Ceramic capacitors are made by coating high-permittivity ceramic dielectric with metal films (usually silver), then sintering at high temperature to form electrodes. They are compact, high-capacitance, stable at high frequencies, and temperature-resistant, making them widely used in consumer electronics.
However, sometimes the actual capacitance of a ceramic capacitor is much lower than its rated value. Is it a defective component? Not necessarily—it could be due to the DC bias effect.
What Is the DC Bias Effect?
The DC bias effect means that as a DC voltage is applied across the capacitor, its capacitance decreases, and the rate of decrease grows as the voltage increases.
When a DC voltage is applied, the actual capacitance drops.
This is especially significant for Class II ceramic capacitors.
Class I vs Class II Ceramic Capacitors
Class I Ceramic Capacitors
Made from non-ferroelectric materials, with low dielectric constant but stable structure.
Capacitance is almost unaffected by DC bias, even within the rated voltage range.
Ideal for RF circuits and high-precision instruments.
Class II Ceramic Capacitors
Made from ferroelectric ceramic materials, with high dielectric constant but unstable structure.
Capacitance varies with external electric field.
Applying DC voltage creates an internal electric field that restricts dipole rotation, which is crucial for storing charge.
As a result, the dielectric constant drops, and actual capacitance decreases.
Higher DC voltages cause more severe capacitance loss, which can impact signal transmission and device performance.
Conclusion
When selecting ceramic capacitors, consider the actual capacitance under DC bias. Choosing based on the nominal value alone may lead to insufficient performance in your circuit. Accounting for DC bias ensures the capacitor performs as intended.
This article is provided by JYH HSU (JEC) Electronics. JEC is a research, development, production, and sales-oriented company specializing in manufacturing and selling various electronic components such as capacitors and resistors.
Post time: Jan-20-2026