In general, how should we choose a suitable capacitor for our circuit? I believe that it should be based on the following considerations:
1. Electrostatic capacity;
2, rated pressure;
3. Tolerance error;
4, the amount of capacitance change under DC bias;
5, noise level;
6, the type of capacitor;
7, the specifications of the capacitor.
So, is there a shortcut to find? In fact, the capacitor as a peripheral component of the device, almost every device's Datasheet or Solutions, more clearly specify the selection parameters of the peripheral components, that is, according to this, the basic device can be obtained Select the requirements and then further refine the refinement.
In fact, when choosing a capacitor, it is not only about the capacity and the package. It depends on the environment in which the product is used. Special circuits must use special capacitors.
The following is a classification of chip capacitors based on the dielectric constant of the dielectric. The dielectric constant directly affects the stability of the circuit.
NP0 or CH (K < 150): The electrical performance is the most stable, basically does not change with temperature, voltage and time, suitable for high-frequency circuits with high stability requirements. In view of the small K value, it is difficult to have a large capacity capacitor in the 0402, 0603, and 0805 packages. Such as 0603 is generally the largest 10nF or less.
X7R or YB (2000 < K < 4000 ): The electrical performance is relatively stable, and the change in performance is not significant when temperature, voltage and time change (∆C < ±10%). Suitable for DC blocking, coupling, bypass and full frequency identification circuits that do not require high capacity stability.
Y5V or YF (K > 15000): The capacity stability is worse than X7R (∆C < +20% ～ -80%). The capacity and loss are sensitive to the test conditions such as temperature and voltage, but because of its large K value, Applicable to some occasions with high capacitance requirements.
