US 12,085,423 B2
Sensor interface circuit, sensor system, and method of signal measurement
Keith L. Kraver, Gilbert, AZ (US); and Pascal Kamel Abouda, Saint Lys (FR)
Assigned to NXP USA, Inc., Austin, TX (US)
Filed by NXP USA, Inc., Austin, TX (US)
Filed on May 6, 2021, as Appl. No. 17/313,554.
Claims priority of application No. 20305583 (EP), filed on Jun. 3, 2020.
Prior Publication US 2021/0381854 A1, Dec. 9, 2021
Int. Cl. G01D 5/24 (2006.01); G01L 9/12 (2006.01); G01R 27/26 (2006.01)
CPC G01D 5/24 (2013.01) [G01L 9/125 (2013.01); G01R 27/2605 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A sensor interface circuit comprising:
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 having 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, wherein the C/V output end of the continuous-time C/V converter is electrically coupled to the first and second filter input ends of the filter circuit; and
a buffer circuit electrically coupled with the first and second filter output ends of the filter circuit.