| 摘要 |
A balanced type DDA 1 is combined with a single end type DDA 2 to form a differential amplifier circuit 3 which is a balanced type DDA- The balanced type DDA 1 has four input terminals VPP, VPN, VNN and VNP which are input terminals of two differential input stages, and two output terminals VoutP and VoutN which are output terminals of two output stages. These terminals are four input terminals and two output terminals of the differential amplifier circuit 3. The single end type DDA 2 has four input terminals, which are input terminals of two differential input stages and which are connected to the four input terminals of the differential amplifier circuit 3, respectively. The single end type DDA 2 also has an output terminal vout of one output stage, which serves as a control output terminal for the feedback control of the differential amplifier circuit 3. By the negative feedback of the signal of the control output terminal Vout, a virtual short-circuit can be established between two input terminals of each differential input stages, so that it is possible to reduce distortion without reducing gains.
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