Hardware UM2042
8/25 DocID029132 Rev 3
2.2.4 Antenna and matching network components
This schematic contains the matching network and the automatic antenna tuning capacitors,
as well as the alternative NFC Forum matching components. In the default configuration,
the ST25R3911B-DISCO is populated with a VHBR matching, with communication speeds
up to 3.4 Mbps.
To support VHBR, the antenna is matched to a system Q-Factor of 8. By switching to the
NFC Forum matching components the system Q-Factor is increased to 16. This can
increase the read range up to 20%, depending on the used communication technology, but
limits the maximum supported communication bit rate to 848 kbps. Additional details about
antenna matching can be found on www.st.com/st25r.