The functions of capacitors in the single-chip GSM SMS module

Decoupling, bypass, filtering, energy storage.

Bypass refers to equalizing the output of the voltage regulator, and decoupling refers to charging and discharging the capacitor to complete the signal transition. Filtering is the process of charging and discharging. The storage capacitor collects charge through the rectifier and transfers the stored energy to the output of the power supply through the converter leads.