| 摘要 |
PURPOSE:To make an amplifier into ICs by connecting a dummy load to the collectors of the 1st and 2nd transistors, negatively feeding back an output supplied to said load to a drive amplifier, and connecting the load to the collectors of the 3rd and fourth transistors. CONSTITUTION:The collectors of the transistors Q7 and Q8 and the emitters of transistors Q9 and Q10 are connected to the bases of transistors Q9 and Q10 with reverse polarities and positive and negative power source terminals T2 and T3, respectively. The emitters of the transistors Q7 and Q8 and the collectors of the transistors Q9 and Q10 are connected to some end of a dummy load resistance R0 and the base of a transistors Q2. When a sound signal is supplied to a terminal T1, it is sequentially current-amplified by transistors Q1-Q10 and supplied to the resistance R0. However, in this case, a 100% negative feedback is applied, and the gain of an amplifier, viewing from the resistance R0, is the same. At that time, since the transistors Q9 and Q10 employ the resistance R0 as a load, oscillation never occurs even if a large amount of negative feedbacks are applied. Thus capacitors C2 and C3 for a high frequency compensation and a capacitor C1 for negative feedback are made unnecessary, thereby facilitating to make the amplifier into ICs.
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