| 摘要 |
PURPOSE:To obtain a DC amplifier which has a low distortion, low noise and high stability, by using a balanced constant current circuit for the load of the 2nd differential amplifying circuit and then giving a control to the balanced constant current circuit from the side of the constant current circuit of the 1st differential amplifying circuit. CONSTITUTION:For the balanced constant current circuit 5, the emitter is connected to the negative current source -V via the resistance RN and the collector is connected to the collectors of transistors (TR)3 and 4 with use of these TR3 and TR4 plus the opposite conduction type TR7 and TR8. The differential amplifying circuit 2 and then circuit 5 are symmetrical to each other to the earth, and the bases of the TR7 and TR8 are connected in common to part of the common emitter circuit of the differential amplifying circuit 1 as well as to one end of the resistance RE which converts the current of the constant current circuit 4 into the voltage. In such way, the distortion of the output Vout can be reduced owing to the good symmetrical property of the output stage. Furthermore, the power supply fluctuation or the noise given from th power source can be reduced since the output resistance R5 is connected to the plus-and minus-power sources +V and -V via the circuits 2 and 5 having the constant current characteristics. |
