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I am designing a PCB for a Bluetooth 5 device using Qualcomm chip and a Murata BP filter. The RF circuit is composed of:

  • an SMT antenna that has a 50 Ohm unbalanced feed point impedance,
  • a Murata 2.45GHz Bandpass filter that has a characteristic nominal impedance of 50 Ohm
  • a BT IC which has a 50 Ohm port impedance for BT_RF.

Below is the design guidelines from the SMT antenna datasheet: Matching network for SMT antenna

ANTENNA>>---(1 w/ P1&P2)--->>BP Filt>>---(2 w/ Pi-LC)--->>BT_RF

With all these components having a 50 Ohm impedance, how should I design the PCB traces (1) and (2) and their matching networks? Should (1) and (2) individually have a 50 Ohm impedance or should the whole transmission line from SMT antenna feed point to BT_RF have a 50 Ohm impedance?

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If Qualcomm or Murata has a reference layout that would be a good starting point - it appears you have this. Generally you want to use 50 ohm routing for everything. Use microstrip with guard grounds surrounding it, as shown in the reference.

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    \$\begingroup\$ And make sure to work with the board house. They can tell you the precise trace geometries to get 50 Ohms in their process with your board specs. \$\endgroup\$ – Matt Young Jul 8 at 4:47

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