Integration Manual

ANNA-B4 series - System integration manual
UBX-21000517 - R03 Contents Page 26 of 76
C1-Public
☞ A de-facto standard for SMA connectors suggests that the use of reverse polarity connectors
(RP-SMA) on Wi-Fi and Bluetooth end products can deter end users from replacing the antenna
with higher gain types that exceed regulatory limits.
Observe the following recommendations for a proper layout of the connector:
• Strictly follow the connector layout recommended by the manufacturer.
• SMA Pin-Through-Hole connectors require GND keep-out (void clearance area) on all layers around
the central pin up to the annular pads of the four GND posts.
• U.FL surface mounted connectors require non-conductive traces (void clearance area) in the area
below the connector between the GND land pads.
• If the RF pad size of the connector is wider than the microstrip, remove the GND layer beneath the
RF connector to minimize the stray capacitance and retain a 50  RF line resistance. To reduce
the parasitic capacitance to ground for example, the active pad of the UF.L connector must
include, at the very least, a GND keep-out (void clearance area) on the first inner layer.
Figure 10: U.FL connector layout example with pi-matching components placed on top of microstrip
3.4 Supply interfaces
VCC application circuits
The SMPS is the ideal choice when the available primary supply source has a more than moderately
higher voltage than the operating supply of the module. The use of SMPS provides the best power
efficiency for the overall application and minimizes current drawn from the main supply source.
Customers are advised to perform power and thermal budgets to find the solution that is best suited
for their full application.
⚠ When using SMPS, ensure that AC voltage ripple at switching frequency is kept as low as possible.
The layout shall be implemented to minimize impact of high frequency ringing.
The use of an LDO linear regulator is convenient for a main supply with a relatively low voltage, where
the typical 85-90% efficiency of the switching regulator only provides minimal current saving. As
linear regulators dissipate a considerable amount of energy, these are not recommended for stepping
down high voltages. The benefit of an LDO source over SMPS is that an LDO is simpler to integrate
and does not generate switching noise. However, with a larger voltage difference the superior
efficiency of an SMPS converter provides less heat dissipation and longer operating time in battery-
powered products.