WO2000019623A1 - Utilisation d'un melangeur de bandes laterales uniques pour ecarter des signaux d'image dans un appareil sans fil - Google Patents

Utilisation d'un melangeur de bandes laterales uniques pour ecarter des signaux d'image dans un appareil sans fil Download PDF

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Publication number
WO2000019623A1
WO2000019623A1 PCT/US1999/022820 US9922820W WO0019623A1 WO 2000019623 A1 WO2000019623 A1 WO 2000019623A1 US 9922820 W US9922820 W US 9922820W WO 0019623 A1 WO0019623 A1 WO 0019623A1
Authority
WO
WIPO (PCT)
Prior art keywords
signal
single side
side band
mixer
received
Prior art date
Application number
PCT/US1999/022820
Other languages
English (en)
Inventor
Simon Hughes
John R. Rowland, Jr.
Emmanuel Ngompe
Original Assignee
Conexant Systems, Inc.
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 Conexant Systems, Inc. filed Critical Conexant Systems, Inc.
Publication of WO2000019623A1 publication Critical patent/WO2000019623A1/fr

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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
    • H04B1/005—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 adapting radio receivers, transmitters andtransceivers for operation on two or more bands, i.e. frequency ranges
    • H04B1/0053—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 adapting radio receivers, transmitters andtransceivers for operation on two or more bands, i.e. frequency ranges with common antenna for more than one band
    • H04B1/0057—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 adapting radio receivers, transmitters andtransceivers for operation on two or more bands, i.e. frequency ranges with common antenna for more than one band using diplexing or multiplexing filters for selecting the desired band
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03D—DEMODULATION OR TRANSFERENCE OF MODULATION FROM ONE CARRIER TO ANOTHER
    • H03D7/00—Transference of modulation from one carrier to another, e.g. frequency-changing
    • H03D7/18—Modifications of frequency-changers for eliminating image frequencies
    • 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
    • H04B1/005—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 adapting radio receivers, transmitters andtransceivers for operation on two or more bands, i.e. frequency ranges
    • 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
    • H04B1/005—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 adapting radio receivers, transmitters andtransceivers for operation on two or more bands, i.e. frequency ranges
    • H04B1/0053—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 adapting radio receivers, transmitters andtransceivers for operation on two or more bands, i.e. frequency ranges with common antenna for more than one band
    • H04B1/006—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 adapting radio receivers, transmitters andtransceivers for operation on two or more bands, i.e. frequency ranges with common antenna for more than one band using switches for selecting the desired band
    • 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
    • H04B1/06—Receivers
    • H04B1/16—Circuits
    • H04B1/26—Circuits for superheterodyne receivers
    • H04B1/28—Circuits for superheterodyne receivers the receiver comprising at least one semiconductor device having three or more electrodes

Definitions

  • the invention relates to processing signals in a wireless communication system and,
  • signals are transmitted in multiple
  • Each wireless station in the network must be able to receive and process
  • each station must process radio frequency (RF) signals in both the Global System for Mobile
  • GSM Global System for Mobile communications
  • DCS Digital Communication Service
  • the receiver in each wireless station must be able to discern a true received signal from
  • Each station therefore includes multiple filtering circuits, one for each
  • FIG. 1 is a simplified schematic diagram of a typical GSM/DCS dual-mode wireless
  • the phone 10 includes a transmitter 12 and a receiver 14 that send and receive
  • the receiver 14 includes two front-end receiver circuits coupled to the antenna
  • GSM and DCS receiver circuits are virtually identical in structure, the GSM circuit including a GSM- band surface acoustic wave (SAW) filter 20, a low-noise amplifier 22, and a GSM-band image-reject filter 24 arranged in series; and the DCS circuit including a DCS-band SAW filter 26, a low-noise amplifier 28, and DCS-band image reject filter 30 arranged in series.
  • SAW surface acoustic wave
  • a switch 32 applies the output signal from one of the receiver circuits, via a buffer amplifier 34, to a double side band (DSB) mixer 36.
  • the double side band mixer 36 mixes the signal from the filter circuits with an amplified signal from a voltage controlled oscillator (NCO) 38 and delivers the resulting intermediate frequency (IF) signals to subsequent circuitry for processing and demodulation.
  • NCO voltage controlled oscillator
  • the front-end receiver circuitry in a multiple-mode wireless receiver can be modified to reduce the number of components in the receiver and therefore to reduce the receiver's size and cost.
  • the invention relates to removing an image signal from a radio
  • RF frequency
  • the filter circuits each associated with one of the communication bands. Only one of the filter circuits allows the received RF signal to pass.
  • the RF signal then is delivered to a single side band mixer, which converts the RF signal into an intermediate frequency (IF) signal from which information can be obtained.
  • IF intermediate frequency
  • the SSB mixer serves to remove the image signal from the RF
  • the single side band mixer includes two mixer circuits that
  • the filtering circuits each include a surface acoustic wave (SAW)
  • Each filtering circuit also may include a high-pass filter at the front end to improve
  • FIG. 1 is a simplified schematic diagram of a typical GSM/DCS dual-mode wireless
  • FIG. 2 is a simplified schematic diagram of a GSM/DCS dual-mode phone having a
  • FIG. 3 is a schematic diagram of a single side band mixer that may be used to reject
  • FIG. 4 is a schematic diagram of a fifth-order elliptical high pass filter that may be
  • FIG. 5 is a graph showing the rejection characteristics of the filter of FIG. 4.
  • FIG. 2 is a simplified schematic diagram of a dual-mode wireless phone 50 having a single side band mixer that rejects image signals.
  • the front-end receiver circuits in this phone 50 include only one bandpass filter each.
  • the GSM receiver circuit includes a GSM-band SAW filter 54 and a low-noise amplifier 56
  • the DCS receiver circuit includes a DCS-band SAW filter 58 and a low- noise amplifier 60.
  • the bandwidth of the GSM band SAW filter 54 is approximately 935 to 960 MHZ
  • the bandwidth of the DCS-band SAW filter 58 is approximately 1805 MHZ to 1880 MHZ.
  • the GSM and DCS filter circuits do not include image reject filters because the receiver 52 includes a single side band (SSB) mixer 62, which naturally rejects image signals not lying in the same side band as the true signal.
  • a switch 66 selectively apply the received RF signal to the appropriate front-end filter circuit and from the selected receiver circuit to the SSB mixer 62, as required by the mode (i.e., GSM or DCS) in which the phone 50 is operating.
  • the DCS filter circuit also may include a high pass filter 64 to improve image rejection in the lower side band, as described below.
  • FIG. 3 is a schematic diagram of a SSB mixer 100 that may be used in the phone 50 of FIG. 2.
  • the mixer 100 receives a processed RF signal SI from the front-end filter circuitry and provides the signal SI to a phase-shifting circuit 102 and to a first mixer 104.
  • the phase shifting circuit 102 shifts the phase of the RF signal SI by ⁇ 90°, depending upon the communication mode, and provides the phase-shifted signal S2 to a second mixer 106.
  • a local oscillator (LO) 108 provides an oscillating signal S3 at an offset frequency to both of the mixers 104, 106, which mix the oscillating signal with the RF signal SI and the shifted RF signal S2, respectively, to produce two intermediate frequency (IF) signals S4, S5.
  • LO local oscillator
  • a second phase-shifting circuit 110 shifts, by ⁇ 90°, the phase of the IF signal S4 produced by the first mixer 104 to produce a phase-shifted IF signal S6.
  • a summing circuit 112 combines the IF signal S5 and the phase-shifted IF signal S6 to form an IF output signal S7, which the SSB mixer 100 provides to subsequent circuitry for processing and demodulation, as shown
  • the SSB mixer 100 suppresses the image signal, which is an unwanted spurious signal external to the receiver station.
  • the image signal lies at a frequency such that it will be mixed with the internal oscillator signal S3, to generate an unwanted signal at the output
  • the image signal lies a frequency approximately 21 F above or below the frequency of the IF signal if interest, depending on communication mode and implementation..
  • the SSB mixer 100 switches the local oscillator 108 and the phase-shifting circuits 102, 110 between two different frequency and
  • phase-shift values respectively. This switching may be accomplished, for example, by on- chip switches that respond to a microcontroller signal indicating the phone's communication mode.
  • FIG. 4 shows a fifth-order elliptical filter 120 that may be used as a an additional high pass filter 64 (FIG. 2) to improve image signal rejection in the DCS-band front-end filter circuit of FIG. 2.
  • the filter 120 includes three capacitors Cl, C2, C3 connected in series with each other and with the DCS-band SAW filter 58 (FIG. 2).
  • the filter 120 also includes two L-C circuits that connect the three series-connected capacitors Cl , C2, C3 to ground.
  • the first terminal 122 of the first capacitor Cl receives the incoming RF signal as input, and its second terminal 124 connects to the first terminal 126 of the second capacitor C2 in the series.
  • the second terminal 128 of the second capacitor C2 connects to the first terminal 130 of the third capacitor C3 in the series, the second terminal 132 of which connects to the DCS-band SAW filter.
  • the first L-C circuit includes a capacitor C4 connected to the first two capacitors Cl, C2 in the series and to an inductor LI, the other end of which is connected to ground.
  • the second L-C circuit includes a capacitor C5 connected to the last two capacitors C2, C3 in the series and to an inductor L2 that also connects to ground.
  • C, 2.7 pF
  • C 2 5.6 pF
  • C 3 1.8 pF
  • C 4 3.3 pF
  • C 5 3.3 pF
  • L 2 4.7 nH.
  • FIG. 4 shows the signal rejection characteristics of the high pass filter 120 of FIG. 3 using components with the values given above.
  • the filter exhibits a well defined pass-band between 1805 MHZ and 1880 MHZ and provides approximately 53.587 dB and 51.578 dB total rejection at 1005 MHZ and 1080 MHZ, respectively.

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Power Engineering (AREA)
  • Superheterodyne Receivers (AREA)
  • Transceivers (AREA)

Abstract

Un signal d'image est éliminé d'un signal de fréquence radioélectrique (RF) reçu dans une des deux bandes de fréquence de radiocommunications telles que la bande GSM et la bande DCS. Le signal RF reçu est présenté à deux circuits filtrants passe-bande (58, 54) qui sont chacun associés à une des bandes de radiocommunications. Un seul des circuits filtrants laisse passer le signal RF reçu. Le signal RF est ensuite envoyé à un mélangeur (62) de bandes latérales uniques (BLU) qui transforme le signal RF en un signal de fréquence intermédiaire (FI) à partir duquel l'information peut être obtenue. Le mélangeur BLU sert à éliminer le signal d'image du signal RF, quelle que soit la bande de radiocommunications dans laquelle se trouve le signal RF. Par conséquent les signaux RF reçus ne traversent pas des filtres de réjection d'image après leur sortie des circuits filtrants passe-bande.
PCT/US1999/022820 1998-09-30 1999-09-29 Utilisation d'un melangeur de bandes laterales uniques pour ecarter des signaux d'image dans un appareil sans fil WO2000019623A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US16371298A 1998-09-30 1998-09-30
US09/163,712 1998-09-30

Publications (1)

Publication Number Publication Date
WO2000019623A1 true WO2000019623A1 (fr) 2000-04-06

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ID=22591251

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1999/022820 WO2000019623A1 (fr) 1998-09-30 1999-09-29 Utilisation d'un melangeur de bandes laterales uniques pour ecarter des signaux d'image dans un appareil sans fil

Country Status (2)

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TW (1) TW448633B (fr)
WO (1) WO2000019623A1 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2003067775A1 (fr) * 2002-02-06 2003-08-14 Koninklijke Philips Electronics N.V. Recepteur multibande
KR20030078314A (ko) * 2002-03-29 2003-10-08 삼성전기주식회사 코드레스폰의 이미지 제거용 필터
KR100438533B1 (ko) * 2000-11-30 2004-07-03 엘지전자 주식회사 이미지 주파수 제거 회로

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
TWI729588B (zh) 2019-11-26 2021-06-01 立積電子股份有限公司 多模式處理電路及其多模式控制方法

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5369790A (en) * 1990-09-07 1994-11-29 Fujitsu Limited Radio receiver
US5926751A (en) * 1997-02-19 1999-07-20 Motorola, Inc. Method and apparatus for receiving communication signals
US5966646A (en) * 1997-05-13 1999-10-12 Ericsson, Inc. Dual-band radio receiver

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5369790A (en) * 1990-09-07 1994-11-29 Fujitsu Limited Radio receiver
US5926751A (en) * 1997-02-19 1999-07-20 Motorola, Inc. Method and apparatus for receiving communication signals
US5966646A (en) * 1997-05-13 1999-10-12 Ericsson, Inc. Dual-band radio receiver

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100438533B1 (ko) * 2000-11-30 2004-07-03 엘지전자 주식회사 이미지 주파수 제거 회로
WO2003067775A1 (fr) * 2002-02-06 2003-08-14 Koninklijke Philips Electronics N.V. Recepteur multibande
KR20030078314A (ko) * 2002-03-29 2003-10-08 삼성전기주식회사 코드레스폰의 이미지 제거용 필터

Also Published As

Publication number Publication date
TW448633B (en) 2001-08-01

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