Inside the chip are thousands of transistors that make up internal gates, combinational logic, registers, counters, delay lines, state machines, and other logic functions. As the integration level of the chip becomes higher and higher, the number of internal transistors becomes larger and larger. The chip has a limited number of external pins, and it is not practical to provide a single power supply pin for a transistor. The external power supply pin of the chip provides a common power supply node for the internal transistors, so the transition of the internal transistor states will inevitably cause the transmission of power supply noise inside the chip.