Publikacje
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wszystkich: 481
Katalog Publikacji
2020

A 1nS 1V Sub1µW Linear CMOS OTA with RailtoRail Input for HzBand Sensory Interfaces
PublikacjaThe paper presents an operational transconductance amplifier (OTA) with low transconductance (0.62–6.28 nS) and low power consumption (28–270 nW) for the lowfrequency analog frontends in biomedical sensor interfaces. The proposed OTA implements an innovative, highly linear voltagetocurrent converter based on the channellengthmodulation effect, which can be railtorail driven. At 1V supply and 1Vpp asymmetrical input driving,...

A Conformal Circularly Polarized SeriesFed Microstrip Antenna Array Design
PublikacjaA conformal circularly polarized seriesfed microstrip array design for broadside radiation is presented. The array aperture under design is conformal to a cylindrical surface of a given radius. The approach we present primarily addresses focusing of the circularly polarized major lobe of the conformal array by proper dimensioning of the aperture spacings. The proposed analytical models yield the values of the element spacings...

A framework for accelerated optimization of antennas using design database and initial parameter set estimation
PublikacjaThe purpose of this paper is to exploit a database of preexisting designs to accelerate parametric optimization of antenna structures is investigated. Design/methodology/approach The usefulness of preexisting designs for rapid design of antennas is investigated. The proposed approach exploits the database existing antenna base designs to determine a good starting point for structure optimization and its response sensitivities....

A PowerEfficient Digital Technique for Gain and Offset Correction in Slope ADCs
PublikacjaIn this brief, a powerefficient digital technique for gain and offset correction in slope analogtodigital converters (ADCs) has been proposed. The technique is especially useful for imaging arrays with massively parallel image acquisition where simultaneous compensation of dark signal nonuniformity (DSNU) as well as photoresponse nonuniformity (PRNU) is critical. The presented approach is based on stopping the ADC clock by...

Accelerated design optimization of miniaturized microwave passives by design reusing and Kriging interpolation surrogates
PublikacjaElectromagnetic (EM) analysis has become ubiquitous in the design of microwave components and systems. One of the reasons is the increasing topological complexity of the circuits. Their reliable evaluation—at least at the design closure stage—can no longer be carried out using analytical or equivalent network representations. This is especially pertinent to miniaturized structures, where considerable EM crosscoupling effects occurring...

Accelerated multiobjective design of miniaturized microwave components by means of nested kriging surrogates
PublikacjaDesign of microwave components is an inherently multiobjective task. Often, the objectives are at least partially conflicting and the designer has to work out a suitable compromise. In practice, generating the best possible trade‐off designs requires multiobjective optimization, which is a computationally demanding task. If the structure of interest is evaluated through full‐wave electromagnetic (EM) analysis, the employment of...

Accelerated ReDesign of Antenna Structures Using SensitivityBased Inverse Surrogates
PublikacjaThe paper proposes a novel framework for accelerated redesign (dimension scaling) of antenna structures using inverse surrogates. The major contribution of the work is a sensitivitybased model identification procedure, which permits a significant reduction of the number of reference designs required to render the surrogate. Rigorous formulation of the approach is supplemented by its comprehensive numerical validation using a...

Antenna Modeling Using VariableFidelity EM Simulations and Constrained CoKriging
PublikacjaUtilization of fast surrogate models has become a viable alternative to direct handling of fullwave electromagnetic (EM) simulations in EMdriven design. Their purpose is to alleviate the difficulties related to high computational cost of multiple simulations required by the common numerical procedures such as parametric optimization or uncertainty quantification. Yet, conventional datadriven (or approximation) modeling techniques...

Circular polarization diversity implementation for correlation reduction in wideband lowcost multipleinputmultipleoutput antenna
PublikacjaIn this paper, a multipleinputmultipleoutput (MIMO) antenna featuring circular polarization diversity, and designed on a common coplanar ground is presented. The proposed antenna design utilizes a coplanar waveguide (CPW) feeding technique with three parallel coplanar ground planes, and two feedlines inbetween. For circular polarization (CP), quasiloops are created by etching slots on the outermost ground planes. With this...

Compact DualPolarized Corrugated Horn Antenna for Satellite Communications
PublikacjaIn this paper, a structure and design procedure of a novel compact dualpolarized corrugated horn antenna with high gain and a stable phase center for satellite communication is presented. The antenna incorporates an OrthoMode Transducer (OMT), a mode converter, and a corrugated structure. The compact OMT section is designed to be fed by standard WR75 waveguides. The proposed compact design utilizes only ten corrugated slots...

Computationallyefficient design optimisation of antennas by accelerated gradient search with sensitivity and design change monitoring
PublikacjaElectromagnetic (EM) simulation tools are of primary importance in the design of contemporary antennas. The necessity of accurate performance evaluation of complex structures is a reason why the final tuning of antenna dimensions, aimed at improvement of electrical and field characteristics, needs to be based on EM analysis. Design automation is highly desirable and can be achieved by coupling EM solvers with numerical optimisation...

CostEfficient BiLayer Modeling of Antenna Input Characteristics Using Gradient Kriging Surrogates
PublikacjaOver the recent years, surrogate modeling has been playing an increasing role in the design of antenna structures. The main incentive is to mitigate the issues related to high cost of electromagnetic (EM)based procedures. Among the various techniques, approximation surrogates are the most popular ones due to their flexibility and easy access. Notwithstanding, datadriven modeling of antenna characteristics is associated with serious...

Cost‐efficient performance‐driven modelling of multi‐band antennas by variable‐fidelity electromagnetic simulations and customized space mapping
PublikacjaElectromagnetic (EM) simulations have become an indispensable tool in the design of contemporary antennas. EM‐driven tasks, for example, parametric optimization, entail considerable computational efforts, which may be reduced by employing surrogate models. Yet, data‐driven modelling of antenna characteristics is largely hindered by the curse of dimensionality. This may be addressed using the recently reported domain‐confinement...

CostEfficient Surrogate Modeling of HighFrequency Structures Using Nested Kriging with Automated Adjustment of Model Domain Lateral Dimensions
PublikacjaSurrogate models are becoming popular tools of choice in mitigating issues related to the excessive cost of electromagnetic (EM)driven design of highfrequency structures. Among available techniques, approximation modeling is by far the most popular due to its versatility. In particular, the surrogates are exclusively based on the sampled simulation data with no need to involve engineering insight or problemspecific knowledge....

Designoriented computationallyefficient featurebased surrogate modelling of multiband antennas with nested kriging
PublikacjaDesign of modern antenna structures heavily depends on electromagnetic (EM) simulation tools. EM analysis provides reliable evaluation of increasingly complex designs but tends to be CPU intensive. When multiple simulations are needed (e.g., for parameters tuning), the aggregated simulation cost may become a serious bottleneck. As one possible way of mitigating the issue, the recent literature fosters utilization of faster representations,...

DesignOriented TwoStage Surrogate Modeling of Miniaturized Microstrip Circuits with Dimensionality Reduction
PublikacjaContemporary microwave design heavily relies on fullwave electromagnetic (EM) simulation tools. This is especially the case for miniaturized devices where EM crosscoupling effects cannot be adequately accounted for using equivalent network models. Unfortunately, EM analysis incurs considerable computational expenses, which becomes a bottleneck whenever multiple evaluations are required. Common simulationbased design tasks include...

Editorial for the special issue on advances in forward and inverse surrogate modeling for highfrequency design
PublikacjaThe design of modern‐day high‐frequency devices and circuits, including microwave/RF, antenna and photonic components, historically has relied on full‐wave electromagnetic (EM) simulation tools. Initially used for design verification, EM simulations are nowadays used in the design process itself, for example, for finding optimum values of geometry and/or material parameters of the structures of interest. In a growing number of...

EnhancedPerformance Circularly Polarized MIMO Antenna with Polarization/Pattern Diversity
PublikacjaDesign of a compact wideband circularly polarized (CP) multipleinput multipleoutput (MIMO) antenna with polarization diversity is proposed and characterized for offbody communication. The antenna is based on a simple coplanar waveguide (CPW)fed monopole extension of the microstrip line. The orthogonal field components required by CP are induced using a simply modified right/left side ground plane. In particular, a stub extending...

Expedited antenna optimization with numerical derivatives and gradient change tracking
PublikacjaDesign automation has been playing an increasing role in the development of novel antenna structures for various applications. One of its aspects is electromagnetic (EM)driven design closure, typically applied upon establishing the antenna topology, and aiming at adjustment of geometry parameters to boost the performance figures as much as possible. Parametric optimization is often realized using local methods given usually reasonable...

Expedited Design Closure of Antenna Input Characteristics by Trust Region Gradient Search and Principal Component Analysis
PublikacjaOptimizationbased parameter tuning has become an inherent part of contemporary antenna design process. For the sake of reliability, it is typically conducted at the level of fullwave electromagnetic (EM) simulation models. This may incur considerable computational expenses depending on the cost of an individual EM analysis, the number of adjustable variables, the type of task (local, global, single/multiobjective optimization),...

Expedited FeatureBased QuasiGlobal Optimization of MultiBand Antenna Input Characteristics with Jacobian Variability Tracking
PublikacjaDesign of modern antennas relies—for reliability reasons—on fullwave electromagnetic simulation tools. In addition, increasingly stringent specifications pertaining to electrical and field performance, growing complexity of antenna topologies, along with the necessity for handling multiple objectives, make numerical optimization of antenna geometry parameters a highly recommended design procedure. Conventional algorithms, particularly...

Expedited Globalized Antenna Optimization by Principal Components and VariableFidelity EM Simulations: Application to Microstrip Antenna Design
PublikacjaParameter optimization, also referred to as design closure, is imperative in the development of modern antennas. Theoretical considerations along with rough dimension adjustment through supervised parameter sweeping can only yield initial designs that need to be further tuned to boost the antenna performance. The major challenges include handling of multidimensional parameter spaces while accounting for several objectives and...

Expedited optimization of antenna input characteristics with adaptive Broyden updates
PublikacjaSimulationdriven adjustment of geometry and/or material parameters is a necessary step in the design of contemporary antenna structures. Due to their topological complexity, other means, such as supervised parameter sweeping, does not usually lead to satisfactory results. On the other hand, rigorous numerical optimization is computationally expensive due to a high cost of underlying fullwave electromagnetic (EM) analyses, otherwise...

Expedited Yield Optimization of Narrow and MultiBand Antennas Using PerformanceDriven Surrogates
PublikacjaUncertainty quantification is an important aspect of engineering design, also pertaining to the development and performance evaluation of antenna systems. Manufacturing tolerances as well as other types of uncertainties, related to material parameters (e.g., substrate permittivity) or operating conditions (e.g., bending) may affect the antenna characteristics. In the case of narrow or multiband antennas, this usually leads to...

Fast MultiObjective Aerodynamic Optimization Using Sequential Domain Patching and Multifidelity Models
PublikacjaExploration of design tradeoffs for aerodynamic surfaces requires solving of multiobjective optimization (MOO) problems. The major bottleneck here is the timeconsuming evaluations of the computational fluid dynamics (CFD) model used to capture the nonlinear physics involved in designing aerodynamic surfaces. This, in conjunction with a large number of simulations necessary to yield a set of designs representing the best possible...

Fast multiobjective design optimization of microwave and antenna structures using datadriven surrogates and domain segmentation
PublikacjaPurpose Strategies and algorithms for expedited design optimization of microwave and antenna structures in multiobjective setup are investigated. Design/methodology/approach Formulation of the multiobjective design problem oriented towards execution of the populationbased metaheuristic algorithm within the segmented search space is investigated. Described algorithmic framework exploit variable fidelity modeling, physics and...

Fast multiobjective optimization of antenna structures by means of datadriven surrogates and dimensionality reduction
PublikacjaDesign of contemporary antenna structures needs to account for several and often conflicting objectives. These are pertinent to both electrical and field properties of the antenna but also its geometry (e.g., footprint minimization). For practical reasons, especially to facilitate efficient optimization, singleobjective formulations are most often employed, through either a priori preference articulation, objective aggregation,...

Fixed Pattern Noise Reduction and Linearity Improvement in TimeMode CMOS Image Sensors
PublikacjaIn the paper, a digital clock stopping technique for gain and offset correction in timemode analogtodigital converters (ADCs) has been proposed. The technique is dedicated to imagers with massively parallel image acquisition working in the time mode where compensation of dark signal nonuniformity (DSNU) as well as photoresponse nonuniformity (PRNU) is critical. Fixed pattern noise (FPN) reduction has been experimentally validated...

Hybrid‐mode single‐slope ADC with improved linearity and reduced conversion time for CMOS image sensors
PublikacjaIn the paper, a single‐slope analog‐to‐digital converter (ADC) for integrated CMOS image sensor applications with an improved technique of conversion has been proposed. The proposed hybrid‐mode ADC automatically uses one of the following conversion techniques: time based (i.e. PWM) or voltage based (i.e. single‐slope). During the ADC operation, the clock frequency and reference voltage are modified in order to reduce the conversion...

Implementation of spatial/polarization diversity for improvedperformance circularly polarized multipleinputmultipleoutput ultrawideband antenna
PublikacjaIn this paper, spatial and polarization diversities are simultaneously implemented in an ultrawideband (UWB) multipleinputmultipleoutput (MIMO) antenna to reduce the correlation between the parallelplaced radiators. The keystone of the antenna is systematically modified coplanar ground planes that enable excitation of circular polarization (CP). To realize one sense of circular polarization as well as ultrawideband operation,...

ImprovedEfficacy Optimization of Compact Microwave Passives by Means of FrequencyRelated Regularization
PublikacjaElectromagnetic (EM)driven optimization is an important part of microwave design, especially for miniaturized components where the crosscoupling effects in tightly arranged layouts make traditional (e.g., equivalent network) representations grossly inaccurate. Efficient parameter tuning requires reasonably good initial designs, which are difficult to be rendered for newly developed structures or when redesign for different operating...

Kriging metamodels and design re‐utilization for fast parameter tuning of antenna structures
PublikacjaThe paper addresses the problem of computationally efficient electromagnetic (EM)‐driven design closure of antenna structures. The foundations of the presented approach are fast kriging interpolation metamodels, utilized for two purposes: (a) producing a good starting point for further parameter tuning, and (b) yielding a reasonable Jacobian matrix estimate to jump‐start the optimization procedure. The models are rendered using...

LightPowered Starter for MicroPower Boost DC–DC Converter for CMOS Image Sensors
PublikacjaThe design of a starter for a lowvoltage, micropower boost DC–DC converter intended for powering CMOS image sensors is presented. A unique feature of the starter is extremely low current, below 1 nA, supplying its control circuit. Therefore, a highvoltage (1.3 V) configuration of seriesconnected photovoltaic diodes available in a standard CMOS process or a small external LED working in photovoltaic mode can be used as an auxiliary...

LowCost Automated Design of Compact BranchLine Couplers
PublikacjaBranchline couplers (BLCs) are important components of wireless communication systems. Conventional BLCs are often characterized by large footprints which make miniaturization an important prerequisite for their application in modern devices. Stateoftheart approaches to design of compact BLCs are largely based on the use of highpermittivity substrates and multilayer topologies. Alternative methods involve replacement of transmissionline...

Lowcost performancedriven modelling of compact microwave components with twolayer surrogates and gradient kriging
PublikacjaUtilization of electromagnetic (EM) simulation tools has become indispensable for reliable evaluation of microwave components. As the cost of an individual analysis may already be considerable, the computational overhead associated with EMdriven tasks that require massive simulations (e.g., optimization) may turn prohibitive. One of mitigation methods is the employment of equivalent network models. Yet, they are incapable of accounting...

LowPower Receivers for Wireless Capacitive Coupling Transmission in 3DIntegrated Massively Parallel CMOS Imager
PublikacjaThe paper presents pixel receivers for massively parallel transmission of video signal between capacitive coupled integrated circuits (ICs). The receivers meet the key requirements for massively parallel transmission, namely lowpower consumption below a single μW, small area of less than 205 μm2, high sensitivity better than 160 mV, and good immunity to crosstalk. The receivers were implemented and measured in a 3D IC (two facetoface...

Nested Kriging with Variable Domain Thickness for Rapid Surrogate Modeling and Design Optimization of Antennas
PublikacjaDesign of modern antennas faces numerous difficulties, partially rooted in stringent specifications imposed on both electrical and field characteristics, demands concerning various functionalities (circular polarization, pattern diversity, bandnotch operation), but also constraints imposed upon the physical size of the radiators. Conducting the design process at the level of fullwave electromagnetic (EM) simulations, otherwise...

On ComputationallyEfficient Reference Design Acquisition for ReducedCost Constrained Modeling and ReDesign of Compact Microwave Passives
PublikacjaFullwave electromagnetic (EM) analysis has been playing a major role in the design of microwave components for the last few decades. In particular, EM tools allow for accurate evaluation of electrical performance of miniaturized structures where strong crosscoupling effects cannot be adequately quantified using equivalent network models. However, EMbased design procedures (parametric optimization, statistical analysis) generate...

On Inadequacy of Sequential Design of Experiments for PerformanceDriven Surrogate Modeling of Antenna Input Characteristics
PublikacjaDesign of contemporary antennas necessarily involves electromagnetic (EM) simulation tools. Their employment is imperative to ensure evaluation reliability but also to carry out the design process itself, especially, the adjustment of antenna dimensions. For the latter, traditionally used parameter sweeping is more and more often replaced by rigorous numerical optimization, which entails considerable computational expenses, sometimes...

PerformanceDriven Surrogate Modeling of HighFrequency Structures
PublikacjaThe development of modern highfrequency structures, including microwave and antenna components, heavily relies on fullwave electromagnetic (EM) simulation models. Notwithstanding, EMdriven design entails considerable computational expenses. This is especially troublesome when solving tasks that require massive EM analyzes, parametric optimization and uncertainty quantification being representative examples. The employment of...

Photoplethysmographic TimeDomain Heart Rate Measurement Algorithm for ResourceConstrained Wearable Devices and its Implementation
PublikacjaThis paper presents an algorithm for the measurement of the human heart rate, using photoplethysmography (PPG), i.e., the detection of the light at the skin surface. The signal from the PPG sensor is processed in timedomain; the peaks in the preprocessed and conditioned PPG waveform are detected by using a peak detection algorithm to find the heart rate in real time. Apart from the PPG sensor, the accelerometer is also used to...

QuasiGlobal Optimization of Antenna Structures Using Principal Components and Affine SubspaceSpanned Surrogates
PublikacjaParametric optimization is a mandatory step in the design of contemporary antenna structures. Conceptual development can only provide rough initial designs that have to be further tuned, often extensively. Given the topological complexity of modern antennas, the design closure necessarily involves fullwave electromagnetic (EM) simulations and—in many cases—global search procedures. Both factors make antenna optimization a computationally...

Rapid multiobjective optimization of antennas using nested kriging surrogates and singlefidelity EM simulation models
PublikacjaEver increasing performance requirements make the design of contemporary antenna systems a complex and multistage process. One of the challenges, pertinent to the emerging application areas but also some of the recent trends (miniaturization, demands for multifunctionality, etc.), is the necessity of handling several performance figures such as impedance matching, gain, or axial ratio, often over multiple frequency bands. The...

Rapid optimization of compact microwave passives using kriging surrogates and iterative correction
PublikacjaDesign of contemporary microwave components is—in a large part—based on fullwave electromagnetic (EM) simulation tools. The primary reasons for this include reliability and versatility of EM analysis. In fact, for many microwave structures, notably compact components, EMdriven parameter tuning is virtually imperative because traditional models (analytical or network equivalents) are unable to account for the crosscoupling effects,...

Rapid redesign of multiband antennas with respect to operating conditions and material parameters of substrate
PublikacjaThis work addresses geometry parameter scaling of multiband antennas for Internet of Things applications. The presented approach is comprehensive and permits redesign of the structure with respect to both the operating frequencies and material parameters of the dielectric substrate. A twostep procedure is developed with the initial design obtained from an inverse surrogate model constructed using a set of appropriately prepared...

Rapid tolerance‐aware design of miniaturized microwave passives by means of confined‐domain surrogates
PublikacjaThe effects of uncertainties, primarily manufacturing tolerances but also incomplete information about operating conditions or material parameters, can be detrimental to the performance of microwave components. Quantification of such effects is essential to ensure a meaningful evaluation of the structure, in particular, its reliability under imperfect fabrication procedures. The improvement of the circuit robustness can be achieved...

Recent advances in highfrequency modeling by means of domain confinement and nested kriging
PublikacjaDevelopment of modern highfrequency components and circuits is heavily based on fullwave electromagnetic (EM) simulation tools. Some phenomena, although important from the point of view of the system performance, e.g., EM crosscoupling effects, feed radiation in antenna arrays, substrate anisotropy, cannot be adequately accounted for using simpler means such as equivalent network representations. Consequently, the involvement...

Recent Advances in PerformanceDriven Surrogate Modeling of HighFrequency Structures
PublikacjaDesign of high‐frequency structures, including microwave and antenna components, heavily relies on full‐wave electromagnetic (EM) simulation models. Their reliability comes at a price of a considerable computational cost. This may lead to practical issues whenever numerous EM analyses are to be executed, e.g., in the case of parametric optimization. The difficulties entailed by massive simulations may be mitigated by the use of...

Reliable Surrogate Modeling of Antenna Input Characteristics by Means of Domain Confinement and Principal Components
PublikacjaA reliable design of contemporary antenna structures necessarily involves fullwave electromagnetic (EM) analysis which is the only tool capable of accounting, for example, for element coupling or the effects of connectors. As EM simulations tend to be CPUintensive, surrogate modeling allows for relieving the computational overhead of design tasks that require numerous analyses, for example, parametric optimization or uncertainty...

Surrogate modeling of impedance matching transformers by means of variable‐fidelity electromagnetic simulations and nested cokriging
PublikacjaAccurate performance evaluation of microwave components can be carried out using full‐wave electromagnetic (EM) simulation tools, routinely employed for circuit verification but also in the design process itself. Unfortunately, the computational cost of EM‐driven design may be high. This is especially pertinent to tasks entailing considerable number of simulations (eg, parametric optimization, statistical analysis). A possible...