Motohiro Takayasu

A 0.5-V 5.8-GHz ultra-low-power RF transceiver for wireless sensor network in 65nm CMOS

This paper proposes the RF CMOS transceiver that is suitable for wireless sensor network applications. To reduce the size of the antenna, target frequency is chosen to be 5.8 GHz band, therefore proposed transceiver has potentiality to achieve ultra-small size wireless sensor module. Supply voltage of 0.5 V can reduce the power consumption of overall RF transceiver. Current-reuse VCO and injection-locked frequency divider can enable ultra-low-power consumption of the PLL. In order to achieve both low power and high sensitivity, uncertain-IF and active mixer first architecture of the receiver are employed. Inverter-based topology of the transmitter is suitable for low supply voltage. The prototype transceiver was fabricated in 65 nm CMOS process, and the transmitter achieved EVM of 12.6% while consuming 2.86 mW including the PLL, and the receiver realizes sensitivity of -75 dBm while consuming 0.83 mW including the local oscillator.

A 2.3 pJ/bit frequency-stable impulse OOK transmitter powered directly by an RF energy harvesting circuit with −19.5 dBm sensitivity

The proposed 2.5-GHz-band impulse transmitter technology realizes frequency-stable impulse generation against PVT variation and superior energy-per-bit operation, and it can be powered directly from a - 19.5-dBm-sensitivity RF energy harvesting circuit without any regulators that are generally essential to power RF circuits. The transmitter occupies 0.38 mm2 in a 65nm CMOS technology. The maximum frequency difference among measured output return-loss peak of 9 chips with 3 different process corners under 0.5 V supply is about 50 MHz without any frequency calibration. Our prototype achieves 1 Mb/s signal transmission under 2.3 μW power consumption from 0.5 V supply thanks to pulse-level duty cycling operation of maximally digital architecture.

A sub-1G CMOS-MEMS accelerometer

We report experimental evaluation results of a CMOS (complementary-metal-oxide semiconductor)-MEMS (microelectromechanical systems) accelerometer for sensing sub-1G (1G = 9.8 m/s2) acceleration. The sub-1G MEMS sensor has been successfully implemented on a 180-nm CMOS LSI (large scale integrated circuits) for the first time. For the MEMS fabrication, we utilized multi-layered metal technology for the post-CMOS process. The accelerometer was developed within the footprint of 4 × 4 mm2. The sensitivity was measured to be 0.604 (V/G) at the input of acceleration from -1 G to +1 G. The experimentally obtained results were consistent with the design values.

A 0.5-V 5.8-GHz low-power asymmetrical QPSK/OOK transceiver for wireless sensor network

This paper presents design of the low power RF transceiver [1] which is suitable for wireless sensor network. Using 5.8GHz band has potentiality to achieve small size wireless sensor module because of smaller antenna in higher frequency. The proposed transceiver utilizes different modulation schemes for uplink and downlink to optimize power consumption and spectral efficiency. In addition, supply voltage of 0.5V can reduce the power consumption of overall RF transceiver. The prototype transceiver was fabricated in 65nm CMOS process, and the transmitter achieved EVM of 12.6% while consuming 2.86mW, and the receiver realizes sensitivity of -75dBm while consuming 0.83mW.

An 8-ch, 20-V Output CMOS Switching Driver with 3.3-V Power Supply for Integrated MEMS Devices Controlling

Abstract An 8-ch output switching driver has been implemented for integrated MEMS (Micro Electro Mechanical Systems) devices controlling by using the 0.18-m CMOS process technology. The driver can output 20-V switching signals for 1-nF capacitive loads with 3.3-V power supply. To get high output voltage exceeding the transistor’s breakdown voltage, optimal transistor-well-biasing techniques for triple-well-structured n-MOS transistors, employed in the charge pump and the discharge circuits, has been investigated.