Shengxi Diao

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 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 50-Mb/s CMOS QPSK/O-QPSK Transmitter Employing Injection Locking for Direct Modulation

A 50-Mb/s quadrature phase-shift keying (QPSK)/offset quadrature phase-shift keying (O-QPSK) transmitter suitable for biomedical high-quality imaging application is presented. Centered at 915 MHz, the phase modulation is achieved by directly modifying the self-resonant frequency of an LC voltage-controlled oscillator through capacitor bank switching. By eliminating many unnecessary building blocks in the conventional QPSK/O-QPSK transmitter, significant power and area savings are achieved. Implemented in 0.18- μm CMOS technology, it occupies an active core area of 0.28 mm2. With 305-MHz injection frequency and consuming 5.6 mW under 1.4-V supply, the transmitter achieves error vector magnitude (EVM) of 11.4%/5.97% for O-QPSK/QPSK modulation while delivering output power of -3 dBm at 50 Mb/s. By lowering the injection frequency to 101.67 MHz, it consumes 5.88 mW under the same supply voltages while delivering an output power of -3.3 dBm. The transmitter achieves measured EVM of 6.4% at 50 Mb/s under QPSK modulation.

A 0.92/5.3nJ/b UWB impulse radio SoC for communication and localization

UWB has shown great potential for short-range low data-rate low-power wireless communications. Recently, wireless body area networks for wearable and implant devices are emerging, which require energy-efficient radios to sustain longer battery life and potentially enable power supplied by energy harvesting [1]. Some energy-efficient UWB solutions have been reported [2–6]. However, only RF transceivers have been presented and the publications did not show a complete radio except in reference [6]. Also, location awareness for ambient intelligent sensor networks becomes the next important feature to implement besides communications [7]. UWB offers unique merit for accurate localization by using the narrow and wideband pulses. In this work, we present a complete impulse UWB SoC radio including RF transceiver and digital PHY. It can be configured as communication or localization or both modes, therefore enabling a uniform energy-efficient radio platform for WSN, WPAN, and WBAN applications.

Low power ultra-wideband wireless telemetry system for capsule endoscopy application

A low power wireless telemetry system for capsule endoscopy is presented in this paper. The proposed system is based on impulse-radio ultra-wideband (IR-UWB) technology, it consists of a UWB transmitter utilizing fast on-off LC VCO and a non-coherent UWB receiver using energy detection. The whole system is implemented in 0.18-µm CMOS process and integrated in a single chip with 3 mm × 4 mm chip size. The measurement results show that the transmitter consumes ultra low average power of 2.5mW at 10Mbps data rate and the receiver draw 40 mA current under 1.8V power supply. An ex-vivo animal experiment shows that the proposed system can successfully transmit the real-time image data out from the capsule to the external base station.

A 7.2mW 15Mbps ASK CMOS transmitter for ingestible capsule endoscopy

This paper presents an amplitude shift keying (ASK) transmitter for high-quality imaging in ingestible capsule endoscopy application. A carrier frequency of 900MHz is generated by a complementary LC voltage-controlled oscillator, and directly modulated with a digital baseband ASK signal by switching on and off a driver amplifier (DA). The modulated signal is amplified by the DA and transmitted through an inductive coupling. The transmitter has been fabricated in 0.18µm CMOS process. A peak output power of 1dBm can be transmitted and power consumption is 7.2mW at a data rate of 15Mbps.

A resistive-feedback LNA in 65nm CMOS with a gate inductor for bandwidth extension

In order to get a wideband and flat gain, a resistive-feedback LNA using a gate inductor to extend bandwidth is proposed in this paper. This LNA is based on an improved resistive-feedback topology with a source follower feedback to match input. A relative small inductor is connected in series to transistor?s gate, which boosts transistor?s effective transconductance, compensates gain loss and then leads the proposed LNA with a flat gain and wider bandwidth. Moreover, the LNA?s noise is partially inhibited by the gate inductor, especially at high frequency. Realized in standard 65-nm CMOS process, this LNA dissipates 12mW from a 1.5-V supply while its core area is 0.076mm2. Across 0.4-10.6GHz band, the proposed LNA provides 9.5?0.9dB power gain (S21), better than -11-dB input matching, 3.5-dB minimum noise figure, and higher than -17.2-dBm P1dB.

A 5.9mW 50Mbps CMOS QPSK/O-QPSK transmitter employing injection locking for direct modulation

900MHz QPSK/O-QPSK transmitter suitable for biomedical high quality imaging application is presented. The phase modulation is achieved by directly modifying the self-resonant frequency of a sub-harmonic injection-locked oscillator through capacitor bank switching. Due to the simplicity of the proposed architecture, implemented in 0.18μm CMOS technology, it consumes very low power of 3mW and 5.88mW with 1.2V and 1.4V supply voltages respectively, while transmitting at 50Mbps data rate. The transmitter can deliver output power of −3.3dBm at 1.4V supply with an EVM of 6.6%.

An Asymmetrical QPSK/OOK Transceiver SoC and 15:1 JPEG Encoder IC for Multifunction Wireless Capsule Endoscopy

This paper presents a chipset including an asymmetrical QPSK/OOK transceiver SoC and a JPEG image encoder for wireless capsule endoscopy. The transceiver SoC supports bi-directional telemetry for high data-rate image transmission with QPSK modulation and low data-rate command link with OOK modulation. A low power JPEG encoder is designed to compress raw image data with compression ratio as high as 15:1 using sub-sampling technique in YUV color plane. Implemented in 0.18 μm CMOS, the QPSK TX consumes 5 mW at -6 dBm of output power with 3 Mb/s data rate while the OOK RX achieves -65 dBm of sensitivity at 500 kb/s data rate with 4.5 mW power consumption. A prototype capsule has been implemented with the chipset and the performance has been verified with in vivo animal experiment. With duty cycling, the average power consumption of TX is 2.5 mW when transmitting at 3 fps frame rate.

A low power interference robust IR-UWB transceiver SoC for WBAN applications

An integrated 3-5 GHz impulse radio ultrawideband (IR-UWB) wireless transceiver SoC for wireless body area network (WBAN) applications is reported in this paper. To enhance system robustness against narrow band interference (NBI) signals, receiver low noise amplifier (LNA) input matching network is optimized to reject outband NBI below 2.5 GHz. A non-coherent energy detection scheme using analog squarer with band-pass filtering is utilized to increase the rejection to both in-band/out-band NBI. The proposed transceiver achieves energy efficiency of 0.3 nJ/bit and 4.3 nJ/bit for TX and RX respectively and a receiver sensitivity of -88 dBm (BER=10-3) for UWB OOK signal at 1 Mbps pulse rate. The measured in-band/out-band SIR is better than -34 dB and -45 dB, respectively.