I am using an i2c controlled FM tuner IC (RDA5807M) in a DIY fm radio, but I am a little bit worried about ESD protection on the Antenna line (A headphone lead being used for this). Can i add standard 1n4148 diodes for this purpose? There will not be any strong human body ESD because i live in a quite hot and humid country, so just basic protection will do. I want to achieve this using standard parts only and not some specialised TVS diode or fancy ESD protection diodes. I want to know if there will be any signal attenuation due to the stray capacitance of 1n4148 diodes (3pF max, according to datasheet) or its leakage currents. I have attached the relevant part of my circuit diagram. Datasheet of the FM tuner IC - https://cxem.net/tuner/files/tuner84_RDA5807M_datasheet_v1.pdf

Is this ESD protection implementation correct?

  • \$\begingroup\$ why dont u use tvs diode ? st.com/resource/en/datasheet/esdalc12-1t2.pdf more adapted for ESD protection. your switching diode 1N4148 is not enough! \$\endgroup\$
    – R Djorane
    Aug 21, 2020 at 10:09
  • \$\begingroup\$ I've never seen 1N4148 diodes used as ESD protection for FM antennas or other RF applications. And I wouldn't rely on 1N4148 for these purposes. Instead, I'd prefer low capacitance (<1pF) ESD diodes (e.g. this one). \$\endgroup\$ Aug 21, 2020 at 11:04
  • \$\begingroup\$ i understand that 4148 will not give adequate protection against ESD. Can you tell me if it will cause any rf signal attenuation in the FM band? \$\endgroup\$
    – aditya444
    Aug 22, 2020 at 5:15

1 Answer 1


You don't need additional protection. The radio input is protected if you do not have an outdoor antenna.

  • 1
    \$\begingroup\$ The word is "capacitance". \$\endgroup\$
    – Andy aka
    Aug 21, 2020 at 8:39
  • \$\begingroup\$ No this will not be an outdoor device. it will be a small battery powered radio, with the earphone leads used as an antenna. Do i still need to add TVS diodes? will 1n4148 cause problems with reception? or attenuate FM signal? \$\endgroup\$
    – aditya444
    Aug 22, 2020 at 5:16
  • 1
    \$\begingroup\$ @aditya444 Of course, this does not require any additional protection. The radio input is protected if you do not have an outdoor antenna. \$\endgroup\$
    – csabahu
    Aug 23, 2020 at 9:28
  • \$\begingroup\$ @csabahu Oh dear god I totally missed that diagram in the datasheet. Thank you. Could you repost this as an answer so that I can mark it as accepted? \$\endgroup\$
    – aditya444
    Aug 23, 2020 at 12:04

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