Digital-to-analog converter

• US 7,924,198 B2
• Filed: 12/23/2009
• Issued: 04/12/2011
• Est. Priority Date: 12/26/2008
• Status: Expired due to Fees

• Current Assignee: LG Display Co., Ltd.
• Original Assignee: LG Display Co., Ltd.
• Inventors: Kim, Namsoo, Chung, Injae, Cui, Zhiyuan
• Primary Examiner(s): Nguyen; Khai M
• Application Number:
  US12/646,309
• Publication Number:
  US 20100164777A1
• Time in Patent Office: 475 Days
• Field of Search: 341/135, 341/144, 341/145
• US Class Current: 341/144
• CPC Class Codes: H03M 1/002 Provisions or arrangements for saving power, e.g. by allowing a sleep mode, using lower supply voltage for downstream stages, using multiple clock domains or by selectively turning on stages when needed
• CPC Class Codes: H03M 1/747 with equal currents which are switched by unary decoded digital signals

Abstract

A digital-to-analog converter is disclosed. The digital-to-analog converter includes a decoder that receives a plurality of digital input signals to output a plurality of thermometer decode signals, a current supply part including a plurality of current sources, each of which operates in one of a sleeping mode and an operating mode under the control of the thermometer decode signals, and a switching part including a plurality of switching units, each of which operates in one of a sleeping mode and an operating mode under the control of the thermometer decode signals. The current supply part selectively outputs a plurality of switching power signals. The switching part outputs an analog signal under the control of the thermometer decode signals.

Claims

1. A digital-to-analog converter comprising:

a decoder that receives a plurality of digital input signals to output a plurality of thermometer decode signals;

a current supply part including a plurality of current sources, each of which operates in one of a sleeping mode and an operating mode under the control of the thermometer decode signals, the current supply part selectively outputting a plurality of switching power signals; and

a switching part including a plurality of switching units, each of which operates in one of a sleeping mode and an operating mode under the control of the thermometer decode signals, the switching part outputting an analog signal under the control of the thermometer decode signals,

wherein an i-th current source of the plurality of current sources operates in the operating mode when an output of an (i−

1)-th current source and an i-th thermometer decode signal are activated, and the i-th current source is converted into the sleeping mode when at least one of the output of the (i−

1)-th current source and the i-th thermometer decode signal are inactivated, where “

i”

is a positive integer,

wherein when the i-th current source is converted into the sleeping mode, an (i+1)-th current source cascade-connected to an output terminal of the i-th current source to a last current source and an i-th switching unit to a last switching unit of the plurality of switching units are converted into the sleeping mode.

2. The digital-to-analog converter of claim 1, wherein the i-th current source outputs an input current of the (i+1)-th current source and an i-th switching power signal to be input to the i-th switching unit in the operating mode.

3. The digital-to-analog converter of claim 1, wherein the i-th switching unit does not output an input current of the (i+1)-th current source and an i-th switching power signal to be input to the i-th switching unit in the sleeping mode.

4. The digital-to-analog converter of claim 1, wherein the decoder continuously activates bits of the thermometer decode signals in successive order from a least significant bit.

5. The digital-to-analog converter of claim 1, wherein each of the plurality of current sources includes a current mirror circuit that generates an output through a current mirror operation only when the thermometer decode signal is activated.

6. The digital-to-analog converter of claim 1, wherein the i-th current source is converted into the sleeping mode and does not generate an output when a current is not output from the (i−

1)-th current source or the i-th thermometer decode signal is inactivated.

7. The digital-to-analog converter of claim 1, wherein the i-th switching unit is converted into the sleeping mode and does not generate an output when an i-th switching power signal is not input to the i-th switching unit or the i-th thermometer decode signal is inactivated.

8. A digital-to-analog converter comprising:

a decoder that receives a plurality of digital input signals to output a plurality of thermometer decode signals;

a current supply part including a plurality of current sources, each of which operates in one of a sleeping mode and an operating mode under the control of the thermometer decode signals, the current supply part selectively outputting a plurality of switching power signals; and

a switching part including a plurality of switching units, each of which operates in one of a sleeping mode and an operating mode under the control of the thermometer decode signals, the switching part outputting an analog signal under the control of the thermometer decode signals,

wherein when an output of an (i−

1)-th current source and an i-th thermometer decode signal are activated, an i-th current source operates in the operating mode to output an input current of an (i+1)-th current source and an i-th switching power signal to be input to an i-th switching unit, where “

i”

is a positive integer,

wherein when the i-th switching power signal and the i-th thermometer decode signal are activated, the i-th switching unit operates in the operating mode to output the analog signal.

9. The digital-to-analog converter of claim 8, wherein the decoder continuously activates bits of the thermometer decode signals in successive order from a least significant bit.

10. The digital-to-analog converter of claim 8, wherein each of the plurality of current sources includes a current mirror circuit that generates an output through a current mirror operation only when the thermometer decode signal is activated.

11. The digital-to-analog converter of claim 8, wherein the i-th current source is converted into the sleeping mode and does not generate an output when at least one of an output of the (i−

1)-th current source and the i-th thermometer decode signal are inactivated.

12. The digital-to-analog converter of claim 8, wherein the i-th switching unit is converted into the sleeping mode and does not generate an output when at least one of the i-th switching power signal and the i-th thermometer decode signal are inactivated.

13. A digital-to-analog converter comprising:

a decoder that receives a plurality of digital input signals to output a plurality of thermometer decode signals;

a current supply part including a plurality of current sources, each of which operates in one of a sleeping mode and an operating mode under the control of the thermometer decode signals, the current supply part selectively outputting a plurality of switching power signals; and

a switching part including a plurality of switching units, each of which operates in one of a sleeping mode and an operating mode under the control of the thermometer decode signals, the switching part outputting an analog signal under the control of the thermometer decode signals,

wherein an i-th current source of the plurality of current sources operates in the operating mode when an output of an (i−

1)-th current source and an i-th thermometer decode signal are activated, and the i-th current source is converted into the sleeping mode when at least one of the output of the (i−

1)-th current source and the i-th thermometer decode signal are inactivated, where “

i”

is a positive integer,

wherein an i-th switching unit of the plurality of switching units operates in the operating mode when an i-th switching power signal and the i-th thermometer decode signal are activated, and the i-th switching unit is converted into the sleeping mode when at least one of the i-th switching power signal and the i-th thermometer decode signal are inactivated,

wherein when the i-th current source is converted into the sleeping mode, an (i+1)-th current source cascade-connected to an output terminal of the i-th current source to a last current source and the i-th switching unit to a last switching unit are converted into the sleeping mode.

14. The digital-to-analog converter of claim 13, wherein the decoder continuously activates bits of the thermometer decode signals in successive order from a least significant bit.

15. The digital-to-analog converter of claim 13, wherein each of the plurality of current sources includes a current mirror circuit that generates an output through a current mirror operation only when the thermometer decode signal is activated.

16. The digital-to-analog converter of claim 13, wherein each of the plurality of current sources does not generate an output in the sleeping mode.

17. The digital-to-analog converter of claim 13, wherein each of the plurality of switching units does not generate an output in the sleeping mode.