With lower sensor frequencies, skin depths increase, such that the sensor field can pass through the target and interact with conductive objects behind the target. Interference can occur with conductors located behind thin targets. Movement of a conductive object behind the target can affect the LDC measurement, as shown in Figure 2-8.

Figure 2-8 Interference from a Conductor Behind The Target

Depending on the system accuracy and resolution requirements, this can be a concern even with targets that are 3 skin depths thick. Simply increasing the sensor frequency will reduce the effect if it is not feasible to use a thicker target.

Some LDC devices, such as the LDC1612 and LDC1614, have specific sensor frequency ranges which provide higher measurement resolution (as discussed in section 2.4 of the TI application note Optimizing L Measurement Resolution for the LDC161x and LDC1101). If the increased sensor frequency is outside of the optimum range for the LDC, the LDC’s internal input dividers can be used to mitigate this degradation. For applications that require a wider frequency range, the LDC3114 and LDC2112/4 devices can operate with a sensor frequency up to 30 MHz.