Wei-Da Toh

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 110pJ/b multichannel FSK/GMSK/QPSK/p/4-DQPSK transmitter with phase-interpolated dual-injection DLL-based synthesizer employing hybrid FIR

The IEEE 802.15.6 Wireless Body-Area-Network (WBAN) standard has recently specified narrowband (NB) PHY covering GMSK and D-PSK modulations targeted at varying data rates [1]. There are also reported energy efficient FSK or QPSK transmitters for biomedical applications [2,3]. Hence, a reconfigurable TX that can support multichannel and multimodulation with reconfigurable data rate, spectrum and energy efficiency would be desirable. Although a conventional mixer-based or fractional-N-PLL-based TX with two-point modulation [4] can achieve the aim, the need of power hungry blocks and sophisticated calibration does not lead to power-efficient solutions. On the other hand, energy efficient injection-locked FSK or QPSK TX with good noise performance does not provide multichannel support due to the use of fixed references [2-3]. Energy efficient FSK TXs [5] with open-loop VCO have also been reported. However, they exhibit poor spectrum efficiency and do not support PSK modulation due to the poor phase noise of free-running VCOs.

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 Image Sensor Controller and JPEG Encoder IC for Wireless Capsule Endoscopy

In this paper, a low power CMOS image sensor controller and baseline JPEG compression encoder for wireless capsule endoscopy is presented. The proposed JPEG encoder can be integrated into a wireless capsule system to compresses the raster YCbCr 4:2:2 raw image data from image sensor into JPEG format file and then send to external receiver through wireless transmission. To achieve low power and high image compression ratio, the JPEG compression algorithm is optimized for biomedical image compression. The compressed image data are being packed into byte format and DMA can be used to retrieve the JPEG image. The JPEG image compression chip is designed using 0.18-μm CMOS technology. It consumes 1.69 mW under 6 MHz system clock for VGA (640×480) image resolution when compressing at 7.5 frames per second.

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.

A 103 pJ/bit multi-channel reconfigurable GMSK/PSK/16-QAM transmitter with band-shaping

A 401~406MHz GMSK/PSK/16-QAM TX with band-shaping is realized in 65nm CMOS occupying area of 0.4mm2. Coupled DLL based phase interpolated synthesizer with injection-locked ring oscillator, we achieve frequency tuning and multi-phase output without any need of phase calibration. Through direct quadrature modulation at digital PA, the TX achieves less than 6% EVM for data rate up to 12.5Mb/s. The band-shaping maximizes spectral efficiency with ACPR of -33dB. Consuming 2.57mW, the TX achieves energy efficiency of 103pJ/bit.

A Reference-Less Injection-Locked Clock-Recovery Scheme for Multilevel-Signaling-Based Wideband BCC Receivers

Body channel communication (BCC) integrated circuits for emerging wireless body area network multimedia applications call for the need of high-speed inter-device data communication at ultra-low-power consumption and smaller device footprint. In this paper, a novel low-power injection-locking-based clock-recovery circuit (CRC) is proposed for BCC transceivers that employ multilevel direct digital signaling for high data rates. The CRC utilizes transition detection for generating pulses from transmitted digital data and injects them directly into the VCO to recover the clock. The pulse-based direct injection-locking architecture achieves instantaneous clock recovery from random multilevel data with a sensitivity of up to -43 dBm, and eliminates the need for a reference crystal used in conventional phase-locked-loop-based CRC circuits. Measured results verify that the proposed CRC achieves clock recovery for two- and three-level signals for data rates up to 160 Mb/s. Implemented in 65-nm CMOS technology, the CRC consumes 0.84 mW with a footprint of 0.12 mm2.

A low-power, high data-rate CMOS ASK transmitter for wireless capsule endoscopy

This paper presents a low-power, high data-rate amplitude shift keying (ASK) radio frequency transmitter for wireless capsule endoscopy. This transmitter consists of a complementary LC voltage-controlled oscillator to generate the 900 MHz carrier frequency and a switchable driver amplifier (DA) controlled by the digital baseband signal to implement the direct ASK modulation. The modulated signal is amplified by the DA and radiated out by a miniaturized coil antenna. The proposed transmitter is implemented in a commercial 0.18-µm CMOS process with 0.32 mm2 active area. Measurement results show that the peak output power is 1 dBm in the 902–928 MHz ISM band and the average DC power consumption is 7.2 mW at a data rate of 15 Mbps.

An asymmetrical QPSK/OOK transceiver SoC and 15:1 JPEG encoder IC for multifunction wireless capsule endoscopy

A chipset including a low power asymmetrical QPSK/OOK transceiver SoC and a 15:1 JPEG image encoder IC is presented for wireless capsule endoscopy. The proposed asymmetrical bi-directional telemetry link supports high-data-rate image transmission with QPSK modulation and low-data-rate actuator control data reception with OOK modulation. To transmit high-quality images with high spectral efficiency, a low power JPEG encoder with compression ratio as high as 15:1 is employed to compress raw image data with subsampling technique in YUV color plane. Implemented in 0.18-μm CMOS, the QPSK TX consumes 5 mW at -6 dBm of output power with 3Mb/s data rate while the OOK RX achieves -60 dBm of sensitivity at 500-kb/s data rate with 6-mW power consumption. A prototype capsule system has been implemented for wireless endoscopy using the developed chipset. With duty cycling, the average power consumption of TX is 2.5 mW when transmitting at 3-fps frame rate.