High-speed three-stage operational transconductance amplifiers for switched-capacitor circuits

Abstract

In this paper, three-stage operational transconductance amplifiers (OTAs) for use in switchedcapacitor (SC) circuits using nanometer CMOS technologies are described. Two three-stage OTAs, one with nested-Miller compensation (NMC) as a basic compensation scheme and another with damping factor control frequency compensation (DFCFC) as an advanced compensation scheme are presented. The open-loop small-signal analysis as well as the large signalanalysis for both OTAs are investigated and their speed performance is compared and discussed. Circuit level simulations are carried out using a 90 nm CMOS technology with HSPICE. Simulation results show that the NMC and the DFCFC OTAs achieve a settling time of 17.5 ns and 8.4 ns with 0.02% accuracy, respectively, while consuming 3 mW from a 1.2 V power supply and have the same input-referred thermal noise.

A 1.8‐V 240‐MHz 2.19‐mW Four‐Stage CMOS OTA with a Segmenting Frequency Compensation Technique

“…Note: Results in Refs. [ 27 , 28 ] are obtained from pre‐layout simulation, while those in Ref. [19] are from post‐layout simulation.…”

“…Year & Ref. 2010 [27] 2014 [28] 2015 [19] 2019 [21] This work I dd @V dd 1.8@3 2.4@1.2 0.388@2.5 10.5@1.2 1.2@1.8 (mA@V) Note: Results in Refs. [27,28] are obtained from pre-layout simulation, while those in Ref.…”

“…However, the architecture of a multistage operational amplifier always results in the closed‐loop instability on account of the increased number of high‐resistance nodes. To solve the instability issue, various frequency compensation techniques have been studied [ 6 – 29 ] .…”