适用于无线体域网的可重构、鲁棒的、超低功耗发射机系统研究与电路设计

Due to more than 500MHz channel bandwidth and inherently duty-cycled nature, impulse-radio ultra-wideband (IR-UWB) is one of three physical layers for the wireless body area network standard released in 2012, not only applicable for the low data rate low power wireless sensor network, but also a viable low cost low power solution to high data rate wireless personal healthcare monitoring system. In this proposal, based on the real-life applications, a low power reconfigurable IR-UWB transmitter is studied on both its architecture and the topologies of its key blocks with the purpose of saving the hardware cost; an on-chip automatic calibration technique is studied for the calibrations of impedance matching and output center frequency; an efficient measurement method is also considered. This reconfigurable transmitter is expected to be fabricated by 0.13μm CMOS process. For the on-body low data rate application, low power consumption is critical, and the tageted energy efficiency is dozens of pJ/s; in the in-body scenario with high singal attenuation and high data rate transimission, the output amplitude is needed to be high enough. Main innovative points include: (1) according to the application requirements, modify the ring-oscillator-based architecture and put forward a low power reconfigurable one suitable for the studied system; (2) for reliable and robust data transmission, propose an automatic calibration technique to eliminate the influence of body tissues on the characteristic impedance of the antenna and to calibrate out the effects stemmed from PVT variations.

脉冲式超宽带（IR-UWB）具有超过500MHz的信道带宽及周期性工作的特点，是无线体域网标准的三个物理层之一，不仅适用于低速低功耗的无线传感网络，同时也为高速无线个人健康监护系统提供了低功耗低成本的解决方案。本项目从实际应用需求出发，研究可配置低功耗IR-UWB发射机系统架构及重要模块的电路结构，以尽可能少的硬件开销满足不同应用；研究输出阻抗匹配和中心频率片上自动校准技术；研究有效的系统性能验证方法。采用0.13μm CMOS工艺，研制该可配置发射机芯片，在低速应用下，目标能效为几十pJ/s；在高信号衰减、高速数据传输应用里，低功耗下输出尽可能高的脉冲幅度。本项目的创新点：根据实际的应用要求，对基于环形振荡器的发射机系统进行改进，提出契合本项目特点的可配置低功耗体系架构；采用片上阻抗匹配自动校准技术，消除人体寄生对天线特征阻抗的影响，校正PVT效应对阻抗匹配造成的偏差，提高工作的可靠性。

脉冲式超宽带（IR-UWB）具有超过500MHz的信号带宽及周期性发射脉冲的特点，不仅适用于低速低功耗的无线传感网络，也为无线健康监护系统提供了高速、低功耗、低成本的解决方案。按照计划的研究目标，完成了以下工作：（1）采用SMIC 0.13um CMOS工艺研究设计了基于延时线的全数字IR-UWB发射机，实现了中心频率、输出幅度、频谱及带宽可调。测试结果表明-10dB信号带宽在0.9-1.5GHz可调，与国际先进水平相当。（2）采用TSMC 65nm CMOS工艺研究设计了基于Class-E功率放大器的低功耗IR-UWB发射机。通过三级反相器级联的VCO产生高频脉冲，功耗低，中心频率可调；Class-E结构的功放没有静态功耗，提高了功放及整个发射机的效率。测试结果表明：当中心频率为2.56GHz时，差分输出电压峰峰值为2800mV，此时负载输出功率为18.8mW（12.74dBm），适用于高速率、高衰减的数据传输场合；当输入数据率达到20M时，功放峰值效率为30.6%，发射机整体效率达到14%，说明高数据率下可以实现低功耗。（3）还对IR-UWB接收机的前端电路低功耗、射频数字化技术进行了研究。这些研究工作表明：IR-UWB发射接收系统很有希望应用于在短距离无线传感网络当中。