A fast and accurate automatic matching network designed for ultra low power medical applications

We present a method to automatically match a system to the load variation accurately with a very short matching time for ultra low power medical applications. A demonstrator was fabricated and an experimental set-up in the medical implant communication system (MICS) frequency band of 402-405 MHz was realized including a pacemaker antenna prototype immersed on a homogeneous lossy liquid. The matching network consists of a low pass pi structure with tunable components made of varactors. Methodologies for simplifying the matching network design are introduced. The measurements show that a S11 up to -30 dB is obtained with a matching time of 900 mus.