Datasheet
ATBTLC1000 Hardware Design Guidelines – Ultra Low Power BLE 4.1 SoC [USER GUIDE]
Atmel-42537B-ATBTLC1000-Hardware-Design-Guidelines_UserGuide_102015
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Figure 3-9. Incorrect Stub Route To Capacitor Pad
4 Interferers
One of the major problems with RF receivers is poor performance due to interferers on the board radiating
noise into the antenna or coupling into the RF traces going to input LNA. Care must be taken to make
sure that there is no noisy circuitry placed anywhere near the antenna or the RF traces. All noise
generating circuits should also be shielded so they do not radiate noise that is picked up by the antenna.
Also, make sure that no traces route underneath the RF portion of the ATBTLC1000. Also, make sure that
no traces route underneath any of the RF traces from the antenna to the ATBTLC1000 input. This applies
to all layers. Even if there is a ground plane on a layer between the RF route and another signal, the
ground return current will flow on the ground plane and couple into the RF traces.
5 Antenna
Make sure to choose an antenna that covers the proper frequency band; 2.400GHz to 2.500GHz. Talk to
the antenna vendor and make sure he understands that the full frequency range must be covered by the
antenna.
Make sure the antenna is designed for a 50Ω system.
Make sure the PCB pad that the antenna is connected to is properly designed for 50Ω impedance. This is
extremely important! The antenna vendor must specify the pad dimensions, the spacing from the pad to
the ground reference plane, and the spacing from the edges of the pad to the ground fill on the same layer
as the pad. Also, since the ground reference plane for the 50 trace going from the antenna pad to the
ATBTLC1000 will probably be on a different layer than the ground reference for the antenna pad, make
sure the pad design has a proper transition from the pad to the 50Ω trace.
Make sure that the antenna matching components are placed as close to the antenna pad as possible.
The antenna cannot be properly matched if the matching components are far away from the antenna.