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FDC2214EVM: URGENT: Any best practices to make FDC2214 sensor directional in proximity sensing?

Patrick Lee
Prodigy 70 points
Part Number: FDC2214EVM
Other Parts Discussed in Thread: FDC2214

Hi Forum members,

i am testing the FDC 2214EVM kit for proximity sensing. it works very well in the range of 0-10 mm in a un-grounded setup.

However any capacitance such a hand, piece of metal, a circuit, a cell phone, behind the sensor(s) significantly affects reading of the sensor. In other words, the sensors reacts with great sensitivity to capacitive mass BOTH in front AND behind the sensors. The mass in front of the sensors is the target of the proximity sensing. The mass behind the sensors represent "noise".   

How could I make the sensors react only or mainly towards the capacitive mass in FRONT of the sensors, and "ignore" the capacitive mass behind the sensors? Any best practices? Any documents or advice on this? 

FDC2214 shall be a winner for me for a new wearable device if this issue can be resolved, because there have to be other components such circuits behind the sensor. 

I look forward to any comments, thoughts, and or advice at your earliest convenience. Thank you for your help in advance. 

Kind regards, 

Patrick Lee

  • 0
    TI__Expert 6480 points
    Hi Patrick,

    You can try passively shielding the sensor by placing a ground plate behind the sensor. This way, any interference coming in behind the sensor will be minimized by the ground plane. Please let me know if that helps although please keep in mind that the sensitivity may decrease due to the added capacitance. However, with the sensing distances you have, this may not be an issue.

    Thanks,
    Rachel
  • 0 in reply to Rachel Liao
    Prodigy 70 points

    Dear Rachel, 

    Thank you very much for your response. we shall try it out. 

    Kind regards, 

    Patrick