US2224200A - Circuit for amplifying carrier frequencies - Google Patents

Circuit for amplifying carrier frequencies Download PDF

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Publication number
US2224200A
US2224200A US207563A US20756338A US2224200A US 2224200 A US2224200 A US 2224200A US 207563 A US207563 A US 207563A US 20756338 A US20756338 A US 20756338A US 2224200 A US2224200 A US 2224200A
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United States
Prior art keywords
frequency
circuits
band
frequencies
curves
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Expired - Lifetime
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US207563A
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English (en)
Inventor
Schienemann Rudolf
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Telefunken AG
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Telefunken AG
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Publication date
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Publication of US2224200A publication Critical patent/US2224200A/en
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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
    • H03F1/42—Modifications of amplifiers to extend the bandwidth
    • H03F1/48—Modifications of amplifiers to extend the bandwidth of aperiodic amplifiers
    • H03F1/50—Modifications of amplifiers to extend the bandwidth of aperiodic amplifiers with tubes only
    • 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
    • H03H7/0153—Electrical filters; Controlling thereof
    • H03H7/0161—Bandpass filters

Definitions

  • the invention relates to circuits for amplifying carrier frequencies which comprise resonant circuits tuned to different frequencies. Such arrangements are necessary, e. g., for television or telephony purposes in order to amplify the band of frequencies to be transmitted.
  • the invention more particularly is concerned with the problem of obtaining approximately constant amplification over the whole band with a given width of the band of frequencies to be amplified.
  • the independent variables which are available for obtaining this desired uniform amplification are the resonance frequencies of the different circuits and their attenuations.
  • the distances or intervals between the separate resonance frequencies had to be made equal, and that also the attenuations of the resonant circuits had to be equal.
  • the optimal frequency interval and the optimal attenuation would have to be increased or decreased steadily in the direction from the lower towards the higher fre- 2 quencies within the band to be amplified.
  • the invention is based on the knowledge that a constant amplification is obtained, on the contrary, when either the distances of the separate resonance frequencies or their attenuations are made to decrease towards the upper and lower cut-off limits of the frequency band to be transmitted. Preferably the distances as well as the attenuations should simultaneously decrease.
  • Fig. 1 is a graphical representation on a linear frequency scale of a plurality of resonance curves which serve to explain the invention
  • Fig. 2 is a similar representation on a logarithmic scale
  • Fig. 3 is a graphical representation of the resonance curves when the distances between the resonant frequencies of the several circuits are decreased toward the limits of the band but with equal attenuations of the circuits
  • Fig. 4 is a graphical representation of the resonance curves when the attenuations of the several circuits are decreased towards the limits of the band but with equal intervals between the resonant frequencies of the circuits
  • Fig. 5 is an amplifier circuit embodying the features of this invention.
  • Fig. 1 appears as shown in Fig. 2 when logarithmic scales are used for the frequency axis as well as for the ordinate axis.
  • the range at the limits of which the curve V falls off to the amount 0.7 is called the width b of the band to be amplified.
  • the corresponding attenuations d are indicated at the different curves R1 to Re.
  • the distances be tween the resonance frequencies must be decreased towards the limits of the band to be transmitted in order to obtain an approximately constant amplification factor. It is to be noticed, thereby, that the amplification factor for a single frequency within the band to be transmitted'is proportional to the product of the amplitudes of all resonance curves at this position.
  • the resonance curves R2 to Re fall off, while only the resonance curve R1 rises.
  • the increase of the amplitude of the curve R1 must approximately compensate the decrease of the amplitudes of the curves R2 to Re. If, however, one proceeds from the frequency is to the frequency f2, it is only the curves R3 to Re which decrease (as compared with the curves R2 to Rs proceeding from f2 to f1), while two curves increase namely R1 and R2 (in contrast to only the curve R1 when proceeding from f2 to h).
  • the decrease of the curves R3 to Rs (in contrast to R2 to Rs in the former case) must at least approximately be compensated by the increase of R1 and R2.
  • the maximum or crest value of R2, i. e., the frequency f2 may be spaced farther apart from f3 than the frequency f1 from the frequency 12.
  • the curves R3 to Re have a greater amplitude at the frequency f2 than at the frequency f1 so that also by this reason the distance f2-f1 must be smaller than the distance fa-fz.
  • the maximum of R2 ought not to be as great as the maximum of R1 in the first treated case.
  • the'curves R3 to R6 have smaller amplitudes at the frequency f1 than at the frequency f2 so that also for this reason the attenuation of the circuit R1 must be smaller than that of the circuit R2.
  • Particularly favorable conditions i. e., a scarcely perceptible decrease of" the amplification factor up to the neighborhood'of the both limits of the band, are obtained, if one makes both the intervals between the resonance frequencies and the attenuation of the respective resonant circuits decrease towards the ends of the band. This fact shall be demonstrated by calculation in a manner as hereinafter to be outlined, without however a proof thereof being furnished.
  • the frequency intervals A between the resonant frequencies of each pair of symmetrical tuned circuits and the damping d of each pair may be determined from the following equations, in which the value of used is that whose subscript corresponds to the pair of circuits in question.
  • A signifies the distance between every two neighboring resonant circuits of equal attenuation (indicated in Fig. 2).
  • the attenuation is herein as above the so-called parallel attenuation, i. e., it is calculated by the formula wherein R is the resistance in parallel to the resonant circuit L and C.
  • the resonant circuits preferably with the plate-earth capacities C10 and C11 drawn in dotted lines, the resonant circuits.
  • the requisite attenuation may be obtained, e. g., by suitably dimensioning the parallel resistances I4, I5 or the inherent resistances of the coils l2 and I3.
  • the terminals l6 and H are connected to the positive pole of the plate-voltage source,
  • the invention inter alia also may be applied to the amplification of speech currents. If, e. g., along a telephone line eight repeater stations comprising four tubes each are provided, according to the invention all 32 resonant circuits forming part of them may be differently tuned and damped. Likewise one may perhaps distribute the resonance frequencies of the first 16 circuits over the whole band according to the rules given by the invention and choose the frequencies of the second 16 circuits in the same manner as the frequencies of the first circuits. In this manner also the subdivision of the whole amplifying channel even may be carried on by forming four groups comprising eight resonance circuits each or eight groups comprising four differently tuned and/or damped circuits each.
  • each group the frequencies and/ or the attenuations are graduated according to the invention.
  • eight groups comprising four differently tuned and/or damped resonant circuits each of the four circuits are differently designed, but the various repeater stations are conformable to each other.
  • the first station contains throughout circuits equal to each other, the second station likewise nothing but circuits equal to each other, which, however, are different from the circuits of the first station etc.
  • a circuit arrangement for amplifying carrier frequencies is provided, which comprises resonant circuits tuned to different frequencies.
  • a circuit for substantially uniformly amplifying a relatively wide band of carrier frequencies comprising a plurality of cascaded resonant circuits which are tuned to diiferent frequencies within said band, characterized in that the distances between the resonance peaks of successive resonant circuits progressively decrease in each direction from the center of the frequency band to be transmitted towards the limits of said band.
  • a circuit for substantially uniformly amplifying a relatively wide band of carrier frequencies comprising a plurality of cascaded resonant circuits which are tuned to different frequencies within said band, characterized in that the attenuations of the several resonant circuits progressively decrease in each direction from the center of the frequency band to be transmitted towards the limits of said band.
  • a circuit for substantially uniformly amplifying a relatively wide band of carrier frequencies comprising a plurality of cascaded resonant circuits which are tuned to different frequencies within said band, characterized in that both the distances between the peaks of successive resonant circuits and the attenuations of said circuits progressively decrease in each direction from the center of the frequency band to be transmitted towards the limits of said band.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Amplifiers (AREA)
US207563A 1937-05-13 1938-05-12 Circuit for amplifying carrier frequencies Expired - Lifetime US2224200A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE509080X 1937-05-13

Publications (1)

Publication Number Publication Date
US2224200A true US2224200A (en) 1940-12-10

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ID=6547123

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US207563A Expired - Lifetime US2224200A (en) 1937-05-13 1938-05-12 Circuit for amplifying carrier frequencies

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US (1) US2224200A (en)van)
BE (1) BE428065A (en)van)
FR (1) FR837911A (en)van)
GB (1) GB509080A (en)van)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2451893A (en) * 1945-08-30 1948-10-19 Wallman Henry Stagger tuned amplifier
US2989581A (en) * 1954-04-23 1961-06-20 Rca Corp Color television receiver signal transfer system
US3249794A (en) * 1959-08-06 1966-05-03 Varian Associates High frequency tube method and apparatus

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2451893A (en) * 1945-08-30 1948-10-19 Wallman Henry Stagger tuned amplifier
US2989581A (en) * 1954-04-23 1961-06-20 Rca Corp Color television receiver signal transfer system
US3249794A (en) * 1959-08-06 1966-05-03 Varian Associates High frequency tube method and apparatus

Also Published As

Publication number Publication date
GB509080A (en) 1939-07-11
FR837911A (fr) 1939-02-23
BE428065A (en)van)

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