SX1262 LoRa Matching Network Design
Thought for 1 min 44 sec
For exact numeric values, I would not guess. The Semtech material I could access says the 915 MHz network is region-specific, that each region has its own BOM, and that the shown matching values may not be the most up to date; it also notes real designs usually need final tuning for PCB parasitics. That lines up with the rule to use the datasheet/reference design as the source of truth rather than memory
What I can say from the Semtech documentation:
Recommended starting point
- For 902–928 MHz (US/Canada): start from the PCB_E428V03A SX1262 reference design.
- For 915–928 MHz (Australia): start from the PCB_E449V01A SX1262 reference design.
- RX balun / impedance transform: 3-element network plus optional shunt part
- TX match / harmonic filtering: multi-element network from
RFO/VR_PAto antenna - Semtech gives these 915 MHz impedance targets in the note:
- TX example load target: 11.7 + j4.8 Ω for max power, or 13.5 + j7.6 Ω for better efficiency
- RX optimal differential source impedance: 74 + j134 Ω
Your U1 already has the right kind of external network, but the RF parts are still generic and don’t currently show values:
- RX side around
RFI_P/RFI_N: L10, C27, C28, C29 - TX / PA side around
RFO/VR_PA: L6, L7, L8, L9, C21, C22, C23, C24, C25, C26
- Use the Semtech 902–928 MHz SX1262 reference BOM values exactly as the first-spin starting point
- Then expect to trim with:
- VNA/S11 on the antenna port
- conducted TX power / current
- harmonic measurements
If you want, I can do one of these next:
- map your current RF network to the Semtech reference topology node-by-node, or
- help you find the exact 902–928 MHz BOM values from the reference schematic/BOM if you upload that PDF.
Map to reference
Upload reference BOM
Review RF layout
vasyl
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