SNOA930C March 2015 – May 2021 LDC0851 , LDC1001 , LDC1001-Q1 , LDC1041 , LDC1051 , LDC1101 , LDC1312 , LDC1312-Q1 , LDC1314 , LDC1314-Q1 , LDC1612 , LDC1612-Q1 , LDC1614 , LDC1614-Q1 , LDC2112 , LDC2114 , LDC3114 , LDC3114-Q1
The RS of the sensor capacitor is added to the sensor, but this contribution is typically very low compared to the inductor – for a 1000-pF 0603 C0G capacitor, the RS is typically around 20 mΩ (compared to 2 Ω or more for the inductor). Due to its very low RS, the capacitor Q is typically very high – well over 100, and reaching 1000 in some cases. However, the lower Q of the inductor is what dominates the response.
Capacitors also have a SRF, but it is typically much higher than the SRF of the inductor due to the smaller physical size and the construction. For example, 1000-pF capacitors with SRF above 200 MHz are readily available. Since the SRF is so much higher than that of the sensor inductor, it typically does not affect the performance of the sensor.