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Caravel Analog User

License CI Caravan Build

PLL-BASED CAPACITIVE SENSOR INTERFACE

This project involves the design of a capacitive sensor-to-digital converter using time-based circuit techniques. It uses basic digitally-oriented building blocks (two oscillators, a D-flipflop and a feedback loop including a capacitive element and a switch) to convert input capacitive values into digital single bit traces in the time domain. The basic block diagram can be seen below:

image

The architecture has been tested for a DC sweep of input capacitive values. Example output trace values for different capacitance inputs are shown below:

image

The characteristic plot for an average window of 10us is seen below:

image

Refer to README for this sample project documentation.