Method for amplifying voltage signal and operational amplifier

Abstract

The invention provides a method for voltage signal amplification. An input signal is directly input to input stage circuits, the number of which is N (N is more than or equals to 2); a signal which is output form a first input stage circuit is transmitted to a first gain stage circuit; the signal which is amplified through the first gain stage circuit is then added with an output signal of a second input stage circuit; the added signal is input to a second gain stage, the connection continues gradual in this way until the output signal of an N input stage circuit and the output signal of an N-1 gain stage circuit are added, and finally, the signal which is amplified is output through an output stage circuit. An operational amplifier which is obtained according to the method is also provided. The multi-input stage operational amplifier can ensure the increase of the DC gain, and have the phase reserve sufficing to stabilize and the unity-gain bandwidth which is wide enough.

Description

technical field [0001] The invention relates to a method for amplifying a voltage signal, in particular to an operational amplifier circuit. Background technique [0002] Operational amplifier is a key module of analog circuit design, and it is widely used in the design of filters, digital-to-analog converters, and analog-to-digital converters. [0003] Operational amplifiers are usually used in closed-loop applications. In order to achieve ideal operational amplifier characteristics, it is desirable to increase the open-loop gain of the operational amplifier as much as possible. The way to increase the gain is to increase the number of gain stages in series (see figure 1 ), but its disadvantage is that each additional gain stage will add a part of the high-frequency phase shift to the open-loop function of the op amp, which will eventually cause stability problems. Therefore, the higher the DC gain of the traditional operational amplifier, the narrower its bandwidth, so a...

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Problems solved by technology

The way to increase the gain is to increase the number of gain stages in series (see figure 1 ), but its disadvantage is that each additional gain stage will add a part of the high-frequency phase shift to the open-loop func...

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