CapSense Capacitive Sensors Sigma Delta Algorithm

Cypress' CapSense Sigma-Delta algorithm (CSD) uses switched capacitor circuitry and analog/digital components to convert changes in capacitance from a sensor electrode into a digital bit stream. The bit stream is analyzed to determine if a conductive object is present by measuring the change in counts over measurement windows. CSD modulates the sensor capacitance using a switched capacitor network and comparator to create a variable duty cycle bit stream. This enables low power capacitive sensing for touch interfaces.