NXP Semiconductors
AN145715
PN544 Antenna Design Guide
145715
© NXP B.V. 2006. All rights reserved.
Application Note
Rev. 1.5 — 28th August 2009
25 of 43
Fig. 20 Smith chart Reader/Writer mode
51B51B
Adjustments on antenna
According to the results of the measurement slight modifications on C2a/C2b and C1 are
needed to finally meet the Z
match
requirements.
See section
71H71H
4.5 for the impact of the antenna matching components.
7.
6B6B
Step 4 – Card mode tuning
The tuning steps of PN544 circuitry needs to be done without powering the chip.
After accomplishing “Step 3” we need to verify the card mode.
The 10Ohm resistor has to be removed now!
Card mode tuning is measured with the PN544 being not powered and configured as
card.
5.
The resonance frequency of the card mode is measured contactless as described in
71H
Appendix B
