A Triple-Mode Performance-Optimized Reconfigurable Incremental ADC for Smart Sensor Applications

This paper proposes a triple-mode discrete-time incremental analog-to-digital converter (IADC) employing successive approximation register (SAR)-based zooming and extended counting (EC) schemes to achieve programmable trade-off capability of resolution and power consumption in various smart sensor applications. It mainly consists of an incremental delta???sigma modulator and the proposed SAR-EC sub-ADC for alternate operation of the coarse SAR conversion and EC. They can be reconfigured to operate separately depending on the application requirements. The SAR-based zooming structure allows the IADC to have better linearity and resolution, and additional activation of the EC function gives the further resolution. During this reconfigurable conversion process, pipelined reusing operation of sub-blocks reduces the silicon area and the number of cycles for target resolutions. A prototype ADC is fabricated in a 180-nm CMOS process, and its triple-mode operation of high-resolution, medium-resolution, and low-power is experimentally verified to achieve 116.1-, 109.4-, and 73.3-dB dynamic ranges, consuming 1.60, 1.26, and 0.39 mW, respectively

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Department of Electrical EngineeringA Sensor system is advanced along sensor technologies are developed. The performance improvement of sensor system can be expected by using the internet of things (IoT) communication technology and artificial neural network (ANN) for data processing and computation. Sensors or systems exchanged the data through this wireless connectivity, and various systems and applications are possible to implement by utilizing the advanced technologies. And the collected data is computed using by the ANN and the efficiency of system can be also improved. Gas monitoring system is widely need from the daily life to hazardous workplace. Harmful gas can cause a respiratory disease and some gas include cancer-causing component. Even though it may cause dangerous situation due to explosion. There are various kinds of hazardous gas and its characteristics that effect on human body are different each gas. The optimal design of gas monitoring system is necessary due to each gas has different criteria such as the permissible concentration and exposure time. Therefore, in this thesis, conventional sensor system configuration, operation, and limitation are described and gas monitoring system with wireless connectivity and neural network is proposed to improve the overall efficiency. As I already mentioned above, dangerous concentration and permissible exposure time are different depending on gas types. During the gas monitoring, gas concentration is lower than a permissible level in most of case. Thus, the gas monitoring is enough with low resolution for saving the power consumption in this situation. When detecting the gas, the high-resolution is required for the accurate concentration detecting. If the gas type is varied in the above situation, the amount of calculation increases exponentially. Therefore, in the conventional systems, target specifications are decided by the highest requirement in the whole situation, and it occurs increasing the cost and complexity of readout integrated circuit (ROIC) and system. In order to optimize the specification, the ANN and adaptive ROIC are utilized to compute the complex situation and huge data processing. Thus, gas monitoring system with learning-based algorithm is proposed to improve its efficiency. In order to optimize the operation depending on situation, dual-mode ROIC that monitoring mode and precision mode is implemented. If the present gas concentration is decided to safe, monitoring mode is operated with minimal detecting accuracy for saving the power consumption. The precision mode is switched when the high-resolution or hazardous situation are detected. The additional calibration circuits are necessary for the high-resolution implementation, and it has more power consumption and design complexity. A high-resolution Analog-to-digital converter (ADC) is kind of challenges to design with efficiency way. Therefore, in order to reduce the effective resolution of ADC and power consumption, zooming correlated double sampling (CDS) circuit and prediction successive approximation register (SAR) ADC are proposed for performance optimization into precision mode. A Microelectromechanical systems (MEMS) based gas sensor has high-integration and high sensitivity, but the calibration is needed to improve its low selectivity. Conventionally, principle component analysis (PCA) is used to classify the gas types, but this method has lower accuracy in some case and hard to verify in real-time. Alternatively, ANN is powerful algorithm to accurate sensing through collecting the data and training procedure and it can be verified the gas type and concentration in real-time. ROIC was fabricated in complementary metal-oxide-semiconductor (CMOS) 180-nm process and then the efficiency of the system with adaptive ROIC and ANN algorithm was experimentally verified into gas monitoring system prototype. Also, Bluetooth supports wireless connectivity to PC and mobile and pattern recognition and prediction code for SAR ADC is performed in MATLAB. Real-time gas information is monitored by Android-based application in smartphone. The dual-mode operation, optimization of performance and prediction code are adjusted with microcontroller unit (MCU). Monitoring mode is improved by x2.6 of figure-of-merits (FoM) that compared with previous resistive interface.clos

Identification of keratinolytic function in Chryseobacterium camelliae Dolsongi-HT1 isolated from Green Tea

Keratin forms a major component of the epidermis, hair, feathers, nails, scales and etc. However, old keratins on the skin are not preferred for the beauty purpose. Therefore, in the highly efficient and low irritative method to remove old keratin on the skin is highly desired. For this purpose, one of the appropriate methods is the enzymatic lysis of keratin. To screen a novel keratinase, a novel microorganism having keratinolytic activity was isolated by enrichment culture. Newly screened microorganism was isolated from green tea in dolsong-i tea garden, Jeju and identified as Chryseobacterium camelliae Dolsongi-HT1. The keratinase activity of C. camelliae Dolsongi-HT1 was confirmed in the culture media. The effect of pH and temperature were studied using cell culture media. Crude keratinase showed high activity over a wide range of temperature (37 to 60°C) and showed the highest activity at 50°C. Optimum pH of keratinase activity of crude keratinase was pH 8. Interestingly, this enzyme activity was maintained over 50% at pH 6. This feature is promising for the application to cosmetics. The effect of nitrogen source for cell culture was also investigated. Among the various nitrogen sources, the highest keratinase activity (relative activity of 366.4%) was detected when cells were cultured using tryptone extract. To study the keratinolytic activity effect of keratin on the skin, the keratin of skin was obtained using tape stripping. It was found that the structure of keratin was degraded by crude keratinase. To identify the keratinase, the complete genome of C. camelliae Dolsongi-HT1 was sequenced. Because keratinases are regarded as serine or metalloprotease group, we searched for those proteases in the C. camelliae Dolsongi-HT1 genome sequence. As s result, over twenty putative keratinases could be identified. Further research to identify desired keratinases should be performed

A Reconfigurable Readout Integrated Circuit for Heterogeneous Display-Based Multi-Sensor Systems

This paper presents a reconfigurable multi-sensor interface and its readout integrated circuit (ROIC) for display-based multi-sensor systems, which builds up multi-sensor functions by utilizing touch screen panels. In addition to inherent touch detection, physiological and environmental sensor interfaces are incorporated. The reconfigurable feature is effectively implemented by proposing two basis readout topologies of amplifier-based and oscillator-based circuits. For noise-immune design against various noises from inherent human-touch operations, an alternate-sampling error-correction scheme is proposed and integrated inside the ROIC, achieving a 12-bit resolution of successive approximation register (SAR) of analog-to-digital conversion without additional calibrations. A ROIC prototype that includes the whole proposed functions and data converters was fabricated in a 0.18 ??m complementary metal oxide semiconductor (CMOS) process, and its feasibility was experimentally verified to support multiple heterogeneous sensing functions of touch, electrocardiogram, body impedance, and environmental sensors.ope

A Three-Step Resolution-Reconfigurable Hazardous Multi-Gas Sensor Interface for Wireless Air-Quality Monitoring Applications

This paper presents a resolution-reconfigurable wide-range resistive sensor readout interface for wireless multi-gas monitoring applications that displays results on a smartphone. Three types of sensing resolutions were selected to minimize processing power consumption, and a dual-mode front-end structure was proposed to support the detection of a variety of hazardous gases with wide range of characteristic resistance. The readout integrated circuit (ROIC) was fabricated in a 0.18 ??m CMOS process to provide three reconfigurable data conversions that correspond to a low-power resistance-to-digital converter (RDC), a 12-bit successive approximation register (SAR) analog-to-digital converter (ADC), and a 16-bit delta-sigma modulator. For functional feasibility, a wireless sensor system prototype that included in-house microelectromechanical (MEMS) sensing devices and commercial device products was manufactured and experimentally verified to detect a variety of hazardous gases

A wireless ExG interface for patch-type ECG holter and EMG-controlled robot hand

This paper presents a wearable electrophysiological interface with enhanced immunity to motion artifacts. Anti-artifact schemes, including a patch-type modular structure and real-time automatic level adjustment, are proposed and verified in two wireless system prototypes of a patch-type electrocardiogram (ECG) module and an electromyogram (EMG)-based robot-hand controller. Their common ExG readout integrated circuit (ROIC), which is reconfigurable for multiple physiological interfaces, is designed and fabricated in a 0.18 ??m CMOS process. Moreover, analog pre-processing structures based on envelope detection are integrated with one another to mitigate signal processing burdens in the digital domain effectivel

Sclerostin inhibits Wnt signaling through tandem interaction with two LRP6 ectodomains

Low-density lipoprotein receptor-related protein 6 (LRP6) is a coreceptor of the beta -catenin-dependent Wnt signaling pathway. The LRP6 ectodomain binds Wnt proteins, as well as Wnt inhibitors such as sclerostin (SOST), which negatively regulates Wnt signaling in osteocytes. Although LRP6 ectodomain 1 (E1) is known to interact with SOST, several unresolved questions remain, such as the reason why SOST binds to LRP6 E1E2 with higher affinity than to the E1 domain alone. Here, we present the crystal structure of the LRP6 E1E2-SOST complex with two interaction sites in tandem. The unexpected additional binding site was identified between the C-terminus of SOST and the LRP6 E2 domain. This interaction was confirmed by in vitro binding and cell-based signaling assays. Its functional significance was further demonstrated in vivo using Xenopus laevis embryos. Our results provide insights into the inhibitory mechanism of SOST on Wnt signaling. The low-density lipoprotein receptor-related protein 6 (LRP6) is a co-receptor of the beta -catenin-dependent Wnt signaling pathway and interacts with the Wnt inhibitor sclerostin (SOST). Here the authors present the crystal structure of SOST in complex with the LRP6 E1E2 ectodomain construct, which reveals that the SOST C-terminus binds to the LRP6 E2 domain, and further validate this binding site with in vitro and in vivo experiments.Y

A 4b/cycle flash-assisted SAR ADC with comparator speed-boosting technique

This paper presents flash-assisted successive approximation register (SAR) analog-to- digital converter (ADC) with an energy-efficient speed-boosting structure. The incorporation of a 3-bit flash sub-ADC into the SAR conversion path enables 4b/cycle conversion. For further speed boosting, the comparator is designed to include an auxiliary bootstrap capacitor which relieves settling-time bottleneck of capacitive digital-to-analog converters (C-DACs) in asynchronous SAR operation. This 4b/cycle conversion scheme requires only five switching events of C-DACs switching for 8-bit conversion, resulting in 22.32% reduction of additional switching energy. Prototype circuit implementation reveals that the proposed scheme achieves 75% speed enhancement compared to a conventional SAR scheme. For feasibility verification, the proposed flash-assisted SAR ADC was fabricated using a 0.18 mm CMOS process. Measured signal-to- noise and distortion (SNDR) and spurious-free dynamic range (SFDR) of the prototype were 48.49 dB and 64.95 dB respectively

A Triple-mode Reconfigurable Incremental SigmaDelta ADC with SAR-based Zooming and Extended Counting

This paper proposes a triple-mode discrete-time incremental sigma-delta ADC employing SAR-based zooming and extended counting for programmable resolutions. A SAR-based zooming structure allows the sigma-delta modulator to have better linearity and resolution, and also additional activation of extended counting function gives additional resolution. A prototype ADC is fabricated in a 180 nm CMOS process, and it achieves 111.9 dB, 106.6 dB, and 73.3 dB dynamic range for the triple mode consuming 1.60 mW, 1.26 mW, and 0.31 mW respectively

An Energy-efficient Multi-channel Dual-mode Wireless Gas-sensor System with Performance Regulation Capability

This paper presents the prototype of a wireless gas sensor system with real-time monitoring interface. A learning-based performance regulation scheme is proposed to improve the system efficiency. The scheme can adjust the pattern recognition, mode control and prediction of successive approximation register analog-to-digital converter (SAR ADC) results with neural network algorithm. The ROIC is supported 8-channel gas sensors and multi-mode as monitoring mode and precision mode. In order to optimize the power consumption of precision mode further, auto controlled correlated double sampling (CDS) zooming is proposed in the ROIC. Thus, the system can optimize the required resolution and power consumption depending on the critical level of each gas type and concentration. The prototype ROIC was fabricated with CMOS technology and 15.8x efficiency improvement of the system were verified experimentally through real gas sensing