Unified Frequency-Domain Analysis of Switched-Series-RC Passive Mixers and Samplers

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    Abstract

    Abstract—A wide variety of voltage mixers and samplers are implemented with similar circuits employing switches, resistors, and capacitors. Restrictions on duty cycle, bandwidth, or output frequency are commonly used to obtain an analytical expression for the response of these circuits. This paper derives unified expressions without these restrictions. To this end, the circuits are decomposed into a polyphase multipath combination of single-ended or differential switched-series-RC kernels. Linear periodically timevariant network theory is used to find the harmonic transfer functions of the kernels and the effect of polyphase multipath combining. From the resulting transfer functions, the conversion gain, output noise, and noise figure can be calculated for arbitrary duty cycle, bandwidth, and output frequency. Applied to a circuit, the equations provide a mathematical basis for a clear distinction between a “mixing‿ and a “sampling‿ operating region while also covering the design space “in between.‿ Circuit simulations and a comparison with mixers published in literature are performed to support the analysis.
    Original languageEnglish
    Pages (from-to)2618-2631
    Number of pages14
    JournalIEEE transactions on circuits and systems I: regular papers
    Volume57
    Issue number10
    DOIs
    Publication statusPublished - 1 Oct 2010

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    Keywords

    • noise folding
    • passive mixing
    • linear periodically time variant (LPTV)
    • voltage sampling
    • METIS-275609
    • IR-73654
    • Frequency conversion
    • Low noise
    • EWI-18143

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