NINA-B1 series - System integration manual
UBX-15026175 - R16
Design-in
Page 43 of 63
C1-Public
Figure 30: NFC antenna design
𝐶𝐶
𝑡𝑡𝑡𝑡𝑡𝑡𝑡𝑡
′
=
1
(2
𝜋𝜋
× 13.56
𝑀𝑀𝑀𝑀𝑀𝑀
)
2
𝐿𝐿
𝑎𝑎𝑡𝑡𝑡𝑡
𝑤𝑤𝑤𝑤𝑤𝑤𝑤𝑤
𝐶𝐶
𝑡𝑡𝑡𝑡𝑡𝑡𝑡𝑡
′
=
1
2 ×
�𝐶𝐶
𝑝𝑝
+
𝐶𝐶
𝑖𝑖𝑡𝑡𝑡𝑡
+
𝐶𝐶
𝑡𝑡𝑡𝑡𝑡𝑡𝑡𝑡
�
𝐶𝐶
𝑡𝑡𝑡𝑡𝑡𝑡𝑡𝑡
=
2
(2
𝜋𝜋
× 13.56
𝑀𝑀𝑀𝑀𝑀𝑀
)
2
𝐿𝐿
𝑎𝑎𝑡𝑡𝑡𝑡
− 𝐶𝐶
𝑝𝑝
− 𝐶𝐶
𝑖𝑖𝑡𝑡𝑡𝑡
3.6.1
Battery protection
If the antenna is exposed to a strong NFC field, current may flow in the opposite direction on the
supply due to parasitic diodes and ESD structures.
If the battery used does not tolerate return current, a series diode must be placed between the battery
and the device to protect the battery.
3.7
General High Speed layout guidelines
These general design guidelines are considered as best practices and are valid for any bus present in
NINA-B1 series modules; the designer should prioritize the layout of higher speed busses. Low
frequency signals are generally not critical for layout.
⚠
One exception is represented by High Impedance traces (such as signals driven by weak pull
resistors) that may be affected by crosstalk. For those traces, a supplementary isolation of 4w
from other busses is recommended.
3.7.1
General considerations for schematic design and PCB floor-planning
•
Verify which signal bus requires termination and add series resistor terminations to the
schematics.
•
Carefully consider the placement of the module with respect to antenna position and host
processor.
•
Verify with PCB manufacturer allowable stack-ups and controlled impedance dimensioning.
•
Verify that the power supply design and power sequence are compliant with the NINA-B1 series
module specification. See also section 1.4.
3.7.2
Module placement
•
Accessory parts like bypass capacitors should be placed as close as possible to the module to
improve filtering capability, prioritizing the placement of the smallest size capacitor close to
module pads.
