variable inductor

What Is a Variable Inductor?

The variable inductor is a device that can be tuned to a specific frequency. It is used in tunable filters, oscillators and impedance-matching circuits. It is also highly reliable and has a high Q factor.

The variable inductor consists of multiple coils wrapped around a core, which are called taps. By connecting these taps properly, engineers can adjust the inductance value of the device.

Modifiable magnetic core

The movable magnetic core of a variable inductor is an important part of the circuit, since it allows the value of the inductance to be changed. This is because the inductance value depends on the magnetic permeability of the core. The higher the permeability of the core, the more inductive reactance it has.

This is because a higher permeability means that more current can pass through the core. However, increasing the permeability of a magnetic core will also increase its losses. To avoid this, the movable magnetic core must be designed so that the loss is as low as possible.

In order to achieve this, the inductor is built with a control winding that is wound around one outer leg of the EE core. This control winding consists of a number of turns and is controlled by a switch. When the switch is closed, it generates a control magnetic flux that opposes the inductor magnetic flux in one or more shared high-permeability sections of the EE core.

In an alternative method, a secondary coupling coil is used to provide control current to the core. This coil occupies different percentages of the projection area of the primary coil. As a result, the inductance changes when the primary coil is short-circuited. This method of variable inductance has been used successfully in ballasts for HID lamps.

Parasitic capacitance

The parasitic capacitance of a variable inductor can affect signal integrity. This is because the impedance of a circuit depends on both its capacitance and inductance. Impedance mismatch caused by parasitic capacitance can displaylink adapter cause reflections, leading to noise. This is why it is important to use a PCB layout that limits parasitic capacitance.

The best way to reduce parasitic capacitance is to use a larger area between signal lines. This will help you avoid cross-coupling and improve signal transmission. In addition, you should minimize the number of vias in a circuit. This will reduce the total capacitance and inductance of the signal lines.

Parasitic capacitance is also affected by the number of helix turns and the copper wire gauge. For example, the lump-sum parasitic capacitance of a 10 nF capacitor increases linearly with the number of helix turns. However, the turn-to-turn parasitic capacitance does not increase with the number of helix turns. This is because the helix turns have a similar effect on the overall structure of the capacitor.

The parasitic capacitance of a VPI can be determined using a PCB modeling software, such as EMI Analyst. It has a built-in model Analog multiplier for real components and accurately reflects their impedance characteristics. This makes it easy to extract the element values needed for EMI filter and emissions calculations.

High frequency performance

A variable inductor is a passive component that stores energy in a magnetic field when current flows through it. It has good RF performance and can be used in a variety of circuits, such as filters, VCOs, and impedance matching networks. The inductance can be changed by inserting and moving a magnetic core. This type of inductor is also known as a choke.

Variable inductor performance is dependent on the design of its coil stack and the distance between layers. It is important to keep these factors in mind when designing the inductor, especially at higher frequencies. This is because the inductance may change with the frequency of the signal, affecting the performance of the circuit.

Another factor to consider when designing a variable inductor is the amount of core loss. A variable inductor with a high core loss will have lower inductance tuning performance, but is still useful for many applications. Consequently, the inductor design must be optimized to maximize performance.

The variable inductor consists of two or three windings that are connected to a movable ferrite or iron core. Each winding can be disconnected and connected at different points, which are called taps. Engineers can use these taps to adjust the inductance of the device. This allows them to achieve the exact inductance they need for a specific application.


A variable inductor is an electronic component that is used to adjust the inductance of a circuit. It consists of a magnetic core that is capable of storing electrical energy. The inductor is designed to have a cylindrical shape and a high quality factor (Q-factor). It also has low parasitic capacitance. This makes it suitable for high-frequency applications.

The inductor can be fabricated by winding a copper wire around a hollow cylinder. This design enables the inductor to change its inductance value, depending on the desired frequency. It can also be modified by changing the number of turns of the coil. However, this design has limitations that make it unsuitable for certain circuits.

Variable inductors are commonly used in radio & other high frequency-based applications. They are also employed in coupling & timing circuits. These components have excellent high frequency performance and are highly sensitive. They are also ideal for use in power factor correction panels.

The variable inductor consists of an inductor winding and a control winding. A dc bias current IBIAS flows through the control winding, producing a bias magnetic flux PhC that is superimposed on the main magnetic flux produced by the inductor current. The two windings are separated by a non-magnetic gap, preventing unwanted induced ac currents and power losses in the control winding.

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