1. Technical Field
The present invention relates to an analog-to-digital conversion method, and more particularly, to an analog-to-digital conversion method using, and more particularly, to a method for analog-to-digital conversion using an RC time constant calibrator and an analog-to-digital converter therefor.
2. Discussion of the Related Art
Modem communication systems include microchips containing analog-to-digital converters (ADCs) and filters. The ADCs digitize low-frequency signals such as touch panel signals, backlight brightness control signals for liquid crystal displays (LCDs), and temperature sensor signals. The filters remove unwanted signal components and/or strengthen desired signal components.
The filters use a cut-off frequency to pass those components of the input signal that fall within a particular frequency range and block those components of the input signal that fall outside of the particular frequency range. The cut-off frequency of a filter can be controlled by a time constant. For example, a filter can include an RC time constant calibrator for controlling a time constant. The RC time constant calibrator can control a cut-off frequency that may be affected by an external environment by adjusting resistance and/or capacitance.
However, the RC time constant calibrator is used for a very short time compared to an overall system operating time. For example, the RC time constant calibrator may operate just for a moment when power is turned on in a system or at a predetermined time. In addition, with the compactness of modem chips, the ADC and the RC time constant calibrator are implemented together in a single microchip. As a result, excess layout space is used in accommodating these components.