Compensation technique for current-to-voltage converters for lsi patch clamp system using high resistive feedback

Hiroki Yotsuda, Retdian Nicodimus, Masahiro Kubo, Taro Kosaka, Nobuhiko Nakano

    Research output: Contribution to journalArticle

    Abstract

    Patch clamp measurement technique is one of the most important techniques in the field of electrophysiology. The elucidation of the channels, nerve cells, and brain activities as well as contribution of the treatment of neurological disorders is expected from the measurement of ion current. A current-to-voltage converter, which is the front end circuit of the patch clamp measurement system is fabricated using 0.18 μmCMOS technology. The current-to-voltage converter requires a resistance as high as 50Mω as a feedback resistor in order to ensure a high signal-to-noise ratio for very small signals. However, the circuit becomes unstable due to the large parasitic capacitance between the poly layer and the substrate of the on-chip feedback resistor and the instability causes the peaking at lower frequency. The instability of a current-to-voltage converter with a highresistance as a feedback resistor is analyzed theoretically. A compensation circuit to stabilize the amplifier by driving the N-well under poly resistor to suppress the effect of parasitic capacitance using buffer circuits is proposed. The performance of the proposed circuit is confirmed by both simulation and measurement of fabricated chip. The peaking in frequency characteristic is suppressed properly by the proposed method. Furthermore, the bandwidth of the amplifier is expanded up to 11.3 kHz, which is desirable for a patch clamp measurement. In addition, the input referred rms noise with the range of 10 Hz ∼ 10 kHz is 2.09 pArms and is sufficiently reach the requirement for measure of both whole-cell and a part of single-channel recordings.

    Original languageEnglish
    Pages (from-to)531-539
    Number of pages9
    JournalIEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences
    VolumeE99A
    Issue number2
    DOIs
    Publication statusPublished - 2016 Feb 1

    Keywords

    • Current-to-voltage converter
    • High resistive feedback
    • Lownoise amplifier
    • Patch clamp measurement
    • Stabilization

    ASJC Scopus subject areas

    • Electrical and Electronic Engineering
    • Computer Graphics and Computer-Aided Design
    • Applied Mathematics
    • Signal Processing

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