Current compensation circuit of differential structure and rail-to-rail operational amplifier

Abstract

The invention discloses a current compensation circuit of a differential structure and a rail-to-rail operational amplifier. The differential structure comprises a bias circuit, a differential circuit and a current circuit which are connected in sequence, and a compensation bias circuit, a compensation differential circuit and a compensation current circuit which are connected in sequence. The compensation bias circuit and the bias circuit are of a cascode structure, the compensation differential circuit and the differential circuit are of a cascode structure, the input of the compensation current circuit is connected with the output of the compensation differential circuit and the output of the differential circuit, and the input of the compensation current circuit is connected with the current circuit and used for enabling the current of the differential circuit to flow out, so that the output current of the differential circuit does not flow through the current circuit. The rail-to-rail operational amplifier comprises a current compensation circuit of a differential structure, current of a differential input circuit directly flows into the current compensation circuit and is not injected into a middle stage of the operational amplifier, it is guaranteed that the current of the differential input stage does not affect a current source of the middle stage of the operational amplifier, and the influence of amplifier input on output is avoided; and the amplifier performance is improved.

Description

technical field [0001] The invention relates to the technical field of operational amplifier circuits, in particular to a current compensation circuit with a differential structure and a rail-to-rail operational amplifier. Background technique [0002] At present, the rail-to-rail input and rail-to-rail output operational amplifier design uses a folded cascode structure as the input stage and intermediate stage, and a push-pull structure as the output stage. The intermediate stage of the folded cascode structure usually uses a fixed current source to provide bias current, and the floating current source provides bias voltage for the push-pull output stage. The total current of the intermediate stage is equal to the current generated by the fixed current source and the current injected by the differential input stage. The sum of the currents, in this structure, the current injected into the differential input stage will vary with the level of the input common-mode voltage, ca...

AI Technical Summary

Problems solved by technology

The intermediate stage of the folded cascode structure usually uses a fixed current source to provide bias current, and the floating current source provides bias voltage for the push-pull output stage. The total current of the intermediate stage is equal to the current generated by the fixed current source and the current injected by the differential input stage. The sum of the currents, in this structure, the current injected into the differential input stage will vary with the level of the input common-mode voltage, causing the total current of the intermediate stage to change with the level of the input common-mode voltage, floating The voltage at both ends of the current source and the rail-to-rail output stage current will also change with the input common-mode voltage. The change of the total current of the intermediate stage will cause the rail-to-rail intermediate stage to switch between the amplification area and the switching area, thus affecting to the performance of the entire op amp

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