| 摘要 |
PURPOSE:To prevent the variation of a bias current due to the fluctuation of an input signal source, by giving the base current of a transistor in the first stage from transistors which have bases connected commonly and are different in conduction type. CONSTITUTION:A base current IB3 of a transistor (TR) Q5 is determined by a grounded emitter current amplification factor hFE3 of a TR Q and a collector current IC1 flowed to TRs Q1 and Q3. A base current IB1 required for driving the TR Q1 is determined by a grounded emitter current amplification factor hFE4 of a TR Q4 and a collector current IC2 flowed to TRs Q4 and Q5. By these relations, the current IB1 is obtained by expression 4. That is, grounded emitter current amplification factors of TRs Q1 and Q3 and TRs Q4 and Q5 are equalized to each other to supply the current IB1 from TRs Q3, Q4, and Q5. |
