It should be understood that in the circuit, the inductance that exists due to the distribution of wire wiring and components is called distributed inductance.
For example, an electrolytic capacitor is a two-layer film rolled up. This rolled structure has a certain inductance at high frequencies. Its effect on the circuit is equivalent to that of a inductor connected to the circuit. This inductance value is distributed inductance. According to the frequency characteristics of the inductor, it can be known that because the value of the distributed inductor is generally small, the influence of the distributed inductor can not be considered at the low frequency, but for the high-frequency AC circuit, the influence of the distributed inductor can not be ignored.
1. Distribution parameters(distributed capacitance and distributed inductance) of wire winding precision resistors and potentiators
Since there are distribution parameters for precision resistors and potentiometers for wire winding, when there are more ramps for precision resistors and potentiometers, there is often a non-inductive winding method, that is, the number of ramps for positive winding and reverse winding. The same number of ramps is used to minimize distributed inductors.
2. Distribution parameters of transmission cables
A transmission cable can be regarded as an equivalent circuit composed of a distributed capacitor, a distributed inductance, and a resistor.
3. Distribution parameters of lead of printing plate
For the lead on the high frequency circuit printing board, its distributed inductance can not be ignored. Remove these distributed inductance effects and widen the power cord and ground line to reduce the impedance of the power cord and ground line.
4. Distribution parameters of connectors
The plug-in on the circuit board has a 520nH distributed inductance. Double inline(24) pin integrated circuit socket with a distributed inductance of 4 to 18 nH.
5. Distribution parameters of capacitors
The actual capacitor is different from the "ideal" capacitor. Because of its packaging, material, etc., the "actual" capacitor has only an additional characteristic of inductance and resistance. Single-chip ceramic capacitors have a very low equivalent series inductance, that is, they have a wide decoupling band, so they are more suitable for use as decoupling capacitors for high-frequency circuits.
In summary, these small distribution parameters are negligible for circuits at lower frequencies; In high-frequency circuits, attention must be paid.