| 摘要 |
PURPOSE:To prevent the change of a DC level shift amount by providing an NPN transistor (TR) so that the collector is connected to an emitter of a PNP TR, connecting the collector of the PNP TR to the base of the NPN TR and at the same time providing a constant current source at the joint area between said collector and base. CONSTITUTION:The collector of a PNP TR Q7 is connected to the emitter of a PNP TR Q4 with the base connected to the collector of the TR Q4 respec tively. At the same time, a constant current source I0 is provided at the joint area between said base and collector. When the base voltage of the TR Q4 is lowered and the TR Q4 is turned on, the electric charge charged to a capaci tor C is discharged. This discharged current is branched to both TRs Q4 and Q7. In other words, only the current that decided by the source I0 flows to the TR Q4. Then the overcurrent higher than the current flowed to the TR Q4 flows with bypass to the TR Q7. |
