Driver circuit with device variation compensation and operation method thereof

An operation method of a driver circuit, the driver circuit comprising a pull-up switch unit, an isolating switch and a pull-down switch unit, a first terminal and a second terminal of the pull-up switch unit being coupled to a first voltage and an output terminal of the driver circuit respectively, the first voltage being a first system voltage, a first terminal of the isolating switch being coupled to the second terminal of the pull-up switch unit, a first terminal and a second terminal of the pull-down switch unit being coupled to a second terminal of the isolating switch and a second voltage respectively, the second voltage being a second system voltage, the pull-down switch unit comprises a pull-down switch and a capacitor, a first terminal of the pull-down switch is coupled to the second terminal of the isolating switch, a second terminal of the pull-down switch is coupled to the second voltage, a first terminal and a second terminal of the capacitor are coupled to a control terminal of the pull-down switch unit and a control terminal of the pull-down switch respectively, and the operation method comprising:

• turning off the isolating switch when the driver circuit operates in an initialization mode;
• sampling a threshold voltage of the pull-down switch of the pull-down switch unit to obtain a pull-down threshold voltage value when the driver circuit operates in the initialization mode;
• turning on the isolating switch when the driver circuit operates in a normal mode;
• and
• using the pull-down threshold voltage value to compensate an input voltage of the pull-down switch of the pull-down switch unit when the driver circuit operates in the normal mode,
• wherein the step of sampling the threshold voltage of the pull-down switch comprises:
• during a charging period of the initialization mode, coupling the first terminal and the second terminal of the capacitor to the second terminal of the pull-down switch and a third voltage respectively, wherein the third voltage is the first system voltage;
• and
• during a discharging period of the initialization mode, coupling the first terminal of the capacitor to the second terminal of the pull-down switch, and coupling the second terminal of the capacitor to the first terminal and the control terminal of the pull-down switch.

An operation method of a driver circuit, the driver circuit comprising a pull-up switch unit, an isolating switch and a pull-down switch unit, a first terminal and a second terminal of the pull-up switch unit being coupled to a first voltage and an output terminal of the driver circuit respectively, the first voltage being a first system voltage, a first terminal of the isolating switch being coupled to the second terminal of the pull-up switch unit, a first terminal and a second terminal of the pull-down switch unit being coupled to a second terminal of the isolating switch and a second voltage respectively, the second voltage being a second system voltage, the pull-down switch unit comprises a pull-down switch and a capacitor, a first terminal of the pull-down switch is coupled to the second terminal of the isolating switch, a second terminal of the pull-down switch is coupled to the second voltage, a first terminal and a second terminal of the capacitor are coupled to a control terminal of the pull-down switch unit and a control terminal of the pull-down switch respectively, and the operation method comprising:

• turning off the isolating switch when the driver circuit operates in an initialization mode;
• sampling a threshold voltage of the pull-down switch of the pull-down switch unit to obtain a pull-down threshold voltage value when the driver circuit operates in the initialization mode;
• turning on the isolating switch when the driver circuit operates in a normal mode;
• and
• using the pull-down threshold voltage value to compensate an input voltage of the pull-down switch of the pull-down switch unit when the driver circuit operates in the normal mode,
• wherein the step of sampling the threshold voltage of the pull-down switch comprises:
• during a charging period of the initialization mode, coupling the second terminal and the first terminal of the capacitor to a third voltage and a fourth voltage respectively, wherein the third voltage is the first system voltage, and the fourth voltage is the second system voltage;
• and
• during a discharging period of the initialization mode, coupling the first terminal of the capacitor to the fourth voltage, and coupling the second terminal of the capacitor to the first terminal and the control terminal of the pull-down switch.