Differential amplifying circuit capable of automatically adjusting amplification factor

Abstract

The invention discloses a differential amplifying circuit capable of automatically adjusting amplification factor, belonging to the differential amplifying circuit. The differential amplifying circuit comprises a differential signal input end 1, a voltage output end 2, a direct current bias 5, a differential amplifying circuit 3 and an active filter circuit 4. The connection relationship is that the differential signal input end 1 receives a differential signal and transfers the differential signal to the differential amplifying circuit 3 with no difference; the direct current bias 5 outputs a constant bias voltage signal Vb; a control signal input end 19 receives a control signal which is output by the control end and transfers the control signal to the differential amplifying circuit 3; the output end of the differential amplifying circuit 3 is connected with the input end of the active filter circuit 4; the amplifying circuit amplifies a useful signal in the difference value of a V1 and a V2; a V3 is processed by the active low-pass filter circuit 4 to obtain a voltage signal V4; the voltage output end 2 transfers the voltage signal V4 which is output by the active low-pass filter circuit 4 with no difference. The differential amplifying circuit has the advantage of detecting a weak differential signal and is capable of automatically changing the amplification factor according to the input differential signal.

Description

technical field [0001] The invention relates to a differential amplifier circuit of a semiconductor integrated circuit, in particular to a differential amplifier circuit capable of automatically adjusting the amplification factor. Background technique [0002] The differential amplifier circuit uses the symmetry and negative feedback of circuit parameters to effectively stabilize the static operating point. It is characterized by amplifying differential mode signals and suppressing common mode signals. It is widely used in the input stage of direct coupling circuits and measurement circuits. However, the structure of the differential amplifier circuit is complex and the analysis is cumbersome. In particular, it has different analysis methods for differential-mode input and common-mode input signals, which is difficult to understand. Therefore, it has always been a difficult point in analog electronic technology. Differential amplifier circuit: According to input and output m...

AI Technical Summary

Problems solved by technology

However, the structure of the differential amplifier circuit is complex and the analysis is cumbersome, especially it has different analysis methods for differential mode input and common mode input signals, which is difficult to understand, so it has always been a difficulty in analog electronic technology.

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