Data driver
AssigneeToppoly Optoelectronics Corp.
InventorWei-Chieh Hsueh
Life of this patent
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Abstract
A data driver for driving pixels in an active matrix organic LED (AMOLED) is provided the data driver includes a plurality of converters configured to convert to analog current signal digital voltage signals in order to drive the pixels to emit light. Each converter has a plurality of current mirror devices configured to generate mirrored current signals by inputting two control signals. Meanwhile, the mirrored current signals can maintain their preciseness even if deviation of the characteristics of the transistors implanted within the current mirror devices occurs during fabricating.
Claims15
A data driver of an active matrix organic light emitting display (AMOLED), comprising:
- a first shift register configured to provide an N-bit first control signal;
- a data register configured to store N M-bit digital voltage signals responsive to the first control signal;
- a data latch configured to receive and transmit the N digital voltage signals in response to an enabling signal;
- a second shift register configured to provide an (M+1)-bit second control signal;
- and
- N converters, each of the N converters comprising:
- M first devices, respectively responsive to preceding M bits of the second control signal, configured to generate M first mirrored currents respectively;
- and
- M second devices, responsive to a last bit of the second control signal and the M first mirrored currents, configured to convert one of the N digital voltage signals into an analog current signal.
A digital-voltage-to-analog-current converter for converting an M-bit digital voltage signal into an analog current signal in response to a first control signal and a second control signal, the converter comprising:
- M first devices, responsive to the first control signal, configured to generate M first mirrored currents respectively;
- and
- M second devices, responsive to the second control signal and the M first mirrored currents, configured to convert the digital voltage signal into the analog current signal.
A current mirror device, comprising:
- a current source configured to provide a reference current;
- a high level voltage source;
- a low level voltage source;
- a first control signal;
- a second control signal;
- a first transistor, comprising a first terminal, a second terminal, and a gate;
- a second transistor, comprising a first terminal, a second terminal, and a gate;
- a third transistor, comprising a first terminal, a second terminal, and a gate;
- a fourth transistor, comprising a first terminal, a second terminal, and a gate;
- a fifth transistor, comprising a first terminal, a second tennis, and a gate;
- a sixth transistor, comprising a first terminal, a second terminal, and a gate;
- a seventh transistor, comprising a first terminal, a second terminal, and a gate;
- a first capacitor, comprising a first end and a second end;
- and
- a second capacitor, comprising a first end and a second end;
- wherein the gate of the first transistor is configured to input the first control signal, the second terminal of the first transistor is connected to the current source, the first terminal of the first transistor is respectively connected to the first terminal of the second transistor and the second terminal of the third transistor, the gate of the second transistor is connected to the gate of the first transistor, the second terminal of the second transistor is respectively connected to the gate of the third transistor and the second end of the first capacitor, the first end of the first capacitor is respectively connected to the first terminal of the third transistor and the high level voltage source, the gate of the fourth transistor is configured to input the second control signal, the second terminal of the fourth transistor is connected to the second terminal of the third transistor, the first terminal of the fourth transistor is respectively connected to the first terminal of the fifth transistor and the second terminal of the sixth transistor, the gate of the fifth transistor is connected to the gate of the fourth transistor, the second terminal of the fifth transistor is respectively connected to the gate of the sixth transistor and the second end of the second capacitor, the first end of the second capacitor is respectively connected to the first terminal of the sixth transistor and the low level voltage source, and a current flowing through the sixth transistor is substantially equal to the reference current.
Dependencies are inferred from the claim text.