US2230122A - Amplifier - Google Patents

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Publication number
US2230122A
US2230122A US168155A US16815537A US2230122A US 2230122 A US2230122 A US 2230122A US 168155 A US168155 A US 168155A US 16815537 A US16815537 A US 16815537A US 2230122 A US2230122 A US 2230122A
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amplifier
amplifiers
impedance
output
amplitude
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US168155A
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Posthumus Klaas
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RCA Corp
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RCA Corp
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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
    • H03F1/02—Modifications of amplifiers to raise the efficiency, e.g. gliding Class A stages, use of an auxiliary oscillation
    • H03F1/04—Modifications of amplifiers to raise the efficiency, e.g. gliding Class A stages, use of an auxiliary oscillation in discharge-tube amplifiers
    • H03F1/06—Modifications of amplifiers to raise the efficiency, e.g. gliding Class A stages, use of an auxiliary oscillation in discharge-tube amplifiers to raise the efficiency of amplifying modulated radio frequency waves; to raise the efficiency of amplifiers acting also as modulators
    • 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
    • H03F1/02—Modifications of amplifiers to raise the efficiency, e.g. gliding Class A stages, use of an auxiliary oscillation
    • H03F1/04—Modifications of amplifiers to raise the efficiency, e.g. gliding Class A stages, use of an auxiliary oscillation in discharge-tube amplifiers
    • H03F1/06—Modifications of amplifiers to raise the efficiency, e.g. gliding Class A stages, use of an auxiliary oscillation in discharge-tube amplifiers to raise the efficiency of amplifying modulated radio frequency waves; to raise the efficiency of amplifiers acting also as modulators
    • H03F1/07—Doherty-type amplifiers

Definitions

  • the invention relates to an amplifying system for modulated high frequency oscillations, which is particularly suitable for the final stage of a transmitter.
  • Figures 1 and 2 illustrate fundamental circuit arrangements utilizing the principle of my invention, while Figures 3 and 4 illustrate modifications of the arrangements of Figures 1 and 2, and,
  • FIG. 5 illustrates details of the arrangement of Figure 4.
  • FIG. 1 In order to obtaina higher efficiency it has previously been proposed to utilize the system shown in Figure 1;
  • I denotes a class B amplifier which is loaded by an impedance which behaves for the frequency of the carrier oscillation as an ohmic resistance of the value 2R.
  • the output circuit of the amplifier I comprises the output terminals 5 and 6 of a network I while the input terminals 8 and 9 are connected to an amplifier 2 whose bias voltage is chosen in such manner that this amplifier only passes current if the amplitude of the oscillations to be amplified surpasses that of the carrier oscillation.
  • the oscillations to be amplified are supplied to the amplifiers I and 2 with a mutual phase displacement of
  • the network I is constructed to have the reversible property that the impedance occurring across the output terminals 5 and 6 is inversely proportional to the impedance connected between the input terminals 8 and 9.
  • the amplifier 2 So long as the amplifier 2 is not conductive, or in other words the amplitude of the oscillations to be amplified is smaller than the carrier wave amplitude, the impedance occurring across the terminals 5 and 6 will be zero and the amplifier I will be loaded by the resistance 2R.
  • the amplifier 2 becomes conductive during that portion oi'the oscillations to be amplified wherein the instantaneous value of the oscillations surpasses the carrier wave amplitude while across the termi nals 5 and B a negative resistance occurs which in the case of maximum conductivity of the amplifier 2, which occurs at the peak voltage of a modulated carrier oscillation, is equal to
  • the load of the amplifier l consequently depends on the instantaneous value of the oscillations to be amplified in such manner that the load amounts to 2R as long as the amplitude of the oscillations to be amplified is smaller than the amplitude of the unmodulated carrier oscillation, whereas the load is reduced from 2R to R if the instantaneous value of the oscillations to be amplified increases to the peak voltage of the 100% modulated carrier wave, i.
  • the load of the amplifier 2 is determined by the impedance connected between the terminals 5 and 6, which impedance is determined by the conductivity of the amplifier I.
  • the circuit arrangement of the amplifier I is so chosen that if the instantaneous value of the oscillations to be amplified increases from the carrier wave amplitude to double this value, the negative resistance presented by the amplifier I decreases from 2R to R and consequently the resistance present between. the terminals 5 and 6 increases from O to R.
  • the-load of the amplifier I is-equal to Rwhile the output energy ofthe amplifier I is twice as large as in the amplification of an'unmodulated carrier oscillation.
  • the load of the amplifier 2 is also equal to R while the energy supplied by this amplifier is equal to the energy'delivered by the amplifier I.
  • the total output energy of the amplifiers I and 2 is consequently'equal to four times the output energy of the amplifier I during the amplification-of an unmodulated carrier oscillation.
  • the efiicien'oy-of the amplifier 'I is slightly smaller than with an unmodulated carrier oscillation, for example 50%, while the efficiency of the amplifier 2, which acts as a class C amplifier, is higher, for example With modulation the efiiciency of the total system is consequently approximately as high as withunmodulated carrier wave.
  • the .usual class B amplifiers the system described consequently offers the advantage that the average efiiciency over an entire day is considerably,
  • FigureZ represents a system which is completely dual to the system described and which functions in a similar. way.
  • amplifier I is connected to a load resistance via a network "I which has the same property as the network 1 in Figure 1. connected to the ends of this resistance and possesses a bias voltage such that current is only
  • the amplifier 2 is passed when the amplitude of the oscillations to be amplified surpasses the carrier wave amplitude.
  • the surge impedance R0 of the network I amounts to R.
  • the amplifier 2 is unoperative while the amplifier -I,,; is loaded by an impedance If the instantaneous value of the oscillations to be amplifiediincreases' to above the carrier wave amplitude; theamplifier 2 becomes conductive so that inpa'rallel with the load resistance carrier oscillation to R with the result-that theamplifier "I is loaded 'by a resist'ance
  • the load of the amplifier 2 decreases from to R.
  • the invention concerns an improvement in a system which operates on the principle of the systems shown in Figures 1 and 2.
  • the amplification of modulated high frequency oscillationsuse is made of four amplifiers'of which one amplifier (I) passes current, with any amplitude of the alternating voltage supplied, during one half wave whereas the other amplifiers only pass current if the amplitude is located above a predetermined threshold Value which is for one of these amplifiers (2) lower and for the two other amplifiers 3 and 4) mutually equal and larger than the carrier wave amplitude while a load impedanceis connected in series or in parallel with animpedance to which "a voltage is supplied by the first mentioned amplifier (I) or the second amplifier (2).
  • This series or parallel connection is connected to the output terminals of a network having connected to its input terminals an impedance across which the second amplifier (2) or the first amplifier (I) set up a voltage while each of the said impedances is connected in series with the output impedance of a network to the input terminals of which are connected the third and the fourth amplifier (3 and 4) respectively.
  • All these networks possess the property that the input impedance is inversely proportional to the impedance connected between the output terminals while the surge impedance of the latter two networks is equal to half the surge impedance of the first mentioned network, which surge impedance is equal respectively to half 'or double the load impedance while the Oscillations to be amplified are supplied to the grid of the four amplifiers with a phase such that the voltages supplied by these tubes to the load impedance are mutually in phase.
  • Figure 3 represents a system which may be considered as an extension of the system according to Figure 1.
  • I denotes a class B amplifier which is loaded by a resistance 2R.
  • the output circuit of the amplifier are located the terminals 5 and 6 of a network I to the input terminals of which is connected an amplifier 2 whose bias voltage is chosen in such manner that this amplifier only passes current if the amplitude of the oscillations to be amplified surpasses a predetermined value which is smaller than the carrier wave amplitude.
  • the output impedance of a network II which has connected to its input terminals an amplifier 4 of which the bias voltage is so chosen that this amplifier only passes current if the amplitude of the oscillations to be amplified surpasses a predetermined value which is greater than the carrier wave amplitude.
  • the output impedance of a network II which has connected to its input terminals an amplifier 3 whose bias voltage is equal to that of the amplifier 4.
  • the networks I, II] and II possess the property that the input impedance is inversely proportional to the impedance connected between the output terminals, the said property being reversible.
  • the surge impedance R0 of the network "I amounts to R. while those of the networks I0 and II are Since each of the networks I, I0 and II brings about a phase 'displacement of 90 the high frequency alternating voltages supplied to the input circuits of the amplifiers 2, 3, and 4 are displaced in phase by 90, 180 and 90 respectively with respect to the voltage supplied to the amplifier I.
  • the amplifier I If an unmodulated carrier oscillationis supplied to the amplifiers, the amplifier I lsoperative during the full wave and the amplifier 2 only during part of the wave. During that part of the wave in which the amplifier 2 is not conductive, the amplifier I is loaded by a resistance 2R. At the moment when the amplifier 2 becomes conductive, the instantaneous value of the voltage set up in the output circuitof the amplifier I attains its highest admissible value so that the amplifier I functions at this moment with the maximum efficiency. During the wave portion wherein the amplifier 2 is conductive, the load of the amplifier I is smaller than 2R owing to which an increase of the anode current of the amplifying tubes is possible without any increase of the anode alternating voltage.
  • the anode alternating voltage of the tube of the amplifier 2 has attained its highest value permissible and the load of the amplifier I is equal to R while furthermore the load of the amplifier 2 amounts to R. At this moment the amount of energy furnished by each of the two amplifiers I and 2 is equally large. If the instantaneous value of the oscillations to be amplified surpasses the threshold value of the amplifiers 3 and 4, the load on the amplifiers I and 2 decreases due to the fact'that a negative resistance occurs between the output terminals of the network II or II] respectively.
  • the negative resistance increases in accordance maximum voltage of the'100% modulated carrier wavethis negative resistance has attained its maximum value /ZR) and the amplifiers 3 and, 4 supply maximum energy while the load of the amplifiers I and .2 has decreased from I the value It to the value /2R. Owing to the increase of the anode currents of the tubes of the amplifiers I and 2, the output energy of these amplifiers has increased to double the value at the moment when the threshold value of the amplifiers 3 and 4 is being surpassed.
  • each of the amplifiers I, 2, 3 and 4 delivers an equally large amount of energy and the efficiency of the whole of the installation is equal to the maximum efiiciency of a class B amplifier which furnishes the same output energy.
  • a particular advantage of the system according to the invention resides in that at the most usual values of the percentage of modulation, which are located between 0 and 30% the amplifiers I and 2 are continuously in operation, owing to which discontinuities due to the tube 2 being switched on and off are avoided.
  • a further advantage consists in that at the most usual values of the percentage of modulation there occurs a linear relation between the amplitudes of the oscillations to be amplified and the current passing through the load resistance.
  • the average efficiency over an. entire day is substantially equal to the efiiciency with unmodulated carrier oscillation, said efficiency being approximately 67%.
  • FIG 4 represents a system according to the invention which is completely dual to the system according to Figure 3 and functions in. a similar manner.
  • the amplifier I is connected to a load impedance via a network I which possesses the same property as the network I in the system of Figure 3.
  • the amplifier 2 is connected to the ends of this impedance.
  • the surge impedance of the filter I amounts to R.
  • the output impedance of the network II whose surge impedance amounts to and to the input terminals of which is connected the amplifier 4.
  • the output impedance of a network III whose surge impedance also amounts to .the carrier wave.
  • Figure 5 represents one mode of execution of the system according to Figure 3.
  • the amplifier I is constituted by a'discharge tube 2
  • the amplifier 2 comprises a discharge tube 22 to which the oscillations to be amplified are supplied with a phase displacement of 90 and whose anode circuit comprises a parallel circuit '32 which is coupled with a series circuitconsist- .ing or" an inductance 42 and a condenser 52.
  • the filter 7 consisted two equal condensers 5'! and 51 and an inductance coil 41, whilethe two condensers are connected in series between the terminals 5 and 8 and the junction point of the condensers is connected via the inductance 41 to the terminals 6 and 9.
  • the networks In and II consist each of two coupled inductances 43, 43 and 44, 44' respectively of which the inductances 43 and 44 respectively are connected .in-series with condensers 53 and 54 respectively .and the other inductances 43' and 44 respectively are connected in series with condensers 53 and 54 respectively between the output terminals, said two series connections being tuned to
  • the amplifiers 3 and 4 comsupplied with a phase displacement of 180 and 9Q? respectivelyand in the anode circuit of which may each comprise any desired number of amplifying tubes connected in cascade while one or more stages of this cascade may consist of two push-pull connected amplifying tubes.
  • a system for amplifying modulated high frequency oscillations which is particularly suitable for the final stage of a transmitter and which comprises four amplifiers each having an input and an output circuit, the first said amplifier being adjusted to pass current with any amplitude of alternating voltages applied thereto during one i'h'alf' wave, whereas the other amplifiers are ad-,
  • a plurality of networks having input and output terminals and each having the property that the input impedance is inversely proportional to the impedance connected between the output terminals, a load impedance connectedin series with theoutputs of thefirst and second of said networks and an impedance to which avoltage is supplied by said first amplifier, thasurge impedance of said first mentioned networkxbeing equal to half the loadimpedanceand having connected to its input'terminals a series connection of an impedance across which a voltage is set up by said-second amplifier and the output of a third network having its input terminals connected to said third amplifier, the input terminals of said second network being connected to the fourth amplifier, the surge impede'nce of saidsecond and third networks being half that of the first network, said oscillations to
  • the said impedances across which voltages are set up by the first and the second amplifier consist each of the series connection of an inductance and a condenser, said inductance being coupled with a parallel resonant circuit included in the output circuit of the amplifier and which is tuned to the carrier wave.
  • networks to the input terminals of which are connected the third and the fourth amplifier respectively comprise each two coupled inductances of which one is connected in series with a condenser between the input terminals and the other in series with a condenser between the output terminals, both these series connections 'tionship, said circuits including networks having inputs and outputs, the impedance at the inputs of said networks being inversely proportional to the impedance at the output thereof.
  • a modulated carrier wave amplifying system a first amplifier biased to operate class B, , a second amplifier biased to pass current when excited by waves of an amplitude less than the means carrier wave ,.amplitude,; a thirdamjplifier biased to pass current when excited by seemswaves of an amplitude greater than said: mean carrier wave amplitude, means for "applying modulated carrier wave energy to' said ampli bombs, the phase of the wave energy applied toatleast one or said amplifiers being displaced 90 relative to the phase of the wave energy appliedto another of said amplifiers, and circuits interconnecting said amplifiers to a load impedance in a mutual in phase relationship, said circuits including networks having inputs and outputs, the impedance at the inputsof said networks being inversely proportional to the impedance at the output thereof.
  • a modulated carrier wave amplifying system a first amplifier biased to operate class B, a second amplifier biased to pass current when excited by waves of an amplitude less than the mean carrier wave amplitude, a third and a fourth amplifier biased to pass current when excited by waves of an amplitude greater than said mean carrier wave amplitude, means for applying modulated carrier wave energy to all of said amplifiers, the wave energy applied to said second and fourth amplifiers being displaced 90 relative to the wave energy applied to said first amplifier and the carrier wave energy ap plied to said third amplifier being displaced 180 relative to the phase of the carrier wave applied to said first amplifier and circuits interconnecting said amplifiers to a load impedance in a mutual in phase relationship, said interconnecting circuits including networks having inputs and outputs, the impedance at the inputs of said networks being inversely proportional to the impedance at the output thereof.
  • a system for amplifying modulated high frequency oscillations which is particularly suitable for the final stage of a transmitter and which comprises four amplifiers each having an input and an output circuit, the first said amplifier being adjusted to pass current with any amplitude of alternating voltages applied thereto during one half wave, whereas the other amplifiers are adjusted to pass current only if the amplitude is located above a predetermined threshold value which is for the second of these amplifiers lower and for the third and fourth amplifiers mutually equal and larger than the carrier wave amplitude, a plurality of networks having input and output terminals and each having the property that the input impedance is inversely proportional to the impedance connected between the output terminals, a load impedance connected in series with the outputs of the first and second of said networks and the output of said first amplifier, a series connection of the output of said second amplifier and the output of a third network having its input terminals connected to said third amplifier connected to the input of said first network, the input terminals of said second network being connected to the fourth amplifier, said oscillations to be
  • a system for amplifying modulated high frequency oscillations which is particularly suitable for the final stage of a transmitter and which comprises four amplifiers each having an input and an output circuit, the first said amplifier being adjusted to pass current with any amplitude of alternating voltages applied thereto during one half wave, whereas the other amplifiers are adjusted to pass current only if the amplitude is located above a predetermined threshold value which is for the second of these amplifiers lower and for the third and fourth amplifiers mutually equal and larger than the carrier Wave amplitude, a plurality of networks having input and output terminals and each having the property that the input impedance is inversely proportional to the impedance connected between the output terminals, a load impedance connected in series with the outputs of the first and second of said networks and the output of said first amplifier, the surge impedance of said first mentioned network being equal to half the load impedance and having connected to its input terminals a series connection of the output of said second amplifier and the output of a third network having its input terminals connected to said third amplifier, the input
  • a system for amplifying modulated high frequency oscillations which is particularly suitable for the final stage of a transmitter and which comprises four amplifiers each having an input and an output circuit, the first said amplifier being adjusted to pass current with any amplitude of alternating voltages applied thereto during one half wave, whereas the other amplifiers are adjusted to pass current only if the amplitude is located above a predetermined threshold value which is for the second of these amplifiers lower and for the third and fourth amplifiers mutually equal and larger than the carrier wave amplitude, a plurality of networks having input and output terminals and each having the property that the input impedance is inversely proportional to the impedance connected between the output terminals, a load impedance connected across the output of one of said networks, the surge impedance of said load being equal to half that of each of the said networks, a series connection of the output circuit of the second of said amplifiers and the output of a second of said networks connected in shunt across said load impedance, the output circuit of the third of said amplifiers being connected across the input
  • a first and second amplifier each having input and output circuits, a plurality of impedance inverting networks each having an input and an output, connections from the output circuits of said amplifiers to the input and output respectively of one of said networks, each of said connections including the output circuit of another of said networks, a third and a fourth amplifier each having an input circuit and an output circuit, said output circuits being connected to the input of said last mentioned networks, a load impedance connected for applying modulated carrier wave energy to the inputs oi each of said amplifiers.
  • a first and second amplifier each having input and output circuits, a plurality of impedance inverting .networks each having an input and an output, connections from the output circuits of said amplifiers to the input and output respectively of one of said networks, each of said connections including the output circuit of another of said networks, a
  • third. and afourth. amplifier each having an input circuit: and output. circuit, said output circuits being connected to the input of said last mentioned networks, a loadimpfidance connected to the output of saidone network and means for applying modulated carrier Wave energy tothe inputs of each of said amplifieisin such phase relationship that the voltages supplied by the amplifiers to theload impedance are mutually in phase 7 KLAAS POSTI-IUMUS.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Amplifiers (AREA)
US168155A 1936-10-22 1937-10-09 Amplifier Expired - Lifetime US2230122A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL203562X 1936-10-22

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Publication Number Publication Date
US2230122A true US2230122A (en) 1941-01-28

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US168155A Expired - Lifetime US2230122A (en) 1936-10-22 1937-10-09 Amplifier

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US (1) US2230122A (de)
BE (1) BE424178A (de)
CH (1) CH203562A (de)
DE (1) DE718958C (de)
FR (1) FR828063A (de)
GB (1) GB493667A (de)
NL (2) NL79687B (de)

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Publication number Publication date
FR828063A (fr) 1938-05-10
NL54395C (de)
BE424178A (de)
NL79687B (de)
DE718958C (de) 1942-03-26
CH203562A (de) 1939-03-15
GB493667A (en) 1938-10-12

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