What is a ceramic capacitor?
Ceramic capacitors are used widely. Ceramic capacitors are non-polarized and have a good frequency response because they offer a low ESR and a low ESL. Small capacitance values can withstand voltages as large as 1 kV. Depending on temperature range, temperature drift and tolerance, ceramic capacitors have two active classes: Class 1 and Class 2. Difference Between Class 1 and Class 2 ceramic capacitor?
Ceramic capacitors are available in disc packages with radial leads. Surface mount multilayer ceramic chip (MLCC) capacitors are very popular. The stacking of very thin layers permits MLCC capacitors to provide relatively large values of capacitance at lower voltages.
Class 1 ceramic capacitors
Class 1 ceramic capacitors are accurate and provide temperature compensation inherently. They are the most stable in terms of temperature sensitivity and drift, and they have the lowest losses. Class 1 ceramic capacitors are well suited for resonant circuit applications where stability is critical or where a well-defined temperature coefficient is needed. Consequently, they are used in applications that require a measure of precision, like timers and oscillators. Temperature coefficients are expressed using notation like the following:
N200 means a negative temperature coefficient of 200 ppm/’C
P100 means a positive temperature coefficient of 100 ppm/’C
NP0 means the temperature coefficient is 0 ppm/’C
The Electronics Industry Alliance (EIA) uses the notation COG instead of NP0. Class 1 ceramic capacitors are NP0.
Class 2 ceramic capacitors
Class 2 ceramic capacitors have improved volumetric efficiency, meaning that larger values of capacitance are available with a relatively smaller physical size. However, their tolerance is wider and they are not as stable as Class 1 ceramic capacitors. The ceramic dielectric is characterized by a non-linear change in capacitance over its temperature range. These capacitors are usually selected for use in less critical coupling, decoupling, and bypass applications. They are very susceptible to aging effects.
Class 2 ceramic capacitors exhibit microphony. The dielectric has a piezoelectric characteristic. If the capacitor experiences mechanical vibrations, they can be transformed into electrical signals—like a microphone. The reverse effect can also occur. The varying electric field between the plates will cause them to move like a loudspeaker, and this can generate an audible sound. Sensitive low-level signal processing systems use only Class 1 ceramic capacitors to avoid the microphony effect.
Applications of ceramic capacitors
Ceramic capacitors find applications in various electronic devices and systems due to their advantageous properties such as high capacitance density, reliability, stability, and low cost. Here are some common applications:
Decoupling and Bypass Capacitors: Used in electronic circuits to filter out high-frequency noise and provide stable power supply voltages to integrated circuits (ICs), microcontrollers, and other semiconductor devices. They are crucial for reducing electromagnetic interference (EMI) and maintaining signal integrity.
Timing and Oscillator Circuits: Ceramic capacitors are used in timing circuits and oscillators where precise timing is required. They help determine the frequency of oscillation in various electronic devices such as clocks, timers, and microprocessor-based systems.
Coupling and DC Blocking Capacitors: Ceramic capacitors are used for coupling AC signals while blocking DC signals in amplifier circuits, filters, and audio applications. They allow AC signals to pass through while preventing DC bias from affecting the circuit.
Voltage Regulation: Ceramic capacitors are employed in voltage regulator circuits to stabilize voltage levels and reduce voltage fluctuations. They help improve the transient response and efficiency of voltage regulators in power supply units.
RF and Microwave Circuits: Ceramic capacitors are integral components in RF (Radio Frequency) and microwave circuits due to their high-frequency performance and low parasitic effects. They are used in antennas, RF amplifiers, filters, and matching networks.
Signal Coupling and Filtering: Ceramic capacitors are utilized for signal coupling and filtering in communication systems, data transmission circuits, and sensor interfaces. They help in transmitting and processing signals while rejecting unwanted noise and interference.
Motor Control and Power Electronics: Ceramic capacitors are used in motor control circuits, inverters, and power electronics for energy storage, snubber applications, and noise suppression. They contribute to the efficiency and reliability of motor drives and power conversion systems.
Consumer Electronics: Ceramic capacitors are widely used in consumer electronics such as smartphones, tablets, laptops, TVs, and audio systems. They serve various functions including power supply filtering, audio signal processing, and RF communication.
Automotive Electronics: Ceramic capacitors are employed in automotive electronics for engine control units (ECUs), safety systems, infotainment systems, and sensors. They withstand harsh environmental conditions and contribute to the reliable operation of automotive electronics.
Industrial and Aerospace Applications: Ceramic capacitors are utilized in industrial automation, aerospace, defense, and medical electronics for critical functions such as control systems, instrumentation, avionics, and medical devices. They offer robust performance in demanding environments.