A 50 Hz SC notch filter for IoT applications

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

3 Citations (Scopus)


This paper presents a SC 50 Hz notch filter for an analog to digital acquisition channel in an IoT water management sensor node. The notch filter is used to attenuate the unwanted 50 Hz interference, allowing to reduce the required effective resolution of the ADC, which is a ΣΔ modulator with a sampling frequency of 2 MHz. Due to the large ratio between the sampling frequency and the pole frequency, which increases the capacitor values dispersion, charge division branches are used to allow the delivery of a small charge using a larger capacitor, reducing the capacitor spread. The factor by which the value of the capacitors can be increased is controlled by the number of set/reset cycles that are used in the charge division branches. The maximum number of cycles is dependent on the time constants of each node and the gain value of the amplifiers. The notch filter has a total power dissipation below 300 μW and electrical simulations show an attenuation of approximately 30 dB in the unwanted 50 Hz signal.

Original languageEnglish
Title of host publication2017 IEEE International Symposium on Circuits and Systems (ISCAS)
Subtitle of host publicationFrom Dreams to Innovation
PublisherInstitute of Electrical and Electronics Engineers (IEEE)
ISBN (Electronic)978-1-4673-6853-7
ISBN (Print)978-1-5090-1427-9
Publication statusPublished - 25 Sept 2017
Event50th IEEE International Symposium on Circuits and Systems, ISCAS 2017 - Baltimore, United States
Duration: 28 May 201731 May 2017

Publication series

NameIEEE International Symposium on Circuits and Systems
ISSN (Electronic)0271-4310


Conference50th IEEE International Symposium on Circuits and Systems, ISCAS 2017
Country/TerritoryUnited States


  • Bandpass filters
  • Internet of things
  • Sensor nodes
  • Water management


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