PULSE DENSITY MODULATING TRANSMITTER FOR RFID

A transmitter (19; 36) built to drive an RFID antenna (20) of the transmitter (19; 36) with an antenna signal (21) with a substantial sinusoidal current/voltage and a carrier frequency in the RFID frequency range of 100kHz to 100MHz, which transmitter (19; 36) comprises: a power amplifier (22) built to provide an amplified transmitter signal (23) and an electromagnetic interference filter (33) built to filter the amplified transmitter signal (23) and built to provide a filtered transmitter signal (34) and a matching circuit (35) connected to the electromagnetic interference filter (33) and the RFID antenna (20) and built to match their impedances and built to receive the filtered transmitter signal (34) and built to provide the antenna signal (21) to the RFID antenna (20), wherein that the transmitter (19; 36) comprises a transmitter signal source (25; 37) connected to the power amplifier (22) and built to provide a pulse density modulated signal as transmitter signal (26) to the power amplifier (22).