converter concept to submicron and heterojunction structures. / Thesis (Ph.D.)-University of Natal, Durban, 1985.

<p> As modern digital communications evolve, the requirements imposed on the systems than are required to transmit/receive the signals involved become more stringent. Amplifiers are required to provide gain from low frequencies, sometimes down to DC, up to high frequencies in the order of few to tens of gigahertz. Not only is the gainbandwidth product to be enhanced, but also the amplifier should introduce minimal distortion to the signal and consume as low power as possible. </p> <p> Distributed amplification is a multi-stage broadband circuit technique that may provide such a function. In distributed amplifiers, inter-stage transmission lines provide the capability to reach higher operational frequencies by absorbing the parasitic capacitances of the transistors used. Unlike other broadband topologies that trade-off gain and bandwidth, distributed amplifiers do not, but rather, the trade-off is between gain and delay. As gain stages are added, the gain increases as the bandwidth remains the same but the signal delay is increased. </p> <p> This work considers the silicon germanium (SiGe) heterojunction bipolar transistor (HBT) implementation of distributed amplifiers. SiGe HBTs incorporate a thin SiGe base with Ge profiling to achieve high cut-off frequencies. SiGe BiCMOS processes are silicon based and hence have the major advantage of integrability to the low cost CMOS process unlike ill-V compound semiconductors. Hence, SiGe is a promising technology capable of bridging the performance gap between silicon and m-v semiconductors. </p> <p> The proposed amplifier achieves an approximately flat gain of 6.5 dB and a noise figure of 5.8-9 dB throughout the -3 dB passband of 10.5 GHz. The power consumed is 12.2 mW, significantly lower than previously published results by up to an order of magnitude is some cases. The group delay of the amplifier was found to be approximately constant in the passband at -60 ps. </p> <p> For the first time, temperature measurements are preformed on SiGe HBT DAs. Analysis show that the gain falls drastically with temperature increase due to deterioration in input matching caused by the significant change in the transistors input impedance with temperature. Similarly the NF, increases with temperature due to the decrease in gain. Moreover, noise analysis of SiGe HBT DAs is investigated, producing simulations predicting the NF of the proposed amplifier giving insight as to how noise may be reduced in future designs. </p> / Thesis / Master of Applied Science (MASc)

Thesis (M.App.Sc.) - Carleton University, 2006. / Includes bibliographical references (p. 147-151). Also available in electronic format on the Internet.

Millimetre-wave technology is used for applications such as telecommunications and imaging. For both applications, the bandwidth of existing systems has to be increased to support higher data rates and finer imaging resolutions. Millimetrewave circuits with very large bandwidths are developed in this thesis. The focus is put on amplifiers and the on-chip integration of the amplifiers with antennas. Circuit prototypes, fabricated in a commercially available 130nm Silicon-Germanium (SiGe) Bipolar Complementary Metal-Oxide-Semiconductor (BiCMOS) process, validated the developed techniques. Cutting-edge performances have been achieved in the field of distributed and resonant-matched amplifiers, as well as in that of the antenna-amplifier co-integration. Examples are as follows: - A novel cascode gain-cell with three transistors was conceived. By means of transconductance peaking towards high frequencies, the losses of the synthetic line can be compensated up to higher frequencies. The properties were analytically derived and explained. Experimental demonstration validated the technique by a Traveling-Wave Amplifier (TWA) able to produce 10 dB of gain over a frequency band of 170GHz.# - Two Cascaded Single-Stage Distributed Amplifiers (CSSDAs) have been demonstrated. The first CSSDA, optimized for low power consumption, requires less than 20mW to provide 10 dB of gain over a frequency band of 130 GHz. The second amplifier was designed for high-frequency operation and works up to 250 GHz leading to a record bandwidth for distributed amplifiers in SiGe technology. - The first complete CSSDA circuit analysis as function of all key parameters was presented. The typical degradation of the CSSDA output matching towards high frequencies was analytically quantified. A balanced architecture was then introduced to retain the frequency-response advantages of CSSDAs and yet ensure matching over the frequency band of interested. A circuit prototype validated experimentally the technique. - The first traveling-wave power combiner and divider capable of operation from the MHz range up to 200 GHz were demonstrated. The circuits improved the state of the art of the maximum frequency of operation and the bandwidth by a factor of five. - A resonant-matched balanced amplifier was demonstrated with a centre frequency of 185 GHz, 10 dB of gain and a 55GHz wide –3 dB-bandwidth. The power consumption of the amplifier is 16.8mW, one of the lowest for this circuit class, while the bandwidth is the broadest reported in literature for resonant-matched amplifiers in SiGe technology.

Recent research focuses on expanding the use of RF/Microwave circuits and systems to include multi-disciplinary applications. One example is the detection of the dielectric properties of chemicals and bio-chemicals at microwave frequencies, which is useful for pharmaceutical applications, food and drug safety, medical diagnosis and material characterization. Dielectric spectroscopy is also quite relevant to detect the frequency dispersive characteristics of materials over a wide frequency range for more accurate detection. In this dissertation, on-chip and on-board solutions for microwave chemical sensing are proposed. An example of an on-chip dielectric detection technique for chemical sensing is presented. An on-chip sensing capacitor, whose capacitance changes when exposed to material under test (MUT), is a part of an LC voltage-controlled oscillator (VCO). The VCO is embedded inside a frequency synthesizer to convert the change in the free runing frequency frequency of the VCO into a change of its input voltage. The system is implemented using 90 nm CMOS technology and the permittivities of MUTs are evaluated using a unique detection procedure in the 7-9 GHz frequency range with an accuracy of 3.7% in an area of 2.5 × 2.5 mm^2 with a power consumption of 16.5 mW. The system is also used for binary mixture detection with a fractional volume accuracy of 1-2%. An on-board miniaturized dielectric spectroscopy system for permittivity detec- tion is also presented. The sensor is based on the detection of the phase difference be- tween the input and output signals of cascaded broadband True-Time-Delay (TTD) cells. The sensing capacitor exposed to MUTs is a part of the TTD cell. The change of the permittivity results in a change of the phase of the microwave signal passing through the TTD cell. The system is fabricated on Rogers Duroid substrates with a total area of 8 × 7.2 cm2. The permittivities of MUTs are detected in the 1-8 GHz frequency range with a detection accuracy of 2%. Also, the sensor is used to extract the fractional volumes of mixtures with accuracy down to 1%. Additionally, multi-band and multi-standard communication systems motivate the trend to develop broadband front-ends covering all the standards for low cost and reduced chip area. Broadband amplifiers are key building blocks in wideband front-ends. A broadband resistive feedback low-noise amplifier (LNA) is presented using a composite cross-coupled CMOS pair for a higher gain and reduced noise figure. The LNA is implemented using 90 nm CMOS technology consuming 18 mW in an area of 0.06 mm2. The LNA shows a gain of 21 dB in the 2-2300 MHz frequency range, a minimum noise figure of 1.4 dB with an IIP3 of -1.5 dBm. Also, a four-stage distributed amplifier is presented providing bandwidth extension with 1-dB flat gain response up to 16 GHz. The flat extended bandwidth is provided using coupled inductors in the gate line with series peaking inductors in the cascode gain stages. The amplifier is fabricated using 180 nm CMOS technology in an area of 1.19 mm2 achieving a power gain of 10 dB, return losses better than 16 dB, noise figure of 3.6-4.9 dB and IIP3 of 0 dBm with 21 mW power consumption. All the implemented circuits and systems in this dissertation are validated, demonstrated and published in several IEEE Journals and Conferences.