| Summary: | 碩士 === 淡江大學 === 電機工程學系碩士班 === 100 === As age advances, the electronic applications in the biomedical develops rapidly. It is the trend that people carry chips or implant chips into their body in order to detect a variety of physiological signals. Also, they use chips to release medicines to achieve the purpose of home care. As those chip’s power source used for the battery, the power generation of body heat or radio energy harvested circuit, therefore the most important requirements in transmission interface circuit design for ultra-low power consumption to extend the service life of purpose. Since the receiver must remain turn on for a long time, the receiver''s power consumption accounted for more than half of the overall power consumption, therefore to achieve an ultra-low power receiver can significantly extend the used time.
In ultra-low power circuit design, whether analog or digital circuits are using transistors operating in subthreshold to reduce power consumption in recent years. In analog and RF circuit design, Christian C. Enz further divided sub-threshold into the weak inversion and the moderate-inversion. His studies shows that when the operating speed less than 100MHz, people operated the transistor in weak inversion in order to achieve the purpose of the ultra-low power. Transistors also provide 20dB intrinsic gain.
We have accomplished an intra-body communication in wearable or implantable type of physiological signal sensor on ultra-low power receiver front-end circuit. Because transmission medium is human body, the path lose is smaller than in the air. It substantially reduced the requirements on the sensitivity of receiver front-end. All transistors are operating on deep weak inversion. Without input of the RF signal, the receiver front-end consumes a static current of 35.4 μA under a supply voltage of 1.8 V, also static power consumption is only 68.4 μW. When input signal is 400 MHz, the power consumption is only 86.4 μW, the voltage gain has 24.1 dB, IIP3 has greater than 18 dB, and bandwidth is 200 KHz.
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