Q: What are the EMC considerations for wireless module integration (BLE WiFi LoRa)?
Answer
Wireless module EMC integration: (1) Antenna placement: keep antenna at the board edge or corner. Keep RF trace from module to antenna as short as possible (<10 mm). Use 50 Ohm coplanar waveguide with ground reference. (2) Antenna clearance: no copper ground plane within the specified keep-out zone (typically 5-15 mm depending on antenna type). (3) Ground plane: module ground pins should connect directly to the PCB ground plane with multiple vias. (4) Supply filtering: add pi filter (LC) to the module VCC supply to prevent digital noise from modulating the RF signal. (5) Crystal oscillator: on the wireless module keep the reference crystal away from sensitive RF circuits. (6) USB/data lines: if the module has USB or high-speed data interfaces filter them to prevent noise coupling to the RF frontend. (7) Certification: modules with pre-certified RF (CE FCC IC) still require system-level testing. Any modification to the antenna or matching network requires re-certification. (8) Coexistence: test WiFi/BLE coexistence with other wireless standards in the same device.
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