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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

Conception en vue de test de convertisseurs de signal analogique-numérique de type pipeline. / Design for test of pipelined analog to digital converters.

Laraba, Asma 20 September 2013 (has links)
La Non-Linéarité-Différentielle (NLD) et la Non-Linéarité-Intégrale (NLI) sont les performances statiques les plus importantes des Convertisseurs Analogique-Numérique (CAN) qui sont mesurées lors d’un test de production. Ces deux performances indiquent la déviation de la fonction de transfert du CAN par rapport au cas idéal. Elles sont obtenues en appliquant une rampe ou une sinusoïde lente au CAN et en calculant le nombre d’occurrences de chacun des codes du CAN.Ceci permet la construction de l’histogramme qui permet l’extraction de la NLD et la NLI. Cette approche requiert lacollection d’une quantité importante de données puisque chacun des codes doit être traversé plusieurs fois afin de moyenner le bruit et la quantité de données nécessaire augmente exponentiellement avec la résolution du CAN sous test. En effet,malgré que les circuits analogiques et mixtes occupent une surface qui n’excède pas généralement 5% de la surface globald’un System-on-Chip (SoC), leur temps de test représente souvent plus que 30% du temps de test global. Pour cette raison, la réduction du temps de test des CANs est un domaine de recherche qui attire de plus en plus d’attention et qui est en train deprendre de l’ampleur. Les CAN de type pipeline offrent un bon compromis entre la vitesse, la résolution et la consommation.Ils sont convenables pour une variété d’applications et sont typiquement utilisés dans les SoCs destinés à des applicationsvidéo. En raison de leur façon particulière du traitement du signal d’entrée, les CAN de type pipeline ont des codes de sortiequi ont la même largeur. Par conséquent, au lieu de considérer tous les codes lors du test, il est possible de se limiter à un sous-ensemble, ce qui permet de réduire considérablement le temps de test. Dans ce travail, une technique pour l’applicationdu test à code réduit pour les CANs de type pipeline est proposée. Elle exploite principalement deux propriétés de ce type deCAN et permet d’obtenir une très bonne estimation des performances statiques. La technique est validée expérimentalementsur un CAN 11-bit, 55nm de STMicroelectronics, obtenant une estimation de la NLD et de la NLI pratiquement identiques àla NLD et la NLI obtenues par la méthode classique d’histogramme, en utilisant la mesure de seulement 6% des codes. / Differential Non Linearity (DNL) and Integral Non Linearity (INL) are the two main static performances ofAnalog to-Digital Converters (ADCs) typically measured during production testing. These two performances reflect thedeviation of the transfer curve of the ADC from its ideal form. In a classic testing scheme, a saturated sine-wave or ramp isapplied to the ADC and the number of occurrences of each code is obtained to construct the histogram from which DNL andINL can be readily calculated. This standard approach requires the collection of a large volume of data because each codeneeds to be traversed many times to average noise. Furthermore, the volume of data increases exponentially with theresolution of the ADC under test. According to recently published data, testing the mixed-signal functions (e.g. dataconverters and phase locked loops) of a System-on-Chip (SoC) contributes to more than 30% of the total test time, althoughmixed-signal circuits occupy a small fraction of the SoC area that typically does not exceed 5%. Thus, reducing test time forADCs is an area of industry focus and innovation. Pipeline ADCs offer a good compromise between speed, resolution, andpower consumption. They are well-suited for a variety of applications and are typically present in SoCs intended for videoapplications. By virtue of their operation, pipeline ADCs have groups of output codes which have the same width. Thus,instead of considering all the codes in the testing procedure, we can consider measuring only one code out of each group,thus reducing significantly the static test time. In this work, a technique for efficiently applying reduced code testing onpipeline ADCs is proposed. It exploits two main properties of the pipeline ADC architecture and allows obtaining an accurateestimation of the static performances. The technique is validated on an experimental 11-bit, 55nm pipeline ADC fromSTMicroelectronics, resulting in estimated DNL and INL that are practically indistinguishable from DNL and INL that areobtained with the standard histogram technique, while measuring only 6% of the codes.
42

Energy-efficient interfaces for vibration energy harvesting

Du, Sijun January 2018 (has links)
Ultra low power wireless sensors and sensor systems are of increasing interest in a variety of applications ranging from structural health monitoring to industrial process control. Electrochemical batteries have thus far remained the primary energy sources for such systems despite the finite associated lifetimes imposed due to limitations associated with energy density. However, certain applications (such as implantable biomedical electronic devices and tire pressure sensors) require the operation of sensors and sensor systems over significant periods of time, where battery usage may be impractical and add cost due to the requirement for periodic re-charging and/or replacement. In order to address this challenge and extend the operational lifetime of wireless sensors, there has been an emerging research interest on harvesting ambient vibration energy. Vibration energy harvesting is a technology that generates electrical energy from ambient kinetic energy. Despite numerous research publications in this field over the past decade, low power density and variable ambient conditions remain as the key limitations of vibration energy harvesting. In terms of the piezoelectric transducers, the open-circuit voltage is usually low, which limits its power while extracted by a full-bridge rectifier. In terms of the interface circuits, most reported circuits are limited by the power efficiency, suitability to real-world vibration conditions and system volume due to large off-chip components required. The research reported in this thesis is focused on increasing power output of piezoelectric transducers and power extraction efficiency of interface circuits. There are five main chapters describing two new design topologies of piezoelectric transducers and three novel active interface circuits implemented with CMOS technology. In order to improve the power output of a piezoelectric transducer, a series connection configuration scheme is proposed, which splits the electrode of a harvester into multiple equal regions connected in series to inherently increase the open-circuit voltage generated by the harvester. This topology passively increases the rectified power while using a full-bridge rectifier. While most of piezoelectric transducers are designed with piezoelectric layers fully covered by electrodes, this thesis proposes a new electrode design topology, which maximizes the raw AC output power of a piezoelectric harvester by finding an optimal electrode coverage. In order to extract power from a piezoelectric harvester, three active interface circuits are proposed in this thesis. The first one improves the conventional SSHI (synchronized switch harvesting on inductor) by employing a startup circuitry to enable the system to start operating under much lower vibration excitation levels. The second one dynamically configures the connection of the two regions of a piezoelectric transducer to increase the operational range and output power under a variety of excitation levels. The third one is a novel SSH architecture which employs capacitors instead of inductors to perform synchronous voltage flip. This new architecture is named as SSHC (synchronized switch harvesting on capacitors) to distinguish from SSHI rectifiers and indicate its inductorless architecture.
43

Time-based All-Digital Technique for Analog Built-in Self Test

Vasudevamurthy, Rajath January 2013 (has links) (PDF)
A scheme for Built-in-Self-Test (BIST) of analog signals with minimal area overhead, for measuring on-chip voltages in an all-digital manner is presented in this thesis. With technology scaling, the inverter switching times are becoming shorter thus leading to better resolution of edges in time. This time resolution is observed to be superior to voltage resolution in the face of reducing supply voltage and increasing variations as physical dimensions shrink. In this thesis, a new method of observability of analog signals is proposed, which is digital-friendly and scalable to future deep sub-micron (DSM) processes. The low-bandwidth analog test voltage is captured as the delay between a pair of clock signals. The delay thus setup is measured digitally in accordance with the desired resolution. Such an approach lends itself easily to distributed manner, where the routing of analog signals over long paths is minimized. A small piece of circuitry, called sampling head (SpH) placed near each test voltage, acts as a transducer converting the test voltage to a delay between a pair of low-frequency clocks. A probe clock and a sampling clock is routed serially to the sampling heads placed at the nodes of analog test voltages. This sampling head, present at each test node consists of a pair of delay cells and a pair of flip-flops, giving rise to as many sub-sampled signal pairs as the number of nodes. To measure a certain analog voltage, the corresponding sub-sampled signal pair is fed to a Delay Measurement Unit (DMU) to measure the skew between this pair. The concept is validated by designing a test chip in UMC 130 nm CMOS process. Sub-mV accuracy for static signals is demonstrated for a measurement time of few milliseconds and ENOB of 5.29 is demonstrated for low bandwidth signals in the absence of sample-and-hold circuitry. The sampling clock is derived from the probe clock using a PLL and the design equations are worked out for optimal performance. To validate the concept, the duty-cycle of the probe clock, whose ON-time is modulated by a sine wave, is measured by the same DMU. Measurement results from FPGA implementation confirm 9 bits of resolution.
44

Metody pro testování analogových obvodů / Methods for testing of analog circuits

Kincl, Zdeněk January 2013 (has links)
Práce se zabývá metodami pro testování lineárních analogových obvodů v kmitočtové oblasti. Cílem je navrhnout efektivní metody pro automatické generování testovacího plánu. Snížením počtu měření a výpočetní náročnosti lze výrazně snížit náklady za testování. Práce se zabývá multifrekveční parametrickou poruchovou analýzou, která byla plně implementována do programu Matlab. Vhodnou volbou testovacích kmitočtů lze potlačit chyby měření a chyby způsobené výrobními tolerancemi obvodových prvků. Navržené metody pro optimální volbu kmitočtů byly statisticky ověřeny metodou MonteCarlo. Pro zvýšení přesnosti a snížení výpočetní náročnosti poruchové analýzy byly vyvinuty postupy založené na metodě nejmenších čtverců a přibližné symbolické analýze.

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