PURPOSE: To obtain two AC output characteristics of positive and negative phases with good symmetry over a broad band by zeroing a series feedback resistor connected to an emitter of transistor (TR) of differential pairs, adding a resistor in series with a collector of a constant current TR or operating the collector and emitter at opposite junction.
CONSTITUTION: A base of the 1st TR is used as an AC signal input and a DC bias setting terminal and each base of the 2nd and 3rd TRs is used as a DC bias setting terminal respectively, in such a series feedback differential amplifier, a total bias current of TRs Q1-7 and Q2-7 is set by adjusting a DC voltage source circuit V3 in caption 12, values of the DC voltage source circuit V1 and a DC voltage source circuit V2 in caption 13 are set so that the currents of the TRs Q1, Q2 are identical, and two balance signals with broad band of positive and opposite phase are obtained from terminals 14, 15 by applying an AC signal to an input terminal 18 being the base of the TRQ1.
AKAZAWA YUKIO
OBARA MAMORU
