US3358246A - Bandpass filter for passing a wide range of frequencies and suppressing a narrow range of frequencies - Google Patents

Bandpass filter for passing a wide range of frequencies and suppressing a narrow range of frequencies Download PDF

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Publication number
US3358246A
US3358246A US330362A US33036263A US3358246A US 3358246 A US3358246 A US 3358246A US 330362 A US330362 A US 330362A US 33036263 A US33036263 A US 33036263A US 3358246 A US3358246 A US 3358246A
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United States
Prior art keywords
branch
frequencies
range
frequency
band
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Expired - Lifetime
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US330362A
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English (en)
Inventor
Bensasson Albert
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US Philips Corp
North American Philips Co Inc
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US Philips Corp
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N5/00—Details of television systems
    • H04N5/44—Receiver circuitry for the reception of television signals according to analogue transmission standards
    • H04N5/4446—IF amplifier circuits specially adapted for B&W TV
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H7/00—Multiple-port networks comprising only passive electrical elements as network components
    • H03H7/01—Frequency selective two-port networks
    • H03H7/06—Frequency selective two-port networks including resistors
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H7/00—Multiple-port networks comprising only passive electrical elements as network components
    • H03H7/01—Frequency selective two-port networks
    • H03H7/17—Structural details of sub-circuits of frequency selective networks
    • H03H7/1741—Comprising typical LC combinations, irrespective of presence and location of additional resistors
    • H03H7/175—Series LC in series path
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H7/00—Multiple-port networks comprising only passive electrical elements as network components
    • H03H7/01—Frequency selective two-port networks
    • H03H7/17—Structural details of sub-circuits of frequency selective networks
    • H03H7/1741—Comprising typical LC combinations, irrespective of presence and location of additional resistors
    • H03H7/1758—Series LC in shunt or branch path
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H7/00—Multiple-port networks comprising only passive electrical elements as network components
    • H03H7/46—Networks for connecting several sources or loads, working on different frequencies or frequency bands, to a common load or source
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N5/00—Details of television systems
    • H04N5/44—Receiver circuitry for the reception of television signals according to analogue transmission standards
    • H04N5/60—Receiver circuitry for the reception of television signals according to analogue transmission standards for the sound signals

Definitions

  • the longitudinal branches are tuned to have a low impedance to a wide band of frequencies.
  • the transverse branch is a series resonant circuit tuned to a narrow band in or near the wide band, so the filter rejects the narrow band.
  • a fourth branch comprised of a series resonant circuit tuned to the narrow band is connected in parallel with part of the transverse branch in order to increase the width of the narrow band.
  • This invention relates to bandpass filters for passing a comparatively wide range of frequencies and also for strongly and selectively suppressing a comparatively narrawo range of frequencies located within the said range or in the vicinity thereof, comprising two longitudinal branches connected in series and each comprising a seriesresonant circuit and a transverse branch coupled to the common point of the longitudinal branches and comprising a series-resonant circuit which is tuned to a frequency located in the comparatively narrow range of frequencies.
  • Such filters are used inter alia in television receivers as intermediate-frequency bandpass filters.
  • the comparatively wide range of frequencies comprises the intermediatefrequency video-signal and the comparatively narrow range of frequencies comprises the sound carrier wave.
  • the sound carrier wave must in many cases be considerably suppressed relative to the intermediate-frequency video-signal in the intermediate-frequency portion of the receiver. Also the sound carrier wave is in many cases derived from said intermediatefrequency portion.
  • the band-pass filter according to the invention is characterized in that parallel with a portion of the transverse branch there is connected a further branch which likewise comprises a series-resonant circuit which is tuned to the frequency located in the comparatively narrow range of frequencies.
  • FIGURE 1 shows a bandpass filter of known type
  • FIGURE 2 shows a bandpass filter according to the invention
  • FIGURE 3 shows a circuit including a bandpass filter according to the invention
  • FIGURE 4 shows a response curve of the filter of FIG- URE 1
  • FIGURE 5 shows a response curve of a bandpass filter according to the invention.
  • the known filter shown in FIGURE 1 is built up from:
  • a primary branch I comprising the series-combination of a capacitor 11, a resistor 12 and an inductor 13;
  • a third branch III comprising the series combination of a capacitor 31, a resistor 32 and an inductor 33.
  • the branch III is tuned to the frequency to be eliminated whereas the branches I and II behave as a transformer of which I is the primary winding and II is the secondary winding.
  • the two branches I and II are usually tuned to the same frequency, the width of the pass band, as is well-known, being substantially de termined by the value of the coupling coefficient.
  • Such a network shows a response curve as illustrated in FIG- URE 4, in which the response A is plotted as a function (f) of the frequency f.
  • the figure shows that said curve has two relative maxima M1 and M2, which are as far remote from each other as possible, and between them a relative minimum m.
  • This filter includes, relative to the filter shown in FIG- URE 1, a fourth branch IV which is tuned to the same frequency f as the branch III of the filter previously described and which is capacitively coupled to the branch III.
  • the capacitor 31 of the branch III of the filter shown in FIGURE 1 is replaced by two seriescapacitors 34 and 35, whilst the branch IV which comprises the series-circuit of a capacitor 41, a resistor 42 and an inductor 43, is connected to the terminals of one of said capacitors, i.e. 35 in the figure.
  • the voltage derived from the terminals of capacitor 21 is applied to the input of the subsequent stage of the intermediate-frequency amplifier of the video-circuit, whereas the voltage set up at the terminals of capacitor 41 is applied to the input of the first stage of the intermediate-frequency amplifier of the sound-circuit.
  • the amplitude of the signal applied to the last-mentioned amplifier increases as the suppression of the sound carrier wave in the filter increases.
  • FIGURE 2 the neutralizing resistor is indicated by 40.
  • FIGURE 3 shows one practical embodiment of a filter as shown in FIGURE 2, which is included between two intermediate-frequency stages of the video-circuit of a television receiver.
  • This filter serves, on one hand, to eliminate the sound carrier wave from the video-circuit and, on the other hand, to apply said sound carrier wave to the sound circuit.
  • the capacity 11 of the branch I is formed by the anode capacity of the tube 14, which precedes the: filter, and the; capacity 21 of the branch II is formed by the input capacity of the tube 24 whichfollows after the filter.
  • the branch IV is coupled to the control grid of tube 44 of the first intermediate-frequency stage of the sound circuit.
  • Capacitors 50 and 50" serve as direct-current uncoupling capacitors.
  • FIGURE 3 shows the tubes 14, 24 and 44 as triodes. It will be evident that these tubes can be pentodes or can even be replaced by transistors.
  • FIGURE 3 the inductors 13 7 and 23, on the one hand, and 33 and 43, on the other,
  • the filter can beadjusted very easily.
  • a bandpass filter for passing a comparatively wide range of frequencies and also for strongly and selectively suppressing a comparatively narrow range of frequencieslocated within the said wide range or in the vicinity thereof, said-filter comprising first and second longitudinal branches connected in series and each comprising a seriesresonant circuit tuned to provide a low longitudinal impedance for said filter in said wide range, a transverse branch coupled to the common point of the longitudinal branches andcomprising a series-resonant circuit tuned toa frequency located in said comparatively narrow range of frequencies and input and output circuits connectedto points on said first and second branches other than said common point; wherein the improvement comprises a fourth branch connected in parallel with only a portion of the transverse branch, saidfourth branch comprising a series-resonant circuit tuned to said frequency located inthe comparatively narrow range of frequencies whercby the range of suppression of said narrow range is increased.
  • a bandpass filter for passing a wide continuous range of frequencies and selectivelysuppre'ssing a narrow range of frequencies adjacent said wide range, com-prising first and second series connected longitudinal branches and a transverse branch connected't'o the junction of said first and second branches; an inputcircuit connected to apoint of said first branch other than said function, an output connected to a point of said second branch other than: said junction, each of' said first and.
  • second branches comprising a series resonant circuit tuned to provide a low longitudinal impedance of said filter in said wide range
  • said transverse branch comprising a series resonant circuit tuned toa frequency in said narrow range, where' by the impedance of said transverse branch is lbw at said frequency; and afourth branch connected in parallel with only a portion. of said transverse branch, said fourth branch comprising a series-- resonant circuit tuned tosaid frequency, wherebythe frequency range of suppressionin said narrowrange is increased.
  • the bandpass filter of claim 2 in which said first and second. series branches are tunedto. substantially the same range of frequencies and also for strongly and'selectively suppressing a comparatively narrow'range offrequencies located" within the saidwide range or in. the vicinity thereof, said filter comprising first. and second longitudinal branches connected inseriesandeachcomprising a-seriesresonant circuit tuned to provide a low longitudinal impedance for said filter in said wider range, a transverse branch coupled to the common point of the longitudinal branches and comprising a series-resonant circuit tuned to a frequency located in said comparatively narrow range of frequencies, and input and output circuits connected to points on saidfirst and' second branches other than said common point, wherein the improvementcomprises. a fourth branch comprising a series-resonant circuit tuned to said frequency located in the comparatively narrow range of frequencies, the capacitor of. the transverse. branch being. comprised of the. series combinationof .twov
  • a bandpass filterfor passing a wide continuous. range of frequencies and selectively suppressing a narrow range of frequencies adjacent said wide range comprising first and second series connected longitudinal branches and a transverse branch. connectedtothe junction of said first and second branches, an input. circuit connected to a pointof: said first branch other than said junction, an output connected to. a. point of'said second branch other than said junction, each. of. said first and second branches comprising aseries resonant. circuit tuned to provide a lowlongitudinal impedance of. said filter. insaid wide range, said transversebranch comprising a series resonant circuit tuned to a frequency in said narrow range and being, comprised of the series circuit of aninductor; and.
  • first; and second capacitor-s connected: inthat order between said junction and: a point of reference potential; whereby the impedance; of said transverse branch is low at. said frequency; and a fourth branch connected in par" allelzwith: saidsecond capacitofisaid fourtli branch comprising a series resonant circuit tuned tosaidfrequency; whereby the frequency range of suppression said narrow range is increased.

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  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Filters And Equalizers (AREA)
  • Television Receiver Circuits (AREA)
  • Amplifiers (AREA)
  • Superheterodyne Receivers (AREA)
US330362A 1963-01-02 1963-12-13 Bandpass filter for passing a wide range of frequencies and suppressing a narrow range of frequencies Expired - Lifetime US3358246A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR920307A FR1352223A (fr) 1963-01-02 1963-01-02 Filtre de bande à quatre circuits accordés, notamment pour télévision

Publications (1)

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US3358246A true US3358246A (en) 1967-12-12

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US330362A Expired - Lifetime US3358246A (en) 1963-01-02 1963-12-13 Bandpass filter for passing a wide range of frequencies and suppressing a narrow range of frequencies

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US (1) US3358246A (enrdf_load_html_response)
AT (1) AT241556B (enrdf_load_html_response)
CH (1) CH416864A (enrdf_load_html_response)
ES (1) ES294961A3 (enrdf_load_html_response)
FR (1) FR1352223A (enrdf_load_html_response)
GB (1) GB1022306A (enrdf_load_html_response)
NL (1) NL301922A (enrdf_load_html_response)
OA (1) OA00791A (enrdf_load_html_response)
SE (1) SE307995B (enrdf_load_html_response)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3452303A (en) * 1965-07-20 1969-06-24 Warwick Electronics Inc Bandpass network having a high attenuation rejection characteristic
US3680011A (en) * 1970-08-03 1972-07-25 Stanford Research Inst Loss cancelling resonator and filters
US3778720A (en) * 1972-03-08 1973-12-11 Stewart Warner Corp Intermediate frequency amplifier circuit
US3906350A (en) * 1973-03-12 1975-09-16 Comark Ind Inc Nyquist slope filter useful for monitoring video modulation at transmitting station
US3944755A (en) * 1974-02-25 1976-03-16 Victor Company Of Japan, Ltd. Composite filter circuit
DE3040251A1 (de) * 1979-10-26 1981-05-07 RCA Corp., 10020 New York, N.Y. Signaltrennschaltung
FR2469070A1 (fr) * 1979-10-26 1981-05-08 Rca Corp Reseaux de separation de signaux
US4376953A (en) * 1979-10-26 1983-03-15 Naimpally Saiprasad V Signal separation networks
EP1536557A1 (en) * 2003-11-21 2005-06-01 Alps Electric Co., Ltd. Intermediate frequency circuit

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5142371A (en) * 1990-08-06 1992-08-25 Thomson Consumer Electronics, Inc. Fm trap for a television tuner permitting both tv and fm reception through the same tuner

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2707730A (en) * 1951-05-21 1955-05-03 Rca Corp Amplifier circuits for television picture signal channels
US3188566A (en) * 1962-10-08 1965-06-08 Collins Radio Co Intermodulation measurement system including resonant filter trap means

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2707730A (en) * 1951-05-21 1955-05-03 Rca Corp Amplifier circuits for television picture signal channels
US3188566A (en) * 1962-10-08 1965-06-08 Collins Radio Co Intermodulation measurement system including resonant filter trap means

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3452303A (en) * 1965-07-20 1969-06-24 Warwick Electronics Inc Bandpass network having a high attenuation rejection characteristic
US3680011A (en) * 1970-08-03 1972-07-25 Stanford Research Inst Loss cancelling resonator and filters
US3778720A (en) * 1972-03-08 1973-12-11 Stewart Warner Corp Intermediate frequency amplifier circuit
US3906350A (en) * 1973-03-12 1975-09-16 Comark Ind Inc Nyquist slope filter useful for monitoring video modulation at transmitting station
US3944755A (en) * 1974-02-25 1976-03-16 Victor Company Of Japan, Ltd. Composite filter circuit
DE3040251A1 (de) * 1979-10-26 1981-05-07 RCA Corp., 10020 New York, N.Y. Signaltrennschaltung
FR2469069A1 (fr) * 1979-10-26 1981-05-08 Rca Corp Reseaux de separation de signaux
FR2469070A1 (fr) * 1979-10-26 1981-05-08 Rca Corp Reseaux de separation de signaux
DE3040250A1 (de) * 1979-10-26 1981-05-14 RCA Corp., 10020 New York, N.Y. Signaltrennschaltung
US4283741A (en) * 1979-10-26 1981-08-11 Rca Corporation Signal separation networks
US4376953A (en) * 1979-10-26 1983-03-15 Naimpally Saiprasad V Signal separation networks
EP1536557A1 (en) * 2003-11-21 2005-06-01 Alps Electric Co., Ltd. Intermediate frequency circuit

Also Published As

Publication number Publication date
GB1022306A (en) 1966-03-09
AT241556B (de) 1965-07-26
ES294961A3 (es) 1963-10-16
FR1352223A (fr) 1964-02-14
CH416864A (de) 1966-07-15
SE307995B (enrdf_load_html_response) 1969-01-27
NL301922A (enrdf_load_html_response) 1965-10-11
OA00791A (fr) 1967-11-15

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