DIGITAL-TO-ANALOG CONVERTER WITH NON-UNIFORM RESOLUTION

• US 20120146828A1
• Filed: 12/09/2010
• Published: 06/14/2012
• Est. Priority Date: 12/09/2010
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Narathong, Chiewcharn, Park, Jong Min, Hung, Tsai-Pi
• Granted Patent: US 8,462,036 B2
• Time in Patent Office: Days
• US Class Current: 341/154
• CPC Class Codes: H03B 5/1215 the current source or degeneration circuit being in common to both transistors of the pair, e.g. a cross-coupled long-tailed pair
• CPC Class Codes: H03B 5/1228 the amplifier comprising one or more field effect transistors
• CPC Class Codes: H03B 5/1243 the means comprising voltage variable capacitance diodes
• CPC Class Codes: H03B 5/1265 switched capacitors
• CPC Class Codes: H03G 11/008 of digital or coded signals
• CPC Class Codes: H03L 2207/06 Phase locked loops with a controlled oscillator having at least two frequency control terminals
• CPC Class Codes: H03L 7/093 using special filtering or amplification characteristics in the loop H03L7/087 - H03L7/091 take precedence
• CPC Class Codes: H03L 7/099 concerning mainly the controlled oscillator of the loop
• CPC Class Codes: H03M 1/66 Digital/analogue converters H03M1/001 – H03M1/10 take precedence
• CPC Class Codes: H03M 1/664 Non-linear conversion not otherwise provided for in subgroups of H03M1/66
• CPC Class Codes: H03M 1/765 using a single level of switches which are controlled by unary decoded digital signals

Abstract

A circuit includes a digital-to-analog converter with non-uniform resolution for converting a digital signal into an analog signal. The digital-to-analog converter includes high-resolution circuitry, reduced-resolution circuitry coupled to the high-resolution circuitry and a switch coupled to the high-resolution circuitry and to the reduced-resolution circuitry. The switch couples one of the high-resolution circuitry and the reduced-resolution circuitry to an output node. The circuit also includes a decoder coupled to the switch. The decoder receives the digital signal to control the switch.

Claims

1. A circuit, comprising:

a 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 circuit, comprising:

a digital-to-analog converter having an input for receiving a digital signal;

a voltage-controlled oscillator coupled to the digital-to-analog converter, comprising a capacitor bank coupled to a plurality of switches for adjusting an operating range of the voltage-controlled oscillator;

an operating range controller coupled to the voltage controlled oscillator configured to determine whether the digital signal at the digital-to-analog converter input corresponds to a designated operating range and control the plurality of switches to adjust the operating range of the voltage-controlled oscillator if the digital signal does not correspond to the designated operating range.

9. The circuit of claim 8, wherein the designated operating range corresponds to a high-resolution operating region of the digital-to-analog converter.

10. The circuit of claim 8, wherein the designated operating range comprises a range within a high-resolution operating region of the digital-to-analog converter.

11. The circuit of claim 8, wherein the circuit is used in conjunction with a modulator.

12. The circuit of claim 8, wherein the operating range controller adjusts the operating range by:

determining a first adjustment based on the digital signal; and

applying the first adjustment to the voltage-controlled oscillator.

13. The circuit of claim 12, wherein the first adjustment is determined according to the equation

14. The circuit of claim 12, wherein the operating range controller:

determines whether an updated digital signal corresponds to the designated operating range;

determines a scaled second adjustment based on the first adjustment if the updated digital signal does not correspond to the designated operating range; and

applies the scaled second adjustment to the voltage-controlled oscillator if the updated digital signal does not correspond to the designated operating range.

15. The circuit of claim 14, wherein the scaled second adjustment is determined according to the equation α

N_A2, wherein α

N_A2 is the second scaled adjustment, wherein N_A2 is a second adjustment and

16. The circuit of claim 15, wherein the second adjustment is determined according to the equation

17. The circuit of claim 8, wherein the digital-to-analog converter comprises high-resolution circuitry and reduced-resolution circuitry.

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

receiving a digital signal;

decoding, by the 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.

19. The method of claim 18, 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.

20. The method of claim 19, wherein the first resistor has a higher sheet resistance than the second resistor.

21. The method of claim 18, wherein the digital-to-analog converter is a single-stage resistor-string digital-to-analog converter.

22. The method of claim 18, 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.

23. The method of claim 18, wherein the digital-to-analog converter is an integrated circuit.

24. The method of claim 18, wherein the digital-to-analog converter comprises an X-Y decoder.

25. A method for controlling an operating range, comprising:

receiving a digital signal by a digital-to-analog converter and an operating range controller;

determining, by the operating range controller, whether the digital signal corresponds to a designated operating range; and

adjusting, by the operating range controller, the operating range of a voltage-controlled oscillator if the digital signal does not correspond to the designated operating range.

26. The method of claim 25, wherein the designated operating range corresponds to a high-resolution operating region of the digital-to-analog converter.

27. The method of claim 25, wherein the designated operating range comprises a range within a high-resolution operating region of the digital-to-analog converter.

28. The method of claim 25, wherein the digital-to-analog converter, the operating range controller and the voltage-controlled oscillator are used in conjunction with a modulator.

29. The method of claim 25, wherein the operating range controller adjusts the operating range by:

determining a first adjustment based on the digital signal; and

applying the first adjustment to the voltage-controlled oscillator.

30. The method of claim 29, wherein the first adjustment is determined according to the equation

31. The method of claim 29, further comprising:

determining whether an updated digital signal corresponds to the designated operating range;

determining a scaled second adjustment based on the first adjustment if the updated digital signal does not correspond to the designated operating range; and

applying the scaled second adjustment to the voltage-controlled oscillator if the updated digital signal does not correspond to the designated operating range.

32. The method of claim 31, wherein the scaled second adjustment is determined according to the equation α

N_A2, wherein α

N_A2 is the second scaled adjustment, wherein N_A2 is a second adjustment and

33. The method of claim 32, wherein the second adjustment is determined according to the equation

34. The method of claim 25, wherein the digital-to-analog converter comprises high-resolution circuitry and reduced-resolution circuitry.

35. A computer-program product for controlling an operating range comprising a non-transitory tangible computer-readable medium having instructions thereon, the instructions comprising:

code causing an operating range controller to determine whether a digital signal corresponds to a designated operating range; and

code for causing the operating range controller to adjust the operating range of a voltage-controlled oscillator if the digital signal does not correspond to the designated operating range.

36. The computer-program product of claim 35, wherein the designated operating range corresponds to a high-resolution operating region of a digital-to-analog converter.

37. The computer-program product of claim 35, wherein the designated operating range comprises a range within a high-resolution operating region of the digital-to-analog converter.

38. The computer-program product of claim 35, the instructions further comprising:

code for causing the operating range controller to determine a first adjustment based on the digital signal; and

code for causing the operating range controller to apply the first adjustment to the voltage-controlled oscillator.

39. The computer-program product of claim 38, the instructions further comprising:

code for causing the operating range controller to determine whether an updated digital signal corresponds to the designated operating range;

code for causing the operating range controller to determine a scaled second adjustment based on the first adjustment if the updated digital signal does not correspond to the designated operating range; and

code for causing the operating range controller to apply the scaled second adjustment to the voltage-controlled oscillator if the updated digital signal does not correspond to the designated operating range.

40. 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.

41. The apparatus of claim 40, 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.

42. The apparatus of claim 40, wherein the high-resolution circuitry and the reduced-resolution circuitry comprise a single-stage resistor-string digital-to-analog converter.

43. An apparatus for controlling an operating range, comprising:

means for receiving a digital signal;

means for determining whether the digital signal corresponds to a designated operating range; and

means for adjusting an operating range of a voltage-controlled oscillator if the digital signal does not correspond to the designated operating range.

44. The apparatus of claim 43, wherein the designated operating range corresponds to a high-resolution operating region of a digital-to-analog converter.

45. The apparatus of claim 43, wherein the means for adjusting comprises:

means for determining a first adjustment based on the digital signal; and

means for applying the first adjustment to the voltage-controlled oscillator.

46. The apparatus of claim 45, wherein the means for adjusting further comprises:

means for determining whether an updated digital signal corresponds to the designated operating range;

means for determining a scaled second adjustment based on the first adjustment if the updated digital signal does not correspond to the designated operating range; and

means for applying the scaled second adjustment to the voltage-controlled oscillator if the updated digital signal does not correspond to the designated operating range.