Solid State Circuits Technologies

The evolution of solid-state circuit technology has a long history within a relatively short period of time. This technology has lead to the modern information society that connects us and tools, a large market, and many types of products and applications. The solid-state circuit technology continuously evolves via breakthroughs and improvements every year. This book is devoted to review and present novel approaches for some of the main issues involved in this exciting and vigorous technology. The book is composed of 22 chapters, written by authors coming from 30 different institutions located in 12 different countries throughout the Americas, Asia and Europe. Thus, reflecting the wide international contribution to the book. The broad range of subjects presented in the book offers a general overview of the main issues in modern solid-state circuit technology. Furthermore, the book offers an in depth analysis on specific subjects for specialists. We believe the book is of great scientific and educational value for many readers. I am profoundly indebted to the support provided by all of those involved in the work. First and foremost I would like to acknowledge and thank the authors who worked hard and generously agreed to share their results and knowledge. Second I would like to express my gratitude to the Intech team that invited me to edit the book and give me their full support and a fruitful experience while working together to combine this book

High frequency signal integrity in high-density assemblies

The demand for faster, portable and reliable electronic devices is increasing the pressure on the development of assembly techniques for signal integrity (SI). The advance of integrated circuits toward a large number of Input/Output (I/Os), a high number of operations and up to microwave communication frequencies, is behind the drive for the search for new packaging solutions. The materials and assembly techniques have an important impact on the propagation of high speed signals. Signal integrity issues emerge due to the electrical losses of materials, reflections from impedance discontinuities in the signal path and fast transitions of the signals. For these reasons, signal integrity in lead-free connections of WLCSP, flip chip (FC) and Integrated Module Board (IMB) assemblies were investigated up to 50 GHz. The increase of conductor loss resulting from the presence of thick oxide layers on the surface of solder bumps of hot running components was experimentally studied for the first time. Utilizing theoretical calculations, a design rule was developed to account for the 40 % increase in losses due to the presence of oxide layers at high frequencies. The research into the influence of solder microstructure on signal quality showed that it did not negatively affect the wave propagation. Experimental results proved that the presence of underfills and high density routing on printed wiring boards (PWBs) under the WLCSP components, detuned the components and the connections. The effects of three different underfills on signal propagation were studied. It was proven that the changes resulting from the rheology and parameters of curing process influence the losses and reflections of circuits. The analysis of microwave performances of flip chip (FC) and Integrated Module Board (IMB) assembly techniques demonstrated that they are well suited to Radio frequency (RF) and high speed applications. Comparison showed that IMB performed better as the wave encountered smaller discontinuities and had an optimized propagation path. Full wave simulations of IMB assemblies were performed considering finite ground coplanar waveguide (FGCPW), microstrip and stripline connections with stack-ups that included high dielectric constant materials and four connection possibilities. The research was carried out in the domains of both frequency and time to rigorously determine the sources of signal reflections. The results emphasized that in the design for match impedance and optimal current return path, discontinuities and reference planes had significant impact on signal integrity

Analysis of the high frequency substrate noise effects on LC-VCOs

La integració de transceptors per comunicacions de radiofreqüència en CMOS pot quedar seriosament limitada per la interacció entre els seus blocs, arribant a desaconsellar la utilització de un únic dau de silici. El soroll d’alta freqüència generat per certs blocs, com l’amplificador de potencia, pot viatjar pel substrat i amenaçar el correcte funcionament de l’oscil·lador local. Trobem tres raons importants que mostren aquest risc d’interacció entre blocs i que justifiquen la necessitat d’un estudi profund per minimitzar-lo. Les característiques del substrat fan que el soroll d’alta freqüència es propagui m’és fàcilment que el de baixa freqüència. Per altra banda, les estructures de protecció perden eficiència a mesura que la freqüència augmenta. Finalment, el soroll d’alta freqüència que arriba a l’oscil·lador degrada al seu correcte comportament. El propòsit d’aquesta tesis és analitzar en profunditat la interacció entre el soroll d’alta freqüència que es propaga pel substrat i l’oscil·lador amb l’objectiu de poder predir, mitjançant un model, l’efecte que aquest soroll pot tenir sobre el correcte funcionament de l’oscil·lador. Es volen proporcionar diverses guies i normes a seguir que permeti als dissenyadors augmentar la robustesa dels oscil·ladors al soroll d’alta freqüència que viatja pel substrat. La investigació de l’efecte del soroll de substrat en oscil·ladors s’ha iniciat des d’un punt de vista empíric, per una banda, analitzant la propagació de senyals a través del substrat i avaluant l’eficiència d’estructures per bloquejar aquesta propagació, i per altra, determinant l’efecte d’un to present en el substrat en un oscil·lador. Aquesta investigació ha mostrat que la injecció d’un to d’alta freqüència en el substrat es pot propagar fins arribar a l’oscil·lador i que, a causa del ’pulling’ de freqüència, pot modular en freqüència la sortida de l’oscil·lador. A partir dels resultats de l’anàlisi empíric s’ha aportat un model matemàtic que permet predir l’efecte del soroll en l’oscil·lador. Aquest model té el principal avantatge en el fet de que està basat en paràmetres físics de l’oscil·lador o del soroll, permetent determinar les mesures que un dissenyador pot prendre per augmentar la robustesa de l’oscil·lador així com les conseqüències que aquestes mesures tenen sobre el seu funcionament global (trade-offs). El model ha estat comparat tant amb simulacions com amb mesures reals demostrant ser molt precís a l’hora de predir l’efecte del soroll de substrat. La utilitat del model com a eina de disseny s’ha demostrat en dos estudis. Primerament, les conclusions del model han estat aplicades en el procés de disseny d’un oscil·lador d’ultra baix consum a 2.5GHz, aconseguint un oscil·lador robust al soroll de substrat d’alta freqüència i amb característiques totalment compatibles amb els principals estàndards de comunicació en aquesta banda. Finalment, el model s’ha utilitzat com a eina d’anàlisi per avaluar la causa de les diferències, en termes de robustesa a soroll de substrat, mesurades en dos oscil·ladors a 60GHz amb dues diferents estratègies d’apantallament de l’inductor del tanc de ressonant, flotant en un cas i connectat a terra en l’altre. El model ha mostrat que les diferències en robustesa són causades per la millora en el factor de qualitat i en l’amplitud d’oscil·lació i no per un augment en l’aïllament entre tanc i substrat. Per altra banda, el model ha demostrat ser vàlid i molt precís inclús en aquest rang de freqüència tan extrem. el principal avantatge en el fet de que està basat en paràmetres físics de l’oscil·lador o del soroll, permetent determinar les mesures que un dissenyador pot prendre per augmentar la robustesa de l’oscil·lador així com les conseqüències que aquestes mesures tenen sobre el seu funcionament global (trade-offs). El model ha estat comparat tant amb simulacions com amb mesures reals demostrant ser molt precís a l’hora de predir l’efecte del soroll de substrat. La utilitat del model com a eina de disseny s’ha demostrat en dos estudis. Primerament, les conclusions del model han estat aplicades en el procés de disseny d’un oscil·lador d’ultra baix consum a 2.5GHz, aconseguint un oscil·lador robust al soroll de substrat d’alta freqüència i amb característiques totalment compatibles amb els principals estàndards de comunicació en aquesta banda. Finalment, el model s’ha utilitzat com a eina d’anàlisi per avaluar la causa de les diferències, en termes de robustesa a soroll de substrat, mesurades en dos oscil·ladors a 60GHz amb dues diferents estratègies d’apantallament de l’inductor del tanc de ressonant, flotant en un cas i connectat a terra en l’altre. El model ha mostrat que les diferències en robustesa són causades per la millora en el factor de qualitat i en l’amplitud d’oscil·lació i no per un augment en l’aïllament entre tanc i substrat. Per altra banda, el model ha demostrat ser vàlid i molt precís inclús en aquest rang de freqüència tan extrem.The integration of transceivers for RF communication in CMOS can be seriously limited by the interaction between their blocks, even advising against using a single silicon die. The high frequency noise generated by some of the blocks, like the power amplifier, can travel through the substrate, reaching the local oscillator and threatening its correct performance. Three important reasons can be stated that show the risk of the single die integration. Noise propagation is easier the higher the frequency. Moreover, the protection structures lose efficiency as the noise frequency increases. Finally, the high frequency noise that reaches the local oscillator degrades its performance. The purpose of this thesis is to deeply analyze the interaction between the high frequency substrate noise and the oscillator with the objective of being able to predict, thanks to a model, the effect that this noise may have over the correct behavior of the oscillator. We want to provide some guidelines to the designers to allow them to increase the robustness of the oscillator to high frequency substrate noise. The investigation of the effect of the high frequency substrate noise on oscillators has started from an empirical point of view, on one hand, analyzing the noise propagation through the substrate and evaluating the efficiency of some structures to block this propagation, and on the other hand, determining the effect on an oscillator of a high frequency noise tone present in the substrate. This investigation has shown that the injection of a high frequency tone in the substrate can reach the oscillator and, due to a frequency pulling effect, it can modulate in frequency the output of the oscillator. Based on the results obtained during the empirical analysis, a mathematical model to predict the effect of the substrate noise on the oscillator has been provided. The main advantage of this model is the fact that it is based on physical parameters of the oscillator and of the noise, allowing to determine the measures that a designer can take to increase the robustness of the oscillator as well as the consequences (trade-offs) that these measures have over its global performance. This model has been compared against both, simulations and real measurements, showing a very high accuracy to predict the effect of the high frequency substrate noise. The usefulness of the presented model as a design tool has been demonstrated in two case studies. Firstly, the conclusions obtained from the model have been applied in the design of an ultra low power consumption 2.5 GHz oscillator robust to the high frequency substrate noise with characteristics which make it compatible with the main communication standards in this frequency band. Finally, the model has been used as an analysis tool to evaluate the cause of the differences, in terms of performance degradation due to substrate noise, measured in two 60 GHz oscillators with two different tank inductor shielding strategies, floating and grounded. The model has determined that the robustness differences are caused by the improvement in the tank quality factor and in the oscillation amplitude and no by an increased isolation between the tank and the substrate. The model has shown to be valid and very accurate even in these extreme frequency range.Postprint (published version

Implantable Low-Noise Fiberless Optoelectrodes for Optogenetic Control of Distinct Neural Populations

The mammalian brain is often compared to an electrical circuit, and its dynamics and function are governed by communication across different types neurons. To treat neurological disorders like Alzheimer’s and Parkinson’s, which are characterized by inhibition or amplification of neural activity in a particular region or lack of communication between different regions of the brain, there is a need to understand troubleshoot neural networks at cellular or local circuit level. In this work, we introduce a novel implantable optoelectrode that can manipulate more than one neuron type at a single site, independently and simultaneously. By delivering multi-color light using a scalable optical waveguide mixer, we demonstrate manipulation of multiple neuron types at precise spatial locations in vivo for the first time. We report design, micro-fabrication and optoelectronic packaging of a fiber-less, multicolor optoelectrode. The compact optoelectrode design consists of a 7 μm x 30 μm dielectric optical waveguide mixer and eight electrical recording sites monolithically integrated on each shank of a 22 μm-thick four-shank silicon neural probe. The waveguide mixers are coupled to eight side-emitting injection laser diodes (ILDs) via gradient-index (GRIN) lenses assembled on the probe backend. GRIN-based optoelectrode enables efficient optical coupling with large alignment tolerance to provide wide optical power range (10 to 3000 mW/mm2 irradiance) at stimulation ports. It also keeps thermal dissipation and electromagnetic interference generated by light sources sufficiently far from the sensitive neural signals, allowing thermal and electrical noise management on a multilayer printed circuit board. We demonstrated device verification and validation in CA1 pyramidal layer of mice hippocampus in both anesthetized and awake animals. The packaged devices were used to manipulate variety of multi-opsin preparations in vivo expressing different combinations of Channelrhodopsin-2, Archaerhodopsin and ChrimsonR in pyramidal and parvalbumin interneuron cells. We show effective stimulation, inhibition and recording of neural spikes at precise spatial locations with less than 100 μV stimulation-locked transients on the recording channels, demonstrating novel use of this technology in the functional dissection of neural circuits.PHDBiomedical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/137171/1/kkomal_1.pd

Soft Tactile Sensors for Mechanical Imaging

Tactile sensing aims to electronically capture physical attributes of an object via mechanical contact. It proves indispensable to many engineering tasks and systems, in areas ranging from manufacturing to medicine and autonomous robotics. Biological skin, which is highly compliant, is able to perform sensing under challenging and highly variable conditions with levels of performance that far exceed what is possible with conventional tactile sensors, which are normally fabricated with non-conforming materials. The development of stretchable, skin-like tactile sensors has, as a result, remained a longstanding goal of engineering. However, to date, artificial tactile sensors that might mimic both the mechanical and multimodal tactile sensory capabilities of biological skin remain far from realization, due to the challenges of fabricating spatially dense, mechanically robust, and compliant sensors in elastic media. Inspired by these demands, this dissertation addresses many aspects of the challenging problem of engineering skin-like electronic sensors. In the first part of the thesis, new methods for the design and fabrication of thin, highly deformable, high resolution tactile sensors are presented. The approach is based on a novel configuration of arrays of microfluidic channels embedded in thin elastomer membranes. To form electrodes, these channels are filled with a metal alloy, eutectic Gallium Indium, that remains liquid at room temperature. Using capacitance sensing techniques, this approach achieves sensing resolutions of 1 mm$^{-1}$. To fabricate these devices, an efficient and robust soft lithography method is introduced, based on a single step cast. An analytical model for the performance of these devices is derived from electrostatic theory and continuum mechanics, and is demonstrated to yield excellent agreement with measured performance. This part of the investigation identified fundamental limitations, in the form of nonmonotonic behavior at low strains, that is demonstrated to generically affect solid cast soft capacitive sensors. The next part of the thesis is an investigation of new methods for designing soft tactile sensors based on multi-layer heterogeneous 3D structures that combine active layers, containing embedded liquid metal electrodes, with passive and mechanically tunable layers, containing air cavities and micropillar geometric supports. In tandem with analytical and computational modeling, these methods are demonstrated to facilitate greater control over mechanical and electronic performance. A new soft lithography fabrication method is also presented, based on the casting, alignment, and fusion of multiple functional layers in a soft polymer substrate. Measurements indicate that the resulting devices achieve excellent performance specifications, and avoid the limiting nonmonotonic behavior identified in the first part of the thesis. In order to demonstrate the practical utility of the devices, we used them to perform dynamic two-dimensional tactile imaging under distributed indentation loads. The results reflect the excellent static and dynamic performance of these devices. The final part of the thesis investigates the utility of the tactile sensing methods pursued here for imaging lumps embedded in simulated tissue. In order to facilitate real-time sensing, an electronic system for fast, array based measurement of small, sub-picofarad (pF) capacitance levels was developed. Using this system, we demonstrated that it is possible to accurately capture strain images depicting small lumps embedded in simulated tissue with either an electronic imaging system or a sensor worn on the finger, supporting the viability of wearable sensors for tactile imaging in medicine. In conclusion, this dissertation confronts many of the most vexing problems arising in the pursuit of skin-like electronic sensors, including fundamental operating principles, structural and functional electronic design, mechanical and electronic modeling, fabrication, and applications to biomedical imaging. The thesis also contributes knowledge needed to enable applications of tactile sensing in medicine, an area that has served as a key source of motivation for this work, and aims to facilitate other applications in areas such as manufacturing, robotics, and consumer electronics.Ph.D., Electrical Engineering -- Drexel University, 201

Multiphysics modeling and simulation for large-scale integrated circuits

This dissertation is a process of seeking solutions to two important and challenging problems related to the design of modern integrated circuits (ICs): the ever increasing couplings among the multiphysics and the large problem size arising from the escalating complexity of the designs. A multiphysics-based computer-aided design methodology is proposed and realized to address multiple aspects of a design simultaneously, which include electromagnetics, heat transfer, fluid dynamics, and structure mechanics. The multiphysics simulation is based on the finite element method for its unmatched capabilities in handling complicate geometries and material properties. The capability of the multiphysics simulation is demonstrated through its applications in a variety of important problems, including the static and dynamic IR-drop analyses of power distribution networks, the thermal-ware high-frequency characterization of through-silicon-via structures, the full-wave electromagnetic analysis of high-power RF/microwave circuits, the modeling and analysis of three-dimensional ICs with integrated microchannel cooling, the characterization of micro- and nanoscale electrical-mechanical systems, and the modeling of decoupling capacitor derating in the power integrity simulations. To perform the large-scale analysis in a highly efficient manner, a domain decomposition scheme, parallel computing, and an adaptive time-stepping scheme are incorporated into the proposed multiphysics simulation. Significant reduction in computation time is achieved through the two numerical schemes and the parallel computing with multiple processors

Scalable Bundle Design for Massively Parallel Neuronal Recordings <i>In Vivo</i>

Neural coding consists of precise interactions between related neurons. New techniques are needed to measure the time sensitive interactions within entire neural networks to understand how the brain functions. Extracellular recording is the oldest method of measuring neural activity and can sample at a temporal resolution to resolve fast spiking neurons. If scaled to a sufficiently large number of simultaneous recorded neurons, this technique would be an excellent candidate for such large scale recording. I propose the combined use of glass ensheathed microwire bundle electrodes and an infrared camera readout integrated circuit to collect massively parallel neuronal recordings in vivo. This design will allow for the recording of high quality signals because of the non-intrusive dimensions, low stray capacitance, and enhanced surface impedance of the electrodes, as well as the high signal to noise amplification of the camera electronics. Here the construction of a system to record neural activity is described and its electrical properties are characterized. The results demonstrate the ability to successfully connect fabricated bundle electrodes to the indium bumps of the readout integrated circuit chip and to record voltage waveforms with a signal to noise ratio to resolve simulated spikes. In vivo experiments in the olfactory bulb of anaesthetized mice have resulted in recordings of action potentials from single units. The spike rate of these units increases with odor presentation and is pharmacologically inhibited which demonstrates the biological origin of the recorded activity. To further advance this technology, the stability and rate of connection to the readout electronics need to improve and insertion of electrode bundles with hundreds of more recording sites needs to be optimized. This promising design has several distinct advantages over existing fluorescence imaging and extracellular recording neurotechnologies for large scale neuronal recording