Simple Thermal Noise Estimation of Switched Capacitor Circuits Based on OTAs -- Part I: Amplifiers with Capacitive Feedback

TL;DR

This paper introduces a straightforward method for estimating thermal noise in switched-capacitor circuits with OTAs, enabling quick analysis without complex calculations, validated through simulations.

Contribution

It extends Bode's passive network theorem to active OTA-based circuits for simple thermal noise estimation, specifically applied to amplifiers and track&hold circuits.

Findings

Accurate noise variance estimates match simulation results.

Method simplifies thermal noise analysis in SC circuits.

Validated for amplifiers and track&hold circuits.

Abstract

This paper presents a simple method for estimating the thermal noise voltage variance in passive and active switched-capacitor (SC) circuits using operational transconductance amplifiers (OTA). The proposed method is based on the Bode theorem for passive network which is extended to active circuits based on OTAs with capacitive feedback. It allows for a precise estimation of the thermal noise voltage variance by simple inspection of three equivalent circuits avoiding the calculation of any transfer functions nor integrals. In this Part I, the method is applied to SC amplifiers and track&hold circuits and successfully validated by means of transient noise simulations. Part II extends the application of the method to integrators and active SC filters.