Folded cascode operational amplifier

Abstract

The invention discloses a folded cascode operational amplifier comprising a first current mirror circuit, a first amplifier circuit, a second amplifier circuit and a voltage isolation circuit, whereinthe voltage isolation circuit comprises a first NMOS transistor, a second NMOS transistor, and a second current source and a first resistor, the first NMOS transistor and the second NMOS transistor are Native NMOS transistors; the gate of the first NMOS transistor, the gate of the second NMOS transistor and one end of the first resistor are electrically connected with the other end of the secondcurrent source; the source of the first NMOS transistor is electrically connected with an output end of the first amplifier circuit, the source of the second NMOS transistor is electrically connectedwith the output end of the second amplifier circuit, the drain of the first NMOS transistor is electrically connected with an input end of the first current mirror circuit, and the drain of the secondNMOS transistor is electrically connected with the output end and a cascode output end of the first current mirror circuit. The folded cascode operational amplifier disclosed by the invention can stabilize the gain without affecting the output dynamic range.

Description

technical field [0001] The invention belongs to the field of electronic technology, in particular to a folded cascode operational amplifier. Background technique [0002] Under the deep submicron process conditions, the hot carrier effect becomes more and more obvious. When the electric field strength at both ends of the channel is large, the substrate current formed by the electron-hole pairs generated by the collision with the crystal lattice in the depletion region will seriously affect the device characteristics, thereby degrading the performance of the amplifier. For such as figure 1 In the folded cascode operational amplifier shown, the output voltage Cascode_VO of the folded cascode stage is within the entire output swing, and the cascode output transistor N4 is an NMOS (N-type metal-oxide-semiconductor) transistor, N4 The drain of N4 is connected to the output voltage Cascode_VO of the folded cascode stage, the voltage between the drain of N4 and the substrate vari...

AI Technical Summary

Problems solved by technology

[0003] The technical problem to be solved by the present invention is to overcome the changes in the substrate current of the cascode output tube of the folded cascode operational amplifier in the prior art that will cause the output of the folded cascode stage under different DC output voltages The defect that the gain has a large change provides a folded cascode operation that can stabilize the gain of the folded cascode stage under different DC output voltages without affecting the output dynamic range of the folded cascode stage itself amplifier

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