| 摘要 |
PURPOSE:To reduce the transmission quantity of noise included in a reference current by reducing the AC gain of a current mirror circuit. CONSTITUTION:When a reference current Iref is inputted to a transistor TR Q11, and N-fold current I2 is taken out from a TR Q12. Meanwhile, the output current of the TR Q11 is turned back by a second current mirror circuit and is added to the output current I2 of the TR Q12 to become a bias current IB of a TR Q15. Since the voltage of an emitter resistance R2 connected to the TR Q15 is determined by the emitter area ratio of TRs Q11 and Q12 and that of TRs Q13 and Q14 in this case, the emitter resistance value is increased and the voltage value is increased to reduce the AC gain of the TR Q15, and the noise component included in the reference current is so reduced that it cannot appear in the output current.
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