The difference between SMD inductors and SMD magnetic beads

The difference betweenSMD inductors and SMD magnetic beads

A large number of inductive components and EMI filter components appear in the PCB board circuit of electronic equipment. These components include chip inductors and chip magnetic beads. The following describes the characteristics of these two devices and analyzes their general applications and special applications. The benefits of surface mount components are small package size and the ability to meet physical space requirements. With the exception of impedance value, current-carrying capacity, and other similar physical properties, the other performance characteristics of through-hole connectors and surface mount devices are basically the same.

Where chip inductors are required, the inductors are required to fulfill the following two basic functions: circuit resonance and choke reactance. Resonant circuits include resonance generating circuits, oscillator circuits, clock circuits, pulse circuits, waveform generating circuits and the like. The resonant circuit also includes a high-Q bandpass filter circuit. For a circuit to resonate, both capacitance and inductance must be present in the circuit. There is parasitic capacitance at both ends of the inductor, which is caused by the ferrite body between the two electrodes of the device acting as a capacitive medium. In the resonant circuit, the inductor must have high Q, narrow inductance deviation, and stable temperature coefficient in order to meet the requirements of narrow band and low frequency temperature drift of the resonant circuit. High-Q circuits have sharp resonance peaks. The narrow inductance bias ensures that the resonant frequency deviation is as small as possible. The stable temperature coefficient ensures that the resonant frequency has stable temperature variation characteristics. The difference between standard radial and axial lead-out inductors and chip inductors is only in the packaging. Inductor structures include coils wound on dielectric materials, or air-core coils and coils wound on ferromagnetic materials. In power applications, when used as a choke coil, the main parameters of the inductor are DC resistance (DCR), rated current, and low Q value. When used as a filter, a wide bandwidth characteristic is desired, and therefore, the high-Q characteristic of the inductor is not required. Low DCR guarantees minimal voltage drop. DCR is defined as the DC resistance of a component in the absence of an AC signal.

The main function of the magnetic beads is to eliminate the RF noise existing in the transmission line structure. The RF energy is the AC sine wave component superimposed on the DC transmission level, and the DC component is the required useful signal. To remove these unwanted signal energy, chip beads are used to act as high frequency resistors.