US2434295A - Amplifying circuit arrangement for ultra high frequencies - Google Patents

Amplifying circuit arrangement for ultra high frequencies Download PDF

Info

Publication number
US2434295A
US2434295A US480194A US48019443A US2434295A US 2434295 A US2434295 A US 2434295A US 480194 A US480194 A US 480194A US 48019443 A US48019443 A US 48019443A US 2434295 A US2434295 A US 2434295A
Authority
US
United States
Prior art keywords
anode
electrode
electrons
screen
grid
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
US480194A
Other languages
English (en)
Inventor
Strutt Maximiliaan Julius Otto
Ziel Aldert Van Der
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.)
Hartford National Bank and Trust Co
Original Assignee
Hartford National Bank and Trust Co
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
Priority claimed from GB714041A external-priority patent/GB557005A/en
Application filed by Hartford National Bank and Trust Co filed Critical Hartford National Bank and Trust Co
Application granted granted Critical
Publication of US2434295A publication Critical patent/US2434295A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J43/00—Secondary-emission tubes; Electron-multiplier tubes
    • H01J43/02—Tubes in which one or a few electrodes are secondary-electron emitting electrodes
    • H01J43/025—Circuits therefor
    • 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
    • H03F1/08—Modifications of amplifiers to reduce detrimental influences of internal impedances of amplifying elements
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
    • H03F3/54—Amplifiers using transit-time effect in tubes or semiconductor devices

Definitions

  • This invention relates to an electron discharge device and its associated amplifying circuit arrangement for use at ultra-high frequencies in which use is made of an amplifying tube having such a size and operating voltage that the transit time of the electrons is greater than the period of the oscillations to be amplified.
  • phase displacement will occur between the alternating control grid voltage and the electronic stream passing through the apertures of the control grid, which phase displacement is due to the comparatively long transit time of the electrons and involves the appearance of an influencing current to the control grid.
  • This influencing current has a component which is in phase with the alternating control grid voltage and may be conceived to be caused by a. virtual ohmic resistance set up between the control grid and the cathode. The reciprocal value of this resistance is called transit time damping or electron damping.
  • the natural inductances of the supply leads to the various electrodes will exhibit a considerable impedance to the oscillations to be amplified so that high frequency voltages ar set up across these supply leads which voltages rise to currents through the natural tube capacities.
  • a voltage will be set up which leads in phase by 90 with respect to the alternating control grid voltage and produces a current from the control grid to the cathode through the control grid cathode capacity, which current is in phase with th alternating control grid voltage. Similar current will also flow from th control grid through the tube capacities to other electrodes.
  • the damping of the input circuit thus produced may be called lead damping.
  • anode and cathode there is also set up a virtual ohmic resistance whose reciprocal value is called output damping and which is substantially caused under the influence of the impedances of the supply leads for the electrodes in cooperation with the tube capacities. Consequently the output damping may be conceived to be lead damping; as a rule it is much smaller than the input damping.
  • Both the electron damping and the lead damping are substantially proportional to the square of the frequency of the oscillations to be amplified.
  • the input damping resulting from these two components is generally so high that the impedance of the oscillaable amplification per stage substantially corv responds to the product of mutual conductance and input resistance.
  • the attempts are to be directed to an input resistance which is as high as possible.
  • the usual high frequency amplifying tubes exhibit such a small input resistance that amplification is practically no longer possible.
  • the lead damping for instance, can be reduced by making use of a tube having two cathode supply leads, one of which is included in the input circuit nd the other in the output circuit.
  • Another expedient to reduce the lead damping consists in the use of amplifying tubes comprising two push-pull connected amplifying systems of which the cathodes ar connected through as short a lead as possible. This last mentioned expedient also yields a decrease in output damping.
  • Another improvement of the input damping is possible by taking various measures which in principle amount to back coupling, for instance by the interposition of a supplementary inductance in the screen grid lead or, in secondary emission tubes, by connecting the secondary emission electrode to the control grid and to the cathode through suitable impedances.
  • a very suitable method of reducing the input damping consists in the artificial increase of the inductance of the cathode supply lead or the screen grid control grid capacity interposed in the output circuit of a tube having two cathode supply leads.
  • this eifect can still be increased by leading the second- 3 ary emission current through the cathode supply lead interposed in the input circuit and by increasing artificially the inductance of this cathode supply lead or the control grid cathode capacity or both.
  • the tube must generally be given a fairly large size.
  • a suitable expedient for increasing the mutual conductance consists in the use of one or more stages of secondary emission, but in this case it is necessary, for electro-optical reasons, that the distance between two succeeding secondary emission electrodes and between the last secondary emission electrode and the anode respectively at least amounts to about 1.5 cm. Therefore an increase in mutual conductance generally involves such distances between the various electrodes that at ultra high frequencies the transit time of the electrons is greater than the period of the oscillations to be amplified.
  • the invention has for its object the'provision of a tube and circuit for overcoming the above difilculties.
  • the ends of the output impedance are, according to the invention, connected respectively to two electrodes which are located in the path of the electrons and whose mutual distance is covered by the electrons in less than half a period of the oscillations to be amplified.
  • the invention is based on the following recognitions:
  • a triode is provided with an envelope I containing a cathode 2, a control grid 3 and an anode 4.
  • the control grid circuit includes an input impedance 5, and the anode circuit comprises an output impedance 6.
  • the supplies have been omitted.
  • a current Ir will first flow from the cathode to the control grid, a current Is will flow from the control grid to the screen grid and finally a current IE. will flow from the screen grid to the anode,
  • These currents are inic in He 2 represe tin a 1 613. 1 havin a cathode 2, a control grid 3, a screen grid 1 and an anode 4.
  • the anode current is exclusively produced by the charge displacement through the external circuit of the screen grid 1 to the anode 4 during the time in which the electrons travel within the tube from the screen grid to the anode.
  • the anode current is exclusively determined by the displacement of the electrons in the space between the anode and the preceding electrode. It will be obvious that the anode current is larger as there are more electrons between these two electrodes and as these electrons travel more rapidly. On the other hand the anode current is smaller as the distance from the anode to the preceding electrode is larger.
  • the anode current may at least approximately be expressed by the formula:
  • the index N indicating that the summation must be extended to all electrons in the space between the anode and the preceding electrode. If the anode and the preceding electrode have the same potential, so that the speed of the electrons between the said two electron is constant, we have the expression In order that the value of the alternating anode current can be fixed, the influence of the electrons in the space between the anode and the preceding electrode must be more fully considered.
  • the alternating voltage acting at, the control grid divides the electronic stream in succeeding concentrations and deconcentrations; during the positive half cycle of the alternating control grid voltage the number of electrons emitted by the cathode is larger than is normally the case so that concentration occurs, whereas during the negative half cycle the number of emitted electrons is smaller than normal so that deconcentration occurs.
  • the average electronic stream is not contributive to the alternating anode current so that it may be left out of consideration.
  • the alternating anode current may be conceived to result from positive and negative charges alternately passing through the electrode preceding the anode, which charges travel to the anode where they are neutralized.
  • Figure 3 shows the case in which the transit time of the electrons from the screen grid to the anode amounts to an even number of times the period of the oscillations to be amplified.
  • the number of concentrations on the way is always as large as the number of deconcentrations, in other words there are always as many positive as negative bullets on the way from the screen grid to the anode. Consequently the total charge on the way is constant, so that the alternating anode current is equal to zero.
  • the effective mutual conductance equals zero.
  • Figure 4 shows the case in which the transit time of the-electrons is an .odd multiple of the half cycle of the oscillations to be amplified.
  • all bullets but for one will neutralize each other as regards the influence on the alternating anode current, as is schematically indicated by a dotted framing in the figure.
  • the last bullet will alternately be positive and negative so that it will produce an alternating anode current.
  • This bullet is active only during a small part of its transit time andmore particularly for an nth part, if the transit time amounts to n half cycles. Upon calculation it is found that in this case the effective mutual conductance amounts to vrn times the static mutual conductance.
  • the effective mutual conductance is graphically represented as a function of the product wt, in which 0.: represents the angular frequency of the oscillations to be amplified and t the transit time of the electrons from the electrode preceding the anode to the anode.
  • the curve I applies for the above mentioned case in which the electrons travel at a constant speed through the space between the two said electrodes.
  • the mutual conductance equals zero if cut is an even multiple of 1r, whereas the mutual conductance is equal to times the static mutual conductance at the points at which mi is an odd 72-fold of 1r.
  • the invention consists in preventing mutual neutralization of the succeeding bullets by taking care that there always is at the most one bullet in the space between the anode and the preceding electrode. Consequently, in front of the output electrode there must always be an electrode which is connected to the end of the output impedance remote from the output electrode and whose distance from the output electrode is covered by the electrons in less than half a period of the oscillations to be amplified. By complying with this condition it can be achieved, as may be read from the curves shown in Figure 5, that the effective mutual conductance amounts at least to 6,5 to 75% of the static mutual conductance.
  • the anode current is also determined by the electrons in the space between the screen grid and the sup ressor grid.
  • it is in general not the distance from the anode-to the suppressor grid but the distance from the anode to the screen grid which is decisive for the effective mutual conductance in tubes of this kind. Consequently, whenever the distance between the node and the preceding electrode is concerned hereinbefore it is necessary in pentodes and similar tubes to con--. sider the distance between the anode and the screen grid.
  • the use of the invention is of particular importance in cases in which a much greater mutual conductance than that of a miniature tube is required. This is why according to the inven-v tion use is preferably made of an amplifying tube whose mutual conductance exceeds 3 ma./v. Generally one or more of the above exped-ients for reducing the input damping and, if desired, also the. output damping will have to be taken at the same time.
  • anode voltage amounts to 250, voll and the screen grid voltage to.100 volts then Vuat will approxisequently, in accordance with the formula deduced above the known tubes can be used with the said operating voltages to a wavelength of of less than 1 m., the distance between the anode and the screen grid being smaller than 3 mms. and the suppressor grid being preferably shaped as a window.
  • the minimum distance between two electrodes which may be deemed possible at the present state of the art amounts to about 0.8; mm.
  • 0.8 mm By means of a screen grid tube, in which the distance between the anode and the screen grid is. 0.8 mm. sufficient amplification at the above value of the operating voltages would be possible to a minimum wavelength of about 6 cms. At higher operating voltages suflicient amplification of even shorter waves will be possible.
  • the distance between two succeeding secondary. emission electrodes and between the last secondary emission electrode and the anode respectively always amounts at least to 15 mms. forelectro-optical reasons.
  • the voltage between two succeeding secondary emission electrodes and between the last secondary emission electrodes and the anode usually amounts to about 1 00. volts.
  • a -scr-een is, according to the invention, placed in front of the anode at a distance covered by the secondary electrons in less than half a period, which screen is connected to the end of the output impedance remote from the anode so that it will generally be earthed for high frequencies.
  • a secondary emission tube that will amplify wavelengths below 3 m., for instance to a minimum wavelength of 10 cms.
  • To the said .screen is applied a positive bias with respect to the last secondary emission electrode.
  • a secondary emission tube which comprises onesecondar-y emission electrode it is known, to connect the, output impedance between the anodev and the secondary emission; electrode and to connect theccnter ottheoutput In this way itis 9 impedance to the cathode.
  • the sec ondary emission electrode acts as an output electrode at the same time.
  • Such a circuit is also possible for very short waves when, according to the invention, a screen connected for high frequencies to the cathode is provided in front of the secondary emission electrode acting as an output electrode at a distance covered by the electrons in less than half a period of the oscillations to be amplified. Since the stream of secondary electrons is much stronger than the stream of primary electrons impinging on the secondary emission electrode the said screen, if possible, is not located in the path of the primary electrons, but exclusively in the path of the secondary electrons.
  • the distance between the secondary emission electrode and the preceding electrode such a value that the primary alternating current flowing in the circuit of the secondary emission electrode is as small as possible, since this primary alternating current is in phase opposition in regard to the secondary current so that it will only reduce the total current of the secondary emission electrode.
  • the secondary electrons are dislodged by the primary electrons impinging under all conditions on the secondary emission electrode, so that by a suitable choice of the electrode distances a decrease of the external primary current does not involve a decrease of the secondary current.
  • Figure 6 shows a circuit according to the invention including a secondary emission tube 8 which comprises a cathode 9, a control grid l0, 9, screen grid H, a secondary emission electrode I2 and an anode l3. Between the control grid l and the cathode 9 is provided an input circuit l4, and an output circuit l whose electric center I6 is earthed is connected in push-pull arrangement between the anode l3 and the secondary emission electrode 12. Between the two last mentioned electrodes an additional screen grid I 1,
  • the output impedance ( consists of two parts of which the upper part lies between the anode and the screen l1, whereas the bottom part is located between the screen grid l1 and the secondary emission electrode. Consequently, both parts of the output impedance are connected between two electrodes which are placed in the path of the electrons and whose distance is covered by electrons in less than half a period.
  • the proposed push-pull connection of the output impedance between the anode and the secondary emission electrode is only efiective when the phase displacement between the anode current and the current from the secondary emission electrode lies between 90 and 270.
  • the two said electrodes 10 must be connected in parallel to the output impedance.
  • the distance between the screen grid H and the secondary emission electrode I2 is preferably so chosen that the primary current in the external circuit of the secondary emission electrode is as small as possible.
  • a plurality of secondary emission electrodes may contribute to the output current.
  • a screen earthed for high frequencies must be provided for each secondary emission electrode acting as an output electrode, said screen being placed in the path of the secondary electrons issuing from the electrode in question at a distance which is covered by the secondary electrons in less than half a period of the oscillations to be amplified.
  • For earthing these screens use is preferably made of a Lecher wire system, wherein the screens and, if required, the secondary emission electrodes not acting as an output electrode are connected to voltage nodes of the systems, whereas the output electrodes are connected between the voltage nodes at suitable points.
  • An electron discharge device for use at ultra high frequencies having a cathode, a control electrode, a screen electrode and an anode, an input circuit for applying a voltage of a predetermined. frequency to said control electrode, the transit time of the electrons from said cathode to said anode being greater :than the period'of oscillation of the applied voltage, an output circuit'connected'atone end to-said anode, said screen elec- 'trolde and'anode-being spaceda-distance less than the "distancetraveled by-an electron during one- J half-the period of oscillation oftheapplied control voltage, and a-connection' between the screen electrode andsaid'output-circuit at a point-re- -moved fromtheconnection to said: anode.
  • An electron dischargedevice having a cathode, 'a control electrode, a screen electrode and ananode, and a secondaryemitting electrode po- "sitioned between the control electrode and the 60 screen 'electrode, -a circuit for applying voltage "of a predetermined frequency to 'said control electrode.
  • An :electron' :dischargel-device havingra cath 'rode, a: control electrode gascreenelectrode and an ,:anojde;and a secondaryemitting-electrode posiitioned between the ;,control ':816Ci710d6 and the :screen electrode,. ;a-:circuitfor: applying voltage of a1 predeterminedfrequency" to. said control electrode,- andwanoutput'circuithaving one end connected to said-:a-node, :the spacing 1 between said i-screen: electrode ;and saidranode being less than the distance that an electrontravels in one-half the period of oscillation -,of A the. applied control voltage,- an electricalconnection between said sec- .ondary emitting electrode ande-a ,point on .said

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Cathode-Ray Tubes And Fluorescent Screens For Display (AREA)
US480194A 1940-05-30 1943-03-23 Amplifying circuit arrangement for ultra high frequencies Expired - Lifetime US2434295A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
NL2434295X 1940-05-30
GB714041A GB557005A (en) 1941-06-05 1941-06-05 Improvements in or relating to amplifier circuits for ultra high frequencies

Publications (1)

Publication Number Publication Date
US2434295A true US2434295A (en) 1948-01-13

Family

ID=32178840

Family Applications (1)

Application Number Title Priority Date Filing Date
US480194A Expired - Lifetime US2434295A (en) 1940-05-30 1943-03-23 Amplifying circuit arrangement for ultra high frequencies

Country Status (2)

Country Link
US (1) US2434295A (US08197722-20120612-C00042.png)
FR (1) FR872802A (US08197722-20120612-C00042.png)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2537807A (en) * 1946-12-11 1951-01-09 John Logie Baird Ltd Thermionic amplifier
US2596539A (en) * 1947-04-09 1952-05-13 Hartford Nat Bank & Trust Co Circuit for transmitting or generating electrical oscillations of ultrahigh frequency
US2798903A (en) * 1951-03-16 1957-07-09 Henry M Spencer Signal amplification system

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2167201A (en) * 1935-06-28 1939-07-25 Pintsch Julius Kg Electron tube
GB525951A (en) * 1938-03-03 1940-09-06 Telefunken Gmbh Improvements in or relating to electron discharge device amplifier oscillator and like circuit arrangements for use on very high frequencies
US2305395A (en) * 1940-05-30 1942-12-15 Strutt Maximiliaan Julius Otto Electron discharge tube circuit
US2314794A (en) * 1940-06-25 1943-03-23 Rca Corp Microwave device
US2314916A (en) * 1940-06-12 1943-03-30 Alma Gerrit Hendrik Petrus Circuit for the amplification and/or frequency-transformation of electrical oscillations of ultra high frequency

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2167201A (en) * 1935-06-28 1939-07-25 Pintsch Julius Kg Electron tube
GB525951A (en) * 1938-03-03 1940-09-06 Telefunken Gmbh Improvements in or relating to electron discharge device amplifier oscillator and like circuit arrangements for use on very high frequencies
US2305395A (en) * 1940-05-30 1942-12-15 Strutt Maximiliaan Julius Otto Electron discharge tube circuit
US2314916A (en) * 1940-06-12 1943-03-30 Alma Gerrit Hendrik Petrus Circuit for the amplification and/or frequency-transformation of electrical oscillations of ultra high frequency
US2314794A (en) * 1940-06-25 1943-03-23 Rca Corp Microwave device

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2537807A (en) * 1946-12-11 1951-01-09 John Logie Baird Ltd Thermionic amplifier
US2596539A (en) * 1947-04-09 1952-05-13 Hartford Nat Bank & Trust Co Circuit for transmitting or generating electrical oscillations of ultrahigh frequency
US2798903A (en) * 1951-03-16 1957-07-09 Henry M Spencer Signal amplification system

Also Published As

Publication number Publication date
FR872802A (US08197722-20120612-C00042.png) 1942-06-19

Similar Documents

Publication Publication Date Title
US2394857A (en) Electron ray indicating device
US2293414A (en) High frequency amplifier circuit
US2254096A (en) Electron beam discharge device
US2434295A (en) Amplifying circuit arrangement for ultra high frequencies
US2235817A (en) Multiple transconductance vacuumtube amplifier
US2235498A (en) Electron discharge device
US2230546A (en) Circuit for the amplification of ultra-high frequencies
US1995175A (en) Electrical oscillation generator
US2294328A (en) Ultra-high-frequency signal-translating stage
US2293180A (en) Detector system of the velocity modulation type
US2383351A (en) Phase inverter circuit
US2307074A (en) Modulating circuit for high frequencies
US2225469A (en) Relaxation arrangement for deflecting cathode rays
US2562228A (en) Frequency divider
US2139366A (en) Electron discharge device
US1744935A (en) Multivibrator
US2439638A (en) Circuit arrangement for amplifying or generating ultra high frequency oscillations
US2314916A (en) Circuit for the amplification and/or frequency-transformation of electrical oscillations of ultra high frequency
US2470732A (en) Negative transconductance electrical discharge tube
US2790036A (en) Electron-tube stabilized amplifying circuit
US2489132A (en) Electron discharge device
US2454204A (en) Cathode-ray tube
US1954195A (en) Vacuum tube
US2093078A (en) Electric space discharge tube system
US2094477A (en) Circuit arrangement for amplifying and/or frequency transformation of electrical oscillations