16 research outputs found

    Capacitance-to-Digital Converter for Operation Under Uncertain Harvested Voltage down to 0.3V with No Trimming, Reference and Voltage Regulation

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    In Paper 5.2, the National University of Singapore and Politecnico di Torino present a capacitance-to-digital converter (CDC) for direct harvester-powered low-cost systems, showing a 7-bit ENOB down to 0.3V at 1.37nW power without any external reference or voltage-regulation requirements

    A Temperature โ€“ and Supply- Variation Robust 2nd-Order Sigma-Delta Modulation for Capacitive Sensing

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    Capacitance to digital converter, VCO quantizer, Sigma-Delta modulation, Supply variation, temperature variationIn this paper, I proposed a temperature- and supply variation robust 2nd-order sigma-delta modulation circuit for capacitive sensing. Capacitive sensing by conventional circuits is basically supply sensitive. Capacitance is sensed by reading the charge that is equal to the difference between the capacitance value of the capacitor and the capacitor to be sensed. In this method, the amount of charge is dependent on the supply, so it is insensitive to supply variation. In this paper, the capacitance is read by using the time determined by the discharge characteristics when a capacitor called T0V meets the resistance component. The charge accumulated in the capacitor is certainly influenced by the supply value, but capacitive sensing is performed using the characteristic that the time taken to discharge the charge to zero is always constant. In the process, VCO (Voltage-Controlled-Oscillator) based ADC (Analog-to-Digital Converter) was used to increase the resolution by utilizing the noise shaping effect of sigma-delta ADC. In the process, the resistor is switched to a switched capacitor to obtain robust characteristics against temperature variations. Unlike resistance whose values change with temperature, capacitance are relatively robust to temperature effects. By using the characteristics, a circuit having robust characteristics in temperature variation as well as robust in supply variation.openAbstract i List of contents iii List of figures iv List of figures v โ… . Introduction 1.1 Motivation and Objective 1 1.2 Theses outline 3 โ… I. Supply- Variation Robust 2nd-Order Sigma-Delta Modulation 2.1 Supply Independent Technique 4 2.2 Injection Locking Current Controlled Oscillator 8 2.3 VCO Based ADC 13 2.4 Full Architecture 16 2.4.1 Control Block 19 2.4.2 Block Diagram 21 2.5 Schematic and Layout 23 III. Temperature- and Supply- Variation Robust 2nd-Order Sigma-Delta Modulation 3.1 Switched Capacitor DAC 31 3.2 Switched Capacitor Clock Generator 36 3.3 Control Block 38 3.4 Schematic 39 IV. Simulation and Measurement Result 4.1 Resistor DAC Circuit 42 4.1.1 Measurement Result 42 4.2 Switched Capacitor DAC Circuit 45 4.2.1 Simulation Result 45 V. Conclusion๋ณธ ๋…ผ๋ฌธ์€ ์ „์›๋ณ€ํ™” ๋ฐ ์˜จ๋„๋ณ€ํ™”์—๋„ ์•ˆ์ •์ ์œผ๋กœ ์ •์ „์šฉ๋Ÿ‰์„ ์ฝ์–ด๋‚ผ ์ˆ˜ ์žˆ๋Š” 2์ฐจ ์‹œ๊ทธ๋งˆ-๋ธํƒ€ ๋ณ€์กฐ๊ธฐ ํšŒ๋กœ์ด๋‹ค. ์ปคํŒจ์‹œํ„ฐ์˜ ๋ฐฉ์ „ ์‹œ๊ฐ„์ด ์ „์›์˜ ์˜ํ–ฅ์ด ์•„๋‹Œ ์ •์ „์šฉ๋Ÿ‰๊ณผ ์ €ํ•ญ ๊ฐ’์—๋งŒ ์˜ํ–ฅ์„ ๋ฐ›๋Š”๋‹ค๋Š” ์ ์„ ์ด์šฉํ•˜์—ฌ ํšŒ๋กœ๋ฅผ ๊ตฌ์„ฑํ•˜์˜€๋‹ค. ๋˜ํ•œ ์ €ํ•ญ์ด ์˜จ๋„๋ณ€ํ™”์— ๋”ฐ๋ผ์„œ ์ผ์ •ํ•œ ๊ฐ’์„ ์œ ์ง€ํ•˜๊ธฐ ํž˜๋“ค๋‹ค๋Š” ์ ์„ ๋ณด์™„ํ•˜๊ธฐ์œ„ํ•ด switched capacitor ๊ธฐ๋ฒ•์„ ์‚ฌ์šฉํ•˜์˜€๋‹ค. ์ปคํŒจ์‹œํ„ฐ๋Š” ์ €ํ•ญ์— ๋น„ํ•ด ์ƒ๋Œ€์ ์œผ๋กœ ์˜จ๋„๋ณ€ํ™”์—๋„ ์ •์ „์šฉ๋Ÿ‰์„ ์•ˆ์ •์ ์ธ ๊ฐ’์œผ๋กœ ์œ ์ง€ํ•  ์ˆ˜ ์žˆ๋‹ค. ์ด ์ ์„ ์ด์šฉํ•˜์—ฌ ์ „์›๋ณ€ํ™”๋ฟ ๋งŒ์ด ์•„๋‹Œ ์˜จ๋„๋ณ€ํ™”์—๋„ ๊ฐ•์ธํ•œ ํŠน์„ฑ์„ ๊ฐ€์งˆ ์ˆ˜ ์žˆ๊ฒŒ ๋œ๋‹ค. ๋˜ ์ „์••์ œ์–ด๋ฐœ์ง„๊ธฐ๋ฅผ ํ™œ์šฉํ•œ ์•„๋‚ ๋กœ๊ทธ-๋””์ง€ํ„ธ ๋ณ€ํ™˜๊ธฐ๋ฒ•๋„ ์‚ฌ์šฉ๋˜์—ˆ๋‹ค. ์ „์••์ œ์–ด๋ฐœ์ง„๊ธฐ์— โ€˜์ „์••์ œ์–ด๋ฐœ์ง„๊ธฐ ๊ธฐ๋ฐ˜ ์–‘์žํ™”๊ธฐโ€™๋ผ๋Š” ์–‘์žํ™”๋ฅผ ํ•  ์ˆ˜ ์žˆ๋Š” ํšŒ๋กœ๋ฅผ ์—ฐ๊ฒฐํ•˜์—ฌ ๋™์ž‘์ด ์ง„ํ–‰๋œ๋‹ค. ์ด ๊ธฐ๋ฒ•์„ ์‚ฌ์šฉํ•˜๊ฒŒ ๋˜๋ฉด ์–‘์žํ™”์˜ค๋ฅ˜์˜ ์„ฑ๋ถ„๋“ค์ด ๋ฐฑ์ƒ‰์žก์Œ์ฒ˜๋Ÿผ ๋ชจ๋“  ์ฃผํŒŒ์ˆ˜๋Œ€์—ญ์— ๊ฑธ์ณ์„œ ๊ณจ๊ณ ๋ฃจ ์กด์žฌํ•˜๋Š” ๊ฒƒ์ด ์•„๋‹Œ, ๊ณ ์ฃผํŒŒ ์ชฝ์„ ํ–ฅํ•ด 20dB์˜ ๊ธฐ์šธ๊ธฐ๋ฅผ ๊ฐ€์ง€๋ฉฐ ์ƒ์Šนํ•˜๋Š” ํ˜•ํƒœ๋กœ ๋‚˜ํƒ€๋‚œ๋‹ค. ์ตœ์ข…์ ์ธ ์ „์ฒด ๋ฃจํ”„์˜ ํŠน์„ฑ์„ ํ™•์ธํ•˜๋ฉด 40dB์˜ ๊ธฐ์šธ๊ธฐ๋ฅผ ๊ฐ€์ง€๋ฉฐ ์ƒ์Šนํ•˜๋Š” ํ˜•ํƒœ๋ฅผ ๊ฐ–๋Š”๋‹ค. ์ด ํŠน์„ฑ์„ ํ†ตํ•˜์—ฌ ๋™์ž‘ ๋Œ€์—ญํญ์ด ์•„๋‹Œ ๋” ๊ณ ์ฃผํŒŒ ์˜์—ญ์œผ๋กœ ์–‘์žํ™” ์˜ค๋ฅ˜ ์„ฑ๋ถ„๋“ค์„ ๋ฐ€์–ด๋‚ผ ์ˆ˜ ์žˆ๋‹ค๋Š” ์žฅ์ ์ด ์žˆ๋‹ค. ๊ทธ ๊ฒฐ๊ณผ, SNR์ด ์ƒ์Šนํ•˜๊ฒŒ ๋˜์–ด ์ตœ์ข…์ ์œผ๋กœ ์ •์ „์šฉ๋Ÿ‰์„ ์ฝ์–ด๋‚ผ ์ˆ˜ ์žˆ๋Š” ๋ถ„ํ•ด๋Šฅ ์„ฑ๋Šฅ์ด ์ข‹์•„์ง€๊ฒŒ ๋œ๋‹ค.MasterdCollectio

    A Review Of Implementing Adc In Rfid Sensor

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    Conselho Nacional de Desenvolvimento Cientรญfico e Tecnolรณgico (CNPq)The general considerations to design a sensor interface for passive RFID tags are discussed. This way, power and timing constraints imposed by ISO/IEC 15693 and ISO/IEC 14443 standards to HF RFID tags are explored. A generic multisensor interface is proposed and a survey analysis on the most suitable analog-to-digital converters for passive RFID sensing applications is reported. The most appropriate converter type and architecture are suggested. At the end, a specific sensor interface for carbon nanotube gas sensors is proposed and a brief discussion about its implemented circuits and preliminary results is made.Region Rhone-Alpes (France)CNPq (Brazil)INCT/NAMITEC (Brazil)Conselho Nacional de Desenvolvimento Cientรญfico e Tecnolรณgico (CNPq

    A Review of Implementing ADC in RFID Sensor

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    The general considerations to design a sensor interface for passive RFID tags are discussed. This way, power and timing constraints imposed by ISO/IEC 15693 and ISO/IEC 14443 standards to HF RFID tags are explored. A generic multisensor interface is proposed and a survey analysis on the most suitable analog-to-digital converters for passive RFID sensing applications is reported. The most appropriate converter type and architecture are suggested. At the end, a specific sensor interface for carbon nanotube gas sensors is proposed and a brief discussion about its implemented circuits and preliminary results is made

    A Review Of Implementing Adc In Rfid Sensor

    Get PDF
    Conselho Nacional de Desenvolvimento Cientรญfico e Tecnolรณgico (CNPq)The general considerations to design a sensor interface for passive RFID tags are discussed. This way, power and timing constraints imposed by ISO/IEC 15693 and ISO/IEC 14443 standards to HF RFID tags are explored. A generic multisensor interface is proposed and a survey analysis on the most suitable analog-to-digital converters for passive RFID sensing applications is reported. The most appropriate converter type and architecture are suggested. At the end, a specific sensor interface for carbon nanotube gas sensors is proposed and a brief discussion about its implemented circuits and preliminary results is made.Region Rhone-Alpes (France)CNPq (Brazil)INCT/NAMITEC (Brazil)Conselho Nacional de Desenvolvimento Cientรญfico e Tecnolรณgico (CNPq

    Data Conversion Within Energy Constrained Environments

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    Within scientific research, engineering, and consumer electronics, there is a multitude of new discrete sensor-interfaced devices. Maintaining high accuracy in signal quantization while staying within the strict power-budget of these devices is a very challenging problem. Traditional paths to solving this problem include researching more energy-efficient digital topologies as well as digital scaling.;This work offers an alternative path to lower-energy expenditure in the quantization stage --- content-dependent sampling of a signal. Instead of sampling at a constant rate, this work explores techniques which allow sampling based upon features of the signal itself through the use of application-dependent analog processing. This work presents an asynchronous sampling paradigm, based off the use of floating-gate-enabled analog circuitry. The basis of this work is developed through the mathematical models necessary for asynchronous sampling, as well the SPICE-compatible models necessary for simulating floating-gate enabled analog circuitry. These base techniques and circuitry are then extended to systems and applications utilizing novel analog-to-digital converter topologies capable of leveraging the non-constant sampling rates for significant sample and power savings

    DESIGN OF LOW-POWER LOW-VOLTAGE SUCCESSIVE-APPROXIMATION ANALOG-TO-DIGITAL CONVERTERS

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    Ph.DDOCTOR OF PHILOSOPH

    Duty Cycling and Compact Layout Techniques in ADCs and Analog Front-ends

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    A Low-Power, Reconfigurable, Pipelined ADC with Automatic Adaptation for Implantable Bioimpedance Applications

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    Biomedical monitoring systems that observe various physiological parameters or electrochemical reactions typically cannot expect signals with fixed amplitude or frequency as signal properties can vary greatly even among similar biosignals. Furthermore, advancements in biomedical research have resulted in more elaborate biosignal monitoring schemes which allow the continuous acquisition of important patient information. Conventional ADCs with a fixed resolution and sampling rate are not able to adapt to signals with a wide range of variation. As a result, reconfigurable analog-to-digital converters (ADC) have become increasingly more attractive for implantable biosensor systems. These converters are able to change their operable resolution, sampling rate, or both in order convert changing signals with increased power efficiency. Traditionally, biomedical sensing applications were limited to low frequencies. Therefore, much of the research on ADCs for biomedical applications focused on minimizing power consumption with smaller bias currents resulting in low sampling rates. However, recently bioimpedance monitoring has become more popular because of its healthcare possibilities. Bioimpedance monitoring involves injecting an AC current into a biosample and measuring the corresponding voltage drop. The frequency of the injected current greatly affects the amplitude and phase of the voltage drop as biological tissue is comprised of resistive and capacitive elements. For this reason, a full spectrum of measurements from 100 Hz to 10-100 MHz is required to gain a full understanding of the impedance. For this type of implantable biomedical application, the typical low power, low sampling rate analog-to-digital converter is insufficient. A different optimization of power and performance must be achieved. Since SAR ADC power consumption scales heavily with sampling rate, the converters that sample fast enough to be attractive for bioimpedance monitoring do not have a figure-of-merit that is comparable to the slower converters. Therefore, an auto-adapting, reconfigurable pipelined analog-to-digital converter is proposed. The converter can operate with either 8 or 10 bits of resolution and with a sampling rate of 0.1 or 20 MS/s. Additionally, the resolution and sampling rate are automatically determined by the converter itself based on the input signal. This way, power efficiency is increased for input signals of varying frequency and amplitude
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