| 摘要 |
PURPOSE:To execute a low voltage operation, and also to obtain a large gain by supplying differentially an input current to each second electrode to be controlled of the first and the second input Trs to which a control electrode is connected in common, and obtaining an output current from the fourth and the fifth Trs whose control electrodes is connected to the collectors of these Trs, respectively. CONSTITUTION:Constant-currents I11=I12=I, and R21=R22=R are placed, and also input currents Iin1, Iin2 are supplied differentially. When a reference current of this current, a differential current signal, and a differential gain are denoted as Ii, (i), and beta, respectively, and also conditions of R23=R, and a constant- current I13=I are added, output currents Iout1, Iout2 become Ii/2+beta.i, Ii/2-beta.1. Also, when R23=1/2.R, and I13=2.I are set, and an area of the emitter of a TrQ23 is set to two times of that of Q21 and Q22, both output currents become Ii+beta.i, and Ii-beta.i. Therefore, this amplifying circuit has a gain of beta times with respect to the differential current signal (i). Accordingly, the potential of a supplying point of the input current is lower than a base-emitter voltage VBE of the Trs Q21, Q22, by which the operation can be executed, also an useless current is reduced, and the gain can be raised.
|
