Small electronic devices attached to the outer surface of standard capsule can potentially serve as a cost-effective method of validating medication compliance via electronic detection of an ingested e-pill inside the human digestive tract. In this paper, a passive chip design for such a device is discussed,and the detailed design procedure is given.For the volume-constrained device to achieve the best communication efficiency in the human body environment,an novel asymmetric architecture, which employs different carrier frequencies on Downlink / U plink data transfer, is proposed: the data communication from the reader to the ingested device (Downlink) is designed at 13.56MHz to minimize the signal attenuation through the human body,and the 915MHz band is used for the communication from the ingested device to the reader (Uplink) to achieve the best antenna radiation efficiency. A prototype micro-chip is fabricated using UMC CMOS 130nm technology, and measures 1500 ×800μm2. Experimental results demonstrate that the chip can be activated by - 4dBm input power and achieves a data rate of 17kb/s in the Downlink communication. For the Uplink communication,the chip generates periodic pulses at 915MHz with a data rate of 0.75kb/s.%将电子设备附着在医用胶囊外表面构成电子胶囊可以用来监测服药依从性,本文着重讨论了其中无源双向通信芯片的设计方法.综合考虑无线信号在人体内的传输损耗和电子胶囊中微型天线辐射效率等因素,本文在设计中创新地采用了下行/上行通信不同载波频率的非对称系统结构.在下行通信中采用了传输损耗较小的13.56MHz低频信号,实现对芯片的唤醒以及工作模式的配置；在上行通信中则采用了915MHz高频信号,以优化胶囊天线的辐射效率.系统采用标准的UMC 130nm CMOS工艺实现,面积为1500×800μm2.实验结果表明,下行通信时该无源芯片的唤醒灵敏度为- 4dBm,数据率为17kb/s;上行通信时芯片可以周期性的主动发射频率为915MHz的脉冲信号,数据率为0.75kb/s.
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