Quality factor
By Howard Johnson, PhD -- EDN, 12/5/2005
This article is a good intro to some of the considerations in choosing different types of caps for different applications.
By Howard Johnson, PhD -- EDN, 12/5/2005
What matters most in a capacitor depends entirely on how you use it.
For example, capacitors in the Electra pulsed-power fusion-ignition system
require a voltage rating of at least 5 million volts, with an incredible
energy-storage density. Solution? Build a massive coaxial structure and fill
it with water (Reference 1).
A 1V switching power supply has vastly different requirements. This design
needs capacitors with low ESR (equivalent series resistance). Switching
power designs surge huge currents through the capacitors, back and forth,
constantly charging them up and down.
...
Specifications having to do with initial tolerance, temperature drift, and
long-term stability govern the inherent accuracy of your circuits. These
specifications require stable, accurately machined dielectric materials.
Properly aged, low-dielectric-constant ceramic materials fit this
bill.
For example, capacitors in the Electra pulsed-power fusion-ignition system
require a voltage rating of at least 5 million volts, with an incredible
energy-storage density. Solution? Build a massive coaxial structure and fill
it with water (Reference 1).
A 1V switching power supply has vastly different requirements. This design
needs capacitors with low ESR (equivalent series resistance). Switching
power designs surge huge currents through the capacitors, back and forth,
constantly charging them up and down.
...
Specifications having to do with initial tolerance, temperature drift, and
long-term stability govern the inherent accuracy of your circuits. These
specifications require stable, accurately machined dielectric materials.
Properly aged, low-dielectric-constant ceramic materials fit this
bill.