Previous work at Stanford University has demonstrated that inductance in the substrate connection is the principal problem underlying the coupling of digital switching noise into analog circuits. The low impedance substrate can be treated as a single node over a local area. Switching in the digital circuits produces current transients in the substrate. These transients are subsequently amplified in the analog portions of the overall mixed-mode circuit. Various guard rings and other techniques, including the use of new logic circuit families, have been proposed to suppress this noise. This work demonstrates that by using the capacitance of a forward biased guard ring(s), the substrate noise at a specific frequency(ies) can be reduced by resonating the guard ring capacitance with the substrate lead inductance to provide a very low substrate-to-ground impedance. In this manner, noise at particular frequencies, which are problematic to the analog circuit, can be suppressed. Tuning can be accomplished by varying the current in the forward-biased guard ring diodes. / Graduation date: 1995

Based on a thesis in Electrical Engineering, 1966. / Bibliography: p.109-110. / Contract no. DA36-039-AMC-03200(E).

Unsere alltägliche Erfahrung ist mit verschiedenen akustischen Einfluessen wie Lärm, aber auch Musik verbunden. Jeder weiss, wie Lärm stören kann und Kommunikation behindert oder gar unterbindet. Ähnliche optische Effekte sind bekannt: starkes Schneetreiben oder Regengüsse verschlechtern die Sicht und lassen uns Umrisse nur noch schemenhaft erkennen. Jedoch koennen ähnliche Stimuli auch sehr positive Auswirkungen haben: Autofahrer fahren bei leiser Musik konzentrierter -- die Behauptung von Schulkindern, nur bei dröhnenden Bässen die Mathehausaufgaben richtig rechnen zu können, ist allerdings nicht wissenschaftlich erwiesen. Außerordentlich interessant aus dieser Sicht sind auch Reizleitungsprozesse: Reize werden nur weitergleitet, wenn die strukturlosen Signale der Neuronen mit ausreichend starker Intensität erfolgen, also ein Schwellwert überschritten ist. <br /> <br /> Der Physiker Dr. Alexei Zaikin von der Universität Potsdam beschäftigt sich mit sogenannten rauschinduzierten Phänomenen aus theorischer Sicht. Sein Forschungsgebiet sind Prozesse, bei denen Rauschen mehrfach das Systemverhalten beeinflusst: ist es ausreichend gross, d.h. größer als ein kritischer Wert, wird eine reguläre Struktur gebildet, die durch das immernoch vorhandene Rauschen mit der Struktur des Nachbarsystems synchronisiert. Um ein solches System mit kritischem Wert zu erhalten, bedarf es einer weiteren Rauschquelle. Herr Zaikin analysierte noch weitere Beispiele solcher doppelt stochastischen Effekte. Die Ausarbeitung derartiger theoretischer Grundlagen ist wichtig, da diese Prozesse in der Neurophysik, in technischen Kommunikationssystemen und in den Lebenswissenschaften eine Rolle spielen. / Our every-day experience is connected with different acoustical noise or music. Usually noise plays the role of nuisance in any communication and destroys any order in a system. Similar optical effects are known: strong snowing or raining decreases quality of a vision. In contrast to these situations noisy stimuli can also play a positive constructive role, e.g. a driver can be more concentrated in a presence of quiet music. Transmission processes in neural systems are of especial interest from this point of view: excitation or information will be transmitted only in the case if a signal overcomes a threshold.<br /> <br /> Dr. Alexei Zaikin from the Potsdam University studies noise-induced phenomena in nonlinear systems from a theoretical point of view. Especially he is interested in the processes, in which noise influences the behaviour of a system twice: if the intensity of noise is over a threshold, it induces some regular structure that will be synchronized with the behaviour of neighbour elements. To obtain such a system with a threshold one needs one more noise source. Dr. Zaikin has analyzed further examples of such doubly stochastic effects and developed a concept of these new phenomena. These theoretical findings are important, because such processes can play a crucial role in neurophysics, technical communication devices and living sciences.

Objectives.The general objectives of this dissertationwere to examine the effects of acute exposure to meaningfulirrelevant speech and road traffic noise on memory performance,and to explore annoyance responses to noise exposure in theschool environment for pupils and teachers in different agegroups. Methods. The thesis comprises seven papers, representingdifferent methodological approaches: experiments, surveystudies and interviews. In the experiments, reported in PapersI-V, 288 pupils and teachers participated in the age groups,13-14 years (n=96), 18-20 years (n=96), 35-45 years (n=48) and55-65 years (n=48). The subjects were randomly assigned to oneof three conditions: (a) meaningful irrelevant speech, (b) roadtraffic noise, and (c) silence. The equivalent sound level inthe noise conditions was set to 66 dB(A). A test batteryreflecting episodic and semantic memory were used. The surveystudies, reported in Paper VI and VII, included 207 pupils(M=13.5) and 166 teachers (M=45.9). Two separate questionnairesmainly comprising items about annoyance, noise sensitivity andstress symptoms were administered. Paper VI presents results offocus group interviews (n=16) treating the main topics:disturbing sounds, emotions, ongoing activity, and suggestionsconcerning future changes. Results. The overall findings showedthat both noise sources affected episodic and semantic memoryto the same degree for all age groups. The results indicatedthat the similarity of semantic content between noise and thetask at hand was not the only suitable explanation model, sincea non-speech noise impaired memory as much as speech. Resultsalso indicated that attention effects did notmediate the obtained noise effects and that the noise effectsdid not differ between age groups. Therefore, it seemedunlikely that different memory and attentional capacities stoodout as explanatory factors of the memory effects. Sinceperformances of both episodic and semantic memory tasks wereimpaired, the explanation based on level of access to long-termmemory was also ruled out. However, the episodic memory task,reading comprehension, stood out to be most impaired by noise,suggesting that complexity of the task to perform was ofimportance. For reading comprehension there was also adifferent noise pattern obtained. Participants performance wasin this task, more impaired by meaningful irrelevant speechthan by road traffic noise. This effect indicated thatmeaningful irrelevant speech might reduce the availablecognitive resources necessary for learning the text. Theannoyance models derived from the survey studies indicated thatsensitivity acted as a mediator between hearing status andannoyance, with stress symptoms as an outcome. Whetherannoyance arises or not was also determined by control andpredictability of the noise. In the interviews a differentannoyance pattern was found, in that stress symptoms appearedto be a determinant of annoyance. To be involved, respected,take own responsibility and respect others were suggestions onhow to change the environment to become more silent. Conclusions.For both pupils and teachers acute exposureto meaningful irrelevant speech and road traffic noiseinfluenced both the achieving and providing of knowledge. Acommon annoyance pattern was also found for pupils andteachers, where individual and situational factors were ofimportance. To achieve a more silent school environment in thefuture, the pupils pointed out that the interaction betweenthemselves and their teachers was of importance. Key words:Noise, meaningful irrelevant speech, roadtraffic noise, memory, age groups, school environment, pupils,teachers

Objectives.The general objectives of this dissertationwere to examine the effects of acute exposure to meaningfulirrelevant speech and road traffic noise on memory performance,and to explore annoyance responses to noise exposure in theschool environment for pupils and teachers in different agegroups. Methods. The thesis comprises seven papers, representingdifferent methodological approaches: experiments, surveystudies and interviews. In the experiments, reported in PapersI-V, 288 pupils and teachers participated in the age groups,13-14 years (n=96), 18-20 years (n=96), 35-45 years (n=48) and55-65 years (n=48). The subjects were randomly assigned to oneof three conditions: (a) meaningful irrelevant speech, (b) roadtraffic noise, and (c) silence. The equivalent sound level inthe noise conditions was set to 66 dB(A). A test batteryreflecting episodic and semantic memory were used. The surveystudies, reported in Paper VI and VII, included 207 pupils(M=13.5) and 166 teachers (M=45.9). Two separate questionnairesmainly comprising items about annoyance, noise sensitivity andstress symptoms were administered. Paper VI presents results offocus group interviews (n=16) treating the main topics:disturbing sounds, emotions, ongoing activity, and suggestionsconcerning future changes. Results. The overall findings showedthat both noise sources affected episodic and semantic memoryto the same degree for all age groups. The results indicatedthat the similarity of semantic content between noise and thetask at hand was not the only suitable explanation model, sincea non-speech noise impaired memory as much as speech. Resultsalso indicated that attention effects did notmediate the obtained noise effects and that the noise effectsdid not differ between age groups. Therefore, it seemedunlikely that different memory and attentional capacities stoodout as explanatory factors of the memory effects. Sinceperformances of both episodic and semantic memory tasks wereimpaired, the explanation based on level of access to long-termmemory was also ruled out. However, the episodic memory task,reading comprehension, stood out to be most impaired by noise,suggesting that complexity of the task to perform was ofimportance. For reading comprehension there was also adifferent noise pattern obtained. Participants performance wasin this task, more impaired by meaningful irrelevant speechthan by road traffic noise. This effect indicated thatmeaningful irrelevant speech might reduce the availablecognitive resources necessary for learning the text. Theannoyance models derived from the survey studies indicated thatsensitivity acted as a mediator between hearing status andannoyance, with stress symptoms as an outcome. Whetherannoyance arises or not was also determined by control andpredictability of the noise. In the interviews a differentannoyance pattern was found, in that stress symptoms appearedto be a determinant of annoyance. To be involved, respected,take own responsibility and respect others were suggestions onhow to change the environment to become more silent. Conclusions.For both pupils and teachers acute exposureto meaningful irrelevant speech and road traffic noiseinfluenced both the achieving and providing of knowledge. Acommon annoyance pattern was also found for pupils andteachers, where individual and situational factors were ofimportance. To achieve a more silent school environment in thefuture, the pupils pointed out that the interaction betweenthemselves and their teachers was of importance. Key words:Noise, meaningful irrelevant speech, roadtraffic noise, memory, age groups, school environment, pupils,teachers

Aims: The aims of this thesis were to describe and gain an understanding of how people who live in the vicinity of wind turbines are affected by wind turbine noise, and how individual, situational and visual factors, as well as sound properties, moderate the response. Methods: A cross-sectional study was carried out in a flat, mainly rural area in Sweden, with the objective to estimate the prevalence of noise annoyance and to examine the dose-response relationship between A-weighted sound pressure levels (SPLs) and perception of and annoyance with wind turbine noise. Subjective responses were obtained through a questionnaire (n = 513; response rate: 68%) and outdoor, A-weighted SPLs were calculated for each respondent. To gain a deeper understanding of the observed noise annoyance, 15 people living in an area were interviewed using open-ended questions. The interviews were analysed using the comparative method of Grounded Theory (GT). An additional cross-sectional study, mainly exploring the influence of individual and situational factors, was carried out in seven areas in Sweden that differed with regard to terrain (flat or complex) and degree of urbanization (n = 765; response rate: 58%). To further explore the impact of visual factors, data from the two cross-sectional studies were tested with structural equation modelling. A proposed model of the influence of visual attitude on noise annoyance, also comprising the influence of noise level and general attitude, was tested among respondents who could see wind turbines versus respondents who could not see wind turbines from their dwelling, and respondents living in flat versus complex terrain. Results: Dose-response relationships were found both for perception of noise and for noise annoyance in relation to A-weighted SPLs. The risk of annoyance was enhanced among respondents who could see at least one turbine from their dwelling and among those living in a rural in comparison with a suburban area. Noise from wind turbines was appraised as an intrusion of privacy among people who expected quiet and peace in their living environment. Negative experiences that led to feelings of inferiority added to the distress. Sound characteristics describing the amplitude modulated aerodynamic sound were appraised as the most annoying (swishing, whistling and pulsating/throbbing). Wind turbines were judged as environmentally friendly, efficient and necessary, but also as ugly and unnatural. Being negative towards the visual impact of the wind turbines on the landscape scenery, rather than towards wind turbines as such, was strongly associated with annoyance. Self-reported health impairment was not correlated to SPL, while decreased well-being was associated with noise annoyance. Indications of possible hindrance to psycho-physiological restoration were observed. Conclusions: Wind turbine noise is easily perceived and is annoying even at low A-weighted SPLs. This could be due to perceived incongruence between the characteristics of wind turbine noise and the background sound. Wind turbines are furthermore prominent objects whose rotational movement attracts the eye. Multimodal sensory effects or negative aesthetic response could enhance the risk of noise annoyance. Adverse reactions could possibly lead to stress-related symptoms due to prolonged physiological arousal and hindrance to psychophysiological restoration. The observed differences in prevalence of noise annoyance between living environments make it necessary to assess separate dose-response relationships for different types of landscapes.

In this thesis, design aspects of fully integrated multibandmultistandard front-end receivers are investigated based onthree fundamental aspects: noise, linearity and operatingfrequency. System level studies were carried out to investigatethe effects of different modulation techniques, duplexing andmultiple access methods on the noise, linearity and selectivityperformance of the circuit. Based on these studies and thelow-cost consideration, zero-IF, low-IF and wideband-IFreceiver architectures are promising architectures. These havea common circuit topology in a direct connection between theLNA and the mixer, which has been explored in this work toimprove the overall RF-to-IF linearity. One front-end circuitapproach is used to achieve a low-cost solution, leading to anew multiband multistandard front-end receiver architecture.This architecture needs a circuit whose performance isadaptable due to different requirements specified in differentstandards, works across several RF-bands and uses a minimumamount ofexternal components. Five new circuit topologies suitable for a front-endreceiver consisting of an LNA and mixer (low-noise converter orLNC) were developed. A dual-loop wide-band feedback techniquewas applied in all circuits investigated in this thesis. Threeof the circuits were implemented in 0.18 mm RF-CMOS and 25 GHzbipolar technologies. Measurement results of the circuitsconfirmed the correctness of the design approach. The circuits were measured in several RF-bands, i.e. in the900 MHz, 1.8 GHz and 2.4 GHz bands, with S11 ranging from–9.2 dB to–17 dB. The circuits have a typicalperformance of 18-20 dB RF-to-IF gain, 3.5-4 dB DSB NF and upto +4.5 dBm IIP3. In addition, the circuit performance can beadjusted by varying the circuit’s first-stage biascurrent. The circuits may work at frequencies higher than 3GHz, as only 1.5 dB of attenuation is found at 3 GHz and nopeaking is noticed. In the CMOS circuit, the extrapolated gainat 5 GHz is about 15 dB which is consistent with the simulationresult. The die-area of each of the circuits is less than 1mm2.

In many consumer products, e.g., cellular phones and handheld computers, both digital and analog circuits are required. Nowadays, it is possible to implement a large subsystem or even a complete system, that earlier required several chips, on a single chip. A system on chip (SoC) has generally the advantages of lower power consumption and a smaller fabrication cost compared with multi-chip solutions. The switching of digital circuits generates noise that is injected into the silicon substrate. This noise is known as substrate noise and is spread through the substrate to other circuits. The substrate noise received in an analog circuit degrades the performance of the circuit. This is a major design issue in mixed-signal ICs where analog and digital circuits share the same substrate. Two new noise reduction methods are proposed in this thesis work. The first focuses n reducing the switching noise generated in digital clock buffers. The strategy is to use a clock with long rise and fall times in conjunction with a special D flip-flop. It relaxes the constraints on the clock distribution net, which also reduce the design effort. Measurements on a test chip implemented in a 0.35 μm CMOS technology show that the method can be implemented in an IC with low cost in terms of speed and power consumption. A noise reduction up to 50% is obtained by using the method. The measured power consumption of the digital circuit, excluding the clock buffer, increased 14% when the rise and fall times of the clock were increased from 0.5 ns to 10 ns. The corresponding increase in propagation delay was less than 0.5 ns corresponding to an increase of 50% in propagation delay of the registers. The second noise reduction method focuses on reducing simultaneous switching noise below half the clock frequency. This frequency band is assumed to be the signal band of an analog circuit. The idea is to use circuits that have as close to periodic power supply currents as possible to obtain low simultaneous switching noise below the clock in the frequency domain. For this purpose we use precharged differential cascode switch logic together with a novel D flip-flop. To evaluate the method two pipelined adders have been implemented on transistor level in a 0.13 μm CMOS technology, where the novel circuit is implemented with our method and the reference circuit with static CMOS logic together with a TSPC D flip-flop. According to simulation results, the frequency components in the analog signal band can be attenuated from 10 dB up to 17 dB using the proposed method. The cost is mainly an increase in power consumption of almost a factor of three. Comparisons between substrate coupling in silicon-on-insulator (SOI) and conventional bulk technology are made using simple models. The objective is to get an understanding of how the substrate coupling differs in SOI from the bulk technology. The results show that the SOI has less substrate coupling if no guard band is used, up to a certain frequency that is dependent of the test case. Introducing a guard band resulted in a higher attenuation of substrate noise in bulk than in SOI. An on-chip measurement circuit aiming at measuring simultaneous switching noise has been designed in a 0.13 μm SOI CMOS technology. The measuring circuit uses a single comparator per channel where several passes are used to capture the waveform. Measurements on a fabricated testchip indicate that the measuring circuit works as intended. A small part of this thesis work has been done in the area of digit representation in digital circuits. A new approach to convert a number from two’s complement representation to a minimum signed-digit representation is proposed. Previous algorithms are working either from the LSB to the MSB (right-to-left) or from the MSB to the LSB (left-to-right). The novelty in the proposed algorithm is that the conversion is done from left-to-right and right-to-left concurrently. Using the proposed algorithm, the critical path in a conversion circuit can be nearly halved compared with the previous algorithms. The area and power consumption, of the implementation of the proposed algorithm, are somewhere between the left-to-right and right-to-left implementations. / Articles I, II, III, IV, VII and IX are published with permisson from IEEE dated 07/05/18. Copyright IEEE.

The aim of this study is to develop a sound transmission model that can be used to predict the vibration and noise levels of a submerged vessel. The noise transmitted from the mechanical vibrations of the hull of a submarine and the turbulent boundary layer excitation on the submarine are investigated. A simplified physical model of the submarine hull including the effects of bulkheads, end enclosures, ring stiffeners and fluid loading due to the interaction of the surrounding medium is presented in the study. An energy approach, i.e., Statistical Energy Analysis (SEA) is used for the analysis because the characterization of the hull of the structure can be done by a very large number of modes over the frequency range of interest and the deterministic analysis methods such as finite element and boundary element methods are limited to low frequency problems. The application consists of the determination of SEA subsystems and the parameters and the utilization of power balance equations to estimate the energy ratio levels of each subsystem to the directly excited subsystem. Through the implementation of SEA method, the sound pressure levels of the hull of the structure are obtained. In terms of military purposes, the sound levels of the submarine compartments are vital in the aspects of the preserving of submarine stealth.

The tonal character of the low frequency internal noise in cars is often due to energy transmission through the tyre at the first few eigenfrequencies of the air cavity of the tyre. The first acoustic mode in the air cavity of a typical stationary car tyre is approximately 224 Hz. At this frequency the tyre is comparatively stiff resulting in a high transmission of energy from the road wheel contact to the car body itself. In order to investigate possible means of reducing this effect, the acoustic field inside a tyre is modelled. Theoretically it is found that the pressure inside a tyre and the energy transmission through the tyre to the wheel axle and the car body can be reduced by adding a sound absorbing material inside the tyre. This was confirmed by measurements on stationary as well as rotating tyres with and without added sound absorption. For a rotating tyre there is a split of the natural frequency depending on the rotational speed of the tyre. Measurements in a standard passenger car reveal that the noise level inside the car is rather high in a fairly wide frequency range around 224 Hz at normal velocities. This tonal noise can be reduced by adding sound absorption inside a tyre. Models for the prediction and the reduction of the tonal noise are presented. Measured and predicted results are compared and the agreement is found to be good. It is found that the tonal noise can be reduced by up to 9 dB. The effects of the air cavity resonances on the external noise have also been studied. It is estimated that external tyre noise can be reduced 1 dB by adding a sound absorbing material inside tyres. For a car travelling on a road a strong acoustic field is induced between the floor of the car and the road. The impact of this acoustic field can be reduced by mounting a sound absorbing material underneath the car. It is estimated that the A-weighted sound pressure level close to a running car could be reduced by 3 dB by adding this type sound absorption. It is found that aluminium foam could be a suitable sound absorbing material which could be mounted inside tyres and underneath cars. The acoustic and dynamic properties of various types of aluminium foams are discussed. In particular measurement techniques for determining sound absorption at grazing incidence are investigated. / QC 20100923