Rectangular coil and LDC1612, signal crawls down

Hello Sami Lakka,

Do you mean inductance of rectangular coil changes with time when the target is not moving? Are you referring to the inductance values reported by LDC?

L measurement is stable with temperature and has a variation of 30 ppm/^oC.

Make sure you are using C0G capacitors as it has a very good temperature coefficient.

-Best Regards,

 Suhas R C

Yes, the inductance seems to become lower even if the target is not moving. This happens in room temperature so I'm starting to think that perhaps the current would heat the coil? Seems a bit far fetched but that is the only thing that comes to my mind. I'm doing measurements using LDC1612EVM so there isn't anything wrong with circuits. The sample coil that came with EVM is stable.

Sami Lakka,

What is the inductance of both the coils? (rectangular and circular). There could be a possiblity where there is drift in both the coils but seems more significant in case of the rectangular coil compared to circular.

I doubt the current heating up the coil.

-Best Regards,

 Suhas R C