Wu Jianhui

Interference robust channel hopping strategies for wireless sensor networks

Due to the shared nature of the wireless medium, the performance of wireless sensor network is often limited by both internal interference and external interference. The internal interference is that simultaneous traffic activity by neighboring nodes in the same network, while the external interference is from wireless transmissions by other types of devices, such as Wi-Fi and Bluetooth nodes. In this paper, we present two channel hopping algorithms for multichannel, single-radio wireless sensor networks. The first algorithm achieves collision-free transmission environment while do not introduce extra control overhead. The second algorithm, in addition to reducing internal interference effects, reduces the external interference effects from Wi-Fi devices. Simulation results show that both of them significantly improve performance in wireless sensor network.

A 66dB continuous gain adjusting CMOS AGC amplifier with both feedforward and feedback loop

A CMOS continuous gain adjusting AGC amplifier with 66dB maximum gain and 30MHz bandwidth is proposed in this paper. Such AGC amplifier consumes a power of 1.1mW under the supply of 1.2V. It includes a fast responding feedforward loop and a high linearity feedback loop. Hysteresis comparator is adopted to overcome the ripples of successive detection RSSI, generating stable control word to complete the coarse gain adjustment in less than 2μs, which simplifies the design of VGA. The design is completed in TSMC 130nm CMOS technology and simulation results are given at last.

Design and analysis of high power supply rejection CMOS bandgap voltage reference

In this paper, a high power supply rejection (PSR) CMOS bandgap circuit applied in RF receiver is presented. A precise and simple PSR model, useful for pencil and paper analysis is hereby developed for the circuit. By analyzing the model, the ways to improve the circuits performance of PSR in both low and high frequency domain are presented. The PSR of the circuit can reach 102 dB at low frequency and is more than 50 dB at high frequency. The proposed CMOS bandgap voltage reference has been implemented in Chartered 0.25-mum N-Well CMOS process.