Amplifier Output Circuit for Capacitive Load Ringing Suppression
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Solution Overview
Problem
Existing display drivers experience ringing in output voltage, leading to prolonged convergence time to the target voltage when driving a capacitive load, due to hindered charge transfer caused by overshoot and undershoot.
Innovation Solution
A circuit device with an amplifier circuit and a voltage output circuit that overdrives the output voltage above the D/A conversion voltage when the driving voltage overshoots, reducing voltage difference and eliminating or reducing undershoot, thereby accelerating charging of the capacitive load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the amplifier circuit controls the output voltage based on feedback, then the output voltage is regulated to the target voltage, but ringing occurs in the output voltage, resulting in longer convergence time
Solution Approach 1:
The voltage output circuit performs preliminary action by raising the output voltage above the D/A conversion voltage before the amplifier circuit completes its feedback regulation. This anticipatory overdrive ensures that when the amplifier circuit finishes regulating, the output voltage has already reached or exceeded the target voltage, eliminating the need for prolonged feedback adjustment and preventing ringing oscillations.
2Reliability
If the amplifier circuit drives a capacitive load, then the output voltage is regulated, but charge transfer to the capacitor is hindered by ringing, prolonging the convergence time
Solution Approach 1:
The voltage output circuit applies preliminary action by preemptively increasing the output voltage above the D/A conversion voltage. This ensures that sufficient voltage headroom is available to drive charge transfer to the capacitive load without being hindered by subsequent ringing or voltage drops during the amplifier's feedback regulation phase.
3Speed
If the output voltage is increased to accelerate charging of the capacitive load, then charging speed improves, but voltage overshoot occurs, causing ringing
Solution Approach 1:
The voltage output circuit performs preliminary action by raising the output voltage above the D/A conversion voltage at the appropriate moment. This timed overdrive accelerates charging speed while the amplifier circuit simultaneously performs feedback regulation to prevent excessive overshoot and ringing, achieving both fast charging and voltage stability.
Solution Approach 2:
The amplifier circuit uses feedback control to monitor the output voltage and adjust its output accordingly. When the voltage output circuit raises the output voltage above the D/A conversion voltage, the amplifier circuit detects this through feedback and reduces its contribution, preventing excessive overshoot and ringing while maintaining the accelerated charging effect.
Data Source
AI summary
A circuit device includes an amplifier circuit and a voltage output circuit. An output terminal of the amplifier circuit is coupled to an inverted input terminal of the amplifier circuit. The amplifier circuit outputs a driving voltage to a capacitive load. The voltage output circuit outputs, to a non-inverted input terminal of the amplifier circuit, an output voltage corresponding to a D/A conversion voltage of input data. The voltage output circuit raises the output voltage above the D/A conversion voltage when the driving voltage overshoots the D/A conversion voltage due to a change of the input data in a positive direction.