Current source

A current source is a circuit element that supplies a specified current, ideally independent of the voltage across its terminals. Real sources maintain the target current only within limits set by their design and operating conditions.

Ideal current source: A theoretical circuit element that delivers fixed current at any terminal voltage. It states the defining behavior that practical current sources approximate.
Electric current: The rate at which electric charge passes through a surface. A source specifies this flow rate rather than prescribing a terminal voltage.
LED driver: An electronic circuit that regulates current supplied to one or more light-emitting diodes. LED brightness and safe operation depend on controlled forward current.
Voltage source: A circuit element that maintains a specified terminal voltage, ideally independent of load current. It fixes voltage while a current source fixes current.
Current mirror: A transistor circuit that copies a reference current into one or more branches. It is a common integrated-circuit implementation of current-source behavior.
Voltage: The electric potential difference between two points. The load and source together determine the voltage needed to sustain the specified current.
Constant-current source: A circuit designed to maintain nearly fixed current through a load over a specified operating range. This practical device is the usual implementation of the ideal circuit element.
Thevenin's theorem: A theorem that represents a linear two-terminal network as an ideal voltage source in series with a resistance. Its voltage-source form contrasts with the Norton model's current-source form.
Transconductance: The ratio of output current change to input voltage change in an electronic device or circuit. Transconductance lets a voltage-controlled device produce a controlled output current.
Ohm's law: The relation between voltage, current, and resistance in an ohmic conductor. It predicts the voltage a resistive load requires at the source's set current.

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Millman's theoremRelated: A current source connected to the node contributes directly to the current-balance numerator.