Open-loop amplifier with accurately set gain

Abstract

An open-loop fully differential operational amplifier, of which the gain can be set precisely according to a resistance ratio, comprises differential input tubes P1 and P4, source feedback resistors R1 and R3 and a tail current Ib0, wherein P2 and Ib2 (as well as P5 and Ib4) form a gain raising circuit which is used for increasing the transconductance of cascade tubes P3 (and P6); NMOS tubes N1 and N2 form a local feedback loop which is used for forming a low-impedance path; R2 and R4 serve as source negative feedback resistors thereof and output resistors of the whole circuit. The signal gain of the open-loop amplifier is determined by the ratio of R2 to R1 (or R4 to R3). The traditional precise gain amplifier is mainly of the structure of a closed-loop operational amplifier, and the gain value of the traditional open-loop amplifier is usually not precise. The open-loop amplifier with the accurately set gain has the advantages of the traditional closed-loop operational amplifier and the traditional open-loop amplifier, and a precise gain value is obtained by adopting the design of the open-loop amplifier.

Description

technical field [0001] The invention relates to a variable gain amplifier widely used in analog and radio frequency integrated circuits, especially a high-precision and low-power gain amplifier, which adopts CMOS technology and has great advantages in low-voltage and low-power digital-analog hybrid circuits. Compared with the traditional closed-loop amplifier, it has the advantages of simple structure and low power consumption; compared with the traditional open-loop amplifier, it has the advantage that the gain value can be set accurately. It belongs to the field of integrated circuit design. Background technique [0002] With the popularization and promotion of mobile terminal products, the volume of electronic products continues to shrink, and lithium batteries will become the main energy source of products. At the same time, the concept of energy conservation and environmental protection is increasingly accepted by the society and the industry, and green energy-saving ...

AI Technical Summary

Problems solved by technology

[0010] Aiming at the contradiction between gain accuracy and power consumption in the traditional gain amplifier design, the present invention proposes an open-loop fully differential amplifier whose gain can be set precisely. The problem of complex structure and high power consumption also solves the problem that the gain of the traditional open-loop amplifier cannot be set accurately

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