<p>In today’s world the multi-standard wireless receivers are gaining more and more popularity. End-users want to access voice, data and streaming media from a single wireless terminal. An ideal approach for multi-standard receiver front-end is to digitize a wide band RF signal available from the antenna. All radio functions such as downconversion, demodulation and channel selection can be then performed in the digital domain. Analog to Digital Converter in such a case should guarantee very high linearity, speed and bandwidth specifications while consuming a lot of power. Unfortunately an ADC with such stringent requirements cannot be realized in today’s CMOS technology. In a typical receiver a mixer is used to downconvert the RF signal to baseband (or IF) before digitization is performed. A passive mixer is often used in this case to mitigate the effect of the low frequency flicker noise. Specially it can be a sampling mixer which also serves as a S/H circuit usually required for A/D conversion. In this thesis a lowpass sigma-delta converter with RF sampling is presented. The ΣΔ modulator is SC passive circuit plus comparator, so an operational amplifier usually needed to realize the integrator is avoided. To reduce the complexity, the sampling mixer in front of the modulator is merged with the passive loop filter. As a result the sampling mixer is closed in the modulator loop, so the overall linearity of the frontend is improved to some extent. Downconversion is combined with digitization that reduces the circuit complexity as well.The challenges while digitizing high frequency RF signal are discussed in details. Switches required to realize the loop filter are very critical and tend to be nonlinear. Parasitic effects associated with MOS transistors strongly show up at GHz frequencies. Optimized transistor sizes are obtained through simulation while addressing the speed and linearity trade-off. Another major challenge is the kT/C noise that is the real bottleneck in high frequency SC circuit design. A thermal noise model for ΣΔ-modulator with second-order loop filter is presented and it is shown that a passive ΣΔ-modulator is  in fact thermal noise limited rather than quantization noise limited. It is because the capacitor values are limited by the very high sampling frequency used in this case.The downconverting lowpass ΣΔ modulator with second order SC passive loop filter and 1-bit quantizer is simulated at transistor level in 90nm CMOS process. This modulator can operate at very high sampling frequency upto 4GHz and can sample RF signal with carrier of upto 4GHz as well. The designed ΣΔ modulator is flexible and supports sub-sampling by 2 to 8 (fs = 500MHz, ... 2GHz). Besides, the presented design is very power efficient as it does not use OpAmps – which consume most of the power in the typical ΣΔ modulators. From schematic simulation on average, signal-to-noise and distortion ratio (SNDR) of 52 dB is obtained (ENOB = 8.3). SNDR results does not vary much for three different cases of baseband digitalization, RF sampling and RF sub-sampling. This SNDR value seems to be a good number for a passive sigma-delta modulator. The detailed simulation results for the three cases discussed in the thesis work shown that, the modulator performs equally well for a wide range of sampling and RF signal frequencies.</p>

In today’s world the multi-standard wireless receivers are gaining more and more popularity. End-users want to access voice, data and streaming media from a single wireless terminal. An ideal approach for multi-standard receiver front-end is to digitize a wide band RF signal available from the antenna. All radio functions such as downconversion, demodulation and channel selection can be then performed in the digital domain. Analog to Digital Converter in such a case should guarantee very high linearity, speed and bandwidth specifications while consuming a lot of power. Unfortunately an ADC with such stringent requirements cannot be realized in today’s CMOS technology. In a typical receiver a mixer is used to downconvert the RF signal to baseband (or IF) before digitization is performed. A passive mixer is often used in this case to mitigate the effect of the low frequency flicker noise. Specially it can be a sampling mixer which also serves as a S/H circuit usually required for A/D conversion. In this thesis a lowpass sigma-delta converter with RF sampling is presented. The ΣΔ modulator is SC passive circuit plus comparator, so an operational amplifier usually needed to realize the integrator is avoided. To reduce the complexity, the sampling mixer in front of the modulator is merged with the passive loop filter. As a result the sampling mixer is closed in the modulator loop, so the overall linearity of the frontend is improved to some extent. Downconversion is combined with digitization that reduces the circuit complexity as well.The challenges while digitizing high frequency RF signal are discussed in details. Switches required to realize the loop filter are very critical and tend to be nonlinear. Parasitic effects associated with MOS transistors strongly show up at GHz frequencies. Optimized transistor sizes are obtained through simulation while addressing the speed and linearity trade-off. Another major challenge is the kT/C noise that is the real bottleneck in high frequency SC circuit design. A thermal noise model for ΣΔ-modulator with second-order loop filter is presented and it is shown that a passive ΣΔ-modulator is  in fact thermal noise limited rather than quantization noise limited. It is because the capacitor values are limited by the very high sampling frequency used in this case.The downconverting lowpass ΣΔ modulator with second order SC passive loop filter and 1-bit quantizer is simulated at transistor level in 90nm CMOS process. This modulator can operate at very high sampling frequency upto 4GHz and can sample RF signal with carrier of upto 4GHz as well. The designed ΣΔ modulator is flexible and supports sub-sampling by 2 to 8 (fs = 500MHz, ... 2GHz). Besides, the presented design is very power efficient as it does not use OpAmps – which consume most of the power in the typical ΣΔ modulators. From schematic simulation on average, signal-to-noise and distortion ratio (SNDR) of 52 dB is obtained (ENOB = 8.3). SNDR results does not vary much for three different cases of baseband digitalization, RF sampling and RF sub-sampling. This SNDR value seems to be a good number for a passive sigma-delta modulator. The detailed simulation results for the three cases discussed in the thesis work shown that, the modulator performs equally well for a wide range of sampling and RF signal frequencies.

Made available in DSpace on 2016-06-02T19:53:34Z (GMT). No. of bitstreams: 1 SILVA_Brena_2015.pdf: 2472067 bytes, checksum: 94189b9daa94ee6a53a36b5a8274dc05 (MD5) Previous issue date: 2015-02-11 / Financiadora de Estudos e Projetos / Six Sigma is an improvement program adopted by many companies to improve their business performance. However, some studies indicate that the relationship between Six Sigma and competitive advantage is not that clear. In this context, the main objective of this dissertation is to identify the relationship between the implementation factors of Six Sigma and competitive priorities in companies that operating in Brazil. As steps, this research conducted bibliometric analysis, content analysis, descriptive analysis and factor analysis. The research investigated 45 companies, through a survey, to find the relationship between Six Sigma implementation factors with competitive priorities in Brazil. Implantation factors identified were: "collect and availability of data", "previous infrastructure", "performance indicators", "goal setting", "capacity for change", "top management involvement" and "statistical thinking" . The results indicate the implementation factors that have relationship with competitive priorities are "collection and availability of data," "previous infrastructure" and "capacity for change". In addition to this result, it was found that the dimensions of competitive priorities that have relationship with implementation factors are "reliability" and "flexibility". / O Seis Sigma é um programa de melhoria adotado por muitas empresas para melhorar o seu desempenho nos negócios. No entanto, algumas pesquisas apontam que a relação entre o Seis Sigma e a melhoria da vantagem competitiva não está clara. Nesse contexto, o objetivo dessa dissertação é identificar o relacionamento entre os fatores de implantação do Seis Sigma e as prioridades competitivas em empresas que operam no Brasil. Como etapas, essa pesquisa realizou análises bibliométrica e de conteúdo, análise descritiva e análise fatorial. A pesquisa investigou 45 empresas, por meio de uma survey, para encontrar o relacionamento entre os fatores de implantação do Seis Sigma com as prioridades competitivas no Brasil. Os fatores de implantação identificados foram: coleta e disponibilização de dados , infraestrutura prévia , uso de indicadores de desempenho , estabelecimento de metas , capacidade cultural , envolvimento da alta administração e pensamento estatístico . Os resultados apontam para o relacionamento entre os fatores coleta e disponibilização dos dados , infraestrutura prévia e capacidade de mudança com o fator prioridade. Além desse resultado, foi encontrado que as dimensões confiabilidade e flexibilidade das prioridades competitivas possuem relação com os fatores de implantação do Seis Sigma.

A new reality, where human labor is replaced by automated machines is causing production management to rethink how they can steer the production to meet their customers demand. There is a gap of values, techniques and tools to communicate with the processes existing in the new modern factories, where data sometimes is the single output. This thesis purpose was to develop a model out of Lean and Six Sigma, as an answer to how modern factory could work with an information system, reaching the ideal state.   Through a theoretical analysis, Lean and Six Sigma differences in values, techniques and tools were weighted by the ideal state and recommendations from literature. Through a unstructured interview and system design review with a logistic group at a Swedish Modern Factory (SMF) a concept of an information system was developed. A project to test the model was initialized, where Define, Measure and Analyze phase was conducted. The model was thereafter modified from the projects implications.   The result was a Lean Six Sigma model which values are customer focus, ideal state, result orientation, committed leadership, education and involvement. The technique follow a DMAIC cycle and continuous improvements through a current to future state approach. The used techniques were considered Six Sigma heavy, where Leans principles are considered into the models values. The information system supports the model in setting the processes of the factory in either stability or potential state, where they differ in Measure and Analyze phase. The test at SMF developed several assignable causes to variation on the component As lead time. The model adapted after the test to involve a Measurement System Analysis (MSA), before setting the next current state of the process. / En ny verklighet där människor byts ut mot automatiska maskiner får produktionstekniker att fundera hur det ska styra produktionen för att möta kunders behov. Det finns en brist av värderingar, tekniker och verktyg till att kommunicera med processer i de moderna fabrikerna, där data ibland är det enda att analysera. Examensarbetets syfte var att utveckla en Lean och Six Sigma modell, som ett svar för hur moderna företag kan arbeta med ett informationssystem, för att nå det ideala stadiet.   Genom en teoretisk analys har Leans och Six Sigmas skillnader blivit vägda mot rekommendationer från litteraturen och det ideala stadiet. Genom en ostrukturerad intervju och en genomgång av systemets design hos en logistikgrupp, på ett svenskt företag (SMF), har ett koncept av ett informationssystem framtagits. Ett projekt för att testa modellen påbörjades, där Define, Measure och Analyze fasen var genomförda. Modellen blev därefter modifierad genom de implikationer projektet stött på.   Resultatet av den teoretiska analysen gav en Lean Six Sigma modell, vilka värdering är kundfokus, ideala stadiet, resultatorientering, engagerat ledarskap, utbildning och medverkande. Tekniken följde en DMAIC (Define, Measure, Analyze, Improve, Control) cykel och kontinuerliga förbättringar, från nuläge till ett framtida tillstånd. Teknikerna blev Six Sigma tunga, där Leans principer var beaktade i modellens värderingar. Informationssystemet var en supportfunktion av modellen och skapar en status för fabrikens processer, antingen i stabilitet eller potential stadiet, där de skiljer sig åt i mät – och analys fasen. Testet på SMF genererade flera grundorsaker till variation för komponents As ledtid. Modellen anpassades till att innehålla en mätsystemsanalys (MSA), innan nuläget av processen bestäms.

With the rapid growth in the hospitality industry, its owners and managers are also facing serious challenges. The industry is becoming more and more competitive. Managers are pressed to find the balance between cutting cost to increase profit and improving the quality of the service/product to increase the value their customers’ experience. Customers are nowadays more aware of the quality of the service or the product provided to them and more than ever before, hospitality owners and managers need to focus on improving their quality. The main objective of the research was to establish whether the implementation of selected Six Sigma principles would result in a measurable improvement in the quality of a hospitality establishment. An analysis was done based on three different feedback systems, some Sig Sigma-inspired changes were made and a post-measurement was done to establish the effect of the changes. The study concluded that the implementation of selective Six Sigma principles, can improve the quality of services and products in hospitality establishments, as well as reducing their process waste in such establishments. / MBA, North-West University, Potchefstroom Campus, 2015

With the rapid growth in the hospitality industry, its owners and managers are also facing serious challenges. The industry is becoming more and more competitive. Managers are pressed to find the balance between cutting cost to increase profit and improving the quality of the service/product to increase the value their customers’ experience. Customers are nowadays more aware of the quality of the service or the product provided to them and more than ever before, hospitality owners and managers need to focus on improving their quality. The main objective of the research was to establish whether the implementation of selected Six Sigma principles would result in a measurable improvement in the quality of a hospitality establishment. An analysis was done based on three different feedback systems, some Sig Sigma-inspired changes were made and a post-measurement was done to establish the effect of the changes. The study concluded that the implementation of selective Six Sigma principles, can improve the quality of services and products in hospitality establishments, as well as reducing their process waste in such establishments. / MBA, North-West University, Potchefstroom Campus, 2015

In this theses techniques for high-speed digital delta-sigma modulator(DDSM) structures are considered. Four techniques are applied andevaluated: unfolding, increasing the number of delay elements in theinner loop, pipelining/retiming, and optimizations provided by thesynthesis tool. Of interest is to see the speed-area-power trade-offs.For implementation, three different modulators meeting the samerequirements are implemented. Each modulator has a 16-bit input andresults in a 3-bit output. The baseline case is a second-ordermodulator, which has one delay element in its inner loop. Throughoptimization, two new structures are found: to provide two delayelements in the inner loop, a fourth-order modulator is required,while to provide three delay elements, a thirteenth-order modulator isobtained.The results show that in general it is better to unfold the modulatorthan to obtain the speed-up through optimizing the arithmeticoperators with the synthesis tool. Using correct pipelining/retimingis also crucial. Finally, for very high-speed implementation, usingthe structures with more delay elements is required. Also, in manycases these are more area and power efficient compared to usingoptimized arithmetic operators, despite their higher computationalcomplexity.

This research report aims to provide an insight into the implementation of multiple concurrent IT frameworks, and how to best implement each of the chosen frameworks resulting in a hybrid of best practices for implementing multiple concurrent IT frameworks

Submitted in fulfilment of the requirements of the Degree Doctor of Technology: Quality, Durban University of Technology. 2014. / The South African automotive sector is often plagued with complex and competitive business challenges owing to globalisation, economic uncertainty and fluctuating market demands. These challenges prompt business leaders in South Africa to improve their operations and to enhance innovations in processes, products and services in a very reactive manner. Literature shows that one such initiative that can assist the automotive sector to compete with the rest of the world where productivity, quality and operational costs reduction are crucial for economic success is the adoption of the integrated Lean Six Sigma tool. The automotive sector, which purports to be at the forefront of best industry manufacturing practices in South Africa, is certainly lacking in this area. The purpose of this thesis was to assess Lean and Six Sigma techniques as standalone systems, the integration of Lean and Six Sigma as a unified approach to continuous improvement and to develop a proposed Lean Six Sigma framework for the automotive component manufacturing organisations in KwaZulu-Natal (KZN), South Africa. Due to the nature and complexity of this project, it was decided to adopt the action-based research strategy and include both qualitative and quantitative techniques. Two hypotheses were formulated to guide the research. The study was confined to the greater Durban region in KZN, which formed the target population of forty two organisations within the Durban Automotive Cluster (DAC). A survey questionnaire was designed in measurable format to gather practical information from the sample organisations on the status of their existing business improvement programs and quality practices. This information was necessary to critique the sample organisations for Lean and Six Sigma requirements and compare it to the literature in terms of the KZN context. A pilot study was conducted with senior management at five automotive manufacturing organisations to determine if the participants encountered any problems in answering the questionnaire and if the methodology adopted would meet the objectives of this project. The results of the pilot study indicated high reliability scores which were sustainable for the main study. The survey questionnaire was reviewed by Lean and Six Sigma Experts, Academics and members of the DAC executive team to ensure the validity of the questionnaire to the KZN context. The logistics of the main study followed a similar format as the pilot study and the questionnaires were distributed within the DAC over a three month period. A census sample was used in the field study to collect primary data. A response rate of 75% was achieved. The results of the empirical findings revealed that the sample organisations had a very low success rate of Lean and Six Sigma adoption as standalone systems. The sample organisations only practiced certain Lean and Six Sigma tools and techniques as they found it difficult to maintain the complete transition from theory to practice. The synergies that emerged from the study of Lean and Six Sigma that affect manufacturing performance suggested that they complemented and supported each other by tailoring the deficiencies to the given environment. This information was translated into practical considerations for constructing the proposed Lean Six Sigma framework from a KZN perspective. The conclusion of the main study was that if an organisation wants improvement to happen on an ongoing basis, it needs to recognise that there are significant interactions between their management system and the improvement technique. When the organisations understand the characteristics of the environment in which they operate, they will be able to configure appropriate follow up processes to sustain their management systems. The study demonstrated that Lean Six Sigma integration repackages the stronger focus areas of Lean and Six Sigma to create its own unique approach on improving an organisation’s performance. It is anticipated that organisations which implement the proposed Lean Six Sigma framework could contribute significantly to the growth of the South African economy in terms of increased productivity, improved international competition and job creation. The value of this research is that the proposed Lean Six Sigma framework affords the KZN automotive sector a unique opportunity to create its own brand of quality that compliments its management style and industry demands. Future research should focus on testing the applicability of the proposed Lean Six Sigma framework in a real case scenario to ensure that the critical outcomes are adequately ingrained to achieve perceived organisational performance. Lastly, it is recommended that a list of performance evaluators is developed and follow up procedures to monitor the progress of the Lean Six Sigma technique is implemented.

Dissertation submitted in compliance with the requirements for the Masters Degree in Business Administration, Durban University of Technology, 2008. / Increasing competitive pressure from global markets and technological developments has resulted in the continual demand for business improvement philosophies and methodologies to address this challenge. The LSS approach to business improvement has emerged in both the practitioner and academic literature as having a significant role in this area. In 2006, The Valspar Corporation embarked on a LSS initiative as a way to improve the business globally, to achieve sustained profitable growth and to enhance customer value. Valspar (SA) found the implementation of LSS a challenge because the organisation could not afford the appointment of a full-time Black Belt to manage the programme locally. Green Belts were appointed to lead LSS projects part-time. Management wanted to know if they have applied the LSS methodology correctly within the scope of the business, especially since not all organisations were successful in the implementation of LSS. The objective of this study was to determine the critical factors that affect the successful implementation of LSS at Valspar (SA) and to assess the degree to which these critical factors exist at Valspar (SA). In a census, the researcher used the questionnaire to gain information about the current views of employees on the LSS programme at Valspar (SA). The research highlighted the critical success factors for LSS implementation and the results of the evaluation revealed both the positive and negative aspects of the LSS programme at Valspar (SA). / Valspar Corporation