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Video s3
    Details
    Presenter(s)
    Tobias Wolfer Headshot
    Display Name
    Tobias Wolfer
    Affiliation
    Affiliation
    Reutlingen University & None
    Country
    Country
    Germany
    Author(s)
    Display Name
    Tobias Wolfer
    Affiliation
    Affiliation
    Reutlingen University & None
    Display Name
    Eckhard Hennig
    Affiliation
    Affiliation
    Reutlingen University & None
    Abstract

    We propose a novel technique to compensate the effects of R-C / gm-C time-constant (TC) errors due to process variation in continuous-time delta-sigma modulators. Local TC error compensation factors are shifted around in the modulator loop to positions where they can be implemented efficiently with tunable circuit structures, such as current-steering digital-to-analog converters (DAC). This approach constitutes an alternative or supplement to existing compensation techniques, including capacitor or gm tuning. We apply the proposed technique to a third-order, single-bit, low-pass continuous-time delta-sigma modulator in cascaded integrator feedback structure. A feedback path tuning scheme is derived analytically and confirmed numerically using behavioral simulations. The modulator circuit was implemented in a 0.35-µm CMOS process using an active feedback coefficient tuning structure based on current-steering DACs. Post-layout simulations show that with this tuning structure, constant performance and stable operation can be obtained over a wide range of TC variation.

    Slides
    • An Active Feedback Coefficient Tuning Technique for Compensating TC Variations in CT ΔΣ Modulators (application/pdf)