| 摘要 |
PURPOSE:To improve the stability as a negative feedback amplifier at balancing and to improve the response at the transient state by setting the operating current somewhat large when the differential input voltage is unbalanced. CONSTITUTION:When a voltage V11 impressed to an input terminal (a) is constant, voltages V12, V0 at an input terminal (b) and an output terminal (b) are equal to the voltage V11 by the negative feedback operation. When the voltage V11 causes a positive step change at a time t1, the voltages V12, V0 do not follow instantly to the voltage V11, the base-emitter of a transistor (TR) Q14 is biased forward, TRs Q14, Q16 are turned on and a constant current I1' is increased. When the difference between the voltage V11 and the voltages V12, V0 is below the base-emitter forward voltage VBE of the TR Q2 at a time t2 next, the TRs Q14, Q16 are turned off and the current I1' is decreased to the current I1. Then the voltage V11 and the voltages V12, V0 are equal at a time t3 and the operational amplifier is made stable in the balancing state.
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