Everything You Need to Know About Passive Components

The passage of electrical current through electronic circuits powers and controls the electronic devices we see all around us. Each circuit is a collection of electrical components that work together to accomplish a specific task. According to the job(s) the system must complete, circuits can be designed to perform a wide range of operations, from simple actions to complicated jobs.

What is a passive component?

What exactly are Passive Devices? Energy is not generated by passive devices or components, although they can be stored or dissipated. Passive devices, such as resistors, inductors, capacitors, and transformers, are essential components in any electrical or electronic circuit.’

As their name implies, passive components are electrical components that do not require any electrical power to operate, as opposed to “active devices” such as transistors, operational amplifiers, and integrated circuits, which must be powered in some way to function.

By their nature, passive devices do not contribute gain, amplification, or directionality to a circuit but rather an attenuation, as their gain is always less than one unity. As a result, passive devices cannot generate, oscillate, or amplify an electrical signal.

Passive devices can be employed individually or in series or parallel inside a circuit to control complicated circuits or signals, induce a phase shift in the signal, or provide feedback. Still, they cannot multiply a signal by more than one due to their lack of power gain.

Types of passive components



Capacitors are electrical components that passively store electric energy. The condenser was the name given to them in the past. An insulator separates the electrical conductors in a capacitor. A dielectric is a type of insulating layer.

Although all capacitors have the same essential components, the material used and the configuration can differ significantly. They’re often used in electrical circuits. Allowing only AC and blocking DC are two instances, smoothing a power supply output.

What does a capacitor do?

An electrostatic field formed by a potential difference across the conductors can store energy in a capacitor. When a conductor is exposed to a voltage, one of the capacitor’s plates collects a positive charge while the other is negatively charged. The capacitance in farads is the ratio of this electric charge to the potential difference (voltage). This is the most critical parameter to consider when describing a capacitor.

When the distance between the conductors is small, and the surface of the conductors is large, the capacitance is the highest. Although ideal capacitors are described entirely in terms of capacitance, there are several restrictions in the real world. The conductors and lead wires, for example, create parasitic inductance and resistance. The maximal strength of a static electric field has a limit, which is defined by the breakdown voltage. The leakage current is the current that leaks through the dielectric.

Types of capacitors and their applications

Capacitors come in various shapes and sizes and are used for various applications and functions. The most popular types of capacitors used in electronic circuits are listed below.

Film capacitors

Some options are polyester film, metalized film, polypropylene film, PTE film, and polystyrene film capacitors. The dielectric material utilized to separate them is what sets them apart. Based on its qualities, the dielectric should be chosen with care. Film capacitors have various advantages, including excellent reliability and long life. In high-temperature situations, they are preferred.

Film capacitors

Film-based capacitors are utilized in various automobile electrical devices because they are stable in high-temperature and vibrating situations. Film capacitors’ wide range of applications can also be due to their high voltage handling capabilities.

Ceramic capacitors

These capacitors have a set capacitance and no polarity. As a dielectric material, they use a ceramic substance. The two most prevalent ceramic capacitors are the multi-layer (MLCC) and the ceramic disc capacitor.

Ceramic capacitors

It’s worth noting that ceramic materials are poor conductors of electricity, preventing electric charges from flowing through them. The disadvantage of ceramic capacitors is that their capacitance fluctuates when the temperature changes.

Ceramic capacitors are ideal for high-frequency applications due to their low inductance. They are compact and can be found in a variety of electronic devices, such as televisions, mobile phones, digital camcorders, laptops, and so on.

Electrolytic capacitors

Electrolytic capacitors

The electrode material (aluminum, tantalum, or niobium) and the electrolyte property (wet, solid, or a wet/solid hybrid) can be used to classify them. Because most electrolytic capacitors have polarity, adjusting the polarity at both ends when using DC voltages. Electrolytic capacitors are ideal for DC power supply circuits due to their small size and high capacitance. Coupling and decoupling are two of their applications. Electrolytic capacitors have a low voltage rating, which is a drawback.

Paper capacitors

Paper capacitors

These are made with paper as the dielectric and may store a significant electric charge. These have a capacitance range of 0.001 to 2.000 microfarads and a voltage range of up to 2000V. This capacitor absorbs moisture from the air, lowering the dielectric’s insulating resistance. In filtering applications, paper capacitors are utilized. They can also be used for high-voltage and high-current applications.



A resistor is a two-terminal passive electrical component that implements electrical resistance as a circuit element. Resistors reduce current flow while also lowering voltage levels within circuits. Resistors are employed in electronic circuits for various purposes, including controlling current flow, adjusting signal levels, biasing active devices, and terminating transmission lines.

High-power resistors can be employed in motor controllers, power distribution systems, or as generator test loads because they can dissipate several watts of electrical power as heat. Fixed resistance resistors have resistances that do not fluctuate much with temperature, time, or operating voltage. Variable resistors can be used to alter circuit elements (such as volume control or a lamp dimmer) or as heat, light, humidity, force, or chemical activity sensing devices.

Characteristics of Resistor

The electrical engineer specifies varied resistance qualities depending on the application. The resistance value is the crucial parameter since the primary goal is to limit the flow of electrical current. The resistor tolerance indicates the manufacturing accuracy of this value and is given as a percentage of the resistance value (for example, 5%).

Many other characteristics that affect the resistance value, such as long-term stability and temperature coefficient, can be specified. The resistive material and the mechanical design determine the temperature coefficient, frequently stated in high precision applications.

The parasitic capacitance and inductance of high-frequency circuits, such as radio electronics can cause undesirable effects. Wire wound resistors have the highest parasitic reactance, while foil resistors have the lowest. The electric noise of the resistor must be as minimal as feasible for accurate applications such as audio amplifiers. For a 1 MHz bandwidth, this is generally expressed as microvolts noise per volt of applied power. The power rating is critical for high-power applications.

The maximum operational power that the component can handle without affecting its qualities or causing harm is specified here. The power rating is given in free air at ambient temperature in most cases. Higher power ratings necessitate a larger size, and heat sinks may be required. A variety of different parameters can influence the design specification. The maximum voltage or the pulse stability are two examples. This is a critical feature in situations where significant voltage surges may occur.

In some cases, the designer must consider the electrical quantities and the mechanical robustness in severe settings. Military standards can help determine mechanical strength or failure rate in particular cases.

What Do Resistors Do in a Circuit?

What Do Resistors Do in a Circuit?

Resistors are used in a variety of circuits. The functions listed below are the most frequent; most applications require many resistors in serial or parallel arrangements. Resistors are used in a variety of applications, including:

Potential dividers

When two or more resistors are connected in series, the voltage at their junction point is proportional to their values. This feature is commonly utilized to generate intermediate voltages in circuits.

Biasing resistors

Transistors and many other devices must have their AC and DC operating characteristics and gain levels specified for proper operation. This is known as biasing and is done with multiple resistors.

Op-amp gain and feedback

Most op-amp circuits’ gain and feedback functionality must be set by resistors external to the amplifier chip; resistors are the most common way to do this.

Current limiting

Resistors are used to control how much current passes through a circuit part. Many circuits benefit from this safety feature, limiting the amount of current into an LED to control its brightness.

Impedance matching

The receive and transmit ends of a circuit must have the same impedance to maximize power transmission at high frequencies. At least a portion of this requirement can be met using resistors.

Current measuring

Many circuits need to know how much current is flowing, but measuring voltage is much easier, so using a resistor to ‘generate’ a voltage – recall Ohm’s law – is a common way for measuring current.

Data and address bus pullups

This feature aids in the reduction of noise on high-speed computer buses. When a data bus tri-states or is driven high, it’s common to need to draw it into a known state or ensure that its output high is much above the switching point of other logic elements on the bus, which a pull-up aids in.

What is an inductor

An inductor, often known as a coil, reactor, or choke, is a device that conducts electricity. A two-terminal component stores energy in a magnetic field when current flows through it. The inductor will oppose any variations in current via it when the voltage ratio (to current) varies.

Inductor Applications

Inductors can be made to work in a variety of industries and applications.

Standard mode inductors are employed in high-frequency applications to block noise common to both power leads. Toroidal standard mode inductors are particularly useful in noise reduction and EMI reduction applications in switched-mode circuits.

Differential mode inductors are utilized when a current cannot be canceled by an opposing current (as is the case with most common mode inductors). Other core shapes can better meet the mechanical requirements, but toroidal inductors are ideal for minimum volume and weight high-performance applications.

Inductors can be developed and tailored to match your exact demands, no matter how specific your application is.



A transformer is an electrical component that uses electromagnetic field induction to convert electric current or energy from one coil to another. The magnetic field is used to transfer power from one coil to another. The coils do not have any physical connection. The voltage of electric electricity is increased or decreased using transformers.

What are passive components used for

Passive devices or components do not generate energy, but they can be stored or dissipated. Resistors, inductors, capacitors, and transformers are examples of passive devices used in electronics and are required to make any electrical or electronic circuit.

Difference Between Active and Passive Components

Active components use a voltage or current to supply or produce energy or power. Components that use or store energy in voltage or current are passive components.

  • Diodes, transistors, SCRs, integrated circuits, and other active components are examples. Resistors, capacitor, and inductor are all examples of passive components.
  • Active components can provide power growth, but passive components cannot.
  • Active but passive components can control the current flow. Energy givers are active components, while energy acceptors are passive components.
  • The functioning of the active component does not necessitate the use of an external source, but the operation of the passive component must.


A passive element, as a reminder, is an electrical component that dissipates, stores, and releases energy rather than generating it. Resistances, capacitors, and coils are passive elements (also called inductors). These components are called Rs, Cs, and Ls in the circuit schematics. Active elements, such as amplifiers and digital logic chips, are connected to most circuits.

Electronic components are now used in practically every industry. Electronic components are divided into two categories: passive and active. Electronic components revolutionized the world’s way of life. Electronic components are essential components found in all devices. Everything, from a simple toy to military equipment, is electronic components.

Lastly, if you are looking forward to purchasing passive components, contact ICRFQ, the best passive components in China.

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