Digitally controlled analog front end for inductively coupled transponder systems

Inductively coupled transponder systems are the method of choice for wireless communication with sensor and ID transponders in metallic and hydrous environments. It is desirable to combine the freedom of software defined radio with the reliability of an individualized analog receiver circuit. A new concept for a digitally controlled analog front end with a demodulation technique, which, to the best of our knowledge, has not been applied for transponder signals so far, is presented. It enables handling of different antenna coils optimized for the particular application. The presented demodulation technique is implementable with a low complexity and nonetheless suitable for signals with a very low degree of modulation. Furthermore no analog filter is needed in the direct signal path, which allows a free carrier frequency adaptation.