Noise analysis for near-field intra-body communication systems

This paper describes noise analysis for near-field intra-body communication, in which the human body is the transmission medium. In this type of communication system, the transmission line´s impedance balance between the signal and the ground line is extremely degraded. Such a system is affected by large common-mode noise from various kinds of electronic equipment. Impedance balance deteriorates as a result of adding parasitic impedance to the transmission line. A change of impedance balance is estimated by measuring capacitance of the transmission line. We verify that an impedance balance between the signal and the ground line is related to noise power in a nearfield intra-body communication system. A method of connecting an additional electrode to a ground one is an effective way of improving impedance balance and reducing noise.