Audio Play Circuit Grounded Coupling Capacitor for Plosive Suppression

The patent applies a dynamic switching mechanism where the coupling capacitor's ground connection is controlled by a switching transistor. The transistor's gate voltage is dynamically adjusted based on the power supply voltage level: during power-on (when VDD < threshold), the transistor conducts and connects the coupling capacitor to ground, suppressing plosive; when fully powered (when VDD >= threshold), the transistor turns off and disconnects the ground connection, reducing power consumption. This dynamic control resolves the contradiction between noise suppression and energy efficiency.

The patent implements preliminary anti-action by proactively connecting the coupling capacitor to ground through the switching transistor before the power amplifier's output node experiences rapid level changes during power-on. This preemptive grounding action prevents the formation of plosive noise by eliminating the voltage differential that would otherwise cause the harmful effect, while still allowing the power amplifier to reach its working voltage quickly. The switching transistor is controlled to maintain this protective grounding only during the critical power-on transition period.