NXP Semiconductors
AN145715
PN544 Antenna Design Guide
145715
© NXP B.V. 2006. All rights reserved.
Application Note
Rev. 1.5 — 28th August 2009
15 of 43
All tuning and measurement of the NFC antenna has to be performed at the final
mounting position to consider all parasitic effects like metal which influences the
quality factor, the inductance and parasitic capacitance.
4.4.1
30B30B
Transmitter matching resistance R
match
The transmitter (TX) matching resistance R
match
defines the equivalent resistance at the
operating frequency present between the transmitter output pins TX1 and TX2 of the
PN544. Different equivalent resistive loads lead to different transmitter supply currents.
An optimum tuning R
match
for PN544 is 80Ohm
