Basic Applications of R/C/L

R—Resistance in electronic circuits consumes energy to meet the voltage and current required in the circuit.
C—Capacitance The function of the inductor in the circuit is to store energy. Through the process of charging and discharging, the voltage in the entire circuit is adjusted and supplemented. This is the basic application of the capacitor.
L—The application of the inductor itself in the circuit is different from the resistor and capacitor in the passive element. The inductor stores energy in the form of a magnetic field and matches the capacitor and resistor in the circuit. Therefore, the inductor has no effect on the increase or decrease of the voltage in the circuit, but only has a corresponding effect on the current. This is the inherent characteristic of the inductor itself.

Inductor use—1/4

Resonance
Resonance circuits are widely used in communication systems. The main purpose is to select the required signal from a variety of frequency signals and reject other signals. The tuned circuit (turned circuits) in the electronic system is a typical example of the application of resonance. It is mainly composed of inductors and capacitors in parallel. In the receiving system, it is used to select signals and reject unnecessary signals; in the transmitting system, it is used to generate specific frequency signals.

Inductor Uses—2/4

Filtering
Filtering is a circuit that can pass or cut off signals in a certain frequency range. The form of filtering circuits, if classified by their filtering characteristics, can be divided into four types: low pass, high pass, band pass, and band reject. Filtering circuits are composed of energy storage elements such as inductors and capacitors. A basic filter circuit may contain one, two or three energy storage elements. The frequency response of the filter characteristics varies with the number of elements.

The characteristic of the impedance of the chip inductor changing with frequency can also be used to suppress high-frequency electromagnetic noise. Such products used to prevent electromagnetic interference are often called chip ferrite beads.

Impedance increases with frequency. At low frequencies, its impedance is extremely low, allowing low-frequency signals to pass through without loss.

At high frequencies, it has a higher impedance, which can effectively suppress the high-order electromagnetic harmonic waves generated by the signal. This type of product is mostly used in the I/O interface of computer systems, and can effectively filter the noise in the 100-300MHZ frequency band in the signal line.

Inductor use—3/4

Impedance matching
When designing high-frequency circuits, impedance matching is a necessary design technology to achieve maximum power transmission between the signal source and the load. If there is impedance mismatch in the path of the signal, reflection will occur, causing electromagnetic interference or signal distortion. When seeking maximum power transmission, in addition to the equal resistance at the transmitting and receiving ends, the reactance of the two must be conjugate, that is, the counterpart of inductance and capacitance, so that they can offset each other and become a pure resistance circuit. Therefore, inductors and capacitors are often combined to form an L-type impedance matching network. Because the load-end reactance is often capacitive, an inductor is often added to the line to make it resonate at the signal frequency, and the reactance values can offset each other to achieve the purpose of impedance matching. L1-L8 is an example of high-frequency chip inductors used as impedance matching in the transmitter of cellular wireless phones.

Inductor Use—4/4
Choke
Choke coils are mainly used to filter ripples in power circuits; RF chokes are used to block high-frequency signals in circuits.