Yuanjin Zheng

Low-Power Ultrawideband Wireless Telemetry Transceiver for Medical Sensor Applications

An integrated CMOS ultrawideband wireless telemetry transceiver for wearable and implantable medical sensor applications is reported in this letter. This high duty cycled, noncoherent transceiver supports scalable data rate up to 10 Mb/s with energy efficiency of 0.35 nJ/bit and 6.2 nJ/bit for transmitter and receiver, respectively. A prototype wireless capsule endoscopy using the proposed transceiver demonstrated in vivo image transmission of 640 × 480 resolution at a frame rate of 2.5 frames/s with 10 Mb/s data rate.

A 0.18μm CMOS 802.15.4a UWB Transceiver for Communication and Localization

Recently, IEEE 802.15.4a has specified a UWB PHY for low-rate commutation with ranging capability for wireless personnel area and sensor network applications. Related work is reported on low-rate energy-efficient UWB radios. A combination of the burst position modulation (BPM) and binary phase shift keying (BPSK) is adopted. With different coding rate, bursts per symbol, and chips per burst, the mean pulse repetition rate (PRF) could vary from 3.9 to 62.4MHz for data throughput of 120kHz to 31.2MHz. This work presents an UWB RF transceiver which supports 12 channels, variable date rate, and ranging capability as specified in IEEE802.15.4a. Transceiver IC is implemented in 0.18μm CMOS technology.

A CMOS Carrier-less UWB Transceiver for WPAN Applications

A carrier-less impulse-based UWB transceiver (TRX) chipset is presented. The TRX employs high-order pulse transmission with analog pulse-position modulation. Realized in a 0.18mum CMOS process, the TRX achieves a NF in the range of 7.7 to 8.1dB, an IIP3 of -12.3dBm, and a sensitivity of -80 to -72dBm. It consumes 76mW and 81 mW from a 1.8V supply in transmit and receive modes, respectively

A CMOS VGA With DC Offset Cancellation for Direct-Conversion Receivers

A CMOS dB-linear variable gain amplifier (VGA) with a novel I/Q tuning loop for dc-offset cancellation is presented. The CMOS dB-linear VGA provides a variable gain of 60 dB while maintaining its 3-dB bandwidth greater than 2.5 MHz. A novel exponential circuit is proposed to obtain the dB-linear gain control characteristics. Nonideal effects on dB linearity are analyzed and the methods for improvement are suggested. A varying-bandwidth LPF is employed to achieve fast settling. The chip is fabricated in a 0.35-mum CMOS technology and the measurement results demonstrate the good dB linearity of the proposed VGA and show that the tuning loop can effectively remove dc offset and suppress I/Q mismatch effects simultaneously.

Multiple Functional ECG Signal is Processing for Wearable Applications of Long-Term Cardiac Monitoring

In this paper, an integrated electrocardiogram (ECG) signal-processing scheme is proposed. Using a systematic wavelet transform algorithm, this signal-processing scheme can realize multiple functions in real time, including baseline-drift removal, noise suppression, QRS detection, heart beat rate prediction and classification, and clean ECG reconstruction. Utilizing the novel low-cost hardware architecture, the proposed ECG signal-processing scheme is implemented in application-specific integrated circuits with 0.18 μm CMOS technology. This ECG signal-processor chip achieves low area and power consumptions, and is highly suitable for wearable applications of long-term cardiac monitoring.

A low power noncoherent CMOS UWB transceiver ICs

A fully integrated pulse based UWB transmitter and receiver (TRX) using a novel and simple noncoherent architecture is presented. Fabricated in a 0.18/spl mu/m CMOS process, the signal from the transmitter is binary amplitude modulated pulses and meets FCC UWB low frequency band (3.1-5 GHz) specification. The receiver archives a noise figure of 7.5 dB, IIP3 of -14 dBm, and sensitivity of -72 dBm. The TRX can attain a transmission rate up to 50 Mbps without synchronization circuits and consumes 41.4 mW average power.

Thermoacoustic resonance effect and circuit modelling of biological tissue

In this letter, thermoacoustic resonance effect is predicted from theoretical analysis with series resistor-inductor-capacitor resonance circuit model and then observed experimentally using muscle tissue illuminated by multi-pulse microwave source. Through model fitting, the circuit parameters are extracted to characterize quantitatively the resonant response of the tissue. Coherent demodulation is applied to obtain the enhanced signal-to-noise ratio and spatial information by treating tissue as a communication channel. This physical phenomenon shows significantly higher sensitivity than conventional single microwave pulse induced thermoacoustic effect, enabling the potential design of low-power thermoacoustic imaging device for portable and on-site diagnosis.

An Ultra-Low Power ECG Acquisition and Monitoring ASIC System for WBAN Applications

This paper proposes a power and area efficient electrocardiogram (ECG) acquisition and signal processing application sensor node for wireless body area networks (WBAN). This sensor node can accurately record and detect the QRS peaks of ECG waveform with high-frequency noise suppression. The proposed system is implemented in 0.18-μm complementary metal-oxide-semiconductor technology with two chips: analog front end integrated circuit (IC) and digital application specific integrated circuit (ASIC), where the analog IC consumes only 79.6 μW with area of 4.25 mm2 and digital ASIC consumes 9 μW at 32 kHz with 1.2 mm2. Therefore, this ECG sensor node is convenient for long-term monitoring of cardiovascular condition of patients, and is very suitable for on-body WBAN applications.

A CMOS Ultra Low-Power and Highly Efficient UWB-IR Transmitter for WPAN Applications

This brief presents an on-off LC oscillator-based ultrawideband impulse radio (UWB-IR) transmitter for long-range application. A thorough theoretical analysis of the pulse generation is provided. Implemented in a 0.18-mum CMOS, the transmitter works in the UWB lower band of 3-5 GHz and consumes an ultralow average power of 236 muW at 1.8-V power supply. UWB pulses with a bandwidth of 2 GHz and 10-dB sidelobe suppression are generated. The transmitter can deliver a large differential output swing of 4.9 V under 100-Omega load with the highest power efficiency of 25.4% to date. It is targeted for wireless sensor network (WSNs) and wireless personal area network (WPAN) applications.

A 0.18/spl mu/m CMOS Dual-Band UWB Transceiver

A dual-band transceiver able to work on both UWB low band (3 to 5GHz) and high band (7 to 9GHz) is presented. A method of DSB upconversion in TX, and SSB downconversion and detection in RX is proposed to achieve high data rate non-coherent communication. Realized in 0.18 mum CMOS, the RX achieves an NF of 9.4dB, an IIP3 of -10.3dBm, and a sensitivity of -76dBm. It can attain a transmission rate up to 800Mb/s and draw 55mA and 76mA from a 1.8V supply in TX and RX, respectively.