# Advanced methods for nested Miller frequency compensation using voltage buffers

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## Abstract

New methods for the compensation of three-stage amplifiers are presented. In these methods, a rail-to-rail buffer enables designers to control the feedforward path. So far, the use of voltage buffer compensation has been reported merely in two-stage amplifiers. Using this in three-stage amplifiers results in the formation of left-half plane zeros, which can be applied to remove non-dominant poles. Two different methods are introduced. Firstly the voltage buffer is added to the path of the external loop capacitor to improve the gain bandwidth; secondly the voltage buffer is added to the internal loop capacitor. The internal path improves the gain bandwidth significantly (8 times in comparison with conventional NMC) by producing two left half plane zeros. Simulation results demonstrate the stability of the amplifiers and agree with design equations.

## Keywords

Three-stage amplifier Rail-to-rail buffer Compensation method Feedforward path## References

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