What are the classifications of capacitors?

Capacitors are essential basic components in electronic circuits, with their main function being to store charge and electrical energy. According to different standards, capacitors can be classified in various ways, and understanding these classifications can help to make reasonable selections in practical applications.
Classified by medium material
This is the most common classification method. The medium is the key to determining the performance of capacitors.
Ceramic capacitor: Using ceramics as the dielectric, it has a small volume and good stability, and is commonly used in high-frequency filtering and bypass circuits.
Electrolytic capacitor: Using metal oxide film as the dielectric, with a large capacity to volume ratio, but with positive and negative electrodes. Common ones include aluminum electrolytic capacitors and tantalum electrolytic capacitors, which are commonly used for power filtering and low-frequency coupling.
Thin film capacitor: using plastic film as the dielectric, such as polyester film, polypropylene film, etc. This type of capacitor has stable performance and high accuracy, and is suitable for analog circuits, timing, and filtering applications.
Mica capacitor: Using mica as the dielectric, it has the characteristics of high precision, high stability, and low loss, and is commonly used in circuits with high requirements such as high-frequency oscillation.
Classified by structural characteristics
Divided based on whether the capacitance is adjustable.
Fixed capacitor: This is the most widely used type, whose capacitance remains fixed after production. Most of the capacitors classified by medium mentioned above belong to this category.
Variable capacitor: The capacity can be manually adjusted within a certain range, and it was commonly used for tuning and selecting radio stations in the past. Its derivative type fine-tuning capacitor is used for small-scale capacity correction after circuit calibration.
Classified by purpose and function
In practical circuits, capacitors have different application names based on their roles.
Filter capacitor: usually refers to a large capacity electrolytic capacitor used in power circuits to smooth DC voltage.
Coupling capacitor: connected between two circuits, used to transmit AC signals and block DC bias.
Bypass capacitor: provides a low impedance path for high-frequency interference signals, allowing them to be bypassed to maintain local voltage stability.
Other classification perspectives
Capacitors can also be divided into high-voltage capacitors and low-voltage capacitors according to their operating voltage; According to the pin installation method, it can be divided into lead capacitors and surface mount (SMD) capacitors, with the latter being the mainstream choice in modern microelectronic devices.
Choosing the appropriate capacitor requires comprehensive consideration of various factors such as capacity, rated voltage, dielectric loss, temperature characteristics, size, and cost. The correct selection of capacitors is the foundation for ensuring stable and efficient operation of circuits.