Electronic components are fundamental units that are used in electronic systems to manipulate electrons or their associated fields. These components can be packaged individually or in arrays or networks of similar components, or they can be integrated into packages such as semiconductor integrated circuits, hybrid integrated circuits, or thick film devices. These components are typically industrial products that are sold individually and are not to be confused with electrical elements, which are theoretical representations of idealized electronic components and elements.
Each electronic component has a number of electrical terminals or leads that are used to connect it to other components in an electronic circuit in order to achieve a specific function (such as an amplifier, radio receiver, or oscillator). This list focuses on discrete versions of electronic components, treating packages that contain multiple components as individual components in their own right.
Classification of Components
Electronic components can be classified as passive, active, or electromechanical. According to the strict physics definition, passive components are unable to supply energy on their own, while active components, such as batteries, are able to act as a source of energy.
When analysing circuits, electronic engineers use a more restrictive definition of passivity. In these cases, the DC circuit is ignored and it is assumed that power-supplying components, such as transistors or integrated circuits, have their own internal power source (even though they may actually be powered by the DC circuit in reality). This allows the analysis to focus solely on the AC circuit, an abstraction that ignores DC voltages and currents (and the power associated with them) that may be present in a real circuit. For example, this interpretation allows an oscillator to be viewed as “producing energy,” even though it is actually consuming energy from a DC power source, which has been excluded from the analysis. Using this restriction, the following definitions are used in circuit analysis:
- Active components rely on an external source of energy (usually from the DC circuit, which has been excluded from the analysis) and are able to inject power into a circuit. This is not a requirement of the definition, but is a common characteristic of active components. Examples of active components include amplifying components such as transistors, triode vacuum tubes (valves), and tunnel diodes.
- Passive components are unable to introduce net energy into a circuit and cannot rely on an external source of power, except for what is available from the AC circuit they are connected to. As a result, they are unable to amplify a signal (increase its power), although they may increase a voltage or current (such as is done by a transformer or resonant circuit). Passive components include two-terminal components such as resistors, capacitors, inductors, and transformers.
- Electromechanical components are able to perform electrical operations using moving parts or electrical connections.
Most passive components with more than two terminals can be described in terms of two-port parameters that satisfy the principle of reciprocity, although there are some exceptions. In contrast, active components with more than two terminals generally do not have this property.