Software-controlled signal converter for capacitive sensors

A software-controlled signal converter for capacitive sensors with integrated in-situ self-diagnostic functionality has been developed to detect instabilities during the measurement process. The proposed approach is based on the analysis of multi-cycle charge integration parameters in Switched Capacitor Circuits (SCC), implemented on a programmable system-on-chip (PSoC) of the 5LP series. To ensure high measurement accuracy, several software-controlled operating modes have been introduced: accumulation of integration cycle results for statistical evaluation of instabilities; analysis of integrator discharge phases for relaxation process assessment; and examination of the entire signal path without charge accumulation. These modes enable the identification of thermal noise, time drift, and parasitic influences from external objects on the capacitive structure. Results from SPICE modeling and experimental oscilloscope studies confirm the effectiveness of the proposed solution, support the verification of signal path models, and allow for the optimization of measurement parameters. The developed software tools provide flexible configuration of measurement modes, data acquisition, and graphical visualization of signal dynamics, which facilitates comprehensive analysis of external factors affecting sensor stability.