Systems and methods for current matching of LED channels

• US 9,426,850 B2
• Filed: 02/26/2015
• Issued: 08/23/2016
• Est. Priority Date: 08/04/2011
• Status: Active Grant

• Current Assignee: On-Bright Electronics (Shanghai) Co., Ltd. (Orthosie Investment Holdings Ltd.)
• Original Assignee: On-Bright Electronics (Shanghai) Co., Ltd. (Orthosie Investment Holdings Ltd.)
• Inventors: Yang, Jiqing, Li, Meng, Zhu, Liqiang, Fang, Lieyi
• Primary Examiner(s): Le, Tung X
• Application Number:
  US14/632,920
• Publication Number:
  US 20150237691A1
• Time in Patent Office: 544 Days
• Field of Search: 315/185.R, 315/209.R, 315224-226, 315/246, 315/250, 315/291, 315/297, 315/307, 315/312
• US Class Current: 1/1
• CPC Class Codes: G09G 3/32 semiconductive, e.g. using light-emitting diodes [LED]
• CPC Class Codes: H05B 45/397 Current mirror circuits
• CPC Class Codes: H05B 45/46 having LEDs disposed in parallel lines
• CPC Class Codes: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Abstract

System and method are provided for generating a plurality of channel currents. The system includes a channel reference generator configured to receive a first reference current and generate at least a first channel driving current and a second channel driving current, a first channel current divider configured to receive the first channel driving current and generate a first input current, a second input current, and a third input current, a second channel current divider configured to receive the second channel driving current and generate a fourth input current, a fifth input current, and a sixth input current, a first channel driver configured to receive the first input current, the second input current, and the third input current and generate a first channel current, and a second channel driver configured to receive the fourth input current, the fifth input current, and the sixth input current and generate a second channel current.

Claims

1. A system for generating a plurality of channel currents, the system comprising:

a first channel current divider configured to generate a first input current, a second input current, and a third input current based at least in part on a first channel driving current;

a second channel current divider configured to generate a fourth input current, a fifth input current, and a sixth input current based at least in part on a second channel driving current;

a first channel driver configured to generate a first channel current based at least in part on the first input current, the second input current, and the third input current; and

a second channel driver configured to generate a second channel current based at least in part on the fourth input current, the fifth input current, and the sixth input current;

wherein;

a sum of the first input current and the second input current is equal to the first channel driving current;

the second input current is equal to the third input current;

a sum of the fourth input current and the fifth input current is equal to the second channel driving current; and

the fifth input current is equal to the sixth input current.

2. The system of claim 1 wherein:

the first channel driver is further configured to receive the first channel current from one or more first light emitting diodes corresponding to a first channel; and

the second channel driver is further configured to receive the second channel current from one or more second light emitting diodes corresponding to a second channel.

3. The system of claim 2 wherein:

the first channel current flows from the one or more first light emitting diodes into the first channel driver; and

the second channel current flows from the one or more second light emitting diodes into the second channel driver.

4. The system of claim 1 wherein the first channel driver includes:

a first transistor including a first transistor terminal, a second transistor terminal, and a third transistor terminal; and

a second transistor including a fourth transistor terminal, a fifth transistor terminal, and a sixth transistor terminal;

wherein;

the first transistor terminal and the fourth transistor terminal are coupled;

the second transistor terminal is configured to receive the second input current; and

the fifth transistor terminal is configured to receive the third input current.

5. The system of claim 4 wherein the first channel driver further includes:

a first resistor associated with a first resistance and coupled to the third transistor terminal at a first voltage; and

a second resistor associated with a second resistance and coupled to the sixth transistor terminal at a second voltage;

wherein;

a multiplication of the first resistance and a sum of the second input current and the first channel current is equal to a multiplication of the second resistance and a sum of the first input current and the third input current minus an offset voltage; and

the offset voltage is equal to a difference between the second voltage and the first voltage in magnitude.

6. The system of claim 5 wherein the first resistance is proportional to the second resistance in magnitude.

7. The system of claim 5 wherein:

the first transistor is a first bipolar junction transistor;

the second transistor is a second bipolar junction transistor;

the first transistor terminal is a first base terminal; and

the fourth transistor terminal is a second base terminal.

8. The system of claim 7 wherein the first channel driver further includes:

a third transistor including a third base terminal, a seventh transistor terminal, and an eighth transistor terminal;

wherein;

the third base terminal and the second transistor terminal are coupled;

the eighth transistor terminal, the first base terminal, and the second base terminal are coupled;

the first transistor is configured to receive a first base current from the third transistor at the eighth transistor terminal;

the second transistor is configured to receive a second base current from the third transistor at the eighth transistor terminal; and

the third transistor is configured to receive at least a portion of the second input current as a third base current.

9. The system of claim 8 wherein the first channel driver further includes:

a fourth transistor including a fourth base terminal, a ninth transistor terminal, and a tenth transistor terminal; and

a first current mirror circuit;

wherein;

the first current mirror circuit is coupled to the third transistor at the seventh transistor terminal;

the first current mirror circuit is coupled to the fourth transistor at the ninth transistor terminal;

the fourth transistor is configured to receive at least a portion of the third input current as a fourth base current; and

the first current mirror circuit is configured to mirror a first current flowing through the third transistor to generate a second current flowing through the fourth transistor, the fourth base current being equal in magnitude to the third base current.

10. The system of claim 9 wherein the fourth transistor is further configured to receive, through another transistor, at least the portion of the third input current as the fourth base current.

11. The system of claim 9 wherein the first channel driver further includes:

a fifth transistor including a fifth base terminal, an eleventh transistor terminal, and a twelfth transistor terminal;

wherein;

the fifth base terminal is coupled to the fifth transistor terminal; and

the fifth transistor is configured to receive a portion of the third input current as a fifth base current.

12. The system of claim 11 wherein the first channel driver further includes:

a sixth transistor including a sixth base terminal, a thirteenth transistor terminal and a fourteenth transistor terminal; and

a second current mirror circuit;

wherein;

the second current mirror circuit is coupled to the fifth transistor at the fifth base terminal;

the second current mirror circuit is coupled to the sixth transistor at the sixth base terminal; and

the second current mirror circuit is configured to mirror the fifth base current to generate a sixth base current for the sixth transistor, the fifth base current being equal in magnitude to the sixth base current.

13. The system of claim 12 wherein:

the first channel driver further includes a seventh transistor including a fifteenth transistor terminal, a sixteenth transistor terminal, and a seventeenth transistor terminal; and

the seventh transistor is configured to receive a voltage signal at the fifteenth transistor terminal from the fifth transistor and receive the first channel current flowing from one or more light emitting diodes.

14. The system of claim 13 wherein the seventh transistor is a laterally diffused metal oxide semiconductor (LDMOS) transistor.

15. The system of claim 1 wherein the first channel current divider includes:

a first current mirror circuit including a first circuit branch, a second circuit branch, and a third circuit branch, the first circuit branch, the second circuit branch, and the third circuit branch being coupled;

a second current mirror circuit including a fourth circuit branch and a fifth circuit branch, the fourth circuit branch and the fifth circuit branch being coupled; and

a third current mirror circuit including a sixth circuit branch, a seventh circuit branch, and an eighth circuit branch, the sixth circuit branch, the seventh circuit branch, and the eighth circuit branch being coupled;

wherein;

the first current mirror circuit is configured to receive a reference current at the first circuit branch, and to generate a first mirror current in the second circuit branch, the first mirror current being proportional to the reference current in magnitude;

the second current mirror circuit is configured to receive the first channel driving current in the fourth circuit branch and to generate a second mirror current, the second mirror current being proportional to the first channel driving current in magnitude; and

the second current mirror circuit is further configured to divert at least a portion of the second mirror current to generate the first input current, the sum of the first input current and the first mirror current being equal in magnitude to the second mirror current;

wherein;

the first current mirror circuit is further configured to generate a third mirror current in the third circuit branch, the third mirror current being proportional to the reference current in magnitude;

the third current mirror circuit is configured to receive the third mirror current in the sixth circuit branch, and to generate the third input current in the seventh circuit branch, the third input current being proportional to the third mirror current in magnitude; and

the third current mirror circuit is further configured to generate the second input current in the eighth circuit branch, the second input current being proportional to the third mirror current in magnitude.

16. The system of claim 15 wherein the first circuit branch, the second circuit branch, the third circuit branch, the fourth circuit branch, the fifth circuit branch, the sixth circuit branch, the seventh circuit branch and the eighth circuit branch each include one or more transistors coupled in series.

17. The system of claim 16 wherein the first channel current and the second channel current are equal in magnitude.

18. A system for generating a plurality of channel currents, the system comprising:

a first channel current divider configured to generate a first input current, a second input current, and a third input current;

a second channel current divider configured to generate a fourth input current, a fifth input current, and a sixth input current;

a first channel driver configured to generate a first channel current based at least in part on the first input current, the second input current, and the third input current; and

a second channel driver configured to generate a second channel current based at least in part on the fourth input current, the fifth input current, and the sixth input current;

wherein the first channel driver includes;

a first transistor including a first transistor terminal, a second transistor terminal, and a third transistor terminal;

a second transistor including a fourth transistor terminal, a fifth transistor terminal, and a sixth transistor terminal;

a first resistor associated with a first resistance and coupled to the third transistor terminal at a first voltage; and

a second resistor associated with a second resistance and coupled to the sixth transistor terminal at a second voltage;

wherein;

the first transistor terminal and the fourth transistor terminal are coupled;

the second transistor terminal is configured to receive the second input current; and

the fifth transistor terminal is configured to receive the third input current;

wherein;

a multiplication of the first resistance and a sum of the second input current and the first channel current is equal to a first magnitude;

a multiplication of the second resistance and a sum of the first input current and the third input current is equal to a second magnitude;

the first magnitude is equal to the second magnitude minus an offset voltage; and

the offset voltage is equal to a difference between the second voltage and the first voltage in magnitude.

19. The system of claim 18 wherein:

the first channel driver is further configured to receive the first channel current from one or more first light emitting diodes corresponding to a first channel; and

the second channel driver is further configured to receive the second channel current from one or more second light emitting diodes corresponding to a second channel.

20. The system of claim 19 wherein:

the first channel current flows from the one or more first light emitting diodes into the first channel driver; and

the second channel current flows from the one or more second light emitting diodes into the second channel driver.

21. The system of claim 18 wherein:

the first transistor is a first bipolar junction transistor;

the second transistor is a second bipolar junction transistor;

the first transistor terminal is a first base terminal; and

the fourth transistor terminal is a second base terminal.

22. The system of claim 21 wherein the first channel driver further includes:

a third transistor including a third base terminal, a seventh transistor terminal, and an eighth transistor terminal;

wherein;

the third base terminal and the second transistor terminal are coupled;

the eighth transistor terminal, the first base terminal, and the second base terminal are coupled;

the first transistor is configured to receive a first base current from the third transistor at the eighth transistor terminal;

the second transistor is configured to receive a second base current from the third transistor at the eighth transistor teiminal; and

the third transistor is configured to receive at least a portion of the second input current as a third base current.

23. The system of claim 22 wherein the first channel driver further includes:

a fourth transistor including a fourth base terminal, a ninth transistor terminal, and a tenth transistor terminal; and

a current mirror circuit;

wherein;

the current mirror circuit is coupled to the third transistor at the seventh transistor terminal;

the current mirror circuit is coupled to the fourth transistor at the ninth transistor terminal;

the fourth transistor is configured to receive at least a portion of the third input current as a fourth base current; and

the current mirror circuit is configured to mirror a first current flowing through the third transistor to generate a second current flowing through the fourth transistor, the fourth base current being equal in magnitude to the third base current.

24. A method for generating a plurality of channel currents, the method comprising:

generating a first input current, a second input current, and a third input current based on at least a first channel driving current;

processing the first input current, the second input current, and the third input current;

generating a fourth input current, a fifth input current, and a sixth input current based on at least a second channel driving current;

processing the fourth input current, the fifth input current, and the sixth input current;

generating a first channel current based on at least the first input current, the second input current, and the third input current; and

generating a second channel current based on at least the fourth input current, the fifth input current, and the sixth input current;

wherein;

a sum of the first input current and the second input current is equal to the first channel driving current;

the second input current is equal to the third input current;

a sum of the fourth input current and the fifth input current is equal to the second channel driving current; and

the fifth input current is equal to the sixth input current.

25. A method for generating a plurality of channel currents, the method comprising:

generating a first input current, a second input current, and a third input current;

processing the first input current, the second input current, and the third input current;

generating a fourth input current, a fifth input current, and a sixth input current;

processing the fourth input current, the fifth input current, and the sixth input current;

generating a first channel current based on at least the first input current, the second input current, and the third input current; and

generating a second channel current based on at least the fourth input current, the fifth input current, and the sixth input current;

wherein;

a multiplication of a first resistance and a sum of the second input current and the first channel current is equal to a first magnitude;

a multiplication of a second resistance and a sum of the first input current and the third input current is equal to a second magnitude; and

the first magnitude is equal to the second magnitude minus an offset voltage.