Passive components mainly include resistors, capacitors, inductors, converters, gradients, matching networks, resonators, filters, mixers and switches. An electronic component that can display its characteristics without external power supply. Passive components are mainly resistive, inductive and capacitive devices. Their common feature is that they can work when there is a signal without adding power in the circuit. Capacitor capacitor is also one of the most common components in electronic circuits. It is a component that stores electric energy. The capacitor is composed of two conductors of the same size and quality sandwiched with a layer of insulating medium. When a voltage is applied to both ends of the capacitor, an electric charge will be stored on the capacitor. Once there is no voltage, as long as there is a closed circuit, it will release electric energy. Capacitors prevent DC from passing through the circuit and allow AC to pass through. The higher the frequency of AC, the stronger the passing ability. Therefore, capacitors are often used in circuits for coupling, bypass filtering, feedback, timing and oscillation.