A tunable biquad switched-capacitor amplifier-filter for neural recording

Jongwoo Lee, Matthew Johnson, Daryl Kipke

Research output: Contribution to journalArticlepeer-review

31 Scopus citations


With the emerging interest in local field potentials (LFPs) as input signals for brain-machine interfaces, there is a need for integrated circuits capable of amplifying spikes and LFPs. A two-stage complementary metaloxide semiconductor (CMOS) amplifier-filter has been implemented with 0.18-μm CMOS for simultaneous, multimodal recording of extracellular unit spikes and LFPs. For the frequency tuning and the reduction of the 1/f noise, it employs a switched-capacitor technique. The filter bandwidth is reconfigurable by using a different sampling clock frequency. The prototype amplifier has gains of 19.1 dB and 37.5 dB for low-pass only filter and cascaded filter, respectively. With a 100-kHz sampling frequency, the equivalent input noise spectral density is 38.8 nV/√Hz while the total power consumption is 69 μW with a 1.6-V supply, including clock generation and biasing occupying an area of 44 × 148 μm2.

Original languageEnglish (US)
Article number5575366
Pages (from-to)295-300
Number of pages6
JournalIEEE transactions on biomedical circuits and systems
Issue number5
StatePublished - Oct 1 2010
Externally publishedYes


  • Electrophysiological neural recording
  • local field potentials (LFPs)
  • switched-capacitor biquad


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