Level shifter for use in LCD display applications
View Patent ↗A level shifter for use in LCD display applications is provided which includes a group of separate channels each with a signal input and a signal output and with channel control circuitry supporting gate voltage shaping for improving image quality. The level shifter further has a number of flicker clock inputs. The channel control circuitry of each particular channel in the group comprises logic circuitry combining all of said flicker clock inputs with the signal input of the particular channel and signal inputs form other channels into a gate voltage shaping enable signal for the control circuitry of the particular channel. With this configuration it is possible to use the same level shifter IC with only one flicker clock signal for all phases, regardless of how many, without the need for an additional synchronization signal, or multiple flicker clock signals as is conventional. The level shifter automatically determines which input signal needs to be modified for the gate voltage shaping when the active portion of the flicker clock signal is detected.
1. A level shifter for use in LCD display applications, comprising a group of separate channels each with a signal input and a signal output and with channel control circuitry supporting gate voltage shaping for improving image quality; the level shifter further comprising a number of flicker clock inputs, and the channel control circuitry of each particular channel in the group comprising logic circuitry combining all of said flicker clock inputs with the signal input of said particular channel and signal inputs from other channels into a gate voltage shaping enable signal for the control circuitry of the particular channel.
2. The level shifter according to claim 1 , wherein the logic circuitry comprises an AND gate with inputs to each of which one of said signal inputs is applied.
3. The level shifter according to claim 2 , wherein the logic circuitry comprises a flip-flop with a D-input to which an output of the AND gate is applied, a clock input to which an output of the OR gate is applied and an output which provides the gate voltage shaping enable signal.
4. The level shifter according to claim 3 , wherein the number of channels in the group is six and the number of flicker clock inputs is three, and the inputs to the AND gate are as follows
Channel 1 : input 1 , input 2 , input 3 ;
Channel 2 : input 2 , input 3 , input 4 ;
Channel 3 : input 3 , input 4 , input 5 ;
Channel 4 : input 4 , input 5 , input 6 ;
Channel 5 : input 5 , input 6 , input 1 ;
Channel 6 : input 6 , input 1 , input 2 .
5. The level shifter according to claim 3 , wherein the gate voltage shaping is active in each channel during the active state of the corresponding gate voltage shaping enable signal to selectively connect the signal output of the channel to a defined discharge sink.
6. The level shifter according to claim 3 , and further comprising separate channels with control circuitry not supporting gate voltage shaping.
7. The level shifter according to claim 2 , wherein the logic circuitry comprises an OR gate with inputs to each of which one of said flicker clock inputs is applied.
8. The level shifter according to claim 7 , wherein the logic circuitry comprises a flip-flop with a D-input to which an output of the AND gate is applied, a clock input to which an output of the OR gate is applied and an output which provides the gate voltage shaping enable signal.
9. The level shifter according to claim 8 , wherein the gate voltage shaping is active in each channel during the active state of the corresponding gate voltage shaping enable signal to selectively connect the signal output of the channel to a defined discharge sink.
10. The level shifter according to claim 7 , wherein the gate voltage shaping is active in each channel during the active state of the corresponding gate voltage shaping enable signal to selectively connect the signal output of the channel to a defined discharge sink.
11. The level shifter according to claim 2 , wherein the gate voltage shaping is active in each channel during the active state of the corresponding gate voltage shaping enable signal to selectively connect the signal output of the channel to a defined discharge sink.
12. The level shifter according to claim 2 , and further comprising separate channels with control circuitry not supporting gate voltage shaping.
13. The level shifter according to claim 1 , wherein the logic circuitry comprises an OR gate with inputs to each of which one of said flicker clock inputs is applied.
14. The level shifter according to claim 13 , wherein the logic circuitry comprises a flip-flop with a D-input to which an output of the AND gate is applied, a clock input to which an output of the OR gate is applied and an output which provides the gate voltage shaping enable signal.
15. The level shifter according to claim 14 , wherein the gate voltage shaping is active in each channel during the active state of the corresponding gate voltage shaping enable signal to selectively connect the signal output of the channel to a defined discharge sink.
16. The level shifter according to claim 13 , wherein the gate voltage shaping is active in each channel during the active state of the corresponding gate voltage shaping enable signal to selectively connect the signal output of the channel to a defined discharge sink.
17. The level shifter according to claim 13 , and further comprising separate channels with control circuitry not supporting gate voltage shaping.
18. The level shifter according to claim 1 , wherein the gate voltage shaping is active in each channel during the active state of the corresponding gate voltage shaping enable signal to selectively connect the signal output of the channel to a defined discharge sink.
19. The level shifter according to claim 18 , and further comprising separate channels with control circuitry not supporting gate voltage shaping.
20. The level shifter according to claim 1 , and further comprising separate channels with control circuitry not supporting gate voltage shaping.