Integration Guide

HARDWARE INTEGRATION RECOMMENDATIONS
RF INTERFACE
MODULE INTEGRATION GUIDE PROPRIETARY 17
SEQUANS Communications
3.4.3 Test Points and Measurement Access
50 Ohm termination points, for example P1 in Figure 3-2, are needed for
Engineering and Production teams for the validation of the RF performance.
The potential need to optimize the Pi-type matching network in the antenna
path means that access to the IOs of this matching network is needed, so that a
coaxial cable (usually 1.25mm diameter semi-rigid) can be manually attached
for precision impedance measurements. Critically, a sufficient area of GND
metal on the top layer adjacent to these matching networks and
well-grounded to the transmission line reference GND is needed to permit
robust physical attachment of the coaxial cable and with short GND
connection. This area of GND metal does not need any resist removal as this
can be removed manually where needed.
Please refer to Section 3.4.4 Antennas and RF Design Considerations on page
17 for more detail on managing RF Trace Design.
3.4.4 Antennas and RF Design Considerations
Antennas require special interfacing for optimum RX and TX Performance.
3.4.4.1 T-Type Matching
A 3-component T-type matching network is recommended to be fitted. The
purpose of the T-type matching network is to transform the impedance of the
RF-path that extends beyond to 50 Ohm if needed. The 3 components in this
matching network should be as close together as possible to minimise the
interconnecting track lengths.
By default the component pads should be for a 0201-size capacitor which can
be a No Fit by default. There should be a short low-impedance connection
connecting the GND node of this component.
The series matching element should be connected at the junction where first
shunt component and by default a 0 Ohm 0201-size resistor should be fitted
but if matching is needed the pads needs to be able to take 0201-size inductor;
The final shunt matching element should be connected from the node where
the series matching component ends to the signal ground connection. By
default the component pads should be for a 0201-size capacitor which can be a
No Fit by default. There should be a short low-impedance connection
connecting the GND node of this component to the GND node of the first
shunt component. There should be a short low-impedance connection
connecting the GND node of this component to the GND reference of the
50 Ohm transmission line that continues beyond to the
Antenna/Antenna-connector.