Digital-to-analog converter with non-uniform resolution

1. A circuit, comprising:

a resistor-based digital-to-analog converter with non-uniform resolution for converting a digital signal into an analog signal, comprising:

high-resolution circuitry;

reduced-resolution circuitry coupled to the high-resolution circuitry;

a switch coupled to the high-resolution circuitry and to the reduced-resolution circuitry, wherein the switch couples one of the high-resolution circuitry and the reduced-resolution circuitry to an output node; and

a decoder coupled to the switch, wherein the decoder receives the digital signal to control the switch.

2. The circuit of claim 1 , wherein the reduced-resolution circuitry comprises a first resistor with a resistance that is greater than a resistance of a second resistor included in the high-resolution circuitry.

3. The circuit of claim 2 , wherein the first resistor has a higher sheet resistance than the second resistor.

4. The circuit of claim 1 , wherein the digital-to-analog converter is a single-stage resistor-string digital-to-analog converter.

5. The circuit of claim 1 , wherein the high-resolution circuitry comprises a first plurality of resistors and the reduced-resolution circuitry comprises a second plurality of resistors, wherein the first plurality of resistors each have a resistance that is smaller than the resistance of each of the second plurality of resistors.

6. The circuit of claim 1 , wherein the circuit is an integrated circuit.

7. The circuit of claim 1 , wherein the decoder is an X-Y decoder.

8. A method for converting a digital signal into an analog signal using a resistor-based digital-to-analog converter with non-uniform resolution, comprising:

receiving a digital signal;

decoding, by the resistor-based digital-to-analog converter, the digital signal to produce a control signal;

providing a voltage to high-resolution circuitry and reduced-resolution circuitry;

controlling, by the digital-to-analog converter, a switch using the control signal to select an output from one of the high-resolution circuitry and the reduced-resolution circuitry; and

providing an analog signal.

9. The method of claim 8 , wherein the reduced-resolution circuitry comprises a first resistor with a resistance that is greater than a resistance of a second resistor included in the high-resolution circuitry.

10. The method of claim 9 , wherein the first resistor has a higher sheet resistance than the second resistor.

11. The method of claim 8 , wherein the digital-to-analog converter is a single-stage resistor-string digital-to-analog converter.

12. The method of claim 8 , wherein the high-resolution circuitry comprises a first plurality of resistors and the reduced-resolution circuitry comprises a second plurality of resistors, wherein the first plurality of resistors each have a resistance that is smaller than the resistance of each of the second plurality of resistors.

13. The method of claim 8 , wherein the digital-to-analog converter is an integrated circuit.

14. The method of claim 8 , wherein the digital-to-analog converter comprises an X-Y decoder.

15. An apparatus for converting a digital signal into an analog signal, comprising:

means for receiving a digital signal;

means for decoding the digital signal to produce a control signal;

means for providing a voltage to high-resolution circuitry and reduced-resolution circuitry;

means for controlling a switch using the control signal to select an output from one of the high-resolution circuitry and the reduced-resolution circuitry; and

means for providing an analog signal.

16. The apparatus of claim 15 , wherein the reduced-resolution circuitry comprises a first resistor with a resistance that is greater than a resistance of a second resistor included in the high-resolution circuitry.

17. The apparatus of claim 15 , wherein the high-resolution circuitry and the reduced-resolution circuitry comprise a single-stage resistor-string digital-to-analog converter.