Fully differential operational amplifier with start circuit

Abstract

The invention discloses a fully differential operational amplifier with a start circuit. The fully differential operational amplifier comprises an input pair tube and the start circuit; and in the start circuit, a source electrode of a first PMOS transistor is electrically connected with a power supply voltage, a grid electrode is electrically connected with a first bias voltage, a drain electrodeis separately and electrically connected with source electrodes of a second PMOS transistor and a third PMOS transistor, grid electrodes of the second PMOS transistor and the third MPOS transistor are separately and electrically connected with a differential input terminal, drain electrodes of the second PMOS transistor and the third PMOS transistor, grid electrodes of a fourth PMOS transistor and a fifth PMOS transistor, and a drain electrode of a first NMOS transistor are all electrically connected, a grid electrode of the first NMOS transistor is electrically connected with a second bias voltage, drain electrodes of the fourth PMOS transistor and the fifth PMOS transistor are separately and electrically connected with a drain electrode of the input pair tube, and source electrodes of the fourth PMOS transistor and the fifth PMOS transistor are both electrically connected with a source electrode of the input pair tube. Compared with the prior art, according to the fully differentialoperational amplifier, the start circuit is provided so that it is guaranteed that the fully differential operational amplifier can always operate in a normal state.

Description

technical field [0001] The invention relates to the field of electronic technology, in particular to a fully differential operational amplifier with a start-up circuit. Background technique [0002] The intermediate frequency circuit is an important module of the integrated circuit system, and active filters and variable gain amplifiers (PGA, programmable gain amplifier) ​​are widely used in various transceiver systems. Among them, the operational amplifier is an important part of the active filter and PGA, and its stability determines whether the active filter and PGA can work normally. [0003] With the development of technology, the power supply voltage is getting lower and lower. In a more complex intermediate frequency circuit, after the circuit is started, the op amp may form a different stable state. It is more common that the input pair tube is in the sub-threshold region, and the current is extremely high. Low. figure 1 It is a traditional fully differential folde...

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Problems solved by technology

[0004] The technical problem to be solved by the present invention is to overcome the defect of low input-to-tube current in the prior art when the operational amplifier is in an abnormal state during the start-up process, and to provide a low-power consumption and small-area full-scale power amplifier with a start-up circuit Differential Operational Amplifier

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