A quantizer includes: a quantizer capacitor having a first end and a second end; an input calculator that receives input voltages, sums the input voltages, and outputs the summed result to the first end of the quantizer capacitor; a scaler that receives reference voltages and a scale code, generates a scale voltage from the reference voltages depending on the scale code, and outputs the scale voltage to the second end of the quantizer capacitor; and a latch that stores an output voltage of the first end of the quantizer capacitor.