ANNA-B112 - System integration manual
UBX-18009821 - R09
Design-in
Page 39 of 66
C1-Public
3
Design-in
Overview
For an optimal integration of ANNA-B112 in the final application board, it is advisable to follow the
design guidelines stated in this section. Every application circuit must be properly designed to
guarantee the correct functionality of the related interface; however, a number of points require a high
level of 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:
2.
Antenna circuit affects the RF compliance of the device integrating ANNA-B112 module with
applicable certification schemes. Follow the recommendations provided in section 3.2 for
schematic and layout design.
3.
Module supply:
VCC
, and
GND
pins.
4.
The supply circuit affects the performance of the device integrating ANNA-B112 module. Follow
the recommendations provided in section 3.3 for schematic and layout design.
5.
Analog signals: GPIO
6.
Analog signals are sensitive to noise and should be routed away from high frequency signals.
7.
High speed interfaces:
UART, SPI
and
SWD
pins.
8.
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.
9.
System functions: RESET_N, I2C, GPIO and other System input and output pins.
10.
Accurate design is required to guarantee that the voltage level is well defined during module boot.
11.
Other pins:
12.
Accurate design is required to guarantee proper functionality.
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 ANNA-B112 using the internal 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. Using the ANNA-B112 with external antenna offers more
freedom as the 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
ANNA-B112 Internal antenna design
⚠
If a metal enclosure is required, ANNA-B112 using the antenna pin and an external antenna has to
be used.
It is recommended to place the ANNA-B112 module so that the internal antenna is in the corner of
the host PCB. The next best option is to position the antenna along one side of the host PCB ground
plane. It is beneficial to have a large ground plane on the host PCB and have a good grounding for the
ANNA-B112 module. Detailed description of the antenna trace and requirements can be found in
appendix B.
