DC Bias Characteristics of Ceramic Capacitors Written By: Simon Cen Abstract: Most electrical engineers are at least familiar with the different ratings of ceramic capacitors, such as C0G and X7R. In many applications, the meaning of these character codes is relatively unimportant as some other factor, like price or size, may be driving component selection. Designers must be wary, however, as choosing the wrong combination of capacitor dielectric and applied voltage can have critical performance implications for the associated circuit. For class two dielectrics, the change in bulk capacitance with DC bias can be substantial. Understanding why this happens and how to choose a proper ceramic capacitor can eliminate this common pitfall.
Technical Articles / Whitepapers
Low Inductance Capacitors for High-Speed Decoupling Written By: Robert Lu Abstract: Modern integrated circuits (IC’s) consume power at rapidly varying rates due to the density of circuits on-board and the extreme speed at which they can operate. Power supplies are required to respond to these changes in load current while maintaining a constant operating voltage. This task is becoming increasingly difficult as the complexity of power distribution networks grows and printed circuit board (PCB) design requires optimization for parasitic inductance and capacitance. Therefore, any power supply performance slack must be absorbed by the all-too-common decoupling capacitor. As shown in Figure 1, a decoupling capacitor is simply an additional parallel capacitance that provides a stable voltage and source of current when
Polymer Solid Electrolytic Capacitors for Automotive Applications Written By: Jaroslav Tomasko | Slavomir Pala Abstract: Tantalum electrolytic capacitors are constructed using a sintered pellet of powdered tantalum as the anode of the device. A grown oxide layer on the contoured surface of the pellet acts as the dielectric insulator, and a cathode terminal is formed using either a conventional MnO2 electrolyte or a conductive polymer to sufficiently contact the oxide layer. The final capacitor can be packaged in many forms, and the typical J-lead surface mount construction is shown in Figure 2. The capacitive structure is bonded to a molded case and electrically interfaced using carbon as a separation layer and silver for connection with the lead frame.
Analysis of the DC Blocking Capacitor for Stereo High-Fidelity Audio Written By: Rick Liu Abstract: The representation of audio signals in analog and digital electronics can take many forms. Still, they must ultimately be converted back to their mechanical origins as the motion of air molecules propagating as waves. These waves are generated by moving a mass, often the cone of a speaker, back and forth around a neutral position. As such, any fixed offset in the audio signal, represented by a DC bias, is simply a waste of energy and possibly a source of imbalance in the resulting sound wave. Series blocking capacitors are generally used for each audio channel to eliminate the potential of any DC component. While
Variability and Tolerance of Ceramic Capacitors Written By: Robert Lu Abstract: The multi-layer ceramic capacitor (MLCC) is one of the most common capacitor varieties found in electronic design. It offers a wide range of bulk capacitance and voltage tolerance in numerous form factors at relatively low cost. While these devices have become commonplace in the designers’ tool chest, they exhibit some often overlooked peculiarities. Of primary concern is the sensitivity of effective capacitance to several environmental factors, including temperature, applied bias voltage, and age. If these factors are unaccounted for, the risk of product failure becomes very real, especially in manufacturing variability and overall tolerance stack-up.
Platform Structure Clock Oscillators Written By: Toshihiko Koyanagi Abstract: Numerous devices in people‘s lives today are becoming more sophisticated. As a result, the number of crystal devices installed is increasing. For example, with the evolution of autonomous driving, we are using crystal devices for many functions such as sensor systems to detect distance, camera systems to capture images, image processing systems to process captured images, and communication systems to communicate many of those digital data in and out of the vehicle at high speed. In addition, in the network market, the number of crystal devices is increasing along with the further increase in the speed of communication devices, as well as the increase in the frequency and precision. This paper
SuperCapacitor Improvements on Small Generator Power Quality Written By: Ron Demcko | Ashley Stanziola | Daniel West Abstract: To expand portable electronics usage/reach/offering, the renewable power industry has taken an interest in the worldwide awareness of climate change and electronic waste, specifically how batteries affect the environment. One advancement is the emergence of modern low power hand crank generators, which roughly coincides with the accelerating interest in green energy used in portable electronics.
Predicting Metal Film Capacitor Lifetime Using Thermal Simulation Written By: Youssef Laamimat Abstract: In high-power applications like electric vehicles (EVs), customized metal film capacitors are often required to meet energy demands in a specific form factor. These capacitors exhibit a strong temperature dependence of their bulk capacitance over time, which directly limits their total service life. To maximize lifetime while minimizing space requirements, it is important to include accurate thermal simulation as part of the design process to ensure optimized and evenly distributed heat generation.
SuperCapacitors: A Reliable Backup Power Solution Written By: Johnson Jiang Abstract: Electric double-layer capacitors (EDLCs) are electrochemical capacitors called “SuperCapacitors,” or supercaps, due to their high energy density. Compared to traditional electrolytic capacitors, SuperCapacitors store electrical energy about two to three orders of magnitude higher and achieve several hundred thousand to millions of charge-discharge cycles. This advantage comes from the special construction of SuperCapacitors.
Electrostatic Protection Using Ceramic Capacitors Written By: Oliver Zimmermann | John McCarry Abstract: Any conductive interface between an electrical circuit and the outside world introduces the possibility of damage through electrostatic discharge (ESD). Accumulated static charge on a person, a cable, or any similar surface can readily dissipate its stored potential energy upon contact into sensitive components resulting in highly destructive currents. Ideally, varistors and TVS diodes only activate to protect the circuit when a high voltage is present and impart no parasitic effects during normal operation. For high-speed data lines, in particular, it is critical that the protection device introduce as little capacitance as possible (Electronic Design). TVS diodes and varistors are therefore specified not only by their voltage