This master's thesis presents the design and the realization of a low noise amplifier (LNA) for the S band of radio frequency spectrum from 2.3 GHz to 2.4 GHz. This thesis is mainly focused on stability and impedance matching networks study. Ansoft Designer and ANSYS HFSS programs are used for this design to simulate the LNA. Different low noise devices are simulated in order to find the best results for the final design. Moreover, a coaxial cavity resonator is designed in the input of the LNA and works as a band pass filter. Finally, the LNA is fabricated and its properties compared with the simulation results.

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A 5 GHz continuous unlicensed bandwidth is available at millimeter-wave (mm-wave) frequencies around 60 GHz and offers the prospect for multi gigabit wireless applications. The inherent atmospheric attenuation at 60 GHz due to oxygen absorption makes the frequency range ideal for short distance communication networks. For these mm-wave wireless networks, the low noise amplifier (LNA) is a critical subsystem determining the receiver performance i.e., the noise figure (NF) and receiver sensitivity. It however proves challenging to realise high performance mm-wave LNAs in a silicon (Si) complementary metal-oxide semiconductor (CMOS) technology. The mm-wave passive devices, specifically on-chip inductors, experience high propagation loss due to the conductivity of the Si substrate at mm-wave frequencies, degrading the performance of the LNA and subsequently the performance of the receiver architecture. The research is aimed at realising a high performance mm-wave LNA in a Si BiCMOS technology. The focal points are firstly, the fundamental understanding of the various forms of losses passive inductors experience and the techniques to address these issues, and secondly, whether the performance of mm-wave passive inductors can be improved by means of geometry optimising. An associated hypothesis is formulated, where the research outcome results in a preferred passive inductor and formulates an optimised passive inductor for mm-wave applications. The performance of the mm-wave inductor is evaluated using the quality factor (Q-factor) as a figure of merit. An increased inductor Q-factor translates to improved LNA input and output matching performance and contributes to the lowering of the LNA NF. The passive inductors are designed and simulated in a 2.5D electromagnetic (EM) simulator. The electrical characteristics of the passive structures are exported to a SPICE netlist which is included in a circuit simulator to evaluate and investigate the LNA performance. Two LNAs are designed and prototyped using the 13μ-m SiGe BiCMOS process from IBM as part of the experimental process to validate the hypothesis. One LNA implements the preferred inductor structures as a benchmark, while the second LNA, identical to the first, replaces one inductor with the optimised inductor. Experimental verification allows complete characterization of the passive inductors and the performance of the LNAs to prove the hypothesis. According to the author's knowledge, the slow-wave coplanar waveguide (S-CPW) achieves a higher Q-factor than microstrip and coplanar waveguide (CPW) transmission lines at mm-wave frequencies implemented for the 130 nm SiGe BiCMOS technology node. In literature, specific S-CPW transmission line geometry parameters have previously been investigated, but this work optimises the signal-to-ground spacing of the S-CPW transmission lines without changing the characteristic impedance of the lines. Optimising the S-CPW transmission line for 60 GHz increases the Q-factor from 38 to 50 in simulation, a 32 % improvement, and from 8 to 10 in measurements. Furthermore, replacing only one inductor in the output matching network of the LNA with the higher Q-factor inductor, improves the input and output matching performance of the LNA, resulting in a 5 dB input and output reflection coefficient improvement. Although a 5 dB improvement in matching performance is obtained, the resultant noise and gain performance show no significant improvement. The single stage LNAs achieve a simulated gain and NF of 13 dB and 5.3 dB respectively, and dissipate 6 mW from the 1.5 V supply. The LNA focused to attain high gain and a low NF, trading off linearity and as a result obtained poor 1 dB compression of -21.7 dBm. The LNA results are not state of the art but are comparable to SiGe BiCMOS LNAs presented in literature, achieving similar gain, NF and power dissipation figures. / Dissertation (MEng)--University of Pretoria, 2012. / Electrical, Electronic and Computer Engineering / unrestricted

Regression is a central problem in statistics and machine learning with applications everywhere in science and technology. In probabilistic regression the relationship between a set of features and a real-valued target variable is modelled as a conditional probability distribution. There are cases where this distribution is very complex and not properly captured by simple approximations, such as assuming a normal distribution. This thesis investigates how conditional Generative Adversarial Networks (GANs) can be used to properly capture more complex conditional distributions. GANs have seen great success in generating complex high-dimensional data, but less work has been done on their use for regression problems. This thesis presents experiments to better understand how conditional GANs can be used in probabilistic regression. Different versions of GANs are extended to the conditional case and evaluated on synthetic and real datasets. It is shown that conditional GANs can learn to estimate a wide range of different distributions and be competitive with existing probabilistic regression models.

This thesis primarily deals with the concept of designing an antenna based device to harvest energy from Radio Frequency (RF) and using the harvested energy to sense the available Long Term Evolution (LTE) network in order for the Internet of Things (IoT) devices to connect to the network for the purpose of transmitting and receiving data. Secondarily the importance of this project is targeting how to conserve battery power in an IoT device and extend it’s lifetime. Research in the field of energy harvesting has been going on for a long time. Most of the researches concentrate on harvesting significant amount of energy to power up an entire device and so no one has ever thought of using the harvested RF energy to sense the availability of LTE network. This method of using antenna to sense network requires only a small amount of harvested energy. Due to this reason the proposed design works for a very low input received signal strength indicator (RSSI) as well, unlike higer RSSI required for other applications. The proposed design has three major sub-parts such as the (i) Antenna for the purpose of receiving the available ambient radio frequency. (ii) Matching circuit for the purpose of maximum power transfer between the antenna and the rectifier circuit. Finally (iii) rectifier which is used to convert the AC voltage into DC voltage. The device then measures the obtained voltage through the Analog to Digital Converter (ADC) pin in the Micro-Controlling Unit (MCU) available with the attached IoT device. The MCU then maps the harvested voltage into the corresponding analog voltage.Depending on the set threshold voltage the MCU can then advice whether or not to connect to the LTE network. The design implements matching circuit for the two LTE bands that are primarily in use in the European region i.e., band 3, 8 that work in 915, 1800 MHz frequency region respectively. In this way we can identify in which band the device is harvesting energy. The matching circuit also acts as a bandpass filter. For the design and production of the entire harvester device one needs adequate knowledge in the field of RF and Antennas and a high level knowledge in the field of electronics in order to run Simulations and to design Printed Circuit Boards (PCBs). Advanced Design Software (ADS) has been used to run all the simulations and Altium software for the design of PCBs. The final prototype is presented along with the casing and tested on the field in practical scenario. Antenna test chambers were used to test the performance of the antennas being used for the design. The prototype harvests RF energy and indicates whether or not to connect to the LTE network with the help of light emitting diode (LED). The uniqueness of the device is that it can detect signals as low as -110 dBm, this has been set as the threshold for the purpose of sensing LTE networks. / Denna avhandling behandlar primärt konceptet att använda antenner för att hämta energi från RF och att använda den insamlade energin för att känna av det tillgängliga LTE-nätverket för att IoT-enheterna ska kunna ansluta till nätverket för syftet med att överföra och ta emot data. Sekundärt Målet med av detta projekt är att spara batteri i en IoT-enhet och förlänga dess livslängd. Forskning inom området energiskörd har pågått under lång tid nu. De flesta av undersökningarna koncentrerar sig på att skörda betydande mängder energi för att driva en hel enhet och så ingen har någonsin tänkt på att använda den avkända RF-energin för att känna av tillgängligheten för LTE-nätverket. Denna metod för att använda antenn för att känna av nätverk kräver endast en liten mängd skördad energi. På grund av denna anledning fungerar den föreslagna designen även för en mycket låg ingång RSSI, till skillnad från högre RSSI som krävs för andra applikationer. Den föreslagna designen har tre huvuddelar, såsom (i) antennen för att ta emot den tillgängliga omgivande radiofrekvensen. (ii) Matchningskrets för maximal effektöverföring mellan antennen och likriktarkretsen. Slutligen (iii) likriktaren som används för att omvandla AC-spänningen till DC-spänning. Enheten mäter sedan den erhållna spänningen genom ADC-stiftet i MCU som finns tillgänglig med den anslutna IoT-enheten. MCU mappar sedan den genererade spänningen till motsvarande analoga spänning. Beroende på den inställda tröskelspänningen kan MCU sedan ge råd om att ansluta till LTE-nätverket eller inte. Konstruktionen implementerar matchningskrets för de två LTE-banden som primärt används i den europeiska regionen vilka är band 3, 7 som arbetar i 915 respektive 1800 MHz frekvensområdet. På så sätt kan vi identifiera i vilket band enheten hämtar energi i. Matchningskretsen fungerar också som ett bandpassfilter. För design och produktion av hela insamlingsenheten behöver man adekvat kunskap inom området RF och antenner och en hög nivå kunskap inom elektronikområdet för att kunna köra simuleringar och designa PCBs.ADS har använts för att köra alla simuleringar och Altium-mjukvara för design av PCBs. Den slutliga prototypen presenteras tillsammans med höljet och testas på fältet i praktiskt scenario. Antenntestkammare användes för att testa prestandan hos antennerna som användes för konstruktionen. Prototypen skördar RF-energi och indikerar om man ska ansluta till LTE-nätverket eller inte med hjälp av blinkande LED.Det unika med enheten är att den kan upptäcka signaler så låga som - 110 dBm, detta har satts som tröskel för avkänning LTE nätverk.