SHIFT REGISTER

• US 20100226473A1
• Filed: 10/01/2009
• Published: 09/09/2010
• Est. Priority Date: 03/05/2009
• Status: Active Grant

• Current Assignee: AU Optronics Corporation
• Original Assignee: AU Optronics Corporation
• Inventors: Liu, Chun-Hsin, Chen, Yung-Chih, Su, Kuo-Chang, Tsai, Tsung-ting
• Granted Patent: US 8,175,215 B2
• Time in Patent Office: Days
• US Class Current: 377/79
• CPC Class Codes: G11C 19/28 using semiconductor elements G11C19/14, G11C19/36 take precedence

Abstract

A shift register includes multiple cascade-connected stages. Each stage generates an output signal in response to a clock signal and a first control signal. Each stage includes a pull-up module, a pull-up driving module, a first pull-down module, a second pull-down module, and a third pull-down module. The pull-up module is used for providing the output signal based on the clock signal. The pull-up driving module turns on the pull-up module in response to a first control signal. The first pull-down module adjusts voltage level on the first node to a first supply voltage in response to a second control signal. The second pull-down module adjusts voltage level on the output end to a second supply voltage in response to the second control signal. The third pull-down module adjusts voltage level on the second node to a third supply voltage in response to a third control signal.

Claims

1. A shift register comprising:

a plurality of cascade-connected stages, each stage for generating an output signal at an output end based on a clock signal, a first control signal, each stage comprising;

a pull-up module coupled to a first node, for providing the output signal at the output end based on the clock signal;

a pull-up driving module coupled to the first node, for turning on the pull-up module in response to the first control signal;

a first pull-down module coupled to the first node and a first supply voltage, for adjusting voltage level on the first node to the first supply voltage in response to a second control signal;

a second pull-down module coupled to the output end and a second supply voltage, for adjusting voltage level on the output end to the second supply voltage in response to the second control signal; and

a third pull-down module coupled to a second node and a third supply voltage, for adjusting voltage level on the second node to the third supply voltage in response to a third control signal.

2. The shift register of claim 1, wherein the first pull-down module comprises a first transistor of which comprises a drain coupled to the first node, a gate coupled to the second node, and a source coupled to the first supply voltage.

3. The shift register of claim 1, wherein the pull-up driving module comprises a second transistor of which comprises a drain and a gate coupled to the first control signal and a source coupled to the first node.

4. The shift register of claim 3, wherein the first control signal is from an output end of a previous stage.

5. The shift register of claim 1, wherein the third pull-down module comprises a third transistor of which comprises a drain, a gate, and a source coupled to the second node, the third control signal, and the third supply voltage, respectively.

6. The shift register of claim 5, wherein the third control signal is from an output end of a previous stage.

7. The shift register of claim 1, wherein the third pull-down module comprises a third transistor of which comprises a drain, a gate, and a source coupled to the second node, the first node, and the third supply voltage, respectively.

8. The shift register of claim 1, wherein the pull-up module comprises a fourth transistor of which comprises a drain, a gate, and a source coupled to the clock signal, the first node, and the output end, respectively.

9. The shift register of claim 8, wherein the pull-up module comprises a sixth transistor of which comprises a drain, a gate, and a source coupled to the clock signal, the first node, and a driving signal end, respectively.

10. The shift register of claim 1, wherein the second pull-down module comprises a fifth transistor of which comprises a drain, a gate, and a source coupled to the output end, the second node, and the second supply voltage, respectively.

11. The shift register of claim 10, wherein the second pull-down module further comprises a seventh transistor of which comprises a drain, a gate, and a source coupled to a driving signal end, the second node, and the second supply voltage, respectively.

12. The shift register of claim 1, wherein the voltage level of the third supply voltage is less than or equal to that of the first supply voltage.

13. The shift register of claim 1, wherein the voltage level of the first supply voltage is less than or equal to that of the second supply voltage.