Apparatuses and methods for fast analog-to-digital conversion

An apparatus configured to convert an analog input signal into a digital output signal, the apparatus comprising:

• a first amplification circuit configured to amplify differences between the analog input signal and a plurality of reference voltages during a first phase of a clock signal;
• a second amplification circuit configured to amplify differences among signals outputted by the first amplification circuit during a second phase of the clock signal;
• and
• a comparison circuit configured to generate the digital output signal by comparing signals outputted by the second amplification circuit with each other during the first phase of the clock signal.

A method of converting an analog input signal into a digital output signal, the method comprising:

• receiving the analog input signal and a plurality of reference voltages;
• generating first output signals by amplifying differences between the analog input signal and the plurality of reference voltages;
• storing charges corresponding to the first output signals in a plurality of first capacitors;
• generating second output signals by amplifying differences among voltages of the plurality of first capacitors;
• storing charges corresponding to the second output signals in a plurality of second capacitors;
• generating the digital output signal by comparing voltages of the plurality of second capacitors with each other;
• calibrating the generating of the digital output signal in a first interval of a calibration mode;
• calibrating the generating of the second output signals in a second interval of the calibration mode following the first interval of the calibration mode;
• and
• calibrating the generating of the first output signals in a third interval of the calibration mode following the second interval of the calibration mode.