Patent ID: 7642944

Claim:
An A/D converter comprising: a referential voltage generation circuit for generating a plurality of referential voltages; a differential amplifier circuit row, in which a plurality of differential amplifier circuits corresponding to the referential voltages generated by the referential voltage generation circuit are included, each of the differential amplifier circuits receiving a corresponding one of the referential voltages and a common input signal voltage, amplifying a voltage difference between the corresponding referential voltage and the common input signal voltage, and outputting a positive output voltage and a negative output voltage, which are complementary voltages; a voltage comparison circuit row, in which a plurality of voltage comparison circuits corresponding to the differential amplifier circuits are included, each of the voltage comparison circuits outputting a digital signal according to a result of comparing the magnitudes of the positive and negative output voltages from a corresponding one of the differential amplifier circuits; an encoder for encoding the digital signals output from the voltage comparison circuits and outputting a result of the encoding of the digital signals as a digital output signal according to the common input signal voltage; and an adjusting circuit for adjusting the positive and negative output voltages from the differential amplifier circuits so that those positive and negative output voltages fall within an input range of the voltage comparison circuits, wherein the adjusting circuit includes a reference voltage output circuit, which has therein a plurality of voltage generation circuits each for generating a reference voltage and selects and outputs one of the reference voltages; the voltage generation circuits each include a resistor for reference voltage generation; and the resistors in at least two of the voltage generation circuits are connected in series.