Ceramic Capacitors

Ceramic capacitors are among the most widely used capacitor types in the electronics industry. Both SMD and through-hole versions are used in very large quantities across many different electronic circuits.

As the name suggests, ceramic capacitors use a ceramic dielectric material between their electrodes. This dielectric structure gives them several useful properties, such as low ESR, good high-frequency performance and stable behavior depending on the ceramic material used.

However, not all ceramic capacitors behave in the same way. Their electrical performance can change significantly depending on the dielectric class, capacitance value, package size, voltage rating and operating conditions.

Figure 1: (A) A series of THT ceramic capacitors. (B) A series of SMT ceramic capacitors.

General Characteristics of Ceramic Capacitors

Ceramic dielectric materials generally provide lower capacitance per volume compared with some other dielectric technologies. For this reason, ceramic capacitors are commonly found in capacitance values from picofarad levels up to microfarad levels.

In practice, they are especially dominant at capacitance values below 1 µF. Their small size, wide availability, low ESR and good performance from low-frequency circuits up to RF applications make them one of the most preferred capacitor families.

Ceramic capacitors are commonly used for:

• decoupling,

• bypassing,

• filtering,

• timing circuits,

• oscillator circuits,

• RF and high-frequency applications,

• general-purpose signal and power rail conditioning.

Common Ceramic Capacitor Types

Ceramic capacitors are produced in different physical forms depending on the application and mounting method. Some of the most common types are MLCC capacitors, feed-through capacitors and ceramic disk capacitors.

Figure 2: (A) MLCC, (B) feed-through, and (C) ceramic disc capacitors.

MLCC Capacitors

MLCC stands for multilayer ceramic capacitor. It is the most widely used ceramic capacitor type in modern electronic circuits.

An MLCC is formed by stacking many thin ceramic dielectric layers and internal electrode layers together. This multilayer structure allows relatively high capacitance values to be obtained in a very small package.

MLCCs are widely used in power supply decoupling, signal filtering, high-frequency bypassing and many compact electronic designs.

Feed-Through Capacitors

Feed-through capacitors are commonly used in RF and EMI filtering applications. Their structure provides a low-impedance path for high-frequency noise to return to the reference potential, usually ground.

In this way, high-frequency noise components that may be coupled onto a signal or supply line can be filtered before reaching the sensitive part of the circuit.

Ceramic Disk Capacitors

Ceramic disk capacitors are among the most common through-hole ceramic capacitor types. They take their name from their disk-shaped ceramic body.

They are typically formed by coating a ceramic disk with conductive electrodes and then applying a protective resin coating. They can be used in general-purpose circuits, filtering, coupling and some high-voltage applications depending on their type and rating.

Ceramic Capacitor Classes

Ceramic capacitors are grouped into different classes according to their dielectric characteristics and electrical performance. This classification helps designers choose a suitable capacitor according to the needs of the circuit.

The dielectric material directly affects capacitance stability, tolerance, temperature behavior, voltage dependency, losses and aging characteristics.

Common ceramic dielectric types include C0G/NP0, X7R, X5R, Y5V and Z5U.

Class 1 Ceramic Capacitors

Class 1 ceramic capacitors offer the highest stability and lowest losses among ceramic capacitor classes. They have very good temperature stability, low capacitance tolerance and low dissipation.

Because of these properties, they are well suited for oscillator circuits, resonant circuits, filters, timing circuits and other applications where capacitor stability is important.

C0G, also known as NP0, is one of the most widely used Class 1 dielectric types. It provides very stable capacitance over a wide temperature range and is preferred when predictable capacitor behavior is required.

For Class 1 ceramic capacitors, a three-character EIA code is used to describe the temperature coefficient and tolerance behavior.

Character	Meaning
First character	Significant figure of the temperature coefficient
Second character	Multiplier
Third character	Tolerance of the temperature coefficient

A simplified Class 1 code table can be shown as follows:

Code	Temperature Coefficient
C0G / NP0	0 ± 30 ppm/°C
U2J	-750 ± 120 ppm/°C
P2G	+150 ± 30 ppm/°C
N750	-750 ppm/°C nominal

Among these options, C0G/NP0 is especially common because it provides very stable capacitance and low loss. For this reason, it is frequently used in timing, filtering, oscillator and RF-related circuits.

Class 2 Ceramic Capacitors

Class 2 ceramic capacitors provide higher capacitance values in the same physical size compared with Class 1 capacitors. This is possible because Class 2 dielectric materials have higher dielectric constants.

However, this advantage comes with lower stability. Class 2 capacitors may show capacitance variation with temperature, applied DC voltage, aging and operating conditions.

For this reason, Class 2 capacitors are preferred in applications where high capacitance and small size are more important than precise capacitance stability.

X7R and X5R are common Class 2 dielectric types. They are frequently used for decoupling and filtering in digital circuits, power rails and general-purpose electronic designs.

Y5V and Z5U can provide high capacitance values, but their capacitance variation can be much larger. Therefore, they should be selected carefully when the actual capacitance value under operating conditions is important.

For Class 2 ceramic capacitors, a three-character EIA code is used to describe the operating temperature range and capacitance change over that range.

Character	Meaning
First character	Minimum operating temperature
Second character	Maximum operating temperature
Third character	Capacitance change over the temperature range

The following table shows common Class 2 dielectric codes:

Code	Operating Temperature Range	Capacitance Change
X7R	-55 °C to +125 °C	±15%
X5R	-55 °C to +85 °C	±15%
Y5V	-30 °C to +85 °C	+22% / -82%
Z5U	+10 °C to +85 °C	+22% / -56%

This table is useful because the code does not only identify the material family; it also gives a quick indication of how much the capacitance may change with temperature.

Class 3 Ceramic Capacitors

Class 3 ceramic capacitors can provide even higher capacitance values compared with Class 1 and Class 2 types in similar physical dimensions. However, this comes with significant disadvantages.

They generally have wide tolerance ranges, nonlinear temperature characteristics, higher losses, poor voltage stability and stronger aging effects.

Because of these limitations, Class 3 capacitors should be used carefully. Even in applications such as DC blocking, coupling or decoupling, their temperature behavior, voltage dependency and aging characteristics should be considered.

Comparison of Ceramic Capacitor Classes

The basic differences between ceramic capacitor classes can be summarized as follows:

Class	Main Advantage	Main Limitation	Typical Use
Class 1	High stability and low loss	Lower capacitance values	Timing, oscillator, resonant and RF circuits
Class 2	Higher capacitance in small size	Capacitance changes with temperature, voltage and aging	Decoupling, bypassing and filtering
Class 3	Very high capacitance density	Poor stability and higher losses	Limited general-purpose use where precision is not critical

Summary

Ceramic capacitors are compact, widely available and highly useful components for many electronic circuits. They offer very good performance in high-frequency applications and can be found in stable, low-tolerance dielectric types when needed.

However, ceramic capacitor selection should not be based only on capacitance value. Dielectric class, voltage rating, capacitance change with DC bias, temperature stability, package size and application frequency should all be considered.

A simple summary table can be given as follows:

Parameter	Notes
Capacitance range	Commonly from 1 pF to 100 µF
Rated voltage range	Typically from a few volts up to high-voltage versions depending on type
Advantages	Small size, low ESR, good high-frequency performance, stable Class 1 options
Disadvantages	Lower capacitance than polarized capacitors, capacitance variation in Class 2 and Class 3 types