Improving receiver close-in blocker tolerance by base-band Gm-C Notch-filtering

Mohammed Abdulaziz (Corresponding Author), Eric A.M. Klumperink, Bram Nauta, Henrik Sjöland

    Research output: Contribution to journalArticleAcademicpeer-review

    10 Citations (Scopus)
    593 Downloads (Pure)


    This paper presents a receiver front end with improved blocker handling implemented in a 65-nm CMOS technology. Since close-in blockers are challenging to reject at RF, the receiver features a baseband (BB) notch filter, which effectively sinks close-in blocker current directly from the output of an LNTA and passive mixer structure. The notch-filter frequency can be tuned to match the blocker offset frequency, and the measurements indicate a significant improvement in the overall front-end interference robustness, while sensitivity remains unaffected. To optimize notch performance, the BB impedance is analyzed in detail. The front-end RF range is 750 MHz-3 GHz with an RF channel bandwidth of 20 MHz corresponding to 10-MHz BB bandwidth. The notch frequency is programmable from 16, which is less than one octave from the channel edge, up to 160 MHz. The gain-compression improvement is upto 9 dB, while IIP2 can be increased by more than 26 dB without calibration and IIP3 is 1 dBm. The current overhead for the notch function is between 7.5 and 30 mA, but it only exists under strong blocker conditions as the notch filter can be switched off if strong blockers are absent. The total front-end current consumption excluding the notch filter varies with LO frequency from 31 to 44 mA from a 1.2-V supply.
    Original languageEnglish
    Article number8492343
    Pages (from-to)885-896
    Number of pages12
    JournalIEEE transactions on circuits and systems I: regular papers
    Issue number3
    Early online date15 Oct 2018
    Publication statusPublished - 1 Mar 2019


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