Ceramic Capacity Noise

When capacitors are used for power supply decoupling they serve two roles.

Ceramic capacity noise.

Most dielectrics of ceramic capacitors exhibit a characteristic identified as piezoelectric effects than can cause unexpected signals in certain circuits. Protecting the power source from electrical noise generated within the circuit and protecting the circuit from electrical noise generated by other devices connected to the same power source. Piezoelectric noise piezoelectric effect in mlccs multilayer ceramic chip capacitors mlccs multi layer ceramic capacitor have several advantages low equivalent series resistance esr low equivalent series inductance esl small size non polarized a disadvantage of the mlcc can be thepiezoelectric nature of the. Capable of replacing 2 or more conventional devices the x2y ceramic capacitors are ideal for high frequency filtering or noise suppression of supply voltages in digital circuits and can prove invaluable in meeting stringent emc demands in dc motors in automotive audio sensor and other applications.

However when a capacitor is mounted on a board the vibration increases and when the cycle of the amplitude reaches the audible frequency range 20hz 20khz of humans it can be heard as a noise. Johnson nyquist noise thermal noise johnson noise or nyquist noise is the electronic noise generated by the thermal agitation of the charge carriers usually the electrons inside an electrical conductor at equilibrium which happens regardless of any applied voltage thermal noise is present in all electrical circuits and in sensitive electronic equipment such as radio receivers can. There is almost no noise generated by the capacitor itself.