Patent ID: 11886666
Assignee: HIMAX TECHNOLOGIES LIMITED
Field: Basic communication processes (Electrical engineering)
Classification: CPC G  H | IPC G  H

Claim 0:
1. A fingerprint detection system, comprising:
a sensor panel including:
a photo diode having an anode electrode connected to a first common-mode voltage and a cathode electrode providing a photo-detected voltage; and
a sampling switch coupled to receive the photo-detected voltage;

a detection circuit including:
an integrator coupled to receive the photo-detected voltage via the sampling switch and configured to generate time integral of the photo-detected voltage, thereby resulting in a time-integral signal; and
an analog-to-digital converter (ADC) that converts the time-integral signal into a digital form;

wherein the first common-mode voltage is coupled to the integrator to prevent noise occurred in the first common-mode voltage from affecting the time-integral signal;
wherein the integrator comprises:
an integrating amplifier; and
an integrating capacitor connected between an output node and an inverting input node of the integrating amplifier;

wherein the detection circuit comprises:
a first coupling capacitor with a first plate connected to receive the first common-mode voltage and a second plate electrically coupled to a non-inverting input node of the integrating amplifier;

wherein the detection circuit comprises a first detection switch and a first buffer amplifier, via which the second plate of the first coupling capacitor is electrically coupled to the integrating amplifier.