| 摘要 |
PURPOSE:To obtain an output waveform without dependancy of a power supply voltage by holding a base current when an output transistor (Tr) is turned on to a constant value even if a power supply voltage is fluctuated. CONSTITUTION:A TrQ12 is biased by constituting a constant current circuit with a resistor R7 and Trs Q7, Q8, Q9, Q11 of diode connection. A base current IB when an output TrQ5 is turned on is a difference between current I1 and I2, where I1 is a current flowing to a resistor R4 at input H level and I2 is a collector current of a TrQ12, and the relation of IB=VBE/R7 is obtained when the resistance value of the resistors R4 and R7 is selected identically and the circuit is immune to the effect of the power supply voltage. Thus, even if the power supply voltage is fluctuated, the depth of the saturation of the output Tr is kept constant and a stable output waveform is obtained. |
