What is the main purpose of a decoupling capacitor in electrical circuits?

The main purpose of a decoupling capacitor in electrical circuits is to stabilize voltage levels and filter out noise. Decoupling capacitors are placed near the power pins of integrated circuits or other components to smooth out voltage fluctuations caused by varying load conditions. When there's a sudden change in current demand, the capacitor can supply or absorb charge, thereby maintaining a stable voltage. This helps prevent unintended interference or noise that might occur from rapid changes in current draw.

Furthermore, decoupling capacitors can filter out high-frequency noise that can couple into power lines, ensuring that sensitive components receive clean and stable power, which is crucial for optimal performance in electronic circuits. This characteristic is particularly important in digital circuits, where noise can lead to erratic behavior and signal integrity issues.