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

Claim 10:
11. A detection circuit adaptable to a fingerprint detection system, the detection circuit comprising:
an integrating amplifier coupled to receive a photo-detected voltage from a sensor panel and configured to generate time integral of the photo-detected voltage, thereby resulting in a time-integral signal;
an analog-to-digital converter (ADC) that converts the time-integral signal into a digital form;
a conversion switch connected between the integrating amplifier and the ADC;
a conversion capacitor connected between an input node of the ADC and ground;
a first buffer amplifier;
a second buffer amplifier that provides a first reference voltage; and
a first voltage adder that adds the first common-mode voltage and the first reference voltage, thereby resulting a sum voltage fed to a non-inverting input node of the first buffer amplifier, which provides the first reference voltage to a non-inverting input node of the integrating amplifier;
wherein a first common-mode voltage of the sensor panel is coupled to the integrating amplifier to prevent noise occurred in the first common-mode voltage from affecting the time-integral signal.