NXP Semiconductors
AN11740
PN5180 Antenna design
AN11740
All information provided in this document is subject to legal disclaimers.
© NXP B.V. 2018. All rights reserved.
Application note
COMPANY PUBLIC
Rev. 1.1 — 19 June 2018
345311
53 of 62
As can be seen in Fig 48, the card response can be properly received in Fig 48a, where
no noise applies. In Fig 48b the card response together with the noise is shown. The
noise spikes, which are much larger than the sub carrier signal itself, introduce some
clipping effects, which are detected like phase shifts. This disturbs the type B
communication. Such noise must be eliminated or at least reduced to a level, which does
not disturb the communication anymore.
a. Card response, no noise
b. Card re noise
Fig 48. Type B with Card response
