| 摘要 |
PURPOSE:To prevent output constant current from dependence on temperature by setting the resistance value of the second tansistor whose base is connected to the base of the first transistor and the emitter is connected to the constant current source through a resistance, to a specified value. CONSTITUTION:When constant current I1 flows in a constant current source 1, this constant current I1 flows to the emitter of the first transistor 2, and constant current I2 having specified relation with above-mentioned constant current I1 flows from the collector of the second transistor 3 to a load 5. It is denoted by I1=VBE/R1 where VBE represents voltage between the base and emitter of a transistor, and R1 represents the resistance value. If the base current of transistors 2 and 3 is neglected, both ends voltage of the resistance 4 VR2 are shown by VR2=R2I2=VBE1-VBE2. The value of constant current I2 is introduced from this value. By differentiating the result by the temperature T and adjusting, the value R2 of resistance 4 is selected to be reduced to finally a specified value, and output constant current I2 becomes independent of the ambient temperature. |
