Source-follower type analogue buffer, compensating operation method thereof, and display therewith
AssigneeTPO Displays Corp.
InventorsCheng-Ho Yu, Fu-Yuan Hsueh, Wei-Cheng Lin, Keiichi Sano, Ya-Hsiang Tai
Life of this patent
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Abstract
A source-follower-type analogue buffer with an active load, a new compensating operation and a display with the source-follower-type analogue buffers are developed to reduce an error voltage which is the difference between an input voltage and an output voltage of the analogue buffer. The source-follower type analogue buffer can also minimize the variation from both the charging time and the device characteristics and maximize the range of the input voltage.
Claims9
An source-follower type analogue buffer, comprising:
- a storage capacitor, wherein a first terminal of the storage capacitor is connected to an operation voltage source through a first switch (S1), a second terminal of the storage capacitor is connected to an input voltage (Vin) source through a third switch (S3);
- a driving transistor, wherein a gate terminal of the driving transistor is connected to the first terminal of the storage capacitor, a drain terminal of the driving transistor is connected to the operation voltage source, and a source terminal of the driving transistor is connected to the second terminal of the storage capacitor through a second switch (S2);
- and
- an active load, wherein a first terminal of the active load is connected to the source terminal of the driving transistor and an output terminal of the source-follower type analogue buffer through a fourth switch (S4), and a second terminal of the active load is connected to the ground, the active load is controlled by a bias voltage, wherein the input voltage source is connected to the output terminal of the source-follower type analogue buffer through a fifth switch (S5).
A compensating operation method of an analogue buffer, the analogue buffer comprising a driving transistor and a load capacitor, wherein a storage capacitor and a first switch are disposed between a gate terminal and a source terminal of the driving transistor, and a drain terminal of the driving transistor is connected to an operation voltage source, the load capacitor is disposed between an connection of the switch and the source terminal and ground, wherein an input voltage source is connected to an output terminal of the source-follower type analogue buffer through a second switch, wherein the compensating operation method comprising:
- during a compensation period, the first switch is turned on and the storage capacitor is coupled to the operation voltage source, thereby a voltage drop is stored in the storage capacitor;
- and
- during a data-input period, at a first period of the data-input period, an input voltage is applied to a connection between the storage capacitor and the first switch, thereby the gate terminal of the driving transistor is applied with the input voltage and the voltage difference hold in the storage capacitor, and an output voltage of the analogue buffer is compensated by the voltage stored in the storage capacitor, and at a second period of the data-input period, the second switch is turned on and the input voltage source is connected to the output terminal of the source-follower type analogue buffer.
A display having a plurality of source-follower type analogue buffers for driving the load capacitance of a plurality of data buses in the display, each of the source-follower type analogue buffer comprising:
- a storage capacitor, wherein a first terminal of the storage capacitor is connected to an operation voltage source through a first switch (S1), a second terminal of the storage capacitor is connected to an input voltage source through a third switch (S3);
- a driving transistor, wherein a gate terminal of the driving transistor is connected to the first terminal of the storage capacitor, a drain terminal of the driving transistor is connected to the operation voltage source, and a source terminal of the driving transistor is connected to the second terminal of the storage capacitor through a second switch (S2);
- and
- an active load, wherein a first terminal of the active load is connected to the source terminal of the driving transistor and an output terminal of the source-follower type analogue buffer through a fourth switch (S4), and a second terminal of the active load is connected to the ground, the active load is controlled by a bias voltage, wherein the input voltage source is connected to the output terminal of the source-follower type analogue buffer through a fifth switch (S5).
Dependencies are inferred from the claim text.