US2173910A

US2173910A - Circuits for the amplification of electric oscillation

Info

Publication number: US2173910A
Application number: US91274A
Authority: US
Inventors: Mark Jan Van Der; Vries Gerrit De
Original assignee: Philips Gloeilampenfabrieken NV
Current assignee: Koninklijke Philips NV
Priority date: 1934-08-09
Filing date: 1936-07-18
Publication date: 1939-09-26
Anticipated expiration: 1956-09-26
Also published as: NL50277C; GB458066A; NL54812C; FR793102A; US2094477A; BE416910A; GB457928A; FR47599E; DE731698C

Description

Sept. 26, 1939. J. VAN DER MARK El AL 2,173,910

CIRCUITS FOR THE AMPLIFICATIQN ELECTRIC OSCILLATION Filed July 18, 1956 fly I 2 i in. 5 a -L -L F \NVENTORS JAN VAN DER MARK GERRH vmes ATTQRNEY Patented Sept. 26, 1939 PATENT OFFICE CIRCUITS FOR THE AMPLIFICATION OF ELECTRIC OSCILLATION Jan van der Mark and Gerrit de Vries, Eindhoven, Netherlands, assignors to N. V. Philips Gloeilampenfabrieken,

Eindhoven,

Netherlands. a

corporation of the Netherlands Application July 18, 1936,. Serial No. 91,274 In the Netherlands August 9, 1935 '7 Claims.

This invention relates to a circuit arrangement for the amplification of electric oscillations in which use is made of amplifier valves having a negative plate voltage and is an improvement in or modification of the circuit arrangement described and claimed in application, Ser. No. 39,094, filed Sept. 4, 1935, which has issued as Patent 2,094,477 and is assigned to the same assignee as the present application. The oscillations to be amplified are impressed upon the control grid and bring about a variable space charge adjacent the plate electrode. This variable space charge induces a variable charge on the plate which gives rise to a plate current of the same frequency as that of the oscillations impressed on the control grid. The plate current has in addition the property that the amplitude increases proportionally to the frequency of the oscillation and is displaced in phase by 90 relatively to the grid alternating voltage. When the amplified alternating voltage occurs in the plate circuit across a resistance in the plate circuit, this amplified alternating voltage will therefore increase proportionally to the frequency with otherwise constant grid alternating voltage. The amplification is consequently dependent upon frequency. This is disadvantageous because in the majority of cases amplification independent of frequency is required.

According to the invention, amplification independent of frequency is obtained by the plate circuit including an impedance having a primarily capacitative behavior.

The operation of the arrangment according to the invention will be appreciated by the fact that a current having a constant amplitude sets up across an condenser a voltage decreasing with the frequency.

W'hen consequently the amplitude of the our- 40 rent increases proportionally to the frequency, as

is the case with amplifier valves having a negative plate voltage, the voltage across the condenser will be independent of the frequency.

Fig. 1 shows a circuit arrangement for obtaining amplification independent of frequency in accordance with the invention.

Fig. 2 shows a circuit similar to Fig. 1 but employing reaction to reduce the apparent input capacity of one of the valves.

The circuit according to the invention is shown in Fig. 1 of the accompanying drawing. It comprises, for example, two cascade-connected screen grid valves l and 2 having a negative plate voltage which is supplied by a source of voltage Ea through

resistances

3 and 4 respectively. The

plate circuit of each amplifier valve includes in addition a condenser 5 and 6 respectively. The

resistances

3 and 4 have such a value that the plate impedance is governed almost exclusively by the condensers 5 and 6 so that amplification 5 independent of frequency is obtained. Since the amplification is higher according as the condensers 5 and 6 are reduced, it may be desirable, particularly in the case of amplification of oscillations of very high frequency, that the condensers 5 and B should be omitted and that the natural capacity of the amplifier valves between the plate and the cathode and between the control grid and the cathode should be put up with. If even this capacity is still too high, it may be reduced, 5 for example in the case of amplifier circuits comprising three cascade-connected valves, by providing as shown in Fig. 2 for capacitive reaction, such as by the condenser I, from the plate circuit of the third valve to the grid circuit of the second valve, which ensures a decrease of the apparent capacity between the control grid and the cathode of the second valve.

What we claim is:

1. A circuit for the uniform amplification of electric oscillations independent of frequency, comprising an electron discharge tube provided with cathode, grid and plate electrodes an input circuit connected between cathode and grid, and an output circuit connected between cathode and 30 plate electrode, said plate electrode being supplied with a negative operating potential with respect to the cathode, and an impedance included in said plate circuit for rendering said circuit primarily capacitative.

2. A circuit for the amplication of electric oscillations, comprising a vacuum tube provided with cathode, grid and plate electrodes, an input circuit connected between cathode and grid, an output circuit connected between cathode and 0 plate, a source of potential included in said output circuit for impressing a negative potential with respect to the cathode on the plate electrode, and a resistance and a shunt capacity also included in said output circuit. 45

3. A circuit for the amplification of electric oscillations, comprising a vacuum tube provided with a cathode, a control grid, a screen grid and a plate electrode, an input circuit connected between cathode and control grid, an output circuit 50 connected between cathode and plate electrode, a source of potential included in said output circuit for impressing a negative potential with respect to the cathode on the plate electrode, means for impressing a positive potential on said screen 55 grid, and a resistance and a shunt capacity also included in said output circuit.

4. A circuit for the amplification of electric oscillations comprising a plurality of vacuum tubes connected in cascade, each provided with cathode, grid and plate electrodes, an input circuit connected between the cathode and grid of the first tube, each tube having an output circuit which includes a source of potential for impressing a negative potential with respect to the cathode on the plate electrode, a resistance and a shunt condenser, the grid of each succeeding tube being directly coupled to the output circuit of the one preceding.

5. A circuit for the amplification of electric oscillations comprising a plurality of vacuum tubes connected in cascade, each provided with cathode, grid and plate electrodes, an input circuit connected between the cathode and grid of the first tube, each tube having an output circuit which includes a source of potential for impressing a negative potential with respect to the cathode on the plate electrode, the grid of each succeeding tube being directly coupled to the output circuit of the one preceding, and a condenser connected between the plate of one tube and the grid of the preceding tube.

6. A circuit for the amplification of electric oscillations comprising a plurality of vacuum tubes connected in cascade, each provided with a cathode, a control grid, a screen grid and a plate electrode, an input circuit connected between the cathode and the control grid of the first tube, each tube having an output circuit which includes a source of potential for impressing a negative potential with respect to the cathode on the plate electrode a series resistance and a shunt condenser,the grid of each succeeding tube being coupledto the output circuit of the one preceding, and means for impressing a positive potential on each of said screen grids.

7. A circuit for the amplification of electric oscillations according to claim 6 wherein a condenser is connected between the plate electrode of one tube and the control grid of the preceding tube.

JAN VAN DER MARK. GERRIT DE VRIES.