US2212205A - Amplifier - Google Patents

Amplifier Download PDF

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Publication number
US2212205A
US2212205A US249222A US24922239A US2212205A US 2212205 A US2212205 A US 2212205A US 249222 A US249222 A US 249222A US 24922239 A US24922239 A US 24922239A US 2212205 A US2212205 A US 2212205A
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United States
Prior art keywords
impedance
anode
circuit
amplifier
voltage
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Expired - Lifetime
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US249222A
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English (en)
Inventor
Hepp Gerard
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RCA Corp
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RCA Corp
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Publication date
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Publication of US2212205A publication Critical patent/US2212205A/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

Definitions

  • This invention relates to amplifying circuit arrangements for amplifying a given frequency band, particularly widefrequency bands including .the low frequencies, in such a manner that the amplification is independent. of frequency so that uniform amplification throughout the band is obtained.
  • Another object of the invention is to provide a simple wide band amplifier having uniform amplification and time delay.
  • Fig. 1 shows in schematic diagram form, the connections of an amplifier and circuit elements embodying the invention
  • FIGS. 2-5 show in circuit diagram form modifications of the embodiment of the invention shownin Fig. 1.
  • the screen grid conductor generally includes an impedance dependent on frequency which is constituted, for example, by a resistance and a parallel condenser and serves for thesecuringof the desired screen grid voltage and for smoothing the screening grid voltage from the voltage supply feeding the anode.
  • the alternating voltages to be amplified produce a voltage drop across this impedance which is" dependent on frequency and which, due to the control action of the screening grid on the anode current, brings about a voltage circuit arrangement there are, however, frequent drop across the resistance in the anode circuit which, is dependent on frequency.
  • the amplification is consequently dependent on frequency.
  • the lead connecting the anode and the screen grid to the source from which the anode and screen grid voltages are obtained often includes in addition an impedance, for example the internal; impedance, of said source, or a resistance withparallel-condenser, which serves for smoothingby-passing -or uncoupling.
  • This impedance also influences the variation of the amplifier with frequency.
  • the "anode circuit of the amplifier valve includes, in series with the anode resistance, impedances which are respectively proportional to the impedance in the screen grid conductor and/or to the impedance in the common conductor by which the anode "and the screen gridare connected to the "source: of voltage.
  • the amplifier should be insensitive to potential variations of the source ofvoltage. According to a further feature of the invention, as willbe shown hereinafter, this may be ensured by making the resistance in the anode circuit of the amplifier valve equal to the reciprocal of the slope of the anode current-screen grid voltage characteristic. In this case theimpeda'nce in the anode circuit which is proportional tothe impedance in the common lead connecting the anode and the screen grid to the source; of voltage may be omitted.
  • Fig. 1 of the drawing shows a schematic diagram of connections of an amplifier embodying the invention.
  • This circuit arrangement comprises an amplifier valve of the pentode type whose screen gridfconductor 'includes an impedance ZS.
  • the common lead by which the anode and the screen grid are connected to the source of voltage Ea includes an impedance Zc;
  • the resistance Ra in the anode circuit has connected in series therewith two impedances aZS and fiZc which are proportional respectively to Z5 and Z0.
  • aZS and fiZc which are proportional respectively to Z5 and Z0.
  • the ratio between the amplified voltage e2 and the unamplified voltage 21, or in other words the amplification is independent of frequency if the proportionality-factors cc and ,8 are chosen in accordance with the following'conditions:
  • the resist ance Ra is preferably made equal to the reciprocal of the slope of the anode 'current-screen grid voltage characteristic, consequently In this case, due to the control action of the screen grid on theanode current, a potential variation of the source of voltage Ea. brings about an identical but oppositely directed potential variation at the resistance Ra so that the latter compensates exactly for the former.
  • FIG. 3 Such a circuit arrangement is shown inFig. 3 in which it is premised that the form of the impedance Za. corresponds to the data above given.
  • An optional impedance Z1 is connected, in parallel with Za, in series with impedances
  • the output voltage 32 is obtained from the two
  • the amplification of this circuit arrangement is found to'be given by V and if Za is consequently chosen in accordance with the above equation this amplification is again independent of frequency.
  • the total impedance included in the anode circuit may be reduced to a value as small as desired so that the influence of the anode-cathode capacity is reduced.
  • the impedances Z and Z0 need not always be present in the circuit arrangement at the same time. Thus, for example, it is often possible to omit the impedance Zc or, if it forms the internal impedance of the source of voltage Ea, to neglect it. In this case, however, it may be desirable to include in the anode circuit an impedance Zb which isconstituted, for example, as usual by a IGSiSt8.C-Ra with parallel .condenser Cb, as is shown in Fig. 4. Again, as is clearly evident, the amplification is independent of frequency when a proportional impedance is provided in the screen grid circuit.
  • The-impedances Zb and lXZs of Fig. 4 are preferably so transformed as to also assist in smoothing the anode voltage.
  • the impedances Z5, Z0, OtZs and 5Z0 to be associated with the same amplifier stage. It is however, obvious that when the impedances ZS and Zc are associated with an the impedances DtZs and BZc are associated it is also possible to obtain amplification that is independent of frequency. In this case, the proportionality factors must of course be chosen in accordance with the particularities of the tubes and circuit arrangementsin use.
  • An amplifier as claimed in claim 1 and comprising in addition, connected in parallel with said anode circuit, a circuit including a fifth impedance connected in series with a sixth and a seventh impedance, said sixth impedance being proportional to said fifth impedance and said seventh impedance being proportional to the total impedance of said anode circuit.
  • a wide band amplifier having uniform amplification comprising an electron discharge tube having a cathode, a control grid, a screen grid and an anode, a supply source, a connection between the cathode and supply source, a first impedance connected between said screen grid and a second impedance, said second impedance being connected to the cathode through the supply source, an anode circuit comprising a resistor, a third impedance proportional to said first impedance, a fourth impedance proportional to said second impedance connected in series, means to impress signal voltage between the control grid and cathode, and output terminal means connected to said anode and said cathode.
  • a wide band amplifier having uniform amplification comprising an electron discharge tube having a cathode, a control grid, a screen grid and an anode, a supply source, a connection between the cathode and supply source, a first impedance connected between said screen grid and a second impedance, said second impedance being connected to the cathode through thei supply source, an anode circuit comprising a resistor, a third impedance proportional to said first impedance, a fourth impedance proportional to said second impedance connected in series, a circuit connected in parallel with said anode circuit comprising a fifth impedance connected in series with a sixth and seventh impedance, said sixth impedance being proportional to said fifth impedance and said seventh impedance being proportional to the total impedance of said anode circuit, means to impress signal voltage between said control grid and said cathode, and output terminal means connected to the junction of said fifth and said sixth impedance and to said cathode.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Amplifiers (AREA)
US249222A 1938-01-04 1939-01-04 Amplifier Expired - Lifetime US2212205A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE2212205X 1938-01-04

Publications (1)

Publication Number Publication Date
US2212205A true US2212205A (en) 1940-08-20

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US249222A Expired - Lifetime US2212205A (en) 1938-01-04 1939-01-04 Amplifier

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US (1) US2212205A (en))
BE (1) BE431972A (en))
FR (1) FR848430A (en))

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2494657A (en) * 1944-03-11 1950-01-17 Hartford Nat Bank & Trust Co Amplifier coupling network
US3116461A (en) * 1961-02-24 1963-12-31 Philips Corp Linear amplifier for modulated high frequency oscillations

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2494657A (en) * 1944-03-11 1950-01-17 Hartford Nat Bank & Trust Co Amplifier coupling network
US3116461A (en) * 1961-02-24 1963-12-31 Philips Corp Linear amplifier for modulated high frequency oscillations

Also Published As

Publication number Publication date
FR848430A (fr) 1939-10-30
BE431972A (en))

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