Introduction
Recently, wearable solutions for mobile computing and health
monitoring system receive much attention, and wireless
communication with integrated sensors has been adopted in daily
healthcare monitoring system [1]-[2]. Especially, wearable inductor
becomes a strong candidate for inductive coupling in wearable
applications of less than 1cm distance [1]. For example, inductors in
Fig.1 shows inductors made on a fabric, one is stitched and the other
is printed. However, they suffer from static and dynamic variations
during manufacturing process and operation. Stitching and printing
on a fabric is not a precise technology leading to more than 10%
variation of the inductance values. In addition, the human body is
always moving to induce the fabric warp resulting in additional
variations of inductance values. According to the measured values of
the wearable inductor in Fig.1, their static and dynamic variances are
up to 17% and 24%, respectively. The SNR degradation due to these
variations amounts to 16.7dB which makes the wearable wireless
communication very unreliable, and that’s why inductive coupling
has not been widely used in inter-clothes communication for wearable
healthcare monitoring systems. In this paper, we propose a wearable
inductive coupling transceiver with dynamic compensation of
inductance values for robust communication. Especially, a Real-time
Capacitor Compensation (RCC) scheme is proposed with
binary-weighted capacitor banks of 500fF unit capacitance.