Nested Miller compensation using current buffers for multi-stage amplifiers

Abstract

Firstly, a literature review of existing nested Miller compensation (NMC) schemes for low-voltage multi-stage amplifiers is made. Secondly, a novel nested Miller compensation using two current buffers (NMCCB) in the feedback network is introduced. As opposed to previous NMC schemes, this scheme uses a non-inverting gain stage for the first stage and inverting gain stages for both the second and third stages. An inverting current buffer is utilized for the first time whereas previous NMC feedback networks utilized a positive current buffer. In conventional NMC, the major limitation is bandwidth since inner compensation capacitance loads the output node. In the proposed scheme, the two current buffers in the feedback network create two LHP zeros, cancelling one of the non-dominant poles and extending the bandwidth. Detailed small-signal modeling and analysis of the NMCCB compensation network is presented, demonstrating the effectiveness of this strategy.