Speaker: Prashanth Vooka (EE 11D020)
In this talk, a capacitance-to-digital converter (CDC) that employs a novel approach to perform an accurate measurement of the capacitance of a leaky capacitive sensor will be presented. The CDC employs a sinusoidal source as its excitation, which is advantageous for various sensing applications including ice detection, liquid level measurement, humidity measurement, proximity sensing, etc. Recently, an Impedance-to-digital converter (IDC) based on the dual-slope conversion technique has been reported. It can measure the value of capacitance even when a parallel resistance is present, but requires a large number of sinusoidal excitation cycles to complete a conversion, leading to a poor update rate. The CDC that will be presented in this talk gives much higher (about 125 times) update rate compared to the IDC as it requires only a few excitation cycles for the conversion, but still gives an accurate output due to the use of a specially designed clock which helps to count the number of charge packets received by the integrator capacitor during the de-integration. The operation of the proposed CDC and the experimental results from a prototype CDC built will be presented in the talk.