• State Resolved
  • Locked Locked
  • Replies 1 reply
  • Subscribers 46 subscribers
  • Views 440 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

LDC1612: Plane or no plane under traces running between LDC and coil

Matthias Meier1
Prodigy 180 points
Part Number: LDC1612


Hello TI experts,

I'm currently laying out a board for an inductance sensor using the LDC1612 and a planar, stretched PCB coil.  The planes are cut out around the coil.  The tank capacitor is placed near the coil.  I do provide a common mode filter very similar to the one on the eval board close to the LDC.

Due to the application-driven physical distance between the LDC and the sensor coil, the traces running from the LDC to the coil have a length of about 1.7 inches.  I'm debating whether I should run those traces over a ground plane or not.  If I do, I'd essentially be creating a parasitic and - due to the high CTE of the PCB - high-tempco capacitor of a few pF in parallel to the tank capacitor, likely increasing the already significant temperature drift of the sensor.  On the other hand, omitting the ground plane under those traces may increase the noise susceptibility of the sensor due to the resulting higher impedance.  The discrete filter may or may not be sufficient to eliminate noise issues.

Any thoughts and/or empirical data?

Thanks!

Matthias

  • 0
    TI__Genius 17440 points
    Hi Matthias,

    We recommend that you do not use a ground plane beneath the INA and INB traces. As long as you do not have noisy signals routed near the INA and INB traces, they should be protected from noise issues by the LC tank inherently acting as a narrow band-pass filter. The potential parasitic capacitance drift with temperature is more likely to affect your measurements than noise.

    Regards,