D/A converter including higher-order resistor string

1. A resistor string type D/A converter comprising:

a higher-order resistor string that generates a plurality of higher-order analog voltages by dividing a voltage between a first reference voltage and a second reference voltage and outputs the plurality of higher-order analog voltages from a plurality of voltage drawing points;

first higher-order switches each provided for a respective one of the plurality of voltage drawing points, a conductive state of the first higher-order switches being controlled based on a first higher-order control signal;

a higher-order decoder that generates the first higher-order control signal according to a value of a higher-order bit of a digital signal and brings a pair of first higher-order switches corresponding to neighboring higher-order analog voltages among the first higher-order switches into conduction based on the first higher-order control signal, the digital signal indicating one value by a plurality of bits;

a lower-order decoder that generates a lower-order control signal corresponding to a value of a lower-order bit of the digital signal; and

a conversion unit that outputs a voltage between a pair of analog voltage values obtained through the pair of first higher-order switches based on the lower-order control signal.

2. The resistor string type D/A converter according to claim 1 , wherein

the higher-order decoder outputs a second higher-order control signal according to a value of the higher-order bit, and

the resistor string type D/A converter further comprises a second higher-order switch that selects each of the pair of analog voltages based on the second higher-order control signal, and supplies the selected analog voltage to the conversion unit.

3. The resistor string type D/A converter according to claim 2 , wherein the second higher-order switch selects one of a higher-order analog voltage output from an odd-numbered voltage drawing point and a higher-order analog voltage output from an even-numbered voltage drawing point of the pair of analog voltages based on the second higher-order control signal, and supplies the selected higher-order analog voltage to the conversion unit.

4. The resistor string type D/A converter according to claim 2 , wherein when the higher-order resistor string is folded into a plurality of stages,

the resistor string type D/A converter further comprises a plurality of signal lines connecting a first voltage drawing point to a second voltage drawing point, the second voltage drawing point being one of voltage drawing points that is adjacent to the first voltage drawing point in a direction perpendicular to a direction of a resistor string of the higher-order resistor string and do not include a voltage drawing point adjacent to that voltage drawing point in a direction of the resistor string of the higher-order resistor string, and

the second higher-order switch selects each of the pair of analog voltages output through the plurality of signal lines, and supplies the selected analog voltage to the conversion unit.

5. The resistor string type D/A converter according to claim 2 , wherein the conversion unit comprises a lower-order resistor string type D/A converter comprising:

a lower-order resistor string that generates a plurality of lower-order analog voltages by dividing a voltage between the pair of analog voltages and outputs the plurality of lower-order analog voltages from a plurality of lower-order voltage drawing points; and

lower-order switches each provided for a respective one of the plurality of lower-order voltage drawing points, a conductive state of the lower-order switches being controlled based on the lower-order control signal.

6. The resistor string type D/A converter according to claim 1 , wherein the conversion unit comprises an interpolation amplifier that outputs an output voltage obtained by dividing a voltage between the pair of analog voltages based on the lower-order control signal.

7. The resistor string type D/A converter according to claim 3 , wherein the conversion unit comprises a lower-order resister string type D/A converter comprising:

a lower-order resistor string that generates a plurality of lower-order analog voltages by dividing a voltage between the pair of analog voltages and outputs the plurality of lower-order analog voltages from a plurality of lower-order voltage drawing points; and

lower-order switches each provided for a respective one of the plurality of lower-order voltage drawing points, a conductive state of the lower-order switches being controlled based on the lower-order control signal.

8. The resistor string type D/A converter according to claim 4 , wherein the conversion unit comprises a lower-order resister string type D/A converter comprising:

a lower-order resistor string that generates a plurality of lower-order analog voltages by dividing a voltage between the pair of analog voltages and outputs the plurality of lower-order analog voltages from a plurality of lower-order voltage drawing points; and

lower-order switches each provided for a respective one of the plurality of lower-order voltage drawing points, a conductive state of the lower-order switches being controlled based on the lower-order control signal.

9. The resistor string type D/A converter according to claim 2 , wherein the conversion unit comprises an interpolation amplifier that outputs an output voltage obtained by dividing a voltage between the pair of analog voltages based on the lower-order control signal.

10. The resistor string type D/A converter according to claim 3 , wherein the conversion unit comprises an interpolation amplifier that outputs an output voltage obtained by dividing a voltage between the pair of analog voltages based on the lower-order control signal.

11. The resistor string type D/A converter according to claim 4 , wherein the conversion unit comprises an interpolation amplifier that outputs an output voltage obtained by dividing a voltage between the pair of analog voltages based on the lower-order control signal.