Search results
Results from the WOW.Com Content Network
Another example of frequency dependent capacitance occurs with MOS capacitors, where the slow generation of minority carriers means that at high frequencies the capacitance measures only the majority carrier response, while at low frequencies both types of carrier respond.
The self-discharge constant is an important parameter for the insulation of the dielectric between the electrodes of ceramic and film capacitors. For example, a capacitor can be used as the time-determining component for time relays or for storing a voltage value as in a sample and hold circuits or operational amplifiers.
A simple switched-capacitor parasitic-sensitive integrator. Switched-capacitor simulated resistors can replace the input resistor in an op amp integrator to provide accurate voltage gain and integration. One of the earliest of these circuits is the parasitic-sensitive integrator developed by the Czech engineer Bedrich Hosticka. [3]
In this case, they are called grading capacitors. In schematic diagrams, a capacitor used primarily for DC charge storage is often drawn vertically in circuit diagrams with the lower, more negative, plate drawn as an arc. The straight plate indicates the positive terminal of the device if it is polarized (see electrolytic capacitor).
The largest share of these losses in larger capacitors is usually the frequency dependent ohmic dielectric losses. Regarding the IEC 60384-1 standard, the ohmic losses of capacitors are measured at the same frequency used to measure capacitance. These are: 100 kHz, 1 MHz (preferred) or 10 MHz for ceramic capacitors with C R ≤ 1 nF:
The impedance is a frequency dependent AC resistance and possesses both magnitude and phase at a particular frequency. In data sheets of electrolytic capacitors, only the impedance magnitude |Z| is specified, and simply written as "Z". Regarding to the IEC/EN 60384-1 standard, the impedance values of tantalum electrolytic capacitors are ...
Differential variable capacitors also have two independent stators, but unlike in the butterfly capacitor where capacities on both sides increase equally as the rotor is turned, in a differential variable capacitor one section's capacity will increase while the other section's decreases, keeping the sum of the two stator capacitances constant.
This can be accomplished by placing a DC blocking capacitor with a capacitance about 100 times greater than the maximum capacitance of the varicap diode in series with it and by applying DC from a high impedance source to the node between the varicap cathode and the blocking capacitor as shown in the upper left circuit in the accompanying diagram.