Patent ID: 8907834

Claim:
An apparatus for converting an analog signal into multi-bit digital data, the apparatus comprising: a sample holding circuit configured to sample and hold the analog signal; a comparator configured to compare the sampled and held analog signal with an analog reference signal in response to a clock signal; a digital-to-analog converter configured to convert the multi-bit digital data into the analog reference signal and provide the analog reference signal to the comparator; a clock generator configured to generate the clock signal in response to an operation state of the comparator and configured to control a period of the clock signal according to a delay time varied by a control signal; a successive approximation logic circuit configured to successively search for a binary signal that is approximated to an output signal of the comparator from a most significant bit to a least significant bit of the binary signal in response to the clock signal and configured to provide the multi-bit digital data resulting from the search to the digital-to-analog converter; and a background calibration circuit configured to sense a cycle number of the clock signal used in the comparator and the successive approximation logic circuit at a conversion completion time point and configured to generate the control signal such that a next cycle number of the clock signal to be used for a subsequent converting operation cycle follows an N-th clock cycle of the clock signal.