Fully differential two-stage operational amplifier circuit

Abstract

The invention discloses a fully differential two-stage operational amplifier circuit, which relates to the field of analog integrated circuits and comprises a first-stage amplifying circuit, a second-stage amplifying circuit, a common-mode signal acquisition circuit, a common-mode feedback circuit and a biasing circuit. The first-stage amplification circuit is of a sleeve structure and is used for receiving differential input signals INP and INN; the second-stage amplification circuit is of a common-source structure and outputs differential output signals OUTP and OUTN; the common-mode signal acquisition circuit receives the differential output signal and outputs an operational amplifier output common-mode signal VCMO; the common-mode feedback circuit outputs common-mode feedback signals VB1 and VB2 to the first-stage amplification circuit and the second-stage amplification circuit respectively; the bias circuit outputs a bias voltage VB3 to the first-stage amplification circuit, and respectively outputs bias voltages VB4 and VB5 to the first-stage amplification circuit. According to the invention, the consumption of component hardware is reduced, the area of an integrated circuit is saved, fewer poles are provided due to the reduction of transistors, and the stability of a loop is easy to realize.

Description

technical field [0001] The invention relates to the technical field of analog integrated circuits, in particular to a fully differential two-stage operational amplifier circuit. Background technique [0002] Operational amplifiers are widely used in various integrated circuits, and can be used to realize various analog signal operations such as addition, subtraction, multiplication, division, integration, and differentiation. Fully differential op amps are less sensitive to common-mode noise and have larger output swings than op amps with single-ended outputs. Due to the differential output, the operational amplifier needs to add a common-mode feedback loop to stabilize the common-mode level of the output signal. [0003] Such as figure 1 As shown, it is the main structure of the sleeve two-stage operational amplifier, excluding bias circuit and common mode feedback circuit. The first stage of the two-stage operational amplifier uses a sleeve structure to provide high gai...

AI Technical Summary

Problems solved by technology

The common-mode feedback circuit and bias circuit of the above-mentioned operational amplifier contain a total of 21 transistors, the structure is complex, the hardware consumption is large, the production cost is high, and it is not conducive to saving the area of ​​the integrated circuit

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