| 摘要 |
PURPOSE:To improve the S/N and to suppress the generation of distortion by inserting a diode having a forward resistance changed in response to the same forward current as to that of an equivalent emitter resistance of a differential transistor(TR) to the emitter of the TR. CONSTITUTION:Diodes D1, D2 having the forward resistance changed in response to the same forward current as the equivalent emitter resistor of the differential TRs Q4, Q5 are inserted respectively to the emitters of the TRs Q4, Q5. A noise voltage Vn is expressed in equation I. An output noise voltage Von2 at an output terminal 10 is expressed in equation II. Captions re4, re5 are equivalent emitter resistances of the TRs Q4, Q5, captions re6, re7 are forward resistors of the diodes D1, D2, and captions Vn1, Vn2 are noise voltages of the TRs Q4, Q5. Then the gain of the voltage Von2 with respect to the voltages Vn1, Vn2 is decreased by the resistors re6, re7. Thus, the S/N is improved and the generation of distortion is suppressed.
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