MOSFET-ONLY TWO-STAGE OPERATIONAL AMPLIFIERS WITH MILLER COMPENSATION: DESIGN AND FABRICATION IN NANO-SCALE CMOS

Abstract

Nano-scale area-efficient MOS devices are employed in this article to stabilize high-speed operational amplifiers (opamps) for those applications that deal with negative feedback. As an alternative choice, metal-insulator-metal (MIM) capacitors cannot be integrated in every technology as they require additional process masks. Moreover, these components suffer from large silicon area. In this paper, considerations of a successful MOSFET-only amplifier design are highlighted and described. These considerations make it possible to fabricate these amplifiers for a nano-scale digital system-on-chip (SoC). Circuit-level simulations include comparison between MOS capacitors (MOSCAPs) with MIM capacitors (MIMCAPs) in two identical processes. The efficiency of the given design considerations are also validated through simulation in 90-nm CMOS technology. A MOSFET-only amplifier is designed as the main part of a 5 MS/s sample-and-hold. Using the proposed design techniques, the MOSFET-only amplifier with Miller compensation recovers 51% silicon die with respect to a MIMCAP amplifier for identical signal-to-noise-plus-distortion (SNDR) ratio.