Patent ID: 7405691

Claim:
An analog-to-digital conversion circuit configured to convert an input analog signal into a digital signal, said analog-to-digital conversion circuit comprising: a first amplifying unit configured to amplify each of level differences between said analog signal and a plurality of reference signals, and outputting a plurality of differential signals corresponding to a result of the amplification; a second amplifying unit configured to amplify each of the plurality of differential signals output from said first amplifying unit, and outputting a plurality of differential signals corresponding to a result of the amplification; a comparing unit configured to compare each pair of signals of the plurality of differential signals output from said second amplifying unit with each other, and outputting a plurality of binary signals corresponding to a result of the comparison; a first averaging unit including a plurality of averaging resistive elements configured to connect between output terminals of said first amplifying unit; a second averaging unit including a plurality of averaging resistive elements configured to connect between output terminals of said second amplifying unit; and a third averaging unit configured to perform an averaging process by majority logic operation on each of the plurality of binary signals output from said comparing unit with a predetermined number of other binary signals, wherein at least one of said first amplifying unit and said second amplifying unit includes: a differential amplifier circuit configured to amplify an input differential signal; and a voltage follower circuit to which the differential signal output from said differential amplifier circuit is input, and which outputs a differential voltage corresponding to a voltage difference of the input differential signal to said output terminal.