CapSense® Signal-to Noise Ratio - KBA82807

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Question: What is signal-to-noise ratio (SNR) for a CapSense® system? What is the recommended SNR for a CapSense system with a finger capacitance of 0.1 pF?

 

Answer:

The SNR for a CapSense system is defined as the ratio of the increase in the raw counts caused by a finger touch to the peak-to-peak raw counts caused by noise present in the system.

The recommended minimum SNR is 5:1. A typical SNR is between 10:1 and 20:1 when finger capacitance is 0.1pF. The actual SNR depends on your project settings, especially scan time and sensitivity. You can increase the SNR by reducing the scan speed but this results in increased power consumption.