4,950 research outputs found
Low-Floor Tanner Codes via Hamming-Node or RSCC-Node Doping
No full textWe study the design of structured Tanner codes with low error-rate floors on the AWGN channel. The design technique involves the “doping” of standard LDPC (proto-)graphs, by which we mean Hamming or recursive systematic convolutional (RSC) code constraints are used together with single-parity-check (SPC) constraints to construct a code’s protograph. We show that the doping of a “good” graph with Hamming or RSC codes is a pragmatic approach that frequently results in a code with a good threshold and very low error-rate floor. We focus on low-rate Tanner codes, in part because the design of low-rate, low-floor LDPC codes is particularly difficult. Lastly, we perform a simple complexity analysis of our Tanner codes and examine the performance of lower-complexity, suboptimal Hamming-node decoders
A 0.96-mW dB-Linear Variable Gain Amplifier With 0.4-dB Linearity Error Over a 62.4-dB Gain Tuning Range
No full textThis letter presents a low-power dB-linear variable gain amplifier (VGA) with a small linear-in-dB error over a wide gain tuning range. An exponential current ratio is realized in the linear-in-dB control circuit based on the subthreshold I-V characteristic. The VGA is built with subthreshold common-gate transistors as current steering, accurately replicating the exponential current ratio and forming a tunable gain. Implemented in 55-nm CMOS technology, the proposed VGA occupies a compact active area of 0.011 mm2 excluding the buffer. It achieves a linear-in-dB error of 0.4 dB over a gain tuning range of 62.4 dB, corresponding to the state-of-the-art relative error of 0.6%. The proposed design shows constant 80-MHz bandwidth with a power consumption of 0.96 mW. Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Electronic Instrumentatio
DB 2020: Analyzing and Forecasting DB Market Trends
No full textabstract: Over the last two decades, Alternative Project Delivery Methods (APDM), such as Design-Build (DB), have become more popular in the construction industry, specifically in the U.S., and the competition for APDM projects has risen among construction companies. The Engineering News Record (ENR) magazine analyzes DB firms and publishes the list of the top 100 every year. According to ENR articles and many scientific papers, the implementation of DB method has grown drastically over the last decade, however, information about growth trends depending on firm size and segment is lacking. Also missing is knowledge the future market trends over the next five years. Furthermore, public agencies and DB firms may be worried that DB projects do not distribute wealth equally among DB firms. Using the top 100 firms deemed representative of the DB market, the author has divided the market into volumes based on rankings to analyze the total DB market revenue growth. A comparison between international and domestic revenues indicated that the top five DB firms have 64% more involvement in the international market compared to the domestic market. Furthermore, while the research shows increasing market share only for the top five firms, the author has found that (1) a large portion of their market share is due to a large growth in their international market, and (2) revenues for all volumes of the DB market have increased. Moreover, regression and time series analyses allow for the forecasting of the DB market growth, which the author anticipate to move from about 150B in 2020.Dissertation/ThesisMasters Thesis Construction 201
A -109.1 dB/-98 dB THD/THD+N Chopper Class-D Amplifier with >83.7 dB PSRR Over the Entire Audio Band
No full textThis paper reports a chopper Class-D audio amplifier that obtains high PSRR over the entire audio band. A chopping scheme is proposed to minimize intermodulation distortion between pulse-width modulation (PWM) and chopping in the audio band. A high-voltage chopper is developed to handle a 14.4 V PWM signal. Timing matching techniques are proposed to minimize chopping nonidealities which ensure good PSRR and THD. Fabricated in a 180nm BCD process, the prototype obtains a PSRR >109 dB at 217 Hz and >83.7 dB over the entire audio band. It also achieves -109.1 dB/-98 dB THD/THD+N and can deliver a maximum of 13 W to an 8-Ω load.Accepted author manuscriptElectronic Instrumentatio
Multilevel structured low-density parity-check codes
No full textLow-Density Parity-Check (LDPC) codes are typically characterized by a relatively high-complexity description, since a considerable amount of memory is required in order to store their code description, which can be represented either by the connections of the edges in their Tanner graph or by the non-zero entries in their parity-check matrix (PCM). This problem becomes more pronounced for pseudo-random LDPC codes, where literally each non-zero entry of their PCM has to be enumerated, and stored in a look-up table. Therefore, they become inadequate for employment in memoryconstrainedtransceivers. Motivated by this, we are proposing a novel family of structured LDPC codes, termed as Multilevel Structured (MLS) LDPC codes, which benefit from reduced storage requirements, hardware-friendly implementations as well as from low-complexity encoding and decoding. Our simulation results demonstrate that these advantages accrue without any compromise in their attainable Bit Error Ratio (BER) performance, when compared to their previously proposed more complex counterparts of the same code-length. In particular, wecharacterize a half-rate quasi-cyclic (QC) MLS LDPC code having a block length of 8064 that can be uniquely and unambiguously described by as few as 144 edges, despite exhibiting an identical BER performance over both Additive White Gaussian Noise (AWGN) and uncorrelated Rayleigh (UR) channels, when compared to a pseudorandom construction, which requires the enumeration of a significantly higher number of 24,192 edges
A - 121.5-dB THD Class-D Audio Amplifier With 49-dB LC Filter Nonlinearity Suppression
No full textClass-D audio amplifiers produce electromagnetic interference (EMI), which often needs to be suppressed by an external LC filter. However, due to component nonlinearity, this filter can itself cause significant distortion. This article presents a class-D amplifier that suppresses LC filter nonlinearity by 49 dB and is robust to ±30% variations in its cutoff frequency. This is achieved by a dual-loop architecture, in which an inner loop provides stability, while an outer loop provides the high gain needed to suppress the LC filter and output-stage nonlinearity. A prototype, implemented in a 180-nm BCD process, achieves -121.5-dB total harmonic distortion (THD) and -107.1-dB THD+N, which is maintained to within 3 dB even as the LC filter cutoff frequency is varied from 62 to 106 kHz. It can deliver a maximum of 21 W into a 4-Ω load with 87% efficiency and 12 W into an 8-Ω load with 91% efficiency, measured at 10% THD. Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Electronic InstrumentationMicroelectronic
Treatment of African Trypanosomosis with DB 75 : Pharmacokinetics, Relapses and Cross Resistance
No full textResurgent human African trypanosomosis (HAT) displays a major burden for people living in Sub-Saharan Africa, although it had been nearly eradicated in the 50`s, due to selective ground spraying with DDT and an extensive vector control. Today, treatment of HAT relies only on a few drugs at hand. The use of these drugs is restricted, since they show an unacceptable toxicity, complicated administration, emerging and spreading of resistance, shortness of availability and/or show only an impact on gambiense or rhodesiense trypanosomes. Therefore, new drugs are urgently needed. A consortium, the UNC lead consortium to discover new drugs for the treatment of parasitic diseases, was founded with the aim to improve treatment of HAT. The ideal profile of a new drug is an uncomplicated synthesis, easy administration, high efficacy, cost effectiveness and no toxicity. Series of compounds were synthesised in analogy to pentamidine, the first line drug in the treatment of first stage trypanosomosis. The so called DB compounds showed promising results in vitro and in vivo, not only to trypanosomes but also to Leishmania spp, Mycobacterium tuberculosis, Plasmodium spp and Pneumocystis carinii. Lead compound of this project is the diamidine DB 75 and its oral applicable prodrug DB 289. Although the prodrug had entered an open label phase IIa clinical trial already when this thesis started, several questions referring to the interplay between DB 75, trypanosomes and mice had been unanswered. To elucidate development of parasitaemia in first infection, first and second relapse in mice, studies have been undertaken in immunocompetent and –deficient mice, with two different trypanosome strains and various treatment schedules for DB 75. At the same time, parasite clearance after drug application was studied. Since relapse trypanosomes did not show any differences in sensitivity to selected drugs, observed relapses were not due to resistant trypanosomes but rather due to re-invasion from extravascular sites. Identification of these sites was a second goal of this project. A method based on the detection of trypanosomal mRNA by nested PCR was established and tested. Results showed that more time has to be invested to increase the sensitivity of this method. However, one organ was found positive for trypanosomal mRNA, indicating the spleen to be one of the niches. A system was established to check DB 75 for cross resistance in melarsoprol and pentamidine resistant laboratory strains. With the aid of this system, further upcoming drugs may be tested for their cross resistance. For DB 75, only a low cross resistance was obtained in both resistant strains. Additionally, the pharmacokinetics for DB 75, DB 820 and the their corresponding prodrugs DB 289, DB 844 in trypanosome infected and uninfected mice was studied. Differences in plasma levels of uninfected compared to infected mice were obtained. Mainly, two effects were shown to influence plasma levels considerably: accumulation of active drug in case of DB 75 and DB 289, and inhibition of metabolism for DB 820 and DB 844. The extent of DB 75 accumulation in trypanosomes was determined in vitro, to assess that the differences between plasma levels of DB 75 after prodrug application obtained in infected mice compared to uninfected mice were due to accumulation. In a further study, indications of the presence of possible active metabolites were obtained when activity of plasma samples was assessed by bioassay and compared to levels determined by HPLC/MS/MS. In another pharmacokinetic study, it was shown that conversion of DB 289 to DB 75 in P. berghei infected mice was poor, leading to subtherapeutic doses of active compound, which explained that no activity in the in vivo model was obtained for the prodrug compared to a moderate to good activity for the active compound
A Dynamic Zoom ADC with 109-dB DR for Audio Applications
No full textThis paper presents the first dynamic zoom ADC. Intended for audio applications, it achieves 109-dB DR, 106-dB signal-to-noise ratio, and 103-dB SNDR in a 20-kHz bandwidth, while dissipating only 1.12 mW. This translates into the state-of-the-art energy efficiency as expressed by a Schreier FoM of 181.5 dB. It also achieves the state-of-the-art area efficiency, occupying only 0.16 mm2 in the 0.16- μm CMOS. These advances are enabled by the use of concurrent fine and coarse conversions, dynamic error-correction techniques, and a dynamically biased inverter-based operational transconductance amplifier.Accepted author manuscriptElectronic Instrumentation(OLD)Applied Quantum ArchitecturesMicroelectronic
A 280 <i>μ</i>W Dynamic Zoom ADC With 120 dB DR 118 dB SNDR in 1 kHz BW
No full textThis paper presents a dynamic zoom analog-to-digital converter for use in low-bandwidth (&lt;1 kHz) instrumentation applications. It employs a high-speed asynchronous successive approximation register (SAR) ADC that dynamically updates the references of a fully differential &#x0394; &#x03A3; ADC. Compared to previous zoom ADCs, faster reference updates relax the loop filter requirements, thus allowing the adoption of energy-efficient amplifiers. Fabricated in a 0.16-&#x03BC;m CMOS process, the prototype occupies 0.26 mm&#x00B2; and achieves 119.1-dB peak signal-to-noise ratio (SNR), 118.1-dB peak signal-to-noise-and-distortion-ratio (SNDR), and 120.3-dB dynamic range (DR) in a 1-kHz bandwidth while consuming 280 &#x03BC;W. This results in a Schreier figure of merit (FoM) of 185.8 dB.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Electronic Instrumentation(OLD)Applied Quantum ArchitecturesMicroelectronic
A 590 μw, 106.6 dB SNDR, 24 kHz BW Continuous-Time Zoom ADC with a Noise-Shaping 4-bit SAR ADC
No full textThis paper presents a continuous-Time zoom ADC for audio applications. It combines a 4-bit noise-shaping coarse SAR ADC and a fine delta-sigma modulator with a tail-resistor linearized OTA for improved linearity, energy efficiency, and handling of out-of-band interferers compared to previous designs. In 160 nm CMOS, the prototype chip occupies 0.36 mm2, achieves 107.2 dB SNR, 106.6 dB SNDR, and 107.3 dB dynamic range in a 24 kHz bandwidth while consuming 590 μW from a 1.8 V supply. This translates into a Schreier figure-of-merit (FoMs) of 183.4 dB and a FoMSNDR of 182.7 dB. Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Electronic InstrumentationMicroelectronic
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