====== The Testing Fixture for 6-Lead QFN SPDT RF switch ======
[[http://uniteng.com/index.php/about-me/|Neil Hao]]

Starts from 2021/Oct/21 to ~~LASTMOD~~ (Last Modification)

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===== Overview =====
I purchased several SPDT RF switches which manufactured by a Chinese listed company. The chip’s footprint is 1.0mm x 1.0mm x 0.45mm 6-lead QFN package. The manufacturer did not provide S-parameters. Thus, I had to design the fixture and measure the S-parameters by myself.

===== The Testing Fixture for 6-Lead QFN SPDT RF switch =====
{{ :rfmeasurement:testing_fixture_6_lead_qfn.png?nolink&600 |}}
===== RF Specifications from the Datasheet =====
{{ :rfmeasurement:testing_fixture_6_lead_qfn_datasheet_block_diagram.png?nolink&600 |}}
{{ :rfmeasurement:testing_fixture_6_lead_qfn_datasheet.png?nolink&600 |}}
===== The De-embedded Measurements =====
S55 and S66 are original measurement data, S33 and S44 are de-embedded data:
|S44 is ANT|S33 is RF1 |RF1 ENABLED|
{{ :rfmeasurement:testing_fixture_6_lead_qfn_rf1_ant.png?nolink&900 |}}
The measurement data conform to the Insertion loss and Return loss specifications in datasheet.
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|S77 is RF1 |S88 is RF2|ANT is terminated with 50 Ohm terminator|RF1 ENABLED|
{{ :rfmeasurement:testing_fixture_6_lead_qfn_rf1_rf2.png?nolink&900 |}}
Unfortunately, the measurement data exceed the isolation specifications in datasheet.
===== Summary =====
The testing fixture meets my expectation for working within 0GHz to 6GHz. For the isolation, I think the IC may conform to the isolation specifications, because de-embedded algorithm cannot work with crosstalk problem. Crosstalk between the traces RF1 and RF2 on the PCB can downgrade the isolation.