A current source is an electronic circuit that delivers or absorbs an electric current which is independent of the voltage across it. It is the dual of a voltage source, which delivers a constant voltage regardless of the current flowing through it. An ideal current source generates a current that is independent of the voltage changes across it, and it is a mathematical model that real devices can approach very closely. There are two types of current sources in real life: independent and dependent. An independent current source generates a current that can be specified independently of any other variable in a circuit.
A current source establishes a specified amount of electric current in a portion of a circuit, and the value of the current source is the magnitude of current flow created by the source. When you see a current source in a circuit diagram, you know that the conductive path connected to the current source will have current flow equal to the value of the source.
Current sources are less familiar than voltage sources like batteries and AC wall power, and they are usually buried, unseen, inside electronic circuitry. Current sources generate a current that is unaffected by changes in the load, and they are widely used to send analog process signals over long distances. Current sources are also used in the internal circuits of ICs, especially analog circuits, and they are referred to as current mirrors.
In summary, a current source is an electronic circuit that delivers or absorbs an electric current which is independent of the voltage across it. It establishes a specified amount of electric current in a portion of a circuit, and it is widely used to send analog process signals over long distances.
