CONSTANT CURRENT GENERATING CIRCUIT

摘要

PURPOSE:To prevent the variation of the constant current value by connecting the 3rd transistor TR having its current mirror connected to the 1st and 2nd current sources and the 4th TR driven by a starting circuit to the place between the collector of the 1st TR and the common base between the 1st 2nd TR. CONSTITUTION:The transistors TR Q15 and Q16 and a resistance R12 function as a start circuit and the emitter-collector voltage VCE14 of a TR Q14 is approximately equal to the base-emitter voltage VBE14. Thus the Early's effects of both TR Q13 and Q14 are eliminated. While the emitter-collector voltage VCE1 of a TR Q11 is also approximately equal to the emitter-collector voltage VCE12 of a TR Q12. Thus the Early's effects are also eliminated. The constant current thus produced is supplied to the load RL via a TR having the current mirror connection like a TR Q17.