SX1262 LoRa Matching Network Design

flux

1:44

Gathering component information.

Reviewing the bill of materials.

Analyzing the schematic.

Looking for "Recommended RF matching network / balun component values for SX1262 operation around 915 MHz. Include the reference schematic values for RFI_P, RFI_N, RFO, VR_PA, RFIO, and any note about tuning or region-specific frequency optimization." in 1537522406DS_SX1261-2_V1.1_SEMTECH.pdf

Running multiple web searches.

Found 1 results.

Found 7 results.

Found 1 results.

Looking for "For SX1262 or SX1261/2, what are the discrete component values in the 902-928 MHz or 915 MHz RF matching network / reference design? Extract any BOM tables or schematic values for the receive balun and transmitter matching network." in 1537522406DS_SX1261-2_V1.1_SEMTECH.pdf

Mapping network blocks.

Inspecting network connections.

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.
Topology Semtech expects at 915 MHz
  • RX balun / impedance transform: 3-element network plus optional shunt part
  • TX match / harmonic filtering: multi-element network from RFO/VR_PA to 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
In your schematic
Your U1 already has the right kind of external network, but the RF parts are still generic and don’t currently show values:
My recommendation
  • 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:
  1. map your current RF network to the Semtech reference topology node-by-node, or
  2. 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
31 days
Sign up to send

To get started, talk to Flux or create a New Document.

Documents

    Documents are markdown text files which describe project goals, capture details, or even simulation outputs.

    Assets

    No assets added.

    meshtastic

    meshtastic thumbnail
    Welcome to your new project. Imagine what you can build here.

    Properties

    Properties describe core aspects of the project.

    Pricing & Availability

    Distributor

    Qty 1

    Arrow

    $7.09–$10.66

    Digi-Key

    $9.38–$14.48

    LCSC

    $11.98

    Mouser

    $15.41

    TME

    $2.43

    Verical

    $10.13–$18.56

    Controls