| 摘要 |
The present invention relates to a capacitive sensor with a low frequency noise removal function. The capacitive sensor with the low frequency noise removal function comprises: a charge amount detecting unit including a capacitor, a value of which is changed by a change in a charge amount; a charge amplifying unit which amplifies a basic noise applied from the outside when a TX signal is turned on, and amplifies and outputs a changed charge amount inputted from the charge amount detecting unit when the TX signal is turned off; a sampling unit which outputs a first signal by sampling the basic noise inputted from the charge amplifying unit and outputs a second signal by sampling the changed charge amount; a noise component removing unit which calculates and outputs a third signal corresponding to a difference between the first signal and the second signal received from the sampling unit; and an analog-to-digital converting unit (ADC) which converts the third signal received from the noise component removing unit into a digital signal. According to the present invention, since a low frequency noise removal algorithm is processed at a front stage of the ADC, it is possible to sufficiently cope with an external noise and minimize a loss of sensitivity. Also, with regard to an inputted noise signal, a noise is commonly loaded on a reference and a signal, and a common noise component is removed by a differential method, thereby improving sensitivity. In addition, since the low frequency removal algorithm is processed at a front stage of the ADC, it is possible to solve problems caused when the low frequency noise removal algorithm is processed at a rear stage of the ADC, such as a reduction in an operating speed, an increase of a current, and an increase of an area. |
