Patent ID: 11886668
Assignee: INFINEON TECHNOLOGIES AG
Field: Computer technology (Electrical engineering)
Classification: CPC G | IPC G

Claim 0:
1. A touch sensor, comprising:
a housing having an ultrasound chamber;
a touch structure coupled to the housing and arranged over the ultrasound chamber such that the ultrasound chamber forms an enclosed interior volume, wherein the touch structure comprises a touch interface;
a transmitter arranged inside the enclosed interior volume, wherein the transmitter is configured to transmit an ultrasonic transmit wave towards the touch structure;
a receiver arranged inside the enclosed interior volume and coupled to the transmitter via a propagation path, wherein the receiver is configured to receive an ultrasonic reflected wave produced from the ultrasonic transmit wave and the propagation path;
a programmable voltage source configured to provide a bias voltage to the transmitter or to the receiver;
a receiver circuit configured to convert the ultrasonic reflected wave into a measurement signal and generate an error value representative of a difference between a measured value of the measurement signal and a reference value;
a controller configured to adjust the bias voltage to a voltage level that reduces the error value; and
a measurement circuit configured to measure the adjusted bias voltage and determine whether a no-touch event or a touch event has occurred at the touch interface based on a comparison of the measured adjusted bias voltage and a bias voltage threshold.