US2780682A - Difference amplifier - Google Patents

Difference amplifier Download PDF

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Publication number
US2780682A
US2780682A US483621A US48362155A US2780682A US 2780682 A US2780682 A US 2780682A US 483621 A US483621 A US 483621A US 48362155 A US48362155 A US 48362155A US 2780682 A US2780682 A US 2780682A
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United States
Prior art keywords
tubes
resistor
voltage
potential
triodes
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Expired - Lifetime
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US483621A
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English (en)
Inventor
Klein Gerrit
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Hartford National Bank and Trust Co
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Hartford National Bank and Trust Co
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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F5/00—Amplifiers with both discharge tubes and semiconductor devices as amplifying elements
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
    • H03F3/26—Push-pull amplifiers; Phase-splitters therefor
    • H03F3/28—Push-pull amplifiers; Phase-splitters therefor with tubes only
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
    • H03F3/34—DC amplifiers in which all stages are DC-coupled
    • H03F3/36—DC amplifiers in which all stages are DC-coupled with tubes only
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
    • H03F3/42—Amplifiers with two or more amplifying elements having their DC paths in series with the load, the control electrode of each element being excited by at least part of the input signal, e.g. so-called totem-pole amplifiers
    • H03F3/44—Amplifiers with two or more amplifying elements having their DC paths in series with the load, the control electrode of each element being excited by at least part of the input signal, e.g. so-called totem-pole amplifiers with tubes only

Definitions

  • the present invention relates to difference amplifiers. More particularly, the invention relates to difference amplifier circuits utilizing electron discharge tubes in push-pull arrangement.
  • An object of the invention is the provision of a difference amplifier utilizing triodes for the amplification which obtains a high rejection factor nevertheless.
  • each push-pull stage includes a plurality of controlled electron discharge tubes connected in series.
  • Theinput voltages of the tubes are supplied to the control grids thereof, the electrodes of the tubes are at the lowest potential, and the output voltage is obtained between the anodes of the corresponding tubes, which are at a higher potential.
  • the triodes constitute a so-called Oascode, i. e., a cascade connection of a triode in grounded cathode circuit and a triode in grounded grid circuit.
  • This connection operates as a pen tode amplifier, without the occurrence of distribution noise.
  • the grids of the corresponding triodes of the two branches, of which the electrodes are at the highest direct current potential, are connected to each other and are connected through a constant element to the cathode end of a common cathode resistor.
  • the constant voltage element preferably comprises a gas discharge tube, such as, for example, a glow discharge tube or neon tube, the stabilizing properties of which are known in the art.
  • the electrode of the glow discharge tube not connected to the cathode end of the common resistor is connected through a supply resistor of high resistance value to a point of positive potential.
  • the supply resistor conveys only the discharge current of the glow discharge tube, which may be of very low magnitude.
  • the supply resistor may have a resistance value of, for example, one megohm. This is important since the supply resistor contributes to the determination of the rejection factor. If the supply resistor resistance value is not sufficiently high, said resistor may be replaced by a circuit comprising controlled electron disch'arge tubes having a property of substantially preventing a voltage variation at the negative end from producing a current variation.
  • Fig. 1 is a schematic diagram of a diflerence. amplifier circuit of a type known in the art
  • Fig. 2 is a schematic diagram of an embodiment of the difference amplifier circuit of the present invention.
  • Fig. 3 is a schematic diagram of another embodiment of the difference amplifier circuit of the present inventlon.
  • Fig. 1 the input voltages, of which the difference is to be measured, are applied to terminals 1 and 2, which are connected to ground through high resistors 7 and 8 respectively.
  • the terminals 1 and 2 are connected to the control-grids of two amplifying tubes, represented by triodes 5 and 6.
  • the amplified difference voltage is obtained between terminals 3 and 4, which are connected to the anodes of the tubes 5 and 6, respectively.
  • anodes are connected through coupling resistors 9 and.
  • the cathodes are connected to one another and through a common resistor 11 to the negative'terminal of the voltage supply source, which may have a comparatively high negative potential to ground.
  • the cathode leads may, moreover, include impedances, which are not common to the tubes 5 and 6.
  • the amplifier When considering the voltages occurring at the input terminals 1 and 2, it may be advantageous to distinguish between identical components having the same phase (equal-phase voltages) and components being equal in absolute value and having different polarities (unequalphase voltages).
  • the amplifier must be arranged in a manner such that only the unequal-phase voltages are amplified and the equal-phase voltages do not affect the output voltages. With the amplifier shown this is obtained to a certain extent by the provision of the common resistor it. If equal-phase voltages are applied to the control-grids, the tubes 5 and 5 operate in parallel and the resistor 11 produces negative feed-back.
  • the current variations in the tubes approximately compensate one another in the resistor 11, so that the interconnected cathodes do not substantially change their potentials and the tubes have the normal amplifying effect.
  • the compensation is perfect for equal-phase voltages, so that, if the other stages are also identical and if useis made of a recording member responding only to voltage diiferences, only voltage differences between the two input terminals will be recorded.
  • the tubes 5 and 6 are not identical, equal-phase voltages at the grids will, in general, give rise to unequal-phase voltages between the anodes. This is also the case, if the resistor 11 has a very high resistance value.
  • the resistor 11 be constituted by a pentode having a resistor in the cathode lead, this resistor being also included in the grid circuit.
  • the alternating-current resistance which is essential with these amplifiers, may be rendered very high.
  • the term alternating-current resistance is to be understood to mean herein the ratio between the voltage variation at the anode of the pentode and a variation in anode current.
  • H rejection factor
  • I1 SZ (2) wherein S designates the mean mutual conductance of the tubes, Z the total impedance between the common point of the pushpull connection and ground and is the mean amplification factor from the input grid to the output anode. Where reference is made herein to a high rejection factor, this is to be understood to mean the possible minimum rejection factor.
  • Fig. 2 The arrangement of Fig. 2 is distinguished from that of Fig. 1 mainly in that each of the triodes 5 and 6 is replaced by the series combination of two triodes 5, 12 and 6, 13 respectively.
  • Each series combination constitutes a cascode, since the input voltages are applied to the grids of the triodes 5 and 6 and the interconnected grids of the triodes 12 and 13 have a constant voltage relative to the interconnected cathodes of the triodes 5 and 6.
  • This constant voltage is obtained by connecting the grids of the diodes 12 and 13 through a neon glow discharge tube 14 to the said cathodes.
  • the glow discharge tube 14 is fed through a resistor 15.
  • the resistor 15 may have a very high value, since it is only traversed by the discharge current of the glow discharge tube, which may be about 0.03 milliampere.
  • tubes 12, 13 and 5, 6 may be united to form double triodes.
  • Fig. 3 shows an example thereof.
  • triodes 16 and 17 the controlgrids of which are connected to points of a potentiometer 118, 19, 20, which may be constituted partly by voltage stabilizers, for example glow discharge tubes.
  • the resistor 11 may have a lower resistance value in this case than in the arrangements of Figs. 1 and 2.
  • the potential difference between the common cathodes and the negative terminal of the supply is much smaller in the arrangement of Fig. 3 than in that of Fig. 2, the alternat ing-current resistance being the same.
  • the arrangement of Fig. 3 is otherwise not distinguished from that of Fig. 2.
  • the resistor 15 may also be constituted by a circuit comprising controlled tubes, the arrangement being such that a variation in the voltage at the grids of the tubes 12 and 13 does not substantially produce a variation in the current through the resistor 15.
  • the requirements for the control-circuit replacing the resistor 15' are less severe than for the resistor 11, since the current strength is much lower.
  • the amplifiers according to the invention described above are, moreover, particularly suitable for direct-voltage amplification.
  • a difference amplifier comprising a push-pull connected amplifying system, each branch of said push-pull system including a plurality of series-connected electron discharge tubes having control and anode electrodes, means for applying a potential across said series-connected discharge tubes, means for applying an input voltage to the control electrode of a first tube of said plurality of tubes of each of said branches having the lowest potential applied thereto, and means for deriving an output voltage between the anodes of a second tube of said plurality of tubes of each branch having a higher potential applied thereto than said lowest potential, an impedance element for providing a constant voltage thereacross, and a common resistor connected at one end to the cathode of each of said first tubes, the control electrode of each of said second tubes being connected to the cathode of each of said first tubes through said impedance element, said means for applying a potential across said tubes including a negative terminal connected to the cathode of each of said first tubes through said common resistor.
  • a difierence amplifier comprising a push-pull connected amplifying system, each branch of said push-pull system including a plurality of series-connected electron discharge tubes having control and anode electrodes, means for applying a potential across said series-connected discharge tubes, means for applying an input voltage to the control electrode of a first tube of said plurality of tubes of each of said branches having the lowest potential applied thereto, and means for deriving an output voltage between the anodes of a second tube of said plu rality of tubes of each branch having a higher potential applied thereto than said lowest potential, a glow discharge tube for providing a constant voltage thereacross, and a common resistor connected at one end to the oathode of each of said first tubes, the control electrode of each of said second tubes being connected to the cathode of each of said first tubes through said glow discharge tube, said means for applying a potential across said tubes including a negative terminal connected to the cathode of each of said first tubes through said common resistor.
  • a diiferenw amplifier comprising a push-pull connected amplifying system, each branch of said push-pull system including a plurality of series-connected electron discharge tubes having control and anode electrodes, means for applying a potential across said series-connected discharge tubes, means for applying an input voltage to the control electrode of a first tube of said plurality of tubes of each of said branches having the lowest p0- tential applied thereto, and means for deriving an output voltage between the anodes of a second tube of said plurality of tubes of each branch having a higher potential applied thereto than said lowest potential, an impedance element for providing a constant voltage thereacross, and a common resistor connected at one end to the cathode of each of said first tubes comprising a potentiometer and two series-connected triodes having control grids connected to points on said potentiometer, the control electrode of each of said second tubes being connected to 15? the cathode of each of said first tubes through said im- 6 pedance element, said means for applying a potential across

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Amplifiers (AREA)
  • Switches Operated By Changes In Physical Conditions (AREA)
  • Photometry And Measurement Of Optical Pulse Characteristics (AREA)
  • Circuit Arrangements For Discharge Lamps (AREA)
US483621A 1953-08-24 1955-01-24 Difference amplifier Expired - Lifetime US2780682A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
NL761298X 1953-08-24
NL329089X 1954-01-25

Publications (1)

Publication Number Publication Date
US2780682A true US2780682A (en) 1957-02-05

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ID=31980706

Family Applications (1)

Application Number Title Priority Date Filing Date
US483621A Expired - Lifetime US2780682A (en) 1953-08-24 1955-01-24 Difference amplifier

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US (1) US2780682A (en(2012))
BE (2) BE531370A (en(2012))
CH (2) CH331260A (en(2012))
DE (3) DE971705C (en(2012))
FR (3) FR1106637A (en(2012))
GB (3) GB761298A (en(2012))

Cited By (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2896031A (en) * 1957-10-15 1959-07-21 Epsco Inc Differential amplifier
US2909622A (en) * 1956-08-20 1959-10-20 Cons Electrodynamics Corp Direct current differential amplifying system
US2941155A (en) * 1958-06-02 1960-06-14 Epsco Inc Differential amplifier
US2946016A (en) * 1954-10-26 1960-07-19 Lab For Electronics Inc All-pass network amplifier
US2964598A (en) * 1955-07-28 1960-12-13 Telephone Mfg Co Ltd Signal switched telecommunication circuits
US3024361A (en) * 1958-04-18 1962-03-06 Philips Corp Tuning and overload indicator circuit
US3042876A (en) * 1958-01-30 1962-07-03 Statham Instrument Inc Differential transistorized amplifier
US3046487A (en) * 1958-03-21 1962-07-24 Texas Instruments Inc Differential transistor amplifier
US3085209A (en) * 1956-04-05 1963-04-09 Carlson Arthur William Wide-band differential amplification
US3111643A (en) * 1956-05-21 1963-11-19 Gilfillan Bros Inc Air traffic schedule monitoring method and system
US3125755A (en) * 1957-12-09 1964-03-17 Local
US3168708A (en) * 1961-04-28 1965-02-02 Ampex Differential amplifier circuit for magnetic memory sensing
US3168709A (en) * 1960-12-14 1965-02-02 Honeywell Inc Stabilized transistor difference amplifier
US3275944A (en) * 1963-11-26 1966-09-27 Bendix Corp High voltage d.c. coupled differential amplifier including series energized transistors
US3482177A (en) * 1966-10-03 1969-12-02 Gen Electric Transistor differential operational amplifier
US3541465A (en) * 1966-12-28 1970-11-17 Hitachi Ltd Transistor differential amplifier circuit
US3568081A (en) * 1968-09-09 1971-03-02 Honeywell Inc Differential amplifier with predetermined deadband
US3725807A (en) * 1970-08-31 1973-04-03 Westinghouse Electric Corp Direct current amplifier

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1168974B (de) * 1956-07-03 1964-04-30 Telefunken Patent Transistorstufe in Emitterschaltung mit Mass-nahmen zur Kompensation des Einflusses von Betriebsspannungs- und Temperaturaenderungen
US2933693A (en) * 1957-05-03 1960-04-19 Lyle R Battersby Sensitivity control circuit
DE1120584B (de) * 1958-06-14 1961-12-28 Siemens Ag Anordnung zum Erzeugen von ueber lange Zeitraeume hochstabilen Steuerstroemen fuer Hallmesssonden

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2329073A (en) * 1943-01-01 1943-09-07 Rca Corp Thermionic tube circuit
US2424893A (en) * 1944-04-24 1947-07-29 Emi Ltd Amplifier circuits
US2592193A (en) * 1949-03-03 1952-04-08 Us Sec War Means for reducing amplitude distortion in cathode-follower amplifiers
US2631198A (en) * 1950-03-11 1953-03-10 Cons Electric Company Direct current amplifier

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2358428A (en) * 1940-09-07 1944-09-19 Emi Ltd Thermionic valve amplifier circuit arrangement
US2624778A (en) * 1945-10-25 1953-01-06 Gilbert J Perlow Electronic fluxmeter and alternating current amplifier
FR963498A (en(2012)) * 1947-05-23 1950-07-11
US2594530A (en) * 1948-10-02 1952-04-29 Bell Telephone Labor Inc Amplifying system
DE848207C (de) * 1951-02-03 1952-09-01 Fritz Schwarzer Gegentaktumkehrschaltung fuer Verstaerker
DE853297C (de) * 1951-05-03 1952-10-23 Fritz Schwarzer Kaskadenverstaerker in Gleichstromkopplung

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2329073A (en) * 1943-01-01 1943-09-07 Rca Corp Thermionic tube circuit
US2424893A (en) * 1944-04-24 1947-07-29 Emi Ltd Amplifier circuits
US2592193A (en) * 1949-03-03 1952-04-08 Us Sec War Means for reducing amplitude distortion in cathode-follower amplifiers
US2631198A (en) * 1950-03-11 1953-03-10 Cons Electric Company Direct current amplifier

Cited By (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2946016A (en) * 1954-10-26 1960-07-19 Lab For Electronics Inc All-pass network amplifier
US2964598A (en) * 1955-07-28 1960-12-13 Telephone Mfg Co Ltd Signal switched telecommunication circuits
US3085209A (en) * 1956-04-05 1963-04-09 Carlson Arthur William Wide-band differential amplification
US3111643A (en) * 1956-05-21 1963-11-19 Gilfillan Bros Inc Air traffic schedule monitoring method and system
US2909622A (en) * 1956-08-20 1959-10-20 Cons Electrodynamics Corp Direct current differential amplifying system
US2896031A (en) * 1957-10-15 1959-07-21 Epsco Inc Differential amplifier
US3125755A (en) * 1957-12-09 1964-03-17 Local
US3042876A (en) * 1958-01-30 1962-07-03 Statham Instrument Inc Differential transistorized amplifier
US3046487A (en) * 1958-03-21 1962-07-24 Texas Instruments Inc Differential transistor amplifier
US3024361A (en) * 1958-04-18 1962-03-06 Philips Corp Tuning and overload indicator circuit
US2941155A (en) * 1958-06-02 1960-06-14 Epsco Inc Differential amplifier
US3168709A (en) * 1960-12-14 1965-02-02 Honeywell Inc Stabilized transistor difference amplifier
US3168708A (en) * 1961-04-28 1965-02-02 Ampex Differential amplifier circuit for magnetic memory sensing
US3275944A (en) * 1963-11-26 1966-09-27 Bendix Corp High voltage d.c. coupled differential amplifier including series energized transistors
US3482177A (en) * 1966-10-03 1969-12-02 Gen Electric Transistor differential operational amplifier
US3541465A (en) * 1966-12-28 1970-11-17 Hitachi Ltd Transistor differential amplifier circuit
US3568081A (en) * 1968-09-09 1971-03-02 Honeywell Inc Differential amplifier with predetermined deadband
US3725807A (en) * 1970-08-31 1973-04-03 Westinghouse Electric Corp Direct current amplifier

Also Published As

Publication number Publication date
DE1023487B (de) 1958-01-30
DE971705C (de) 1959-03-19
CH329089A (de) 1958-04-15
BE531370A (en(2012)) 1957-11-22
CH331260A (de) 1958-07-15
GB771083A (en) 1957-03-27
DE964331C (de) 1957-05-23
FR1112775A (fr) 1956-03-19
FR1118236A (fr) 1956-06-01
GB767997A (en) 1957-02-13
BE535111A (en(2012)) 1958-12-05
FR1106637A (fr) 1955-12-21
GB761298A (en) 1956-11-14

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