Current source
![Figure 1: An ideal current source, I, driving a resistor, R, and creating a voltage V](/Images/godic/202501/07/Ohms_law_current_source.svg4658.png")
![Figure 3: In an op-amp voltage-controlled current source the op-amp compensates the voltage drop across the load by adding the same voltage to the exciting input voltage.](/Images/godic/202501/07/V-to-i_op-amp_current_source_10004658.jpg")
![Figure 4: Typical BJT constant current source with negative feedback](/Images/godic/202501/07/Const_cur_src_111.svg4658.png")
![Figure 5: Typical constant current source (CCS) using LED instead of Zener diode](/Images/godic/202501/07/Const_cur_src_113.svg4658.png")
A current source is an electronic circuit that delivers or absorbs an electric current which is independent of the voltage across it.
A current source is the dual of a voltage source. The term, constant-current sink, is sometimes used for sources fed from a negative voltage supply. Figure 1 shows the schematic symbol for an ideal current source, driving a resistor load. There are two types. An independent current source (or sink) delivers a constant current. A dependent current source delivers a current which is proportional to some other voltage or current in the circuit.