FAMILY OF CURRENT/POWER-EFFICIENT HIGH VOLTAGE LINEAR REGULATOR CIRCUIT ARCHITECTURES

• US 20090237040A1
• Filed: 03/18/2008
• Published: 09/24/2009
• Est. Priority Date: 03/18/2008
• Status: Active Grant

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Qualcomm MEMS Technologies Incorporated (Qualcomm, Inc.)
• Inventors: Wadhwa, Sameer
• Granted Patent: US 7,977,931 B2
• Time in Patent Office: Days
• US Class Current: 323/234
• CPC Class Codes: G05F 1/565 sensing a condition of the system or its load in addition to means responsive to deviations in the output of the system, e.g. current, voltage, power factor G05F1/563 takes precedence
• CPC Class Codes: G09G 3/3466 based on interferometric effect

Abstract

Power efficient power supply regulator circuits are disclosed. The circuits are configured to modify their overhead current according to current load. This is particularly advantageous for use in display devices with widely varying current loads. Such displays include bi-stable displays, such as interferometric modulation displays, LCD displays, and DMD displays.

Claims

1. A voltage regulator circuit, comprising:

an input stage having an input bias current; and

an output stage having an output bias current, the output stage being configured to supply an output current at a regulated output voltage,

wherein at least one of the input bias current and the output bias current is dependent at least in part on the regulated output voltage.

2. The circuit of claim 1, wherein at least one of the input bias current and the output bias current is dependent at least in part on the output current.

3. The circuit of claim 1, further comprising a substantially fixed current source and a variable current source, wherein the circuit is configured to connect at least one of the fixed current source and the variable current source to a node based at least in part on the output current.

4. The circuit of claim 3, wherein the variable current source varies dependent at least in part on the difference between a voltage based on the regulated output voltage and a reference voltage.

5. The circuit of claim 1, further comprising a differential pair having a tail current and a differential input voltage, wherein the tail current is dependent at least in part on the differential input voltage.

6. The circuit of claim 5, wherein the differential pair produces a differential output current, and comprises first and second variable tail current generators, wherein the first and second tail current generators are configured to generate tail current based on opposite polarities of the differential output current.

7. The circuit of claim 1, wherein the input stage has an input supply voltage and the output stage has an output supply voltage and the input supply voltage is different from the output supply voltage.

8. A method of controlling a bias current in an output stage of voltage regulator circuit, the circuit configured to provide current substantially at a regulated output voltage, the method comprising:

sensing a difference between a voltage based on the output voltage and a reference voltage; and

generating a bias current based on the difference.

9. The method of claim 8, further comprising increasing the bias current if the difference increases.

10. The method of claim 8, further comprising maintaining a fixed bias current if the difference decreases below a threshold.

11. The method of claim 8, further comprising producing a tail current amount for a differential pair of transistors in an amplifier circuit depending on the difference between the output voltage and the reference voltage.

12. A voltage regulator circuit, comprising:

an input stage; and

an output stage having an output bias current, the output stage being selectively connectable to a fixed current source and to a variable current source.

13. The circuit of claim 12, configured to supply an output current at a regulated output voltage, wherein the current of the variable current source is configured to vary based at least in part on the output voltage.

14. The circuit of claim 12, configured to supply an output current at a regulated output voltage, wherein the output stage is configured to be connected to the fixed current when the difference between a voltage based on the output voltage and a reference voltage is below a threshold.

15. The circuit of claim 12, configured to supply an output current at a regulated output voltage, wherein the output stage is configured to be connected to the variable current when the difference between a voltage based on the output voltage and a reference voltage is above a threshold.

16. The circuit of claim 12, wherein the input stage is selectively connectable to a fixed input current source and to a variable input current source.

17. The circuit of claim 16, configured to supply an output current at a regulated output voltage, wherein the current of the variable input current source is configured to vary based at least in part on the output voltage.

18. The circuit of claim 16, wherein when the input stage is connected to the fixed input current source, the variable input current source is configured to be turned off, and when the output stage is connected to the fixed output current source, the variable output current source is configured to be turned off.

19. A voltage regulator circuit, comprising:

an input stage having an input bias current; and

an output stage having an output bias current, the output stage being configured to supply an output current at a regulated output voltage,

wherein at least one of the input bias current and the output bias current is based at least in part on the difference between a voltage based on the output voltage and a reference voltage.

20. The circuit of claim 19, further comprising a differential pair having a tail current and a differential input voltage, wherein the tail current is based at least in part on the differential input voltage.

21. The circuit of claim 20, wherein the differential pair produces a differential output current, and comprises first and second variable tail current generators, wherein the first and second tail current generators are configured to generate tail current based on opposite polarities of the differential output current.

22. A display comprising:

a plurality of bi-stable display elements; and

a voltage regulator circuit, the voltage regulator circuit comprising;

an input stage having an input bias current; and

an output stage having an output bias current, the output stage being configured to supply an output current at a regulated output voltage,

wherein at least one of the input bias current and the output bias current is based at least in part on the output current.

23. The display of claim 22, wherein at least one of the input bias current and the output bias current is based at least in part on the regulated output voltage.

24. The display of claim 22, further comprising a substantially fixed current source and a variable current source, wherein the circuit is configured to connect at least one of the fixed current source and the variable current source to a node based at least in part on the output current.

25. The display of claim 24, wherein the variable current source varies based at least in part on the difference between a voltage based on the regulated output voltage and a reference voltage.

26. The display of claim 22, further comprising a differential pair having a tail current and a differential input voltage, wherein the tail current is based at least in part on the differential input voltage.

27. The display of claim 22, wherein the input stage has an input supply voltage and the output stage has an output supply voltage and the input supply voltage is different from the output supply voltage.

28. A voltage regulator circuit, comprising:

means for sensing a difference between a voltage based on the output voltage and a reference voltage;

means for generating an output current based on the difference; and

means for modifying a bias current based on the output current.

29. The circuit of claim 28, wherein the sensing means comprises a voltage comparator.

30. The circuit of claim 28, wherein the generating means comprises an output stage.

31. The circuit of claim 28, wherein the modifying means comprises a bias current generator.

32. The circuit of claim 31, wherein the bias current generator comprises a substantially fixed current source and a variable current source, wherein the circuit is configured to connect at least one of the fixed current source and the variable current source to a node based at least in part on the output current.

33. The circuit of claim 31, wherein the bias current generator comprises a differential pair having a tail current and a differential input voltage, wherein the tail current is dependent at least in part on the differential input voltage.