1,721,079 research outputs found
FM-based generation of high EMC timing signals
No full textThis contribution represents the slides of a tutorial held by the author
Cell biasing and balancing in E-cell based single ended log filters
No full textLog domain (or instantaneous companding) filtering is a recent appealing paradigm for designing integrable, high-frequency, low-voltage, continuous-time filters. A nonlinear transconductor known as E-cell is the single building block needed for realizing filters of any complexity. Nevertheless, the problem of biasing all the E-cells at proper DC operating points has not yet been systematically solved. Aim of this contribution is to address this topic and to propose a generally applicable mapping which systematically provides proper bias levels. Furthermore, the proposed mapping balances the E-cell branch currents at the DC operating point, allowing overall improved operation
Improved bandwidth, low voltage log domain building blocks
No full textThe possibility of operating low-voltage-supply log-domain filters at high frequencies is investigated, distinguishing the intrinsic maximum bandwidth of the translinear loops exploited for log/exp function synthesis from that of control/interface blocks. Strategies are proposed to widen the latter closer to the former. Simulation results are shown for an integrator as a validation for the considered approach
A heuristic solution to the optimisation of flutter control in compression systems (and to some more binary quadratic programming problems) via ΔΣ modulation circuits
No full textAn example of how circuit related techniques can help solving optimisatin problems originating from completely different domains is provided. It is shown that a specific class of Unconstrained Binary Quadratic Programming (UBQP) problems, including those arising in the optimisation of flutter control via blade mistiming, can be solved by means of ΔΣ modulators. This is done in steps, first restating the UBQP problem as a specific signal processing problem, and then attacking the latter via the design of a ΔΣ modulator with a suitably derived Noise Transfer Function. A (heuristically) optimal solution for the original problem is finally obtained from the modulator output stream. The method is validated by two numerical examples arising in the design of turbo-machines
Experiments on aircraft flight parameter detection by on-skin sensors
No full textAir speed and flight attitude angles are fundamental parameters for manual of automatic control of flying bodies. Conventional measuremen methods rely on probes (e.g. Pitot tubes or vanes) having a one-to-one correspondence with the physical quantities of interest and requiring specific placements. Here, a novel measurement approach is proposed, relying on indirect measurement and on a plurality of pressure readings made by thin capacitive sensors directly placed on the aircraft skin. A redundant number of probes relaxes the accuracy requirements posed on the individual units and helps achieving fault detection or fault tolerance. A strategy for efficiently processing/combining sensor data is herein presented together with an error propagation analysis, and experimental data
Folded sums of chaotic trajectories distribute uniformly
No full textWe investigate the properties of a process where the subsequent values assumed by the state of a chaotic map are summed to each other and the result is constrained within a finite domain by a folding operation. It is found that the limit distribution is always uniform, that the folded sums tend to be independent of the future evolution of the chaotic trajectory and that, whenever the map state is multi-dimensional, the folded sum vectors tend to be made of independent components. As an example, an application to the formal derivation of the spectrum of chaotically frequency modulated signals is also reported
Embeddable ADC-Based True Random Number Generator for Cryptographic Applications Exploiting Nonlinear Signal Processing and Chaos
No full textWe present a true random number generator which,
contrary to other implementations, is not based on the explicit
observation of complex micro-cosmic processes but on standard
signal processing primitives, freeing the designer from the need
for dedicated hardware. The system can be implemented from
now ubiquitous analog-to-digital converters building blocks, and
is therefore well-suited to embedding. On current technologies,
the design permits data rates in the order of a few tens of megabits
per second. Furthermore, the absence of predictable, repeatable
behaviors increases the system security for cryptographic applications.
The design relies on a simple inner model based on chaotic
dynamics which, in ideal conditions, can be formally proven to
generate perfectly uncorrelated binary sequences. Here, we detail
the design and we validate the quality of its output against a
couple of test suites standardized by the U.S. National Institute of
Standards and Technology, both in the ideal case and assuming
implementation errors
Circuito Elettronico Riconfigurabile come Convertitore Analogico/Digitale e Generatore di Sequenze Autenticamente Casuali
No full textLa presente invenzione riguarda un modulo funzionale da utilizzarsi nella progettazione di circuiti integrati ed in grado di operare in alternativa come convertitore analogico/digitale o come generatore di sequenze binarie autenticamente casuali. La riconfigurabilità lo rende particolarmente adatto ad essere inserito in circuiti integrati programmabili e/o riconfigurabili sul campo, quali microcontrollori, array digitali programmabili, digital signal processor, interfacce per sensori e reti di sensori, e in generale in qualunque circuito integrato ove non può essere noto a priori quali funzionalità siano effettivamente richieste. Attraverso l’uso di porte logiche e commutatori elettronici il circuito può passare dalla topologia di un convertitore analogico/digitale di tipo pipeline ad una topologia che realizza un sistema dinamico caotico per la produzione di entropia e la generazione di sequenze casuali, impredicibili e non ripetibili
Reconfigurable ADC/true-RNG for secure sensor networks
No full textA novel circuit configurable either as an Analog to Digital Converter (ADC) or as a true Random Number Generator (RNG) is presented. The architecture derives from pipeline ADCs and its operating mode can be changed on the fly. When used as an ADC, it pairs the performance of normal pipeline converters; otherwise it is capable of tens random Mbit/s and to pass standard randomness tests, including NIST SP800-22, as proved by extensive simulation. Applications include (wireless) sensor networks where RNGs represent an indispensable primitive in the implementation of many security schemes. Since the strength of cryptographic techniques depends on the unpredictability of the RNGs they employ, it has recently been proposed that security related applications should favor true-RNGs, over pseudo-RNGs. With sensor interfaces always including ADCs, the proposed technique makes a true-RNG available at sensor nodes at virtually no hardware/power consumption costs
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