Operational amplifier, source driver of a display, and method for controlling the operational amplifier thereof
AssigneeHimax Technologies Limited
InventorChing-Chung Lee
Life of this patent
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Abstract
An operational amplifier includes a first stage, a second stage, and a switching unit. The first stage receives an analog input signal. The second stage has an output node coupled to an output switch. The switching unit is coupled between the first stage and the second stage. The switching unit includes a capacitive component and a first switch coupled to the capacitive component in series. The first switch is turned off when the output switch is turned on. The first switch is turned off while the analog input signal is in transition, and is turned on while the analog input signal is steady. The first switch is turned on when the output switch is turned off.
Claims17
An operational amplifier, comprising:
- a first stage, for receiving an analog input signal;
- a second stage, having an output node coupled to an output switch;
- and
- a switching unit, coupled between the first stage and the second stage, the switching unit comprising:
- a capacitive component;
- and
- a first switch coupled to the capacitive component in series;
- wherein the first switch is turned off when the output switch is turned on;
- and
- during a whole line period that a line of a display is driven, the first switch has a turn-on period and a turn-off period, the output switch has a turn-on period and a turn-off period, and the turn-off period of the first switch is shorter than the turn-on period of the output switch.
A source driver of a display, comprising:
- a digital-to-analog converter, for converting a digital input signal into an analog input signal;
- an output switch;
- and
- an operational amplifier, coupled to the digital-to-analog converter, for driving at least a data line of the display according to the analog input signal via the output switch, the operational amplifier comprising:
- a first stage, for receiving the analog input signal;
- a second stage, having an output node coupled to the output switch;
- and
- a switching unit, coupled between the first stage and the second stage, the switching unit comprising:
- a capacitive component;
- and
- a first switch, coupled to the capacitive component in series;
- wherein the first switch is turned off when the output switch is turned on;
- and
- during a whole line period that a line of the display is driven, the first switch has a turn-on period and a turn-off period, the output switch has a turn-on period and a turn-off period, and the turn-off period of the first switch is shorter than the turn-on period of the output switch.
A method for controlling an operational amplifier, the operational amplifier comprising a first stage for receiving an analog input signal, a second stage having an output node, and a switching unit having a capacitive component and a first switch coupled to the capacitive component in series, the method comprising:
- connecting the switching unit between the first stage and the second stage;
- connecting the output node of the second stage to an output switch;
- and
- turning off the first switch when the output switch is turned on, where during a whole line period that a line of the display is driven, the first switch has a turn-on period and a turn-off period, the output switch has a turn-on period and a turn-off period, and the turn-off period of the first switch is shorter than the turn-on period of the output switch.
An operational amplifier, comprising:
- a first stage, for receiving an analog input signal;
- a second stage, having an output node coupled to an output switch;
- and
- a switching unit, coupled between the first stage and the second stage, the switching unit comprising:
- a capacitive component;
- and
- a first switch, where the capacitive component is coupled between the first stage and the first switch, and the first switch is coupled between the capacitive component and the second stage, the first switch is selectively coupling the capacitive component to the output node of the second stage, and the capacitive component is connected to the output node of the second stage only when the first switch is switched on;
- wherein the first switch is turned off when the output switch is turned on.
Dependencies are inferred from the claim text.