Abstract: A noised-reduced capacitive image sensor and a method operating the capacitive image sensor are provided. The capacitive image sensor includes: a number of capacitive sensing units forming an array, each capacitive sensing unit for transforming a distance between a portion of a surface of an approaching finger and a top surface thereof into an output electric potential, wherein a value of the output electric potential is changed by a driving signal applied to the sensing unit; at least one sample-and-hold circuit for capturing and retaining different output electric potentials; at least one signal conditioning circuit, each comprising at least one differential amplifier for amplifying a difference between two electric potentials retained by the sample-and-hold circuit; and a driving source, for providing the driving signal to the capacitive sensing units.

Abstract: A noised-reduced capacitive image sensor and a method operating the capacitive image sensor are provided. In order to generate a noise-reduced image of a fingerprint, the capacitive image sensor has an array of capacitive sensing units which each has a protective layer; a sensing electrode; a voltage follower; a comparative capacitor; and a bias voltage supply circuit. The comparative capacitor, a portion of the bias voltage supply circuit, and the voltage follower are formed in an isolated well which is configured in such a way that current is able to be prevented from flowing across an interface in the isolated well and surrounding structures. The driving source is connected to a bulk node of the isolated well such that well potential of the isolated well equals to the output electric potential of a driving source.

Abstract: A capacitive image sensor with noise reduction feature and a method operating the capacitive image sensor are provided. The capacitive image sensor includes: a number of capacitive sensing units, arranged in a form of an array, wherein each of the number of capacitive sensing units switches between three states: sensing state, idle state, and emitting state; a driving source, for providing a driving signal to an adjacent finger overlying the number of capacitive sensing units through the number of capacitive sensing units which are in the emitting state; a number of driving switches, each connected between one of the number of capacitive sensing units and the driving source; and a control and timing logic, connected to each of the number of driving switches, for controlling the state of each of the number of capacitive sensing units.

Abstract: A fingerprint sensing device and a method operating the fingerprint sensing device are provided. The fingerprint sensing device includes at least one sensing core, a system unit, at least one switching unit and a charge holding unit. The switching unit is connected between the sensing core and the system unit to provide four different operation states: a normal state; an isolation state; a drive-up state; and a drive-down state. A voltage shift between the finger and the sensing core is generated by controlling the switching unit to perform different operation states in various orders.

Abstract: A fingerprint sensing device and a method operating the fingerprint sensing device are provided. The fingerprint sensing device includes at least one sensing core, a system unit, at least one switching unit and a charge holding unit. The switching unit is connected between the sensing core and the system unit to provide four different operation states: a normal state; an isolation state; a drive-up state; and a drive-down state. A voltage shift between the finger and the sensing core is generated by controlling the switching unit to perform different operation states in various orders.

Abstract: A capacitive image sensor with noise reduction feature and a method operating the capacitive image sensor are provided. The capacitive image sensor includes: a number of capacitive sensing units, arranged in a form of an array, wherein each of the number of capacitive sensing units switches between three states: sensing state, idle state, and emitting state; a driving source, for providing a driving signal to an adjacent finger overlying the number of capacitive sensing units through the number of capacitive sensing units which are in the emitting state; a number of driving switches, each connected between one of the number of capacitive sensing units and the driving source; and a control and timing logic, connected to each of the number of driving switches, for controlling the state of each of the number of capacitive sensing units.

Abstract: A noised-reduced capacitive image sensor and a method operating the capacitive image sensor are provided. The capacitive image sensor includes: a semiconductor substrate, at least one driving source and an array of capacitive sensing units formed on said semiconductor substrate, characterized in that each of said capacitive sensing unit comprises: a protective layer to be touched by said finger; a sensing electrode arranged underneath said protective layer; a voltage follower, wherein an input node of the voltage follower is connected to the sensing electrode; a comparative capacitor, wherein one node of the comparative capacitor is electrically connected to the voltage follower, and the other node thereof is electrically connected to the driving source; and a bias voltage supply circuit, for providing different bias voltages to the sensing electrode.

Abstract: A noised-reduced capacitive image sensor and a method operating the capacitive image sensor are provided. The capacitive image sensor includes: a number of capacitive sensing units forming an array, each capacitive sensing unit for transforming a distance between a portion of a surface of an approaching finger and a top surface thereof into an output electric potential, wherein a value of the output electric potential is changed by a driving signal applied to the sensing unit; at least one sample-and-hold circuit for capturing and retaining different output electric potentials; at least one signal conditioning circuit, each comprising at least one differential amplifier for amplifying a difference between two electric potentials retained by the sample-and-hold circuit; and a driving source, for providing the driving signal to the capacitive sensing units.