Ceramic and film capacitors are capacitors with a fixed, non-adjustable capacitance. Capacitors are able to store energy and release it later. This implies they have a frequency dependent behaviour.
Typical usage for ceramic and film capacitors are separation (decoupling) from, or combination (coupling) of the AC the signal part and the DC signal part, and in signal filtering.
A ceramic capacitor is capacitor with a fixed capacitance where ceramic material is used as the dielectric. It is constructed of two or more alternating layers of ceramic and a metal layer acting as the electrodes. The composition of the ceramic material defines the electrical behavior and therefore applications.
Ceramic capacitors usually have values in the pF (pico Farad, 1 pF = 1 * 10-12 F) and nF (nano Farad, 1 nF = 1 * 10-9 F) range. They are quite stable over time and temperature, and have a good high frequency behaviour. This makes them ideal to put over the power lines of integrated circuits to stabilize the power supply. Also, the ceramic capacitor is suitable for high voltages.
An alternative to the ceramic capacitor is the film capacitor. Film capacitors use a polymer film as dielectric and are produced differently. They are made out of two pieces of plastic film covered with metallic electrodes, wound into a cylindrical shaped winding, with terminals attached, and then encapsulated.
Film capacitors are also small, well suited for high frequency work, but better sounding in audio applications. They are also available in the higher capacity ranges uF or μF (micro Farad, 1 μF = 1*10-6 F).
Both ceramic and film capacitors are non-polarized (they don’t have a ‘+’ or ‘-‘ side).
For higher capacitance values you can use an electrolytic capacitor.
Most important specifications
- Capacitance (F), usually in the range from pf to μF
- Maximum voltage AC/DC (V)