The thesis addresses the problems of using the antenna system of the TRF7970AEVM development board for passive load modulation in card emulation mode. The measurements, as defined by the standards ISO/IEC 10373, NFC Forum and EMV Contactless, revealed inherent problems with the load modulation of the TRF7970AEVM. A strong signal was in some cases present mostly in the carrier phase, something not all standards and regulations measure.
The measurements also serve as a basis for a simulation model circuit as well as a prototype circuit with similar behavior to the TRF7970AEVM, on which output driver voltage limitations methods, in the form of an added Zener diode, are tested. In addition, other load modulation implementations are tested, namely with an added diode and n-channel MOS transistor on the antenna. The latter proved the most successful out of all the tested implementations.