We start with a typical logic circuit and discuss the local decoupling design method. Figure 7 is a typical NOT GATE circuit. When the input (Input) is low, Q1 is turned on, pulling the base of Q2 low, so the base of Q4 is pulled low, Q3 is turned on, and the output (Output) is high. In the actual circuit design, the devices are connected to each other to form a complete system, so there must be mutual influence between the devices. As an example, let’s cascade two NOT gates, as shown in Figure 8, to see how the two devices interact with each other. The ideal situation should be: the input of the first NOT gate is logic low (logic 0), and its output is high, and the input of the second NOT gate is the output of the first one, which is also high, so the second A NOT gate outputs a low level.