Simulation Study of Full Passive Magnetic Human Body Communication in 65-nm CMOS Technology for Temperature Sensing Application

In this paper, we present a study of full passive magnetic human body communication for a temperature sensing application. The full system contains a transmitter (Tx), battery-less tag, and receiver (Rx). The information from the Tx would be transmitted through the human body and modulated at the proposed tag and then transmitted to the Rx. To validate the effectiveness of the proposed system, the tag is supposed to be attached to the human body. We focus on the design of the tag that works without an attached battery. The tag contains a ring oscillator, regulator, rectifier, and switch. Inductive coupling models are employed to simulate the magnetic field of the human arms. Thanks to the linear relation between the frequency of the ring oscillator and temperature, the proposed tag could be regarded as a temperature-sensing element. The simulation results have confirmed the effectiveness of the proposed tag and full passive human body communication. The power consumption of the proposed tag is 2.8 µW when the supply voltage of the transmitter is 200 mV.