| 摘要 |
PURPOSE:To prevent an output dynamic offset from being generated even in an area where a control current is small by setting the bias current of an emitter follower transistor(TR) according to a detected current flowing through a differential TR circuit. CONSTITUTION:Minute currents flow through TRs Q9 and Q12, and one used as bias currents of emitter follower TRs Q3 and Q4. Thus, the minute collector current IC12 of the Q12 is the composite current of the base current IB2 of a differential TR Q2 and the emitter current IE4 of the emitter follower TR Q4. Therefore, the base current IB4 of the TR Q4 is obtained by dividing its emitter current IE4 by a current amplification factor and its absolute value is extremely small. Settings of current values can be selected variously by varying the current ratio of the current mirror circuit composed of TRs Q14, Q13, and Q15, and the current mirror circuit consisting of TRs Q8 and Q9, and Q11 and Q12. |
