Reference current source circuit

摘要

A reference current source circuit comprises a current sink including a pair of transistors having different emitter areas and an emitter resistor connected to the emitter of one of the transistors having greater emitter area, and producing sink currents of the same magnitude which is dependent on the emitter area ratio and the resistance value of the emitter resistor and independent of a supply voltage. In order to supply the current sink with the sink currents, there are used two constant current sources to produce constant source currents of the same magnitude greater than that of the sink currents and a current mirror connected to these constant current sources. The current mirror absorbs surplus currents of a magnitude equal to the difference between the magnitudes of the source current and sink current.