US2266073A - System for amplifying modulated waves - Google Patents

System for amplifying modulated waves Download PDF

Info

Publication number
US2266073A
US2266073A US312576A US31257640A US2266073A US 2266073 A US2266073 A US 2266073A US 312576 A US312576 A US 312576A US 31257640 A US31257640 A US 31257640A US 2266073 A US2266073 A US 2266073A
Authority
US
United States
Prior art keywords
class
amplifier
impedance
amplifiers
network
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.)
Expired - Lifetime
Application number
US312576A
Other languages
English (en)
Inventor
Posthumus Klaas
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.)
RCA Corp
Original Assignee
RCA Corp
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 RCA Corp filed Critical RCA Corp
Application granted granted Critical
Publication of US2266073A publication Critical patent/US2266073A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • 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

  • This invention relates to a system for amplifying modulated oscillations, which is particularly suitable for the final stage of a transmitter modulated in a preceding stage.
  • the arrangement of the system may also be such that the modulation takes place in the final stage itself.
  • the class B amplifier In order to improve the efiiciency of the final stage of a transmitter, it has previously been proposed to compose the amplifier of a combination of a class B and a class C amplifier. With an unmodulated carrier-wave amplitude the class B amplifier is fully loaded, so that the alternating voltage set up by this amplifier can no longer increase; but the current may still grow. When the instantaneous value of the modulated carrier wave increases so as to exceed the unmodulated carrier wave amplitude, the class C amplifier starts operating and supplies energy to a common load impedance.
  • a so-called impedance inverting network which possesses the property that the impedance occurring between the input terminals is inversely proportional to the impedance connected between the output terminals, and inversely.
  • the class B amplifier is fully loaded.
  • one of the class C amplifiers starts operating owingto the fact that this amplifier has a threshold value which is equal to the said instantaneous value of the carrier wave amplitude.
  • Figures 1 and 2 show diagrammatically efficient amplifying systems of the type involved here and such as disclosed in my said prior application. These figures are used herein to explain the nature of the systems involved and the object of my invention which is to provide improved amplifiers of this type; Figures 3 and 4 show diagrammatically amplifying systems of the present invention comprising several stages and their couplings and the coupling of the amplifier to a load impedance; Figures 5 and 7 illustrate somewhatin greater detail efiicient amplifying systems of the nature shown diagrammatically in Fig. 3; while Figure 6 illustrates in somewhatgreater detail an efficient amplifying system of the nature shown diagrammatically in Figure 4 of the drawings.
  • Figure 1 of the drawings represents the system described in the prior application.
  • l denotes a class B amplifier which is loaded with a resistance 2R.
  • vthe output circuit of the class B amplifier are located'the terminals 5 and 6 of an kimpedance inverting network 1 whilst to the input terminals is connected a class C amplier 2 whose threshold value is chosen by means of the bias Voltage in such manner, that this amplifier passes current only if the instantaneous value of the amplitude of the oscillations to be amplified surpasses a predetermined Value which is smaller than the unmodulated carrier wave amplitude.
  • the load value 2R and the terminals 5 and 6 is included the output impedance of an impedance inverting network Il which has connected to its input terminals a class C amplifier B whose threshold value is chosen by means of the bias voltage in such manner, that the amplifier only passes current if the instantaneous value of the amplitude of the oscillations to be amplified surpasses a pre-determined value which is greater than the unmodulated carrier wave amplitude.
  • the output impedance Vof an impedance network l0 which has connected to its input terminals a class C amplifier 3 whose threshold value has the same value as the class C anplifier 4.
  • the networks 1, I0 and Il are called impedance inverting because they possess the property that the input impedance is inversely proportional to the impedance connected between the output terminals, said property being reversible.
  • the surge impedance Ro of the network 1 is R while those ofthe networks I0 and I I amount to R/2. Sincev each of the networks 1, l0 and Il brings about a phase-displacement of the high-frequency alternating voltages supplied to the input circuits of the class C amplifiers 2, 3, and 4 are displaced in phase by 90, 180, and 90 respectively, with respect to the voltage supplied to the class B amplifier I.
  • the class B amplifier I is operative during the whole cycle and the class C amplifier 2 during only part of the cycle. During that part of the cycle in which the class C amplifier 2 is not conductive, the amplifier I is loaded with a resistance 2R. At the moment when the class C amplifier 2 begins to supply energy, the instantaneous value of the voltage set up in the output circuit of the class B amplifier has attained its highest admissible vene se that at this moment the amplifier I operates with' maximum efficiency.
  • the load resistance of the class B arnpli-v bomb I is smaller than 2R, owing to which an increase of the anode current of the amplifying tubes becomes possible without any increase of the anode alternating voltage.
  • the anode alternating voltage of the class C amplifier 2 has attained its highest permissible value and the load resistance of the class B amplier I is equal to R whilst the load resistance of the class C amplifier 2 also amounts to R. At this moment the amounts of energy furnished by each of th'e two amplifiers 3 I and 2 are equal.
  • the load of the amplifiers I and 2 decreases. At the maximum voltage of the 100% modulated carrier oscillation the amplifiers 3 and 4 are fully loaded with the result that the load resistance of the amplifiers I andZ has decreased from the value R to the value 1/2R.
  • FIG 2 represents another system according to the prior application which is completely dual to the system according to Figure l and which' operates in a similar manner.
  • the class B amplifier I is connected to a, load impedance R/ 2 through the intermediary of an impediance inverting network 'I which possesses the same property as the network 1 in the system of Fig. 1.
  • the class C amplifier 2 is connected to the ends of this impedance.
  • the surge impedance of the filter 1 amounts to R.
  • the output impedance 'of an impedance inventing network II whose surge impedance amounts to R/2 and to the input terminals of which is connected the class C amplifier 4.
  • the circuit which comprises the class C amplifier 2 and the load resistance R/ 2 is included' the output impedance of an impedance inverting network I0 whose impedance amounts to R/ 2 and whose input terminals have a class C amplifier 3 connected to them.
  • the bias voltages and th'e mutual phase displacements of the oscillations supplied to the input circuits of the amplifiers I, 2, 3 and 4 are the same as in the system according to Fig. 1.
  • the Variation of the load resistances of the different amplifiers as a function of the modul-a.- tion is exactly similar to that occurring in the previously described circuit arrangement.
  • 'Ilhe 'present invention relates to a system which comprises, as does the above-described system, four amplifiers which successively supply, at different values of the high-frequency amplitude,Y energy t0. a connnon load impedance and wherein all amplifiers can be earthed withont the. use of inductive coupling.
  • thel class B amplifier I is connected to the input terminals of an impedance inverting network to the output terminals of which is connected one of the class C ampliiiers with a high threshold value 4, whilst the class C amplifier with the lowest threshold value 2 is connected'to the input terminals of an impedance inverting network to the output terminals of which is connected the other class C amplifier of vhigh threshold value 3, the latter amplifier being connected either thro-ugh the intermediary of the impedance inverting network to a load impedance connected in parallel with the other class C amplifier of high threshold value 4 or through a load impedance tothe output termina-ls of an impedance inverting network to the input terminals of which is connected the other class C amplifier of high threshold value 4 whilst the surge impedance of the two first-mentioned networks amounts to double the surge im.- pedance of the last-mentioned ne'twork and is equal to the load impedance or four times as large as this impedance
  • FIG. 3 Vof the drawings represents one embodiment of the system according to the invention. It comprises aclass B amplifier I which is connected to the input terminals I2 and I3 of an impedance inverting network I4 whose surge impedance amounts to R/ 2.
  • a class C amplifier 2 having a threshold value which islower than the unmodulated carrier wave amplitude is connected f, to the input terminals I'I, I8 of an impedance inverting network IQ whose surge impedance' also. amountsto R/2.
  • this network I9 To the output terminals 20 and 2I of this network I9 is connected another class C, amplifier 3 whose th'reshol-d value exceeds the unmodula'ted carrier wave amplitude.
  • This class C amplifier 3 is furthermore connected' to the input terminals 22, 23 ofV an impedance inverting network 24 whose surge impedance amounts to l/.LR and between the output terminalsi25 and 28 of which is connected the common. load impedance 1/l't which is connected at the same time in parallel with, the class Cv amplifier 4.v
  • the class B amplifier supplies energy to the load impedance %R. Since the load impedance is connected to the class B amplifier via an impedance inverting network I4 with a surge impedance R/Z, the latter amplifier is loaded during this period of time with an impedance $4122 gli At the moment when the instantaneous value of the carrier oscillation is such that the class B amplifier is fully loaded and, consequently, the output Voltage of the class B amplifier has attained the maximum permissible value, the threshold value of the class C amplifier 2 is surpassed and in this case this amplier also supplies energy to the load impedance 143B.
  • the class B and class C amplifier I and 2 respectively, supply the same -amount of energy to the load impedance lAgR, which nvolves that the impedance between the terminals I2 and I3 amounts to R and that the load impedance betwen the load terminals I'I and I8 also amounts to R.
  • the threshold value of the class C amplifiers 3 and 4 is surpassed and the load impedance of the amplifiers I and 2 decreases still further owing to the fact that the amplifiers 3 and 4 also supply energy to the load impedance 1/8R.
  • the amplifiers 3 and 4 are also fully loaded and the load impedance of the amplifiers I and 2 betwen the terminals I2, I3 and I1, I8, respectively, has decreased to the value lgR whilst also the amplifiers 3 and 4 are loaded in this case with an impedance 1/2R. All the four ampliers supply in this case the same amount of energy to the load impedance 1A;R. Now, all amplifiers are fully loaded and operate with an efficiency which is equal to the maximum efciency of a class B amplifier which is about 63-67%.
  • FIG. 4 A system equivalent to the system according to Figure 3 is represented in Figure 4. 'Ihe latter may be derived from the former by replacing the network 24 with the load impedance 1/R between the input terminals 25, 26 by the network 24 in Fig. 4 wherein a load impedance is connected in series with the input terminals 22, 23.
  • FIG. 5 represents a practical example of the system according to Figure 3.
  • the amplifiers I, 2, 3 and 4 are represented, comprising amplier tubes 4I, 42, 43 and 44 respectively, the anodes of which are coupled to the respective filter circuits by means of coupling condensers 45, 45, 41 and 48.
  • Each impedance inverting network I4, 24 and I 9 consists of a 1r lter the series impedance of which consists of an inductance I4', 24 or I9', respectively, and the cross-impedance of which consists of the parallel connectionof 'a condenserand an inductance.
  • the condenser and theinductance which are located between the input terminals of the network I4 are denoted by 28 and 29, respectively.
  • the condenser and the inductance which yare located between the output terminals I5 and I6 of the network I4 and between the output terminals 25, 26 of the network 24 are united to form a condenser 30 and an inductance 3
  • the condenser 32 and the inductance 33 form the cross-impedances of the neighboring networks 24 and I9.
  • the crossimpedance connected between the terminals I1 and I 3 of the network I 9 is represented by the condenser 34 and the inductance 35.v
  • Each of the previously mentioned cross-impedances is tuned so as to form for the carrier-wave frequency a capacitive reactance which is equal to the inductive reactance of the corresponding series impedances I4', 24' and I9', respectively.
  • cross-impedances only consisting of a condenser would sufiice, it is advantageous, in View of the suppression of the harmonics of the carrier wave, to utilize the above-mentioned parallel connection of a condenser and an inductance.
  • Figure 6 represents one embodiment of the system shown in Figure 4, which needs no further explanation. It is obvious that the currents supplied by the amplifiers I, 2,3, and 4 to the load impedances l/BR ( Figure 3) and 1/ZR respectively ( Figure 4) must be in phase. Since the networks I4, 24 and I9 each bring about a phase displacement of the oscillations to be amplified must, consequently, be supplied to these amplifiers via phase-displacing networks, in such manner that between the oscillations supplied to the amplifiers I and 2 there exists a phase displacement of 90 whilst between the oscillations supplied to the amplifiers I and 4 or 3 and 4 respectively there exists a phase displacement of 90.
  • Figure 7 a circuit arrangement such as shown diagrammatically in Figure 3.
  • I have shown how the several amplifiers are coupled by the networks without having any tube cathodes operating at high-radiofrequency potentials and thus without the use of inductive couplings.
  • the operation of the arrangement of Figure 7 has been described above and need not be repeated here.
  • the blocking condensers BC are of sufficient size as to operate as short circuits for the radio-frequency potentials, whereby cirsuits 54, and 64 are seen to be operating in parallel and, therefore, can be constituted in practice by a single capacity and a single Vinductance.
  • networks 'I4 and 84 are of sufficient size as to operate as short circuits for the radio-frequency potentials
  • I may use series supply, if plate voltages for all of the tubes are to be the same. In this case the direct-current blocking condensers BC are omitted.
  • a load circuit in a modulated wave amplifier, a load circuit, four electron discharge tube amplifiers each having output electrodes and input electrodes, means coupling the output electrodes of one of said tubes directly to said load circuit, a phase inverting network coupling the output electrodes of a second one of said tubes to said load circuit, a second phase inverting network coupling the output electrodes of a third one of said tubes to said load circuit, a third phase inverting network coupled to said second phase inverting network to couple the output electrodes of the fourth one of said tubes to said load, means for impressing modulated wave energy on the input electrodes of each of said tubes in such phase that the outputs of said tubes are cumulative in said load, means for biassing the second of said tubes for class B operation, and means for biassing the remainder of said tubes for class C operation.
  • a system for amplifying a modulated oscillation which is suitable for the final stage of a transmitter and comprises four amplifiers of which one amplifier operates as a class B amplifier and the other amplifiers act as class C amplifiers with threshold values which are for one of these other amplifiers smaller and for the remaining other amplifiers larger than the unmodulated carrier wave amplitude
  • means amplifiers an impedance inverting network having input terminals coupled to saidclass B amplifier and having output terminals coupled to one of the class C amplifiers of high threshold value, a second impedance inverting network having input terminals coupled to the said class C amplifier with the lowest threshold value and having output terminals coupled to the other class C amplifier of high threshold value, a third impedance inverting network, a coupling between said last named class C amplifier of high threshold value and said third network, a coupling between said third network and the other class C amplifier of high threshold value, and a load impedance in one of said last two couplings, the surge impedance of the first and second networks being about double the surge imped
  • a system for amplifying a modulated oscillation which is suitable for the final stage of a transmitter and comprises four amplifiers of which one amplifier operates as a class B. amplifier and the other amplifiersv act as class C amplifiers with threshold values which are for one of these said other amplifiers smaller andl for the other ⁇ two of said other amplifiers larger than the unmodulated oscillation amplitude comprising, means for impressing modulated oscillations for impressing modulated oscillations on said onsaid amplifiers, an impedance inverting network having input terminals coupled to the class B amplier and having output terminals coupled to one of the said two class C amplifiers of high threshold value, a second impedance inverting network having input terminals coupled to the class C amplifier with the lowest threshold value and having output terminals coupled to the other class C amplifier of high threshold value, a third impedance inverting network, a coupling between said other and last named class C amplifier of high threshold value and said third network, a coupling between said third network and said one class C amplifier of high threshold value, and
  • a system for amplifying -a modulated oscillation which is suitable for the final stage of a transmitter and comprising four amplifiers of which one amplifier operates as a class B amplifier and the other amplifiers act as class C -amplifiers with threshold values which are for one of these amplifiers smaller and for the other amplifiers larger than the unmodulated carrier wave amplitude comprising, means for impressing modulated oscillations on said amplifiers, an impedance inverting network having input terminals coupled to the class B amplifier and having output terminals coupled to one of the said class C amplifiers of high threshold value, a second impedance inverting network having input terminais coupled to the said class C amplifier with the lowest threshold value and having output terminals coupled to the other of said class C amplifiers of high thresholdl value, a third impedance inverting network, a coupling between said last named other Class C amplifier of high threshold value and said third network, a load impedance in said1 last coupling, and a coupling between said third network and said one class C amplifier of high threshold value, the
  • each of the impedance inverting networks consists of a 1r filter whose series impedance is formed by an inductance and whose cross-impedance is formed by the parallel connection of an inductance and a condenser.
  • each of the impedance inverting networks consists of a 1r filter whose series impedance isformed by an inductance and Whose cross-impedance is formed by'the ⁇ parallel connection of an inductance and a condenser and wherein adjoining cross-impedances of adjacent networks have elements in common.

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Amplifiers (AREA)
US312576A 1938-11-10 1940-01-05 System for amplifying modulated waves Expired - Lifetime US2266073A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL533485X 1938-11-10

Publications (1)

Publication Number Publication Date
US2266073A true US2266073A (en) 1941-12-16

Family

ID=19787175

Family Applications (1)

Application Number Title Priority Date Filing Date
US312576A Expired - Lifetime US2266073A (en) 1938-11-10 1940-01-05 System for amplifying modulated waves

Country Status (5)

Country Link
US (1) US2266073A (d)
DE (1) DE734228C (d)
FR (1) FR861511A (d)
GB (1) GB533485A (d)
NL (1) NL57673C (d)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2468911A (en) * 1945-10-19 1949-05-03 Aiken William Ross Communication system

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2468911A (en) * 1945-10-19 1949-05-03 Aiken William Ross Communication system

Also Published As

Publication number Publication date
DE734228C (de) 1943-04-10
GB533485A (en) 1941-02-13
NL57673C (d)
FR861511A (fr) 1941-02-11

Similar Documents

Publication Publication Date Title
US2210028A (en) Amplifier
US2312070A (en) Frequency discriminator circuit
GB460562A (en) Improvements in and relating to thermionic valve circuits
US2294800A (en) Modulation system
US2266073A (en) System for amplifying modulated waves
US2324279A (en) Amplifier
US2240715A (en) Amplifier
US2719191A (en) Circuit-arrangement of the kind comprising a plurality of amplifiers fed in parallel
US2393709A (en) Distortion reduction on modulated amplifiers
US1930339A (en) Amplifier
US1734219A (en) Transmission regulation
US2255476A (en) High efficiency amplifier
US2397850A (en) Amplifier gain control
US2243504A (en) Grid modulated amplifier
US1657462A (en) Nonsinging reamplifying circuits
US2230122A (en) Amplifier
US2195095A (en) High frequency amplifying arrangement for a very broad frequency band
US2196248A (en) Combined amplifier-rectifier circuits
US1517057A (en) Vacuum-tube amplifier
US2241892A (en) Thermionic amplifier
US1687245A (en) Amplifying
US1578679A (en) Modulating system
US2063093A (en) Frequency multiplier circuits
US1763015A (en) Operation of electric space-discharge devices
US2229674A (en) Rectifying and amplifying circuits