Biomedical electronics with proximity wireless
communication have been getting much attention [1]-[3]. In
particular, in-vivo electronics equipments such as capsule
endoscopes [4], [5] are promising application. The capsule
endoscope has a camera, a transceiver circuit, and batteries in a
small capsule, and takes gastrointestinal images, and transmits
them to an external base station. Even images of the small
intestine can be taken by the capsular endoscope, which was not
possible by conventional wired endoscope.