NINA-B1 series - System Integration Manual
UBX-15026175 - R09
Design-in
Page 28 of 49
3
Design-in
3.1
Overview
For an optimal integration of NINA-B1 series modules in the final application board, it is recommended to follow
the design guidelines stated in this chapter. Every application circuit must be properly designed to guarantee the
correct functionality of the related interface, however a number of points require high attention during the
design of the application device.
The following list provides important points sorted by rank of importance in the application design, starting from
the highest relevance:
1.
Module antenna connection:
Ant
pad.
Antenna circuit affects the RF compliance of the device integrating NINA-B1 modules with applicable
certification schemes. Follow the recommendations provided in section 3.2 for schematic and layout design.
2.
Module supply:
VCC
,
VCC_IO
, and
GND
pins.
The supply circuit affects the performance of the device integrating NINA-B1 series module. Follow the
recommendations provided in section 3.3 for schematic and layout design.
3.
Analog signals: GPIO
Analog signals are sensitive to noise and should be routed away from high frequency signals.
4.
High speed interfaces:
UART, SPI
and
SWD
pins.
High speed interfaces can be a source of radiated noise and can affect compliance with regulatory standards
for radiated emissions. Follow the recommendations provided in sections 3.4.1 and 2.4.2 for schematic and
layout design.
5.
System functions:
RESET_N
,
I2C
,
GPIO
and other
System input and output pins
.
Accurate design is required to guarantee that the voltage level is well defined during module boot.
6.
Other pins:
Accurate design is required to guarantee proper functionality.
3.2
Antenna interface
As the unit cannot be mounted arbitrary, the placement should be chosen with consideration so that it does not
interfere with radio communication. The NINA-B112 with an internal surface mounted antenna cannot be
mounted in a metal enclosure. No metal casing or plastics using metal flakes should be used. Avoid metallic
based paint or lacquer as well. The NINA-B111 offers more freedom as an external antenna can be mounted
further away from the module.
According to FCC regulations, the transmission line from the module’s antenna pin to the
antenna or antenna connector on the host PCB is considered part of the approved antenna design.
Therefore, module integrators must either follow exactly one of the antenna reference design used in
the module’s FCC type approval or certify their own designs.
3.2.1
RF transmission line design (NINA-B111 only)
RF transmission lines, such as the ones from the
ANT
pad up to the related antenna connector or up to the
related internal antenna pad, must be designed so that the characteristic impedance is as close as possible to
50
Ω
. Figure 10 illustrates the design options and the main parameters to be taken into account when
implementing a transmission line on a PCB:
•
The micro strip (a track coupled to a single ground plane, separated by dielectric material)
•
The coplanar micro strip (a track coupled to ground plane and side conductors, separated by dielectric
material)
•
The strip line (a track sandwiched between two parallel ground planes, separated by dielectric material).
