abstract: The front end of almost all ADCs consists of a Sample and Hold Circuit in order to make sure a constant analog value is digitized at the end of ADC. The design of Track and Hold Circuit (THA) mainly focuses on following parameters: Input frequency, Sampling frequency, dynamic Range, hold pedestal, feed through error. This thesis will discuss the importance of these parameters of a THA to the ADCs and commonly used architectures of THA. A new architecture with SiGe HBT transistors in BiCMOS 130 nm technology is presented here. The proposed topology without complicated circuitry achieves high Spurious Free Dynamic Range(SFDR) and Total Harmonic Distortion (THD).These are important figure of merits for any THA which gives a measure of non-linearity of the circuit. The proposed topology is implemented in IBM8HP 130 nm BiCMOS process combines typical emitter follower switch in bipolar THAs and output steering technique proposed in the previous work. With these techniques and the cascode transistor in the input which is used to isolate the switch from the input during the hold mode, better results have been achieved. The THA is designed to work with maximum input frequency of 250 MHz at sampling frequency of 500 MHz with input currents not more than 5mA achieving an SFDR of 78.49 dB. Simulation and results are presented, illustrating the advantages and trade-offs of the proposed topology. / Dissertation/Thesis / M.S. Electrical Engineering 2012

In this thesis, we have explained the different types of DAC (Digital-to-Analog) architectures and their advantages and disadvantages. We have mainly focused on current-steering digital-to-analog design for achieving high speed and high performance. The current-steering DAC is designed using binary weighted architecture. The benefits of this architecture is that it occupies less area, consumes less power and the number of control signals required are very less. The requirements for high speed and high performance DAC are discussed in detail. The circuit is implemented in a state-of-the-art 65 nm process, with a supply voltage of 1.2 V and at a sampling speed of 2 GHz. The resolution of the DAC is 8-bits. The design of 8-bit current-steering DAC converts 8 most significant bits (MSBs) into their binary weighted equivalent, which controls 256 unit current sources. The performance of the DAC is measured using the static and dynamic  parameters. In communication applications the static performance measures such as INL and DNL are not of utmost importance. In this work, we have mainly concentrated on the dynamic performance characteristics like SNR (Signal to Noise Ratio) and SFDR (Spurious Free Dynamic Range). For measuring the dynamic parameters, frequency domain analysis is a better choice. Also, we have discussed how the pole-zero analysis can be used to arrive at the dynamic performance metrics of a unit element of the DAC at higher frequencies. Different methods were discussed here to show the effects of poles and zeroes on the output impedance of a unit element at higher frequencies, for example, by hand calculation, using Mathematica and by using cadence. After extensive literature studies, we have implemented a technique in cadence, to increase the output impedance at higher frequencies. This technique is called as “complimentary current solution technique”. This technique will improve the output impedance and SFDR compared to the normal unit element design. Our technique contains mostly analog building blocks, like, current mirrors, biasing scheme and switching scheme and few digital blocks like D-ff (D-flip flop). The whole system is simulated and verified in MATLAB. Dynamic performances of the DAC such as SNR and SFDR are found with the help of MATLAB.

This thesis consists of two topics. A frequency-shift readout circuit is integrated for the rapid IgE measurement biomedical system in the first half. Secondly, we present a ROM-less DDFS (direct digital frequency synthesis) using a non-equal division parabolic polynomial interpolation method, which is used as the frequency generator in the measurement system. The first topic investigates the IgE concentration measurement system and realizes the readout circuit using TSMC 1P6M 0.18 £gm CMOS technology. We integrate the flexural plate wave (FPW) sensor chips and an ASIC comprising control block, digital to analog convertor (DAC), OTA-C oscillators, amplifiers, peak detectors, registers, and a subtractor. By taking advantages of the characteristics that the central frequencies of the loaded FPW sensors will be shifted, sine waves with various frequencies are generated and swept through one pair of FPW sensors. The frequency difference of these sensors is then readout to get concentration by look-up table. The second topic investigates the division method of a quarter sine wave to improve the spurious free dynamic range (SFDR) and realizes a ROM-less DDFS which is used as the frequency generator in the mentioned IgE measurement system. The proposed non-equal division parabolic polynomial interpolation method will generate a complete sine wave by a quarter of a sine digital signal owing to the symmetry. We combine the quasi-linear interpolation and an offset adjustment to derive the quarter sine wave digital signals. The proposed method not only reduces the absolute error between ideal sine wave and generated sine wave, it also improves SFDR.

Hard disk drive applications require a high Spurious Free Dynamic Range (SFDR), 6-bit Analog-to-Digital Converter (ADC) at conversion rates of 1GHz and beyond. This work proposes a robust, fault-tolerant scheme to achieve high SFDR in an av- eraging flash A/D converter using comparator chopping. Chopping of comparators in a flash A/D converter was never previously implemented due to lack of feasibility in implementing multiple, uncorrelated, high speed random number generators. This work proposes a novel array of uncorrelated truly binary random number generators working at 1GHz to chop all comparators. Chopping randomizes the residual offset left after averaging, further pushing the dynamic range of the converter. This enables higher accuracy and lower bit-error rate for high speed disk-drive read channels. Power consumption and area are reduced because of the relaxed design requirements for the same linearity. The technique has been verified in Matlab simulations for a 6-bit 1Gsamples/s flash ADC under case of process gradients with non-zero mean offsets as high as 60mV and potentially serious spot offset errors as high as 1V for a 2V peak to peak input signal. The proposed technique exhibits an improvement of over 15dB compared to pure averaging flash converters for all cases. The circuit-level simulation results, for a 1V peak to peak input signal, demon- strate superior performance. The reported ADC was fabricated in TSMC 0.18 ??mCMOS process. It occupies 8.79mm2 and consumes about 400mW from 1.8V power supply at 1GHz. The targeted SFDR performance for the fabricated chip is at least 45dB for a 256MHz input sine wave, sampled at 1GHz, about 10dB improvement on the 6-bit flash ADCs in the literature.

Uppsatsen studerar svenska aktörers mottagande och perspektiv på den kommande EU taxonomin. Dessa perspektiv har framlagts för att åskådliggöra en outforskad bild av hur svenska aktörer förhåller sig till, och förväntas påverkas, utav taxonomin. Utifrån en empirisk litteraturstudie sammankopplat med intressenternas perspektiv har också ett reglerteoretiskt perspektiv presenterats. Detta för att skapa en teoretisk förhållningsram till de utsagor som samlats in av intressenterna och på sätt skänka förståelse till dess orsak. Uppsatsen följer den svenska skogsnäringen som belysande exempel för en bransch som i synnerhet påverkas av utformningen av taxonomin, och samtidigt inkorporerar de intressentgrenar som valts; finans- näringslivs och forskningsintressenter. Sammantaget så har en delad skeptisism kring, men inte utseslutet till, rapportering, branschspecifik utformning och EU Kommissionens tillika tekniska expertgruppens expertis, identifierats. Skeptisismen har emellertid inte varit enhetlig, men dominerande.

Finance solutions have the potential to play a key role in the transition to sustainable societies. The financial sector has struggled with multiple parallel definitions and standards for sustainable finance. In 2018, the European Union launched an ambitious regulatory effort to standardize sustainable finance and provide increased transparency for investors. This study investigates perceptions of the expanding EU regulations among finance professionals and motivations for the financial sector to engage in meaningful sustainability work. Data is gathered through semi-structured interviews. The study finds positive attitudes to the fundamental idea behind the regulatory effort but more critical views on its practical implementation. Profit-maximizing incentives are part of the key motivations for financial entities to engage in sustainability work. This provides both challenges and opportunities for policy makers to achieve sustainability impacts through regulation.

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Responsible investing is a growing concept as sustainability is becoming a much more apparent problem. Thus, the EU implemented a new regulation in 2021, the SFDR 2019/2088, to decrease information asymmetry between institutional investors and end investors regarding sustainable risks associated with funds’ investments. This thesis aims to study whether Swedish mutual funds are greenwashing in terms of funds that are classified as Article 9 funds and invest in firms with low ESG scores. I find that greenwashing occurs among some Swedish mutual funds classified as Article 9 funds, urging further actions to be taken by scholars, practitioners, and regulators given the complexity of the studied research field.

To redirect capital flows towards sustainable investments, the European Union (EU) has implemented the EU Taxonomy, a classification system with definitions for sustainable economic activities. The Taxonomy constitutes a part of the European Green Deal, which is an initiative to transition the EU towards sustainability and competitiveness. The EU Taxonomy is intended to be used by investors when assessing companies to identify sustainable investment opportunities. Investors have great significance in what impacts the EU Taxonomy will have since the regulation relies on investors using it as a tool when assessing whether to invest in a company or not. Additionally, many companies rely on investors for financial support, and it is therefore essential for companies to have information about to what degree investors will integrate the EU Taxonomy in their investment decisions. There is an information gap between companies and investors where companies lack knowledge about how investors will use the Taxonomy to select which companies to invest in.   The aim of the study is to investigate how the EU Taxonomy is affecting investment decisions of Nordic investment firms and institutional investors. Furthermore, the aim is to examine in what ways the EU Taxonomy will shape the future of sustainable investments and how companies utilize the EU Taxonomy to enhance their attractiveness to investors. A qualitative approach has been used in the thesis, and data constituting the results was collected through 12 semi-structured interviews with investors. In conclusion, all interviewed investors have an interest in promoting sustainable investments. The EU Taxonomy has, moreover, been positively received by investors since many of them have been requesting a tool to define sustainable economic activities. 11 of 12 investors in the study, use the EU Taxonomy when evaluating companies to make investment decisions. However, investors are currently evaluating a variety of factors when assessing companies, such as additional ESG performance indicators. Further, investors consider that the Taxonomy cannot exclusively be used when analyzing companies since it is a narrow tool, excluding multiple economic activities and sectors. A high Taxonomy alignment will be a considerable factor for some investors as they believe that companies with high alignment will be more successful. Other investors will continue to invest in companies with low alignment because these companies have potential to become more sustainable over time. All investors are, however, united in that the most important thing is that companies have an ambition to reach a higher alignment. Further, investors have varying approaches when it comes to prioritizing the environmental objectives when assessing companies' sustainability performance. Some investors value how many and which environmental objectives a company contributes to depending on the company´s operations, while others have not yet considered it. The EU Taxonomy´s significance in the future for sustainable investments will depend on different factors, for example the reporting of alignment. Provided that investors integrate the Taxonomy in their decision making, the framework will likely increase the share of investments which take sustainability aspects into account. However, since the EU Taxonomy only covers companies in the EU and exclude sectors, it is questionable how great significance the regulation will have for sustainable investments on a global scale. Lastly, there are several opportunities for companies to become more attractive to investors by working strategically with the EU Taxonomy and communicate ambitions to reach a higher alignment. The results highlight the importance of companies adapting their business model to the Taxonomy and establishing long-term plans for how to reach a higher share of alignment. Companies can, moreover, improve their attractiveness to investors by improving their Taxonomy data collection and presenting the data in an easily accessible way.