Pixel circuits and methods for driving pixels
A circuit according to one embodiment includes a data line; a select line; a storage node coupled to the select line; a first transistor with a gate coupled to the select line, a first electrode thereof coupled to the storage node, and a second electrode thereof coupled to the data line; a second transistor with a gate coupled to the storage node, a first electrode thereof coupled to the data line; and a light emitting diode coupled to a second electrode of the second transistor. Additional systems and methods are claimed.
1. A sample and hold current device, comprising:
a semiconductor device including a transistor, wherein the semiconductor device is configured to generate a voltage in response to receiving a programming current during a first period; and
a storage node configured to store the voltage, wherein the storage node has two electrically distinct sides, wherein one side of the storage node is coupled to a select line and the other side of the storage node is coupled to one of a gate or base of the transistor,
wherein the semiconductor device is configured to produce a derivative current responsive to the programming current using the stored voltage, wherein the derivative current is produced during a second period that is distinct from the first period.
2. The sample and hold current device of claim 1 , wherein the semiconductor device includes transistor is a single transistor.
3. The sample and hold current device of claim 1 , wherein the storage node includes at least one capacitor.
4. A method for generating a derivative current of a programming current, comprising:
receiving a programming current during a load period;
storing a voltage generated in response to the programming current, wherein the generated voltage is stored in a storage node having two distinct sides, wherein one side of the storage node is coupled to a select line, and wherein the other side of the storage node is coupled to one of a gate or a base of a transistor; and
generating a derivative current of the programming current using the stored voltage and the transistor during an illumination period, wherein the load period is distinct from the illumination period.
5. The method of claim 4 , wherein the derivative current is a scaled replica of the programming current.
6. The method of claim 4 , wherein the transistor is a single transistor, and wherein the single transistor is used sequentially as a reference transistor and then as an output transistor.
7. The method of claim 4 , further comprising using the derivative current to drive a light emitting diode.
8. The method of claim 4 , wherein a relationship between the derivative current and the programming current is substantially insensitive to variations in thin film transistor threshold and mobility.
9. The sample and hold current device of claim 1 , wherein the derivative current is a scaled replica of the programming current.
10. A system, comprising:
one or more light emitting diodes;
a semiconductor device including a transistor, wherein the semiconductor device is configured to generate a voltage in response to receiving a programming current during a load period; and
a storage node configured to store the voltage, wherein the storage node has two electrically distinct sides, wherein one side of the storage node is coupled to a select line and the other side of the storage node is coupled to one of a gate or a base of the transistor,
wherein the semiconductor device is configured to produce a current that is a derivative of the programming current using the stored voltage during an illumination period, wherein the load period is distinct from the illumination period, and wherein the semiconductor device is configured to use the derivative current to drive the one or more light emitting diodes.
11. The system of claim 10 , wherein the transistor is a single transistor.
12. The system of claim 10 , wherein the storage node includes at least one capacitor.
13. The system of claim 10 , wherein the derivative current is a scaled replica of the programming current.
14. The system of claim 10 , wherein a relationship between the derivative current and the programming current is substantially insensitive to variations in thin film transistor threshold and mobility.
15. The sample and hold current device of claim 2 , wherein the single transistor includes a source electrically coupled to a data line, wherein the data line is configured to provide the programming current.
16. The sample and hold current device of claim 15 , wherein the derivative current is produced utilizing the single transistor coupled to the storage node.
17. The sample and hold current device of claim 9 , wherein one electrode of the transistor is electrically coupled to the storage node and another electrode of the transistor is coupled to a data line, wherein the data line is configured to provide the programming current, and wherein the scaled replica current is produced utilizing the transistor.
18. The system of claim 10 , wherein the transistor has one of a source or a collector electrically coupled to a data line, wherein the data line is configured to provide the programming current.
19. The system of claim 13 , wherein one of a source or collector of the transistor is coupled to a data line, wherein the data line is configured to provide the programming current, and wherein the scaled replica is produced utilizing the transistor coupled to the storage node.