Continuous-Time Analog Filters for Audio Edge Intelligence: Review on Circuit Designs
Metadata only
Date
2023Type
- Review Article
ETH Bibliography
yes
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Abstract
Edge audio devices can reduce data bandwidth requirements by pre-processing input speech on the device before transmission to the cloud. As edge devices are required to ensure always-on operation, their stringent power constraints pose several design challenges and force IC designers to look for solutions that use low standby power. One promising bio-inspired approach is to combine the continuous-time analog filter channels with a small memory footprint deep neural network that is trained on edge tasks such as keyword spotting, thereby allowing all blocks to be embedded in an IC. This paper reviews the historical background of the continuous-time analog filter circuits that have been used as feature extractors for current edge audio devices. Starting from the interpretation of a basic biquad filter as a two-integrator-loop topology, we introduce the progression in the design of second-order low-pass and band-pass filters ranging from OTA-based to source-follower-based architectures. We also derive and analyze the small-signal transfer function and discuss their usage in edge audio applications. Show more
Publication status
publishedExternal links
Journal / series
IEEE Circuits and Systems MagazineVolume
Pages / Article No.
Publisher
IEEESubject
Auditory; silicon cochlea; two-integrator-loop; band-pass filter (BPF); continuous-time (CT) filter; flipped voltage follower (FVF); second-order filter; source-follower (SF); super source-follower (SSF)Organisational unit
02533 - Institut für Neuroinformatik / Institute of Neuroinformatics
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ETH Bibliography
yes
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