A Power-Efficient Bio-Potential Acquisition Device with DS-MDE Sensors for Long-Term Healthcare Monitoring Applications

This work describes a power-efficient bio-potential acquisition device for long-term healthcare applications that is implemented using novel microelectromechanical dry electrodes (MDE) and a low power bio-potential processing chip. Using micromachining technology, an attempt is also made to enhance the sensing reliability and stability by fabricating a diamond-shaped MDE (DS-MDE) that has a satisfactory self-stability capability and superior electric conductivity when attached onto skin without any extra skin tissue injury technology. To acquire differential bio-potentials such as ECG signals, the proposed processing chip fabricated in a standard CMOS process has a high common mode rejection ratio (C.M.R.R.) differential amplifier and a 12-bit analog-to-digital converter (ADC). Use of the proposed system and integrate simple peripheral commercial devices can obtain the ECG signal efficiently without additional skin tissue injury and ensure continuous monitoring more than 70 hours with a 400 mAh battery

Rail-to-Rail Operational in Low-Power Reconfigurable Analog Circuitry

Analog signal processing (ASP) can be used to decrease energy consumption by several orders of magnitude over completely digital applications. Low-power field programmable analog arrays (FPAA) have been previously used by analog designers to decrease energy consumption. Combining ASP with an FPAA, energy consumption of these systems can be further reduced. For ASP to be most functional, it must achieve rail-to-rail operation to maintain a high dynamic range. This work strives to further reduce power consumption in reconfigurable analog circuitry by presenting a novel data converter that utilizes ASP and rail-to-rail operation. Rail-to-Rail operation is achieved in the data converter with the use of an operational amplifier presented in this work. This efficient yet elementary data converter has been fabricated in a 0.5$\mu$m standard CMOS process. Additionally, this work looks deeper into the challenges of students working remotely, how MATLAB can be used to create circuit design tools, and how these developmental tools can be used by circuit design students

Comparator Design in Sensors for Environmental Monitoring

This paper presents circuit design considerations of comparator in analog-to-digital converters (ADC) applied for a portable, low-cost and high performance nano-sensor chip which can be applied to detect the airborne magnetite pollution nano particulate matter (PM) for environmental monitoring. High-resolution ADC plays a vital important role in high perfor-mance nano-sensor, while high-resolution comparator is a key component in ADC. In this work, some important design issues related to comparators in analog-to-digital converters (ADCs) are discussed, simulation results show that the resolution of the comparator proposed can achieve 5µV , and it is appropriate for high-resolution application

Real-Time Telemetry System for Amperometric and Potentiometric Electrochemical Sensors

A real-time telemetry system, which consists of readout circuits, an analog-to-digital converter (ADC), a microcontroller unit (MCU), a graphical user interface (GUI), and a radio frequency (RF) transceiver, is proposed for amperometric and potentiometric electrochemical sensors. By integrating the proposed system with the electrochemical sensors, analyte detection can be conveniently performed. The data is displayed in real-time on a GUI and optionally uploaded to a database via the Internet, allowing it to be accessed remotely. An MCU was implemented using a field programmable gate array (FPGA) to filter noise, transmit data, and provide control over peripheral devices to reduce power consumption, which in sleep mode is 70 mW lower than in operating mode. The readout circuits, which were implemented in the TSMC 0.18-μm CMOS process, include a potentiostat and an instrumentation amplifier (IA). The measurement results show that the proposed potentiostat has a detectable current range of 1 nA to 100 μA, and linearity with an R2 value of 0.99998 in each measured current range. The proposed IA has a common-mode rejection ratio (CMRR) greater than 90 dB. The proposed system was integrated with a potentiometric pH sensor and an amperometric nitrite sensor for in vitro experiments. The proposed system has high linearity (an R2 value greater than 0.99 was obtained in each experiment), a small size of 5.6 cm × 8.7 cm, high portability, and high integration

Design of Operational Transconductance Amplifiers for voltage to current conversion in gas sensing applications

This paper presents a study of Operational Transconductance Amplifiers (OTAs) for voltage to current conversion circuits. The paper includes a comparative analysis of three OTA architectures implemented in 0.35\u3bcm CMOS AMS Technology under \ub1 1.65V power supply voltage. The impact of the OTA topology has been investigated by simulation. The designed OTAs managed to deliver large current values of 10mA and 1mA to the load with a worst-case error of 0.02% under worst-case power supply and temperature conditions and a worst percentage error of 0.12% under process variation for both Miller Compensated and Capacitor Multiplier Compensated OTA. \ua9 2016 AEIT

Design and Analysis of a Dual Supply Class H Audio Amplifier

abstract: Efficiency of components is an ever increasing area of importance to portable applications, where a finite battery means finite operating time. Higher efficiency devices need to be designed that don't compromise on the performance that the consumer has come to expect. Class D amplifiers deliver on the goal of increased efficiency, but at the cost of distortion. Class AB amplifiers have low efficiency, but high linearity. By modulating the supply voltage of a Class AB amplifier to make a Class H amplifier, the efficiency can increase while still maintaining the Class AB level of linearity. A 92dB Power Supply Rejection Ratio (PSRR) Class AB amplifier and a Class H amplifier were designed in a 0.24um process for portable audio applications. Using a multiphase buck converter increased the efficiency of the Class H amplifier while still maintaining a fast response time to respond to audio frequencies. The Class H amplifier had an efficiency above the Class AB amplifier by 5-7% from 5-30mW of output power without affecting the total harmonic distortion (THD) at the design specifications. The Class H amplifier design met all design specifications and showed performance comparable to the designed Class AB amplifier across 1kHz-20kHz and 0.01mW-30mW. The Class H design was able to output 30mW into 16Ohms without any increase in THD. This design shows that Class H amplifiers merit more research into their potential for increasing efficiency of audio amplifiers and that even simple designs can give significant increases in efficiency without compromising linearity.Dissertation/ThesisM.S. Electrical Engineering 201

Design and implementation of a multi-modal sensor with on-chip security

With the advancement of technology, wearable devices for fitness tracking, patient monitoring, diagnosis, and disease prevention are finding ways to be woven into modern world reality. CMOS sensors are known to be compact, with low power consumption, making them an inseparable part of wireless medical applications and Internet of Things (IoT). Digital/semi-digital output, by the translation of transmitting data into the frequency domain, takes advantages of both the analog and digital world. However, one of the most critical measures of communication, security, is ignored and not considered for fabrication of an integrated chip. With the advancement of Moore\u27s law and the possibility of having a higher number of transistors and more complex circuits, the feasibility of having on-chip security measures is drawing more attention. One of the fundamental means of secure communication is real-time encryption. Encryption/ciphering occurs when we encode a signal or data, and prevents unauthorized parties from reading or understanding this information. Encryption is the process of transmitting sensitive data securely and with privacy. This measure of security is essential since in biomedical devices, the attacker/hacker can endanger users of IoT or wearable sensors (e.g. attacks at implanted biosensors can cause fatal harm to the user). This work develops 1) A low power and compact multi-modal sensor that can measure temperature and impedance with a quasi-digital output and 2) a low power on-chip signal cipher for real-time data transfer

An Analogue Front-End System with a Low-Power On-Chip Filter and ADC for Portable ECG Detection Devices

Medical diagnostic instruments can be made into portable devices for the purpose of home care, such as the diagnosis of heart disease. These assisting devices are not only used to monitor patients but are also beneficial as handy and convenient medical instruments. Hence, for reasons of both portability and durability, designers should reduce the power consumption of assistant devices as much as possible to extend their battery lifetime. However, achieving the low power requirement of the ECG sensing and the processing board for the ECG with commercial discrete components (A21-0003) is difficult because the low power consumer electronics for ECG acquisition systems are not yet available. With the help of the integrated circuit technology, the power-saving requirement of portable and durable equipment gives circuit designers the impetus to reduce the power consumption of analogue front-end circuits in ECG acquisition systems. In addition, the analogue front-end circuits, which are the interface between physical signals and the digital processor, must be operated at a low-supply voltage to be integrated into the low-voltage system-on-a-chip (SOC) system (Eshraghian, 2006). Therefore, the chapter will present two design examples of low-voltage (1 V) and low-power (<1 W) on-chip circuits including a low-pass filter (LPF) and an analogue-to-digital converter (ADC) to demonstrate the possibility of developing the low-voltage low-power ECG acquisition SO