A comparator circuit. A comparator circuit may include a differential amplifying unit to amplify a difference between a voltage at a first node and a voltage at a second node and/or output a resultant voltage, and/or a current source to supply a first bias current to a first node and/or supply a second bias current to a second node. A comparator may include a first bias switch to bias a current flowing from a first node to a ground voltage source, a second bias switch to bias a part of a current flowing from a second node to a ground voltage source, a third bias switch to bias a remaining part of a current flowing from a second node to a ground voltage source, and/or a bias converting unit to supply a third bias current to a second node.