Computer-Aided Design of Switched-Capacitor Filters

This thesis describes a series of computer methods for the design of switched-capacitor filters. Current software is greatly restricted in the types of transfer function that can be designed and in the range of filter structures by which they can be implemented. To solve the former problem, several new filter approximation algorithms are derived from Newton's method, yielding the Remez algortithm as a special case (confirming its convergency properties). Amplitude responses with arbitrary passband shaping and stopband notch positions are computed. Points of a specified degree of tangency to attenuation boundaries (touch points) can be placed in the response, whereby a family of transfer functions between Butterworth and elliptic can be derived, offering a continuous trade-off in group delay and passive sensitivity properties. The approximation algorithms have also been applied to arbitrary group delay correction by all-pass functions. Touch points form a direct link to an iterative passive ladder design method, which bypasses the need for Hurwitz factorisation. The combination of iterative and classical synthesis methods is suggested as the best compromise between accuracy and speed. It is shown that passive ladder prototypes of a minimum-node form can be efficiently simulated by SC networks without additional op-amps. A special technique is introduced for canonic realisation of SC ladder networks from transfer functions with finite transmission at high frequency, solving instability and synthesis difficulties. SC ladder structures are further simplified by synthesising the zeros at +/-2fs which are introduced into the transfer function by bilinear transformation. They cause cancellation of feedthrough branches and yield simplified LDI-type SC filter structures, although based solely on the bilinear transform. Matrix methods are used to design the SC filter simulations. They are shown to be a very convenient and flexible vehicle for computer processing of the linear equations involved in analogue filter design. A wide variety of filter structures can be expressed in a unified form. Scaling and analysis can readily be performed on the system matrices with great efficiency. Finally, the techniques are assembled in a filter compiler for SC filters called PANDDA. The application of the above techniques to practical design problems is then examined. Exact correction of sinc(x), LDI termination error, pre-filter and local loop telephone line weightings are illustrated. An optimisation algorithm is described, which uses the arbitrary passband weighting to predistort the transfer function for response distortions. Compensation of finite amplifier gain-bandwidth and switch resistance effects in SC filters is demonstrated. Two commercial filter specifications which pose major difficulties for traditional design methods are chosen as examples to illustrate PANDDA's full capabilities. Significant reductions in order and total area are achieved. Finally, test results of several SC filters designed using PANDDA for a dual-channel speech-processing ASIC are presented. The speed with which high-quality, standard SC filters can be produced is thus proven

Switched capacitor networks : a novel prewarping procedure

Bibliography: leaves 152-157.Novel methods for prewarping filter specifications prior to realization. in Switched Capacitor (SC) form are presented. These allow the design of arbitrary response requirements, exhibiting a low amount of error that normally results from the frequency warping associated with sampled-data networks. Adjustment is applied to the pole and zero locations of a reference filter, using three distinct approaches (Center frequency "CF", Selectivity "S" and Complex Mapping "CM" pole/zero prewarping), developed for both the Lossless Discrete Integrator (LOI) and Bilinear (Bil) analog to digital transformations. The derivation of the prewarping expressions is explained with reference to these mappings, and the effect they have on the apparent pole and zero locations of an SC filter realization

Mechanismen der Pikosekunden-Infrarot-Laser-Desorption/Ionisation

Direct analysis of tissues and cells by mass spectrometry is an emerging approach in guided laser surgery, high-throughput clinical bio-diagnostics, and mass spectrometry imaging. Especially for the analysis of labile compounds such as large proteins and non-covalently bound complexes, a soft sampling technique which preserves the integrity of the analyte molecules is desirable. Infrared (IR) laser desorption is a promising method for soft material extraction as it provides high spatial resolution, requires minimal sample preparation, and can be easily coupled to purification and separation techniques such as liquid chromatography. A core limitation to be overcome is the relatively low ionization efficiency when compared to other techniques commonly used with mass spectrometry, such as matrix assisted laser desorption ionization (MALDI) or electrospray ionization (ESI). By using a picosecond infrared laser (PIRL) at 3µm wavelength, desorption by impulsive vibrational excitation (DIVE) establishes optimal ablation conditions. Depositing energy at a higher rate than it can be dissipated by mechanical relaxation leads to a maximal pressure buildup before material ejection ensues, and to less collateral material damage since dissipation channels corresponding to thermal as well as acoustic damage to the specimen are reduced. This leaves even large biomolecules intact for subsequent analysis. Within the scope of this thesis, the ablation and ionization characteristics of PIRL-DIVE were investigated in two different scenarios: first, the material ejection at atmospheric pressure was characterized using time-resolved digital interference microscopy, a photographic technique which showed high contrast for otherwise transparent objects such as acoustic shocks and ejected water vapor. Different ablation regimes exhibiting varying amounts of liquid and vapor-phase material were identified, and droplet generation could be suppressed when smaller volumes of liquid were irradiated. This opened up possibilities to further investigate the role of droplet generation and desolvation in analyte ionization. Second, the suitability of PIRL-DIVE for mass spectrometry imaging was investigated in a custom-built time-of-flight mass analyzer. Substantial improvements in signal strength, stability, and reproducibility were achieved compared to previous IR laser desorption ionization studies performed under vacuum conditions. The influence of several parameters such as laser fluence, extraction voltage, and pH value of the sample solution was investigated. The sample preparation protocol had significant impact on the observed signal quality. The obtained results potentially pave the way towards high-resolution, high-sensitivity mass spectrometry imaging from frozen cryo-sections of tissues and cells using the DIVE process.Die direkte massenspektrometrische Analyse von Geweben und Zellen ist ein relativ neuer Ansatz in der computergestützten Laser-Chirurgie, in der klinischen Biodiagnostik und im Gebiet der massenspektrometrischen Bildgebung. Vor allem für die Analyse labiler Stoffe wie besonders großer Moleküle und nicht-kovalent gebundener Komplexe ist eine Untersuchungsmethode wünschenswert, welche die Integrität der Analytmoleküle bewahrt. Die Infrarot (IR) Laserdesorption ist eine vielversprechende Methode zur "weichen" Probenentnahme, die eine hohe räumliche Auflösung bei minimaler Probenvorbereitung bietet und sich leicht an Aufreinigungs- und Separationstechniken wie die Flüssigchromatographie koppeln lässt. Bisher limitierend ist die relativ niedrige Ionisationseffizienz im Vergleich mit anderen Massenspektrometrie-Methoden wie zum Beispiel der Matrix-unterstützten Laserdesorption und Ionisation (MALDI) und der Elektrospray Ionisation (ESI). Optimale Ablationsbedingungen können durch die Nutzung eines Pikosekunden Infrarot Lasers (PIRL) mit einer Wellenlänge von 3µm erreicht werden, ein Verfahren welches auch Desorption by Impulsive Vibrational Excitation (DIVE) genannt wird. Wird die Energie schneller zugeführt als sie durch mechanische Relaxation abgebaut werden kann, wird ein maximaler Ablationsdruck erreicht und das umliegenden Gewebe weniger beansprucht, da sowohl thermische als auch akustische Dissipationskanäle, die zu Schäden an der Probe führen könnten, vermieden werden. Selbst große Biomoleküle bleiben so für die weitere Analyse intakt. Ziel dieser Arbeit war die Untersuchung der PIRL Ablation und Ionisation in zwei unterschiedlichen Szenarien: Zunächst wurde der Materialausstoß unter Atmosphärendruck mittels zeitaufgelöster digitaler Interferenzmikroskopie charakterisiert, ein photographisches Verfahren mit welchem ein hoher Kontrast für ansonsten transparente Objekte wie Druckwellen und Wasserdampf erzielt werden konnte. Verschiedene Regimes der Materialablation wiesen unterschiedliche Verhältnisse von flüssigem zu gasförmigem Material auf, wobei die Tröpfchenbildung für die Ablation von mikroskopischen Flüssigkeitsvolumen vollständig unterdrückt werden konnte. Dies zeigte eine Möglichkeit zur weiteren Untersuchung der Rolle der Tröpfchenbildung und -desolvatisierung für die Ionisierung von Analytmolekülen auf. Des Weiteren wurde die Eignung von PIRL-DIVE für die massenspektrometrische Bildgebung untersucht. Dazu wurde ein Flugzeit-Massenspektrometer aufgebaut und charakterisiert und der Einfluss mehrerer Parameter wie der Laser-Fluenz, der Extraktionsspannung und des pH-Werts geprüft. Es konnte eine wesentliche Verbesserung der Signalstärke, -stabilität und -reproduzierbarkeit im Vergleich zu vorhergehenden Studien der IR Laserdesorption und Ionisation unter Vakuumbedingungen demonstriert werden. Zudem wurde gezeigt, dass besonders die Probenvorbereitung eine wichtige Rolle für die Signalqualität spielte. Die erzielten Ergebnisse ebnen potenziell den Weg für eine hochauflösende und hoch-sensible massenspektrometrische Bildgebung von gefrorenen Probenschnitten mittels DIVE

Mechanismen der Pikosekunden-Infrarot-Laser-Desorption/Ionisation

Direct analysis of tissues and cells by mass spectrometry is an emerging approach in guided laser surgery, high-throughput clinical bio-diagnostics, and mass spectrometry imaging. Especially for the analysis of labile compounds such as large proteins and non-covalently bound complexes, a soft sampling technique which preserves the integrity of the analyte molecules is desirable. Infrared (IR) laser desorption is a promising method for soft material extraction as it provides high spatial resolution, requires minimal sample preparation, and can be easily coupled to purification and separation techniques such as liquid chromatography. A core limitation to be overcome is the relatively low ionization efficiency when compared to other techniques commonly used with mass spectrometry, such as matrix assisted laser desorption ionization (MALDI) or electrospray ionization (ESI). By using a picosecond infrared laser (PIRL) at 3µm wavelength, desorption by impulsive vibrational excitation (DIVE) establishes optimal ablation conditions. Depositing energy at a higher rate than it can be dissipated by mechanical relaxation leads to a maximal pressure buildup before material ejection ensues, and to less collateral material damage since dissipation channels corresponding to thermal as well as acoustic damage to the specimen are reduced. This leaves even large biomolecules intact for subsequent analysis. Within the scope of this thesis, the ablation and ionization characteristics of PIRL-DIVE were investigated in two different scenarios: first, the material ejection at atmospheric pressure was characterized using time-resolved digital interference microscopy, a photographic technique which showed high contrast for otherwise transparent objects such as acoustic shocks and ejected water vapor. Different ablation regimes exhibiting varying amounts of liquid and vapor-phase material were identified, and droplet generation could be suppressed when smaller volumes of liquid were irradiated. This opened up possibilities to further investigate the role of droplet generation and desolvation in analyte ionization. Second, the suitability of PIRL-DIVE for mass spectrometry imaging was investigated in a custom-built time-of-flight mass analyzer. Substantial improvements in signal strength, stability, and reproducibility were achieved compared to previous IR laser desorption ionization studies performed under vacuum conditions. The influence of several parameters such as laser fluence, extraction voltage, and pH value of the sample solution was investigated. The sample preparation protocol had significant impact on the observed signal quality. The obtained results potentially pave the way towards high-resolution, high-sensitivity mass spectrometry imaging from frozen cryo-sections of tissues and cells using the DIVE process.Die direkte massenspektrometrische Analyse von Geweben und Zellen ist ein relativ neuer Ansatz in der computergestützten Laser-Chirurgie, in der klinischen Biodiagnostik und im Gebiet der massenspektrometrischen Bildgebung. Vor allem für die Analyse labiler Stoffe wie besonders großer Moleküle und nicht-kovalent gebundener Komplexe ist eine Untersuchungsmethode wünschenswert, welche die Integrität der Analytmoleküle bewahrt. Die Infrarot (IR) Laserdesorption ist eine vielversprechende Methode zur "weichen" Probenentnahme, die eine hohe räumliche Auflösung bei minimaler Probenvorbereitung bietet und sich leicht an Aufreinigungs- und Separationstechniken wie die Flüssigchromatographie koppeln lässt. Bisher limitierend ist die relativ niedrige Ionisationseffizienz im Vergleich mit anderen Massenspektrometrie-Methoden wie zum Beispiel der Matrix-unterstützten Laserdesorption und Ionisation (MALDI) und der Elektrospray Ionisation (ESI). Optimale Ablationsbedingungen können durch die Nutzung eines Pikosekunden Infrarot Lasers (PIRL) mit einer Wellenlänge von 3µm erreicht werden, ein Verfahren welches auch Desorption by Impulsive Vibrational Excitation (DIVE) genannt wird. Wird die Energie schneller zugeführt als sie durch mechanische Relaxation abgebaut werden kann, wird ein maximaler Ablationsdruck erreicht und das umliegenden Gewebe weniger beansprucht, da sowohl thermische als auch akustische Dissipationskanäle, die zu Schäden an der Probe führen könnten, vermieden werden. Selbst große Biomoleküle bleiben so für die weitere Analyse intakt. Ziel dieser Arbeit war die Untersuchung der PIRL Ablation und Ionisation in zwei unterschiedlichen Szenarien: Zunächst wurde der Materialausstoß unter Atmosphärendruck mittels zeitaufgelöster digitaler Interferenzmikroskopie charakterisiert, ein photographisches Verfahren mit welchem ein hoher Kontrast für ansonsten transparente Objekte wie Druckwellen und Wasserdampf erzielt werden konnte. Verschiedene Regimes der Materialablation wiesen unterschiedliche Verhältnisse von flüssigem zu gasförmigem Material auf, wobei die Tröpfchenbildung für die Ablation von mikroskopischen Flüssigkeitsvolumen vollständig unterdrückt werden konnte. Dies zeigte eine Möglichkeit zur weiteren Untersuchung der Rolle der Tröpfchenbildung und -desolvatisierung für die Ionisierung von Analytmolekülen auf. Des Weiteren wurde die Eignung von PIRL-DIVE für die massenspektrometrische Bildgebung untersucht. Dazu wurde ein Flugzeit-Massenspektrometer aufgebaut und charakterisiert und der Einfluss mehrerer Parameter wie der Laser-Fluenz, der Extraktionsspannung und des pH-Werts geprüft. Es konnte eine wesentliche Verbesserung der Signalstärke, -stabilität und -reproduzierbarkeit im Vergleich zu vorhergehenden Studien der IR Laserdesorption und Ionisation unter Vakuumbedingungen demonstriert werden. Zudem wurde gezeigt, dass besonders die Probenvorbereitung eine wichtige Rolle für die Signalqualität spielte. Die erzielten Ergebnisse ebnen potenziell den Weg für eine hochauflösende und hoch-sensible massenspektrometrische Bildgebung von gefrorenen Probenschnitten mittels DIVE

Theoretical development and characterisation of a Josephson Traveling Wave Parametric Amplifier for very low power microwave signals

L'abstract è presente nell'allegato / the abstract is in the attachmen

Analog Baseband Filters and Mixed Signal Circuits for Broadband Receiver Systems

Data transfer rates of communication systems continue to rise fueled by aggressive demand for voice, video and Internet data. Device scaling enabled by modern lithography has paved way for System-on-Chip solutions integrating compute intensive digital signal processing. This trend coupled with demand for low power, battery-operated consumer devices offers extensive research opportunities in analog and mixed-signal designs that enable modern communication systems. The first part of the research deals with broadband wireless receivers. With an objective to gain insight, we quantify the impact of undesired out-band blockers on analog baseband in a broadband radio. We present a systematic evaluation of the dynamic range requirements at the baseband and A/D conversion boundary. A prototype UHF receiver designed using RFCMOS 0.18[mu]m technology to support this research integrates a hybrid continuous- and discrete-time analog baseband along with the RF front-end. The chip consumes 120mW from a 1.8V/2.5V dual supply and achieves a noise figure of 7.9dB, an IIP3 of -8dBm (+2dbm) at maximum gain (at 9dB RF attenuation). High linearity active RC filters are indispensable in wireless radios. A novel feed-forward OTA applicable to active RC filters in analog baseband is presented. Simulation results from the chip prototype designed in RFCMOS 0.18[mu]m technology show an improvement in the out-band linearity performance that translates to increased dynamic range in the presence of strong adjacent blockers. The second part of the research presents an adaptive clock-recovery system suitable for high-speed wireline transceivers. The main objective is to improve the jitter-tracking and jitter-filtering trade-off in serial link clock-recovery applications. A digital state-machine that enables the proposed mixed-signal adaptation solution to achieve this objective is presented. The advantages of the proposed mixed-signal solution operating at 10Gb/s are supported by experimental results from the prototype in RFCMOS 0.18[mu]m technology

Quantum acoustics with propagating phonons

Surface acoustic waves (SAWs) are mechanical vibrations that propagate on the surface of solids while dissipating little power, consequently enabling them to propagate freely over long distances. The speed and wavelength of SAWs are reduced a five order of magnitude compared to when light is used as a carrier at gigahertz frequencies. The unique properties of SAWs combined with the possibility to let them interact with artificial atoms, discovered and shown for the very first time in appended Paper I of this thesis, open up for exploration of new regimes of quantum physics. The appended Paper II is a book chapter providing an overview of many of the new areas of research, as well as going into depth of the method and significance of the results ofthe appended Paper I.The essential interaction between artificial atoms and SAWs was further investigated by using Autler-Townes splitting to achieve fast control of the interactions. The appended Paper IV, shows a transmitted field extinction of 80 %, and provides proof of concept for a SAW router in the quantum regime. In addition, due to the artificial atom\u27s highly frequency dependent coupling to SAWs, electromagnetically induced transparency (EIT) could be observed in the appended Paper V. Furthermore, the EIT region was distinguished from the Autler-Townes splitting region by a threshold in the applied power. The results produce parallel findings to quantum optics, but are perhaps best described as part of a different field, quantum acoustics.Among the many possible areas of research emerging as an outcome of this work, a variety of potential quantum experiments would benefit greatly from a higher conversion efficiency between electric signals and SAWs. Due to this, focus was put on improving this conversion efficiency by studying superconducting unidirectional transducers (UDTs), making use of advances in classical SAW devices. The appended Paper III shows that 99.4~\% of the acoustic power can be focused in a desired direction and that the conversion between electric signals and SAWs is greatly improved by using UDTs, thereby eliminating the largest source of loss of symmetric inter-digital transducers. There is, however, a trade-off between conversion efficiency and bandwidth. This finding allows tailoring of quantum experiments based on SAWs that may pave the way towards measuring quantum sound

Recent Trends in Communication Networks

In recent years there has been many developments in communication technology. This has greatly enhanced the computing power of small handheld resource-constrained mobile devices. Different generations of communication technology have evolved. This had led to new research for communication of large volumes of data in different transmission media and the design of different communication protocols. Another direction of research concerns the secure and error-free communication between the sender and receiver despite the risk of the presence of an eavesdropper. For the communication requirement of a huge amount of multimedia streaming data, a lot of research has been carried out in the design of proper overlay networks. The book addresses new research techniques that have evolved to handle these challenges