EP1745544A1 - Systeme et procede evitant le brouillage par l'oscillateur local - Google Patents

Systeme et procede evitant le brouillage par l'oscillateur local

Info

Publication number
EP1745544A1
EP1745544A1 EP05718801A EP05718801A EP1745544A1 EP 1745544 A1 EP1745544 A1 EP 1745544A1 EP 05718801 A EP05718801 A EP 05718801A EP 05718801 A EP05718801 A EP 05718801A EP 1745544 A1 EP1745544 A1 EP 1745544A1
Authority
EP
European Patent Office
Prior art keywords
signal
frequency
mhz
component
phase
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP05718801A
Other languages
German (de)
English (en)
Inventor
Johannes Petrus Antonius Frambach
Paulus Thomas Maria Zeijl
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
NXP BV
Original Assignee
Koninklijke Philips Electronics NV
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Koninklijke Philips Electronics NV filed Critical Koninklijke Philips Electronics NV
Publication of EP1745544A1 publication Critical patent/EP1745544A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/02—Transmitters
    • H04B1/04—Circuits
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03B—GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS
    • H03B19/00—Generation of oscillations by non-regenerative frequency multiplication or division of a signal from a separate source
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03B—GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS
    • H03B27/00—Generation of oscillations providing a plurality of outputs of the same frequency but differing in phase, other than merely two anti-phase outputs
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03B—GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS
    • H03B2200/00—Indexing scheme relating to details of oscillators covered by H03B
    • H03B2200/006—Functional aspects of oscillators
    • H03B2200/007—Generation of oscillations based on harmonic frequencies, e.g. overtone oscillators

Definitions

  • the present invention relates to local oscillator or LO-pulling of a single die radio frequency transceiver. More particularly, the present invention relates to a system and method for at least one way to generate an LO signal for the transceiver. Most particularly, the present invention relates to a system and method for at least one way to generate the
  • LO signal without pulling of a VCO of a transmitter of the transceiver.
  • RF radio frequency
  • LO-pulling occurs when a fraction of the transmit signal couples back to the voltage controlled oscillator (VCO) of the frequency synthesizer.
  • VCO voltage controlled oscillator
  • the transmit signal is modulated with the information to be transmitted, so the VCO is modulated as well.
  • Zolfaghari et al propose the use of a double intermediate frequency (IF) in the up- conversion process.
  • the frequency approach is selected such that no spectral components coincide with the VCO, hence circumventing the pulling problem at the cost of a complex signal path.
  • Another approach is a combination of a classical direct up-conversion transmitter with an alternative LO generation.
  • the frequency plan is selected so that no coinciding spectra are generated.
  • the solution proposed by Darabi et al requires filtering of the mixer output signal before the signal is amplified. If no filter were applied before further amplification, the mixer output signal would be an 800 MHz square wave instead of the desired 2400 MHz signal. This results from the harmonic relation between the two mixer input signals. Hence, this approach requires more precise filtering.
  • the approach proposed by Darabi is illustrated in FIG. 1 and comprises a local oscillator 100 for producing output signals LOI 107 and LOQ 108 having a desired frequency of 2400 MHz.
  • Local oscillator 100 includes a VCO circuit 101, a buffer 109, a frequency divider 102 for producing 800 MHz in-phase LO component I 103 and quadrature component Q 104 signals that are half the output of the VCO, and two mixers 105 106.
  • VCO circuit 101 produces a 1600 MHz signal, which is then provided via buffer 109 to frequency divider circuit 102, which produces an in-phase signal I 103, and a quadrature signal Q 104 having a frequency that is 800 MHz, or half the frequency output by the VCO 101.
  • the present invention provides a system and method for generating an LO signal for a transmitter without the risk of pulling the VCO.
  • the system and method of the present invention employs a filtering technique to select a desired harmonic of the VCO signal.
  • the required in-phase and quadrature LO signals can be derived by means of dividers.
  • the system and method of the present invention avoids any harmonic relation between the transmit signal and the VCO frequency, without generation of intermediate signals close to the VCO frequency. Hence the system and method of the present invention avoids pulling of the VCO.
  • a VCO generates a sinusoidal input signal that is subsequently converted to a square wave, divided and filtered to obtain a desired harmonic in-phase I and quadrature Q signal of a pre-determined output frequency.
  • a local oscillator is provided for generating signals at a desired output frequency.
  • the local oscillator includes an oscillatory circuit configured to generate a first in-phase signal and a first quadrature signal at a first frequency that is lower than the desired output frequency, the first quadrature signal having a phase shift relative to the first in-phase signal; a pair of harmonic filters one coupled to receive the first in-phase signal and the other to receive the first quadrature signal and configured to obtain a pre-determined harmonic of each of these first signals; first and second transmit mixers coupled respectively to be driven by said obtained harmonic of each of said first signals.
  • a desired harmonic of a square wave input signal is obtained and an in-phase and a quadrature signal are generated therefrom such that the quadrature signal is phase-shifted relative to the in-phase signal, the I and Q signals are used to drive transmit mixers.
  • the oscillatory circuit is configured using an LC tank having a high Q and a small area.
  • the desired harmonic is preferably the third harmonic.
  • Alternative embodiments employ one filter to select the desired harmonic.
  • FIG. 1 illustrates a prior art approach to avoiding LO-pulling
  • FIG. 2 illustrates a first preferred embodiment of pulling-free LO generation, according to the present invention
  • FIG. 3 illustrates a second preferred embodiment of pulling-free LO generation, according to the present invention
  • FIG. 4 illustrates a third preferred embodiment of pulling-free LO generation, according to the present invention
  • FIG. 5 illustrates an architecture of a wireless communication system whereto embodiments of the present invention are to be applied
  • FIG. 6 illustrates a simplified block diagram of a wireless devices of the communication system of FIG. 5 according to an embodiment of the present invention.
  • a pulling-free LO is generated as illustrated in FIG. 2.
  • the VCO 201 running at 1600 MHz provides and input 212 to an IQ-generation circuit 200 that is divided in half by divider 202 to generate an in-phase LO component I 203 and a quadrature LO component Q 204, containing odd-order harmonics of 800 MHz.
  • divider 202 provides and input 212 to an IQ-generation circuit 200 that is divided in half by divider 202 to generate an in-phase LO component I 203 and a quadrature LO component Q 204, containing odd-order harmonics of 800 MHz.
  • the output signal of the divider 202 is a square wave 203 204, containing these odd-order harmonics.
  • the system and method of the present invention applies filters 211 to the square waves 203 204 to obtain the third harmonic of these signals, and thus derives a 2400 MHz in-phase signal LOI 207 and a quadrature signal LOQ 208.
  • LOI 207 and LOQ 208 are then used for driving transmit and receive mixers.
  • an LC-tank Q factor of 10 is assumed and the fundamental 800 MHz component is suppressed by 28 dB.
  • the resulting LO signal of 2400 MHz contains an 800 MHz spurious signal of -20 dBc.
  • the first embodiment includes at least one filtering amplifier that accomplishes this matching.
  • a poly-phase (LC) filter is preferred to meet the matching requirements.
  • a pulling-free LO is generated as illustrated in FIG.
  • the VCO 201 running at 1600 MHz provides an input 312 to an IQ-generation circuit 300 such that in the second embodiment, the third harmonic filtering 211 is done prior to the divider, preferably a divide-by-2 202.
  • the quadrature relation of the I and Q signal is now determined by the divider 202, which ensures perfect quadrature.
  • the 3rd harmonic filtering 211 is performed directly on a clipped (amplified) version of the VCO signal, so the LC-tank is tuned to 4800 MHz in the second embodiment.
  • the higher frequency allows for a higher tank Q factor, which, as a side benefit, has a much smaller area.
  • the unwanted spectrum is filtered by one of an antenna filter or a filter located in the transmit chain (both not shown).
  • the regenerative properties of a divide-by-2 413 are used to generate a 1600 MHz square wave input to the third harmonic filter 211 of the second embodiment, as illustrated in FIG. 4.
  • a pulling-free LO is generated by a VCO 201 that is tuned to 3200 MHz, which allows for a higher Q and a smaller area of the LC-tank, and the 3200 MHz signal is input to an IQ-generation circuit 400 in which the 3200 MHz signal is first divided and a resulting 1600 MHz square wave is input to a circuit substantially identical to the second embodiment.
  • the output spectra of the I 407 and Q 408 signals are comparable to I 307 and Q 308 signals of the second embodiment, containing residual spectral components at 1600 MHz and 3200 MHz at least 26 dB down with respect to the desired 2400 MHz signal.
  • the 1600 and 3200 MHz spectra are suppressed further by an antenna filter (not shown).
  • further filtering is applied before the divider 202 to each of the first through third embodiments to suppress the 1600 MHz fundamental signal.
  • This further filtering can be accomplished by any of: AC-coupling with a corner frequency of, say, 4 GHz between the divider output and the filter input, adding a 2nd or even a 3rd stage of filtering, and applying a 1600 MHz notch filter. Filtering is done prior to the final divide-by-2, since division of the signal creates symmetrical sidebands.
  • the third embodiment has an advantage that the signal component that pulls the VCO is only present after the last divide-by-2.
  • the apparatus and method of the pulling-free local oscillator of the present invention can be used for wireless personal area networks (WPANs) and local area networks (WLANs) in which an RF transmitter comprises a mixer configured to modulate the output signal of the LO with a data signal.
  • WLANs local area networks
  • Networks to which the present invention applies may further include GSM, Bluetooth, and DECT devices.
  • FIG. 5 illustrates a representative wireless network whereto embodiments of the present invention are to be applied.
  • a mixer configured to modulate the output signal of an LO with a data signal such that the pulling of the LO is avoided.
  • the network illustrated in FIG. 5 is small for purposes of illustration only. In practice, most WLANs would include a much larger number of mobile transceivers incorporating the present invention.
  • the low-power circuit and architecture of the LO generator of the present invention has application to a WPANs and WLANs and enables wireless devices thereof to reduce both cost and power consumption.
  • the present invention introduces a filtering technique to select a desired harmonic of a VCO signal with a required in-phase and quadrature LO signal being derived by means of dividers.
  • each device within the WPAN/WLAN shown in FIG. 5 may include a transceiver with an architecture that is illustrated in the block diagram of FIG. 6.
  • Each device may include a controller 602 coupled to at least a transmitter 601, an LO generator 603 (200 300 400) according to the present invention, and a receiver 604.
  • the transmitter 601 and the receiver 604 are coupled to an antenna 605. All may be integrated into a single chip along with other components such as the antenna.
  • the controller 602 can provide adaptive programming such that, for example, the transceiver is adapted to different modulation schemes and data rates specific to various communication protocols including IEEE 802.11, Bluetooth, and any other protocol known in the art.
  • the controller can program the LO generator to select a specific harmonic, it not being limited to the third harmonic. While the preferred embodiments of the present invention have been illustrated and described, it will be understood by those skilled in the art that the local oscillator as described herein is illustrative and various changes and modifications may be made to the local oscillator and equivalents may be substituted for elements thereof without departing from the true scope of the present invention.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Transmitters (AREA)
  • Transceivers (AREA)

Abstract

L'invention porte sur un système et un procédé de production du signal de l'oscillateur local (LO) d'un émetteur RF éliminant le risque de brouillage (pulling) par le LO. A cet effet on utilise une technique de filtrage qui sélectionne un harmonique donnée du signal de l'oscillateur commandé par tension (VCO), généralement le troisième. Les signaux en phase et en quadrature du LO peuvent être obtenus par des diviseurs. On évite ainsi toute relation harmonique entre le signal émis et la fréquence du VCO, et cela sans produire de signaux intermédiaires voisins de la fréquence du VCO, dont on supprime de cette manière le brouillage.
EP05718801A 2004-04-30 2005-04-25 Systeme et procede evitant le brouillage par l'oscillateur local Withdrawn EP1745544A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US56679704P 2004-04-30 2004-04-30
PCT/IB2005/051341 WO2005107059A1 (fr) 2004-04-30 2005-04-25 Systeme et procede evitant le brouillage par l'oscillateur local

Publications (1)

Publication Number Publication Date
EP1745544A1 true EP1745544A1 (fr) 2007-01-24

Family

ID=34965448

Family Applications (1)

Application Number Title Priority Date Filing Date
EP05718801A Withdrawn EP1745544A1 (fr) 2004-04-30 2005-04-25 Systeme et procede evitant le brouillage par l'oscillateur local

Country Status (5)

Country Link
EP (1) EP1745544A1 (fr)
JP (1) JP2007535855A (fr)
KR (1) KR20070004890A (fr)
CN (1) CN1985436A (fr)
WO (1) WO2005107059A1 (fr)

Families Citing this family (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1851862B1 (fr) 2005-02-14 2009-03-04 Koninklijke Philips Electronics N.V. Recepteur pour la reception simultanee de normes differentes
CN101322310B (zh) * 2005-03-08 2011-08-17 Dsp集团瑞士股份公司 用于生成具有等于基频小数部分的频率的本振信号的电子装置
US8655296B2 (en) 2007-12-18 2014-02-18 Harris Corporation Frequency synthesizer and related method for generating wideband signals
JP2014039143A (ja) * 2012-08-15 2014-02-27 Nec Corp 周波数変換器及び周波数変換方法
EP2887540A1 (fr) * 2013-12-18 2015-06-24 Telefonaktiebolaget L M Ericsson (publ) Génération de signal d'oscillateur local
US9680454B2 (en) * 2014-10-28 2017-06-13 Mediatek Inc. Frequency tripler and local oscillator generator
KR101902093B1 (ko) * 2017-01-03 2018-09-28 (주)에프씨아이 Ｌｏ 생성 시스템 및 그 생성 방법
CN108418591A (zh) * 2018-02-09 2018-08-17 南京中感微电子有限公司 无线射频发射机
CN117674841B (zh) * 2022-09-06 2025-10-24 加特兰微电子科技(上海)有限公司 一种倍频器、信号发射器和雷达芯片

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Publication number Priority date Publication date Assignee Title
GB1001915A (en) * 1964-03-26 1965-08-18 Communications Patents Ltd Improvements in or relating to variable frequency oscillation generators
WO1997002652A2 (fr) * 1995-06-30 1997-01-23 Philips Electronics N.V. Oscillateur a quartz syntonisable a sortie d'harmonique
JP2001230695A (ja) * 2000-02-16 2001-08-24 Nec Corp 無線機及びそれに使用する周波数変換方法
FR2814606A1 (fr) * 2000-09-25 2002-03-29 Koninkl Philips Electronics Nv Source de signal a filtre polyphase
JP3908591B2 (ja) * 2002-05-01 2007-04-25 ソニー・エリクソン・モバイルコミュニケーションズ株式会社 変復調装置および携帯無線機

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO2005107059A1 *

Also Published As

Publication number Publication date
JP2007535855A (ja) 2007-12-06
KR20070004890A (ko) 2007-01-09
CN1985436A (zh) 2007-06-20
WO2005107059A1 (fr) 2005-11-10

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