An analog-to-digital converter is disclosed, including: a reference generator circuit for generating a plurality of reference voltages; a plurality of amplifying comparators for receiving the reference voltages and analog input signals, each amplifying comparator including: two amplifying paths, each of which has a first amplifier and a second amplifier for alternatively receiving signals from the two paths; a latching comparator having a plurality of latches and receiving output signals from the amplifying comparator; and a digital decoder receiving output signals from the latching comparator and generating a predetermined number of data bits.