4,404 research outputs found
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
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
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
Histological assessment for femora of ovariectomized obesity (db/db) mice carrying mutated leptin receptor
No full textIn order to provide a clue to understand the interplay between leptin and estrogen, we have examined femoral metaphyses of ovariectomized db/db mice carrying a mutated leptin receptor. We performed ovariectomy (OVX) or sham-operation (sham) on 12-week old female wild-type and db/db mice, and then, after 8 weeks, divided the animals into four groups: wild-type sham, wild-type OVX, db/db sham and db/db OVX. Samples from all groups were prepared for histochemical and ultrastructural examinations. As a result, db/db sham mice showed a reduced number and thickness of metaphyseal trabeculae and excessive adipose tissue when compared to wild-type sham mice. The wild-type OVX group exhibited markedly diminished trabecular number, as well as lower populations of osteoblasts and osteoclasts in comparison to wild-type sham group. On the other hand, trabecular numbers were similar for the two db/db groups, suggesting that the effect of the ovariectomy, i.e., estrogen deficiency may be lessened in this animal model. Leptin receptor was mainly found in osteoblasts and in bone marrow stromal cells including adipocytes. In addition, the expression of estrogen receptor did not seem to change after OVX in wild-type mice and in db/db mice. Both db/db sham and OVX mice featured many adipocytes close to the metaphyseal chondro-osseous junction, while osteoblasts accumulated glycogen granules and lipid droplets. Therefore, it seems likely that the disruption of leptin signaling in db/db mice shifts the cell differentiation cascade towards the adipocyte lineage, resulting in an osteoporotic bone independently of estrogen deficiency
A 440-μW, 109.8-dB DR, 106.5-dB SNDR Discrete-Time Zoom ADC With a 20-kHz BW
No full textThis article describes a discrete-time zoom analog-to-digital converter (ADC) intended for audio applications. It uses a coarse 5-bit SAR ADC in tandem with a fine third-order delta-sigma modulator (ΔΣM) to efficiently obtain a high dynamic range. To minimize its over-sampling ratio (OSR) and, thus, its digital power consumption, the modulator employs a 2-bit quantizer and a loop filter notch. In addition, an extra feed-forward path minimizes the leakage of the SAR ADC's quantization noise into the audio band. The prototype ADC occupies 0.27 mm2 in a 0.16-μm technology. It achieves 109.8-dB DR, 106.5-dB SNDR, and 107.5-dB SNR in a 20-kHz bandwidth while dissipating 440 μW. It also achieves state-of-the-art energy efficiency, as demonstrated by a Schreier FoM of 186.4 dB and an SNDR FoM of 183.6 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
A-121.5 dB THD Class-D Audio Amplifier with 49 dB Suppression of LC Filter Nonlinearity and Robust to +/-30% LC Filter Spread
No full textThis paper reports a Class-D audio amplifier that uses multiloop feedback to suppress output LC filter nonlinearity by 49 dB, enabling the use of small, low-cost LC filters with ±30% spread while maintaining low distortion. Fabricated in a 180 nm BCD process, the prototype achieves a THD of-121.5 dB and a THD+N of-107.1 dB. It delivers 12W/21W into an 8-Ω/4-Ω load with 91%/87% efficiency.</p
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