139037 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2013. All rights reserved.
Product data sheet
COMPANY PUBLIC
Rev. 3.8 — 11 November 2013
139038 13 of 48
NXP Semiconductors
SL3ICS1002/1202
UCODE G2XM and G2XL
12. Functional description
12.1 Power transfer
The interrogator provides an RF field that powers the tag, equipped with a UCODE G2X.
The antenna transforms the impedance of free space to the chip input impedance in order
to get the maximum possible power for the G2X on the tag.
The RF field, which is oscillating on the operating frequency provided by the interrogator,
is rectified to provide a smoothed DC voltage to the analog and digital modules of the IC.
The antenna that is attached to the chip may use a DC connection between the two
antenna pads. Therefore the G2X also enables loop antenna design. Possible examples
of supported antenna structures can be found in the reference antenna design guide.
12.2 Data transfer
12.2.1 Reader to G2X Link
An interrogator transmits information to the UCODE G2X by modulating an RF signal in
the 840 MHz - 960 MHz frequency range. The G2X receives both information and
operating energy from this RF signal. Tags are passive, meaning that they receive all of
their operating energy from the interrogator's RF waveform.
An interrogator is using a fixed modulation and data rate for the duration of at least an
inventory round. It communicates to the G2X by modulating an RF carrier using
DSB-ASK, SSB-ASK or PR-ASK with PIE encoding.
For further details refer to Section 17
, Ref. 1, section 6.3.1.2. Interrogator-to-tag (R=>T)
communications.
12.2.2 G2X to reader Link
An interrogator receives information from the UCODE G2X by transmitting a
continuous-wave RF signal to the tag; the G2X responds by modulating the reflection
coefficient of its antenna, thereby generating modulated sidebands used to backscatter an
information signal to the interrogator. The system is a reader talks first (RTF) system,
meaning that a G2X modulates its antenna reflection coefficient with an information signal
only after being directed by the interrogator.
G2X backscatter is a combination of ASK and PSK modulation depending on the tuning
and bias point. The backscattered data is either modulated with FM0 baseband or Miller
sub carrier.
For further details refer to Section 17
, Ref. 1, section 6.3.1.3. tag-to-interrogator (T=>R)
communications.
