Sorry to notice the elephant in the room, but the resistance of copper wire varies several percent over the day/night temperature range. Likewise the temperature coefficient of any target material is likely to vary significantly.
(Copper is 0.393% per K, so 10oC change = 3.9% = 1:25 = 5bits )
So like many real world sensing modalities, the LDC1000 functions best as a thermometer.
Really, really bad oversight not to include a temperature sensor on the chip, otherwise the 16bits are wasted, as you only get 5 usable bits.
One might argue that the Rp is not dominated by the coil resistance, but even at "normal" working ranges you might expect that the coil DCR contributes 10% to the Rp. But as the target is moved further away, the target contributes less to the total Rp. So , without going into the maths, it is fair to guess that the "maximum working range" probably occurs when the target and coil contribute roughly equally to Rp. So effectively 6bits of accuracy here.
Inductance variation with temperature is easier to deal with, as one merely selects the appropriate combination of N750 and NPO capacitors to resonate the coil.
All a bit of a letdown , but if a second channel is added to the LDC100x, then a reference coil can be used to remove temperature and other effects.
Even so , I can still think of many useful apps.
