Liang-Hung Wang

A Low-Power RFID Integrated Circuits for Intelligent Healthcare Systems

This paper presents low-power radio-frequency identification (RFID) technology for intelligent healthcare systems. With attention to power-efficient communication in the body sensor network, RF power transfer was estimated and the required low-power ICs, which are important in the development of a healthcare system with miniaturization and system integration, are discussed based on the RFID platform. To analyze the power transformation, this paper adopts a 915-MHz industrial, scientific, and medical RF with a radiation power of 70 mW to estimate the power loss under the 1-m communication distance between an RFID reader (bioinformation node) and a transponder (biosignal acquisition nodes). The low-power ICs of the transponder will be implemented in the TSMC 0.18-μm CMOS process. The simulation result reveals that the transponders IC can fit in with the link budget of the UHF RFID system.

Low-Power Analog Integrated Circuits for Wireless ECG Acquisition Systems

This paper presents low-power analog ICs for wireless ECG acquisition systems. Considering the power-efficient communication in the body sensor network, the required low-power analog ICs are developed for a healthcare system through miniaturization and system integration. To acquire the ECG signal, a low-power analog front-end system, including an ECG signal acquisition board, an on-chip low-pass filter, and an on-chip successive-approximation analog-to-digital converter for portable ECG detection devices is presented. A quadrature CMOS voltage-controlled oscillator and a 2.4 GHz direct-conversion transmitter with a power amplifier and upconversion mixer are also developed to transmit the ECG signal through wireless communication. In the receiver, a 2.4 GHz fully integrated CMOS RF front end with a low-noise amplifier, differential power splitter, and quadrature mixer based on current-reused folded architecture is proposed. The circuits have been implemented to meet the specifications of the IEEE 802.15.4 2.4 GHz standard. The low-power ICs of the wireless ECG acquisition systems have been fabricated using a 0.18 μm Taiwan Semiconductor Manufacturing Company (TSMC) CMOS standard process. The measured results on the human body reveal that ECG signals can be acquired effectively by the proposed low-power analog front-end ICs.

A CMOS Quadrature VCO With Subharmonic and Injection-Locked Techniques

A 1-V quadrature voltage-controlled oscillator (QVCO) using subharmonic and injection-locked techniques (SHIL-QVCO) is presented. Instead of using the traditional transformer-coupling LC tank with a large area to implement the quadrature output, we use a frequency-doubled differential pair with an injection-locked method. The proposed QVCO is implemented with a TSMC 0.18- μm 1P6M CMOS process having a 1.4 × 0.67 × mm2 chip area. This QVCO has the advantages of low phase noise and low power consumption. Experimental results show that the QVCO has a phase noise of - 126 dBc/Hz at an offset frequency of 1 MHz and a power consumption of 4.9 mW to achieve a 186 figure of merit. Moreover, a tuning frequency between 2.17 and 2.52 GHz can be obtained with a tuning voltage range of 0-1 V for the IEEE 802.15.4.

Implementation of a personal health monitoring system in cardiology application

In this paper, we present a personal health monitoring system that is specialized in monitoring cardiac disorder events. The proposed system comprises the design and implementation of hardware as well as software, which include three subsystems, (1) the electrocardiograph (ECG) acquisition node, (2) the Android-based processing and communication device, and (3) the healthcare box. The ECG acquisition node embeds ECG acquisition front-end circuits, MSP430 micro-processor and the Bluetooth (BT) module. It can be put on patients to acquire ECG signals and relay them back to any Android-based device (e.g., Android phones and PDAs) for display and storage. The healthcare box is a PC-based surveillance system which can perform more advanced ECG signal processing from the acquired ECG signals. Combining with the three subsystems, including hardware and software, remote patients can receive seamless and ambient high quality health care service in cardiology.

Microcalcification Detection in 3-D Breast Ultrasound

The appearance of cluster of microcalcifications in mammography or sonography is an important indicator for malignancy. Microcalcifications are calcium deposits, which can be identified as tiny areas that are slightly brighter than surrounding tissue. Detection of mammographic microcalcification has been proposed in many studies. Since a microcalcification cluster is a three-dimensional (3-D) entity, its projection onto a two-dimensional (2-D) image results in a loss of spatial information and may also cause superimposition of individual calcifications within the cluster. This paper aims to use the 3-D ultrasound to determine microcalcifications. In each slice, the proposed method adopts the top-hat filter to find bright spots, and employs four 2-D criteria to select the spots as candidate microcalcifications. Finally, spots appearing in sequent slices at the same position are considered as a microcalcification. We suggest using a computer automatically to detect the microcalcification being feasible and microcalcifications being a very important criterion of malignancy on future developing the computer-aided diagnosis for ultrasound. In the future, this technique can be adopted in a computer-aided diagnosis system combined with other diagnosis features for improving the diagnosis performance

A low-power RF front-end with merged LNA, differential power splitter, and quadrature mixer for IEEE 802.15.4 (ZigBee) applications

A 2.4 GHz fully integrated CMOS RF front-end with low-noise amplifier (LNA), differential power splitter (DPS), and quadrature mixer based on current-reused folded architecture is proposed. The circuit has been implemented to fit the specifications of IEEE 802.15.4 2.4 GHz standard. To address the low power consumption issue, the active differential power splitter is directly stacked upon the LNA to allow the reuse of the DC bias current. The folded structure is implemented by using the PMOS device as the quadrature mixer to achieve low flicker and thermal noise, simultaneously. Both the LNA and the DPS are biased in the subthreshold region, which can offer superior gain per current consumption as compared with operation in the strong-inversion region. The chip is fabricated in the 0.18 µm CMOS process with an area of 1.69 mm2 at a supply voltage of 1.2 V and power consumption of 1.08 mW. Based on the measurement results, the conversion gain of 20.5 dB and S11 of −17 dB can be obtained, respectively. Moreover, the IIP3 in the whole chip is −7.8 dBm, and the total double-side band noise figure is 13.2 dB.

An IEEE 802.15.4 RF transmitter for 2.4 GHz ISM band healthcare applications

This paper presents a low-power RF-transmitter for intelligent healthcare systems. With attention to power-efficient communication in the local sensor network, the required low-power integrated circuits (ICs) are developed for a healthcare system with miniaturization and system integration. A quadrature CMOS voltage-controlled oscillator and a direct-conversion transmitter with PA and up-conversion mixer have been implemented to fit the specification of the IEEE 802.15.4 2.4 GHz standard. The low-power ICs of the transmitter have been applied in the TSMC 0.18-μm CMOS standard process. The measurement results reveal that the transmitter IC can fit in with the link budget of the UHF ZigBee system for healthcare applications.

Design and implementation of a wireless ECG acquisition and communication system with health-care services

In this paper, we present a system that can provide a better caring service to the remote patients. The system we developed mainly focuses on the cardiac signal acquisition (i.e., ECG) and its communication. A prototype using the ZigBee wireless technology was built to verify the designed functions and required system performance. Results show the hardware and firmware on the end-user device can work together very well to perform reliable ECG signal acquisition as well as communication task via the ZigBee wireless technology. In addition, a PC-based GUI interface is also developed to provide ECG signal processing task and health care video tracking and management functions.

A wireless electrocardiogram detection for personal health monitoring

The current paper presents low-power analog integrated circuits (ICs) for wireless electrocardiogram (ECG) detection in personal health monitoring. Considering the power-efficient communication in the body sensor network (BSN), the required low-power analog ICs are developed for a healthcare system through miniaturization and system integration. The proposed system comprises the design and implementation with three subsystems, namely, (1) the ECG acquisition node, (2) the protocol for standard IEEE 802.15.4 ZigBee system, and (3) the radio frequency (RF) transmitter circuits. A preamplifier, a low-pass filter, and a successive-approximation analog-to-digital converter (SA-ADC) are integrated to detect an ECG signal. For high integration, the ZigBee protocol is adopted for wireless communication. To transmit the ECG signal through wireless communication, a quadrature voltage-controlled oscillator and a 2.4 GHz low-IF transmitter with a power amplifier and up-conversion mixer are also developed. In the receiver, a 2.4 GHz fully integrated CMOS radio-frequency front-end with a low-noise amplifier, and a quadrature mixer is proposed. The low-power wireless bio-signal acquisition SoC (WBSA-SoC) has been implemented in TSMC 0.18-μm standard CMOS process. The measurement results on the human body reveal that the ECG signals can be acquired effectively by the proposed SoC.

Wireless brain signal acquisition circuits for body sensor network

The paper presents the proposed wireless brain signal acquisition circuits for body sensor network. Considering the power-efficient communication in the body sensor network, the required low-power analog integrated circuits (ICs) are developed for a wireless brain signal acquisition system. To acquire the electroencephalogram (EEG) signal, this paper proposes an analog front-end (AFE) circuit, including only one low-noise amplifier with chopping techniques and one high-pass sigma-delta modulator (HPSDM), which can be applied as a sensing circuit for EEG signal acquisition systems. To transmit the EEG signal through wireless communication, a quadrature CMOS voltage-controlled oscillator and a 2.4 GHz direct-conversion transmitter with a power amplifier and up-conversion mixer are also developed. In the receiver, a 2.4 GHz fully integrated CMOS radio-frequency front-end is also implemented. The circuits have been implemented to fit the specifications of the IEEE 802.15.4 2.4 GHz standard. The low-power ICs of the wireless EEG acquisition systems have been fabricated using a 0.18 μm TSMC CMOS standard process. The measured results reveal that the proposed low-power analog front-end ICs can be used for the wireless brain signal acquisition.