Sensor interface circuit, sensor system, and method of signal measurement

US12085423B2 · kind B2 · utility

Assignee

• NXP USA, Inc. · US

Inventors

• Keith L. Kraver · Gilbert, US
• Pascal Kamel Abouda · Saint-Lys, FR

Key dates

• Filing date: May 6, 2021
• Grant date: Sep 10, 2024
• Expiry date: Jun 11, 2042

Classification

• Technology area (CPC G): Physics
• CPC primary: G01R27/2605
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

A sensor interface circuit includes a continuous-time capacitance-to-voltage (C/V) converter having C/V input and output ends, the C/V input end being configured for electrical connection with first and second sense nodes of a capacitive sensor. A filter circuit is electrically coupled to the C/V output ends. The filter circuit has first and second resistors at corresponding first and second filter input ends of the filter circuit, a capacitor connected between first and second filter output ends of the filter circuit, and a chopper circuit interposed between the first and second filter input ends and the first and second filter output ends. A buffer circuit is electrically coupled with the first and second filter output ends of the filter circuit. The filter circuit applies low pass filtering of sense signals from the capacitive sensor before sampling and demodulation operations to reduce high-frequency interference in the sense signals.