Basic knowledge of electronic components, classification and function of ceramic capacitor

Porcelain chip capacitor is often used in audio and high-frequency electronic circuits. The common ceramic chip capacitor has a small capacity, generally from a few pf to a few uf. It is essentially the same as other types of capacitors in terms of function. It is all direct-current AC, but the ceramic chip capacitor has better high-frequency characteristics, and generally plays a role of filtering, coupling, decoupling, vibration, etc. in the circuit.

Classification of ceramic chip capacitance

Ceramic chip capacitors are divided into high-frequency ceramic dielectric and low-frequency ceramic dielectric. Capacitors with small positive capacitance temperature coefficient are used in high stability oscillation circuits as circuit capacitors and pad capacitors. Low-frequency ceramic capacitors are limited to bypass or block DC in the circuit with low working frequency, or in the occasions with low requirements for stability and loss (including high frequency). This kind of capacitor should not be used in pulse circuit because they are easy to be broken down by pulse voltage.

According to the dielectric of ceramic capacitor, it can be divided into Class 1 dielectric (NP0, C0G), Class 2 dielectric (X7R, 2X1) and Class 3 dielectric (Y5V, 2F4) ceramic capacitor.

Role of ceramic chip capacitor

1. Filter function: in the power supply circuit, the rectifier circuit turns AC into pulsating DC, and after the rectifier circuit, a large capacity electrolytic capacitor is connected to make use of its charge-discharge characteristics to make the pulsating DC voltage after rectification become relatively stable DC voltage.

Because large capacity capacitors generally have a certain inductance, which can not effectively filter high-frequency and pulse interference signals, a capacitor with a capacity of 0.001 - 0.1lpF is connected in parallel at both ends to filter high-frequency and pulse interference.

2. Coupling effect: In the process of low frequency signal transmission and amplification, capacitance coupling is often used to prevent the static working points of the front and rear circuits from affecting each other.

3. Decoupling effect: remove the voltage fluctuation caused by the power supply of each part of the circuit to prevent these fluctuations from interfering with each other.

4. Oscillation effect: the ceramic chip capacitor exchanges energy with the parallel inductor, repeatedly charges and discharges, and causes oscillation with the inductor.

Advantages and disadvantages of ceramic capacitor

The capacitance loss of ceramic chip is highly stable with temperature and frequency; It is suitable for high voltage, extremely long-term working reliability, high current climbing rate and non-inductive structure of large current circuit. The disadvantage is that the capacity is relatively small.