A low-power process-scalable superheterodyne receiver with integrated high-Q filters

Mirzaei,; Darabi,; Murphy, .

doi:10.1109/isscc.2011.5746219

Cited by 25 publications

(30 citation statements)

References 2 publications

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“…Passive LC filters show limited Q and tunability. Recently frequency translated filtering has been proposed as a potential solution direction for high Q filtering [1][2][3][4][5]. In [1,2] we showed that by applying the "N-path concept"…”

Section: Textmentioning

confidence: 97%

8-Path tunable RF notch filters for blocker suppression

Ghaffari

Klumperink

Nauta

2012

2012 IEEE International Solid-State Circuits Conference

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Abstract:Periodically time-variant passive 8-path notch filters are demonstrated in 65nm CMOS technology, with a notch frequency tunable from 100MHz to 1.2GHz with a clock signal. In a 50Ω environment, filter insertion loss in the pass band is 1.4-2.8dB, while the rejection at the notch frequency is >20dB.Given their P 1dB > +2dBm and IIP3> +17dBm, the filters can protect radio receivers from blocking over a wide tuning range. TextThe huge growth of the number of wireless devices makes wireless coexistence an increasingly relevant issue. If radios operate in close proximity, blockers as strong as 0dBm may occur, driving almost any receiver in compression (note that 0dBm in 50Ω corresponds to a pk-pk voltage of half a 1.2V supply). Thus RF blocker filtering is highly wanted. However, fixed filters are undesired when aiming for multi-band, software defined or cognitive radio transceivers. Passive LC filters show limited Q and tunability. Recently frequency translated filtering has been proposed as a potential solution direction for high Q filtering [1][2][3][4][5]. In [1,2] we showed that by applying the "N-path concept" 2[6], more than a decade of center frequency range with good linearity, compression point (P 1dB >0dBm, IIP3 >14dBm) and low noise is feasible for a bandpass (BP) filter. In [3] a notch filter with a combination of active and passive mixers is applied in a feedforward path realizing a BP filter.Moreover in [5] the low input impedance of a transimpedance amplifier with feedback is upconverted to create a notch filter at low frequencies (80MHz) suppressing TX leakage in an FDD system. In this work we explore the possibility to realize a notch filter applying the N-path concept at RF frequencies and in a completely passive way. A single-ended (SE) and a differential 8-path notch filter with passive frequency mixing are presented. The filters are power-matched in the input and output in the passband and provide a low insertion loss, high compression point and also low noise property, thus they can be utilized in front of a receiver to provide rejection of high power blockers with a large frequency tuning range. A prototype including a SE and a differential notch filter is implemented in 65nm CMOS technology (see Fig. 4.2.2 and 4.2.7). The circuit operates directly in a 50Ω system. In the differential architecture the notch is suppressed at the even harmonics of f s resulting in a wider passband. The second mixer in switches is set to 300mV to avoid reliability issues at high input swings). Larger switch would increase the insertion loss at high frequencies due to the parasitic capacitance and would require higher digital power drive. In the SE filter C 1 =7pF is chosen in each path targeting to suppress a 6MHz width blockers (e.g. TV channels in the cognitive radio or TV tuner applications). In the differential architecture two capacitors are in series and in order to get the same RC product as the SE version we have doubled the capacitor value (C 2 =14pF).For each filter, a divide-by-8 ring counter i...

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Section: Textmentioning

confidence: 97%

8-Path tunable RF notch filters for blocker suppression

Ghaffari

Klumperink

Nauta

2012

2012 IEEE International Solid-State Circuits Conference

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“…These two main issues reduced the attention of researchers for N-path filters. The substantial improvement in the speed and the matching properties of CMOS technology renewed a great interest into N-path filters [95,96,97,98,99,100,101,102,103,104,105]. Because the main constituents of N-path filters are switches and capacitors, CMOS technology is the best candidate for the realization of this type of filters.…”

Section: N-path Filtersmentioning

confidence: 99%

“…An N-path BPF [81] that has recently attracted much attention [95,96,97,98,99,101,102,103,104,105] is illustrated in Fig. 2.19(a) where the on-resistance of the switches is modeled by a series resistance, R sw .…”

Section: N-path Filtersmentioning

confidence: 99%

Active N-path Filters: Theory and Design

Darvishi¹

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“…Instead of a capacitor only, often also a TIA with RC load is used [53], which allows for realizing impedance matching. In recent years and especially during the period of the research project which led to this thesis some applications of the switched-RC N-path filters were presented in literature [57][58][59]. For instance as indicated in Fig.…”

Section: Frequency Translated N-path Filteringmentioning

confidence: 99%

“…Moreover the RC-filtering at the input of TIA is also upconverted to RF frequencies via passive mixers realizing bandpass filtering at the output of LNA. In [58] N-path filters are applied to provide image rejection in a super-heterodyne receiver.…”

Section: Frequency Translated N-path Filteringmentioning

confidence: 99%

Switched-RC radio frequency N-path filters

Ghaffari¹

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i SamenvattingAfstembare filters zijn zeer gewenst voor mobiele radio communicatie en de wens bestaat deze op chip te realiseren samen met de overige benodigde zend-en ontvangst hardware. Vooral nu mobiele apparaten vele verschillende draadloze communicatie mogelijkheden dienen te ondersteunen (denk bv. aan GSM, Bluetooth, WiFi, UMTS) geïntegreerd op één chip, is er dringend behoefte aan afstembare filters. Ook groeit het mobiele internet gebruik enorm, zodat behoefte bestaat aan programmeerbare radio hardware die op een slimmere manier met het schaars beschikbare radio spectrum omgaat. Dit heeft geleid tot het concept van een "cognitieve radio", een stuk radio hardware dat op een intelligente manier dynamisch het spectrum gebruikt. Zo'n cognitieve radio vraagt om flexibel programmeerbare afstembare filters en meer algemeen "software defined radio" (SDR) hardware.Het beperkte dynamische bereik van radio ontvangers vraagt om filtering van het radiosignaal direct bij de antenne. Dit filter dient de sterke ongewenste stoorsignalen te onderdrukken, die anders de radio ontvanger zodanig zouden oversturen dat door sterke vervorming betrouwbare draadloze communicatie onmogelijk wordt. Traditioneel wordt de filtering geïmplementeerd via aparte zgn. Surface Acoustic Wave (SAW) filters of Bulk Acoustic Wave (BAW) filters. Deze zijn echter relatief groot en duur vergeleken met een schakeling op een chip. Bovendien zijn ze voor een SDR grotendeels ongeschikt, daar ze een vaste (niet-afstembare) filter overdracht hebben. Op chip kunnen weliswaar LC filters gerealiseerd worden maar de kwaliteitsfactor Q van geïntegreerde spoelen is problematisch laag, terwijl "Qenhancement" en "gm-C" filter technieken een te beperkt dynamisch bereik hebben. Er bestaat dus een duidelijke onderzoek uitdaging om tot integreerbare flexibel programmeerbare filters te komen met een groot dynamisch bereik.In dit proefschrift worden zogenaamde "N-path" filters op basis van geschakelde RC circuits onderzocht. Deze filters gedragen zich als resonator voor frequenties rond hun schakelfrequentie, waarbij het mogelijk is zeer selectieve banddoorlaat of bandrejectie filters te maken. Het N-path filter concept past goed bij SDR omdat de filter frequentie digitaal te programmeren is via de schakelfrequentie, d.w.z. via een ii digitale programmeerbare klokfrequentie. Omdat nieuwe CMOS technologieën meer capaciteit per oppervlakte kunnen bieden, terwijl MOS schakelaars een lagere weerstand met minder parasitaire capaciteit kunnen hebben, profiteren N-path filters van Moore's law.Om de haalbaarheid van N-path filter voor SDR aan te tonen, is een 4-path differentieel switched RC banddoorlaat filter gerealiseerd, een 8-path single-ended filter en ook een differentieel bandstop (notch) filter, alle in 65nm CMOS technologie. Via mathematische analyse zijn de relevante filter overdrachten en ook diverse imperfecties geanalyseerd voor zowel N-path banddoorlaat en notch filters. Het geïmplementeerde banddoorlaat filter vertoont een gemeten IIP3 in-band >+14 dBm met ee...

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A low-power process-scalable superheterodyne receiver with integrated high-Q filters

Cited by 25 publications

References 2 publications

8-Path tunable RF notch filters for blocker suppression

8-Path tunable RF notch filters for blocker suppression

Active N-path Filters: Theory and Design

Switched-RC radio frequency N-path filters

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