US2252007A - Thermionic amplifier - Google Patents

Thermionic amplifier Download PDF

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Publication number
US2252007A
US2252007A US266128A US26612839A US2252007A US 2252007 A US2252007 A US 2252007A US 266128 A US266128 A US 266128A US 26612839 A US26612839 A US 26612839A US 2252007 A US2252007 A US 2252007A
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US
United States
Prior art keywords
feedback
grid
control grid
voltage
valve
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
US266128A
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English (en)
Inventor
Jacobsen Bent Bulow
Roche Alleman Holly
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.)
International Standard Electric Corp
Original Assignee
International Standard Electric 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 International Standard Electric Corp filed Critical International Standard Electric Corp
Application granted granted Critical
Publication of US2252007A publication Critical patent/US2252007A/en
Anticipated expiration legal-status Critical
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B15/00—Suppression or limitation of noise or interference
    • H04B15/005—Reducing noise, e.g. humm, from the supply
    • 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
    • H03F1/34—Negative-feedback-circuit arrangements with or without positive feedback
    • H03F1/36—Negative-feedback-circuit arrangements with or without positive feedback in discharge-tube amplifiers

Definitions

  • This invention relates to thermionic amplifiers of the kind in which a portion of the output is fed back to the input in negative phase and more particularly to suchl amplifiers in which the phase of the feedback voltage on the control grid of the first valve has been upset by the connection to the control grid of an external circuit of large impedance.
  • this objection is overcome by the application of feedback of substantially perfect phase shift to an electrode of the valve other than the control grid.
  • the feedback may be applied to both the control grid and the screen grid.
  • both the signal input and the feedback voltage may also be applied to the suppressor grid.
  • FIG. 1 and 2 are schematic diagrams of two embodiments of the invention.
  • Fig. 1 shows the circuit of an amplifier in which the feedback voltage is conveyed to the screen grid of a tetrode (or pentode) via the large condenser C1.
  • the valve V1 has a voltage applied to its control grid from the generator G, its plate circuit being fed through the resistance R1.
  • the resistance R2 is used to apply the required steady voltage to the screen grid.
  • the bias for the control grid is obtained from the usual biasing resistance R3 shunted by the decoupling condenser C3.
  • the load Z is fed through the condenser C2 and the feedback voltage is taken from the output bridge consisting of the resistances R5, Re, R7 and the plate cathode impedance of the valve.
  • the resistance Rs is included in the grid circuit of the valve and is the resistance across which the feedback voltage is generated.
  • the effective feedback voltage on the control grid will generally differ in magnitude and phase from the feedback voltage on the resistance Rs. This is due to the input capacity of the valve. rlhe phase shift is particularly objectionable since it tends to render the amplifier unstable. If, for instance, the generator impedance is Z1 ohms and the input impedance of the valve is Z2 ohms, then the ratio of feedback volts on the grid of the valve to the feedback voltage on Re is it i eing assumed that Ra is small compared with Z1 and Zz.
  • the lead from the condenser C1 .to the resistance Rs in Fig. 1 and also the lead from the generator G to the resistance Ra are made slider contacts lalong the resistance, it will then be obvious that the relationship between the feedback on the control grid and the screen grid may be varied in any required manner.
  • the feedback on the screen grid may be made considerably greater than that on the control grid and this is the preferred condition, as under these circumstances the resultant phase shift of the feedback path will be more suitable.
  • Fig. 2 shows a further possible modification in which both feedback voltage and signal voltage are applied to the suppressor grid of a pentode aswell as to the control grid, feedback voltage being also applied to the screen grid.
  • Fig. 2 shows a further possible modification in which both feedback voltage and signal voltage are applied to the suppressor grid of a pentode aswell as to the control grid, feedback voltage being also applied to the screen grid.
  • An amplifier system comprising' a ⁇ tube havf ing a cathode, an anode, a control grid and another grid, an input circuit ofl relatively high impedance 'connected between said control grid and said cathode, means for applying to said control grid through said input circuit a negative feedback voltage and means for applying to said other grid through a substantially negligible imv pedance a negative feedback voltage of substan-v tially 180 phase shift with respect to the signal voltage applied to said control grid, whereby the stability of said amplier is improved.
  • An amplifier system comprising a tube having a cathode, an anode, a control grid and a screen grid, an input circuit of relatively high impedance connected between said control grid and said cathode, a source of negative feedback voltage, means for applying through said input circuit a Voltage derived from said source to said control grid to cause a feedback at a phase shift of other than 180 with respect to the signal voltage applied to said control grid and means for supplying through a substantially negligible impedance a voltage derived from said source to said screen grid to cause a feedback at a phase shift of substantially 180 with respect to the signal voltage applied to said control grid.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Power Engineering (AREA)
  • Amplifiers (AREA)
  • Electron Tubes For Measurement (AREA)
US266128A 1938-04-23 1939-04-05 Thermionic amplifier Expired - Lifetime US2252007A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB12196/38A GB514059A (en) 1938-04-23 1938-04-23 Improvements in or relating to thermionic amplifiers

Publications (1)

Publication Number Publication Date
US2252007A true US2252007A (en) 1941-08-12

Family

ID=10000096

Family Applications (1)

Application Number Title Priority Date Filing Date
US266128A Expired - Lifetime US2252007A (en) 1938-04-23 1939-04-05 Thermionic amplifier

Country Status (5)

Country Link
US (1) US2252007A (en(2012))
BE (1) BE433886A (en(2012))
FR (1) FR852819A (en(2012))
GB (1) GB514059A (en(2012))
NL (1) NL57008C (en(2012))

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2563245A (en) * 1944-05-12 1951-08-07 Cossor Ltd A C Voltage combining circuits
US2566057A (en) * 1947-10-02 1951-08-28 Gen Electric Audio amplifier system
US2906937A (en) * 1956-12-24 1959-09-29 Daystrom Inc Adjustable electric braking circuit for servo-mechanism
US20070280138A1 (en) * 2006-06-01 2007-12-06 Stern Donald S Information broadcasting system and method

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE874606C (de) * 1943-05-03 1953-04-23 Aeg UEber mehrere Stufen gegengekoppelter Breitbandverstaerker

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2563245A (en) * 1944-05-12 1951-08-07 Cossor Ltd A C Voltage combining circuits
US2566057A (en) * 1947-10-02 1951-08-28 Gen Electric Audio amplifier system
US2906937A (en) * 1956-12-24 1959-09-29 Daystrom Inc Adjustable electric braking circuit for servo-mechanism
US20070280138A1 (en) * 2006-06-01 2007-12-06 Stern Donald S Information broadcasting system and method

Also Published As

Publication number Publication date
NL57008C (en(2012))
FR852819A (fr) 1940-03-04
GB514059A (en) 1939-10-30
BE433886A (en(2012))

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