Design of capacitive sensing chopper amplifier used in artificial nose detection system

Tuševski, Ajda (author), Strle, Drago (author)

In this paper, we present the theoretical background and design procedure of a fully differentiated precision charge amplifier that can be used to detect small capacitive changes in an artificial nose detection system (ANose). We will show that with appropriate topology and optimization of circuit parameters, we can reduce 1/f noise and the offset and thus improve the sensitivity while keeping the power consumption at an acceptable level. Since the rate of capacitive changes due to adsorption/desorption is slow, a well-known technique such as chopping and autozeroing is used in a new way and described in the paper. The advantages and disadvantages of the proposed techniques are described. A combination of these two techniques in a single topology and new capacitive sensor ports are used to improve the detection sensitivity. Ideally, a sensitivity of 3 zF/▫$\sqrt$▫Hz can be achieved, but it could be slightly worse due to various non-idealities not considered.

• Language: English
• Keywords: fully differential chopper amplifier, capacitive sensors, ripple reduction loop (RRL), artificial nose
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FE - Faculty of Electrical Engineering
• Publication status: Published
• Publication version: Version of Record
• Year: 2024
• Number of pages: Str. 247-257
• Numbering: Vol. 54, no. 4
• PID: 20.500.12556/RUL-165923
• UDC: 621.375
• ISSN on article: 2232-6979
• DOI: 10.33180/InfMIDEM2024.402
• COBISS.SI-ID: 218936835
• Publication date in RUL: 13.12.2024

Record is a part of a journal

• Title: Informacije MIDEM
• Publisher: MIDEM
• ISSN: 2232-6979
• COBISS.SI-ID: 264503552

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.

Secondary language

• Language: Slovenian
• Title: Nabojni sekalni ojačevalnik za detekcijo kapacitivnih sprememb v umetnem nosu

Abstract

V članku je predstavljeno načrtovanje ter teoretičen in simulacijski postopek pri izgradnji popolnoma diferencialnega, natančnega sekalnega nabojnega ojačevalnika, ki služi zaznavanju majhnih kapacitivnih sprememb v sistemu Umetni nos. Pokazali bomo, da lahko s pravilno topologijo in optimizacijo parametrov vezja zmanjšamo 1/f šum in ničelno napetost ter tako izboljšamo občutljivost, hkrati pa ohranimo porabo energije na sprejemljivi ravni. Ker je hitrost kapacitivnih sprememb zaradi adsorbcije in desorbcije relativno počasna, smo uporabili tehniko sekanja in zmanjševanje ničelne napetosti in 1/f šuma. Ti dve tehniki sta v članku uporabljeni na nov način in bosta podrobneje opisani. V nadaljevanju sledi opis prednosti in slabosti predlagane tehnike. Kombinacija obeh tehnik sekanja v eni topologiji in nove, diferencialne kapacitivne senzorske povezave se uporabljajo za izboljšanje občutljivosti zaznavanja. Teoretični izračun kaže, da je v idealnem primeru možno doseči občutljivost 3 zF/▫$\sqrt$▫(Hz). V realnosti pričakujemo nekoliko slabšo občutljivost, zaradi različnih neidealnosti, ki jih nismo upoštevali pri teoretičnem izračunu.

• Keywords: popolnoma diferencialen sekalni ojačevalnik, diferencialni kapacitivni senzorji, RRL 3, umetni nos