Source Driver Channel Pre-Charge Circuit for Faster DAC Recovery
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Solution Overview
Problem
Conventional source driver channel circuits are limited by the parasitic capacitance of metal wires, which restricts the operation frequency of display panels due to insufficient recovery time of the digital-to-analog converter's output signal.
Innovation Solution
Incorporating a pre-charge circuit that pre-charges the input terminal of the output buffer circuit during a dedicated pre-charge period, allowing the digital-to-analog converter to provide the analog signal directly during normal operation, thereby reducing the recovery time and increasing the operation frequency of the display panel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the operation frequency of the display panel is increased, then the productivity is improved, but the recovery time becomes insufficient due to parasitic capacitance limitations
Solution Approach 1:
The patent applies preliminary action by introducing a pre-charge period before the normal display operation period. During this pre-charge period, the DAC output is disconnected from the data line and the input terminal of the output buffer circuit is pre-charged to the target voltage level through a pre-charge circuit. This preliminary charging action prepares the circuit in advance, so when the normal operation begins, the DAC can immediately switch to new voltage levels without being constrained by the parasitic capacitance discharge time, thereby enabling higher operation frequencies.
2Loss of time
If the metal wire parasitic capacitance is reduced, then the recovery time is improved, but the wiring complexity increases
Solution Approach 1:
The patent applies the extraction principle by separating the pre-charge function from the normal signal transmission path. A dedicated pre-charge circuit is extracted and connected to the input terminal of the output buffer circuit through a switch. During the pre-charge period, the switch connects the pre-charge circuit to the input terminal while disconnecting the DAC output. This extraction allows the pre-charge operation to occur independently without interfering with the normal signal transmission, effectively reducing the impact of parasitic capacitance on recovery time while maintaining manageable wiring complexity.
3Loss of time
If the DAC pushing power is increased, then the recovery time is improved, but the power consumption increases
Solution Approach 1:
The patent applies periodic action by dividing the operation into distinct periods: a pre-charge period and a normal display operation period. During the pre-charge period, the pre-charge circuit activates to charge the input terminal capacitance to the required voltage level. During the normal operation period, the DAC operates at standard power levels to drive the display data. This periodic operation allows the system to achieve fast recovery times through the dedicated pre-charge phase without requiring the DAC to continuously operate at high power, thereby reducing overall power consumption while still meeting the recovery time requirements for high-frequency operation.
Data Source
AI summary
A channel circuit of source driver and an operation method thereof are provided. The channel circuit includes a digital-to-analog converter (DAC), a first switch, an output buffer circuit and a pre-charge circuit. The terminals of the first switch are coupled to the first output terminal of the DAC and the first input terminal of the output buffer circuit, respectively. The pre-charge circuit is coupled to the first input terminal of the output buffer circuit. The pre-charge circuit pre-charges the first input terminal of the output buffer circuit when the first switch is turned off during a pre-charge period, and not to pre-charge the first input terminal of the output buffer circuit when the first switch is turned on during a normal operation period.