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Comments on How to protect RF switches from ESD?

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How to protect RF switches from ESD?

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Assume that I have some generic antenna connector, followed by a pi-filter/50ohm impedance matching components, then a DC blocking cap (as per the RF switch recommendations) and then a RF switch for split tx/rx semiduplex transceiver, as in this schematic:

antenna schematic

How do I best protect this RF switch from ESD coming in from human fingers touching the antenna connector? I need the highest ESD class (4) of the IEC61000−4−2, meaning 8kV contact discharge, 15kV air discharge.

I'm considering a specialized "ultra-low capacitance" TVS diode such as ESD8472 (rated up to 20kV), which is bidirectional.

Questions:

  • Is this TVS diode the way to go?
  • If so, where do I place it in this schematic? Directly on the antenna or somewhere else?
  • How to determine the suitable breakdown voltage? I'm assuming it should be based on the RF switch supply which is 3.3V.
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2 comment threads

Hello Lundin. I think it would help if you can specify what is the general configuration of your syst... (2 comments)
Are you going for the formal IEC 61000−4−2 certification test? Sometimes passing a test it a harder ... (2 comments)
Are you going for the formal IEC 61000−4−2 certification test? Sometimes passing a test it a harder ...
Nick Alexeev‭ wrote about 2 years ago

Are you going for the formal IEC 61000−4−2 certification test? Sometimes passing a test it a harder design problem than protection from the ESD in the field. That was my experience this December.

Lundin‭ wrote about 2 years ago

Nick Alexeev‭ Yes and these tests are usually not hard to pass, in my experience, I've done lot of such tests in the past. Basically if every metal part is grounded and every input from connectors is protected, you pass. But in this specific case with an antenna (connector), I'm not sure how to add protection if the switch doesn't have it internally, because I suppose the capacitance of a TVS diode might screw everything up.