US2719220A - Circuit-arrangement for superregenerative reception - Google Patents

Description

p 1955 A. J. w. M. VAN OVERBEEK 2,719,220

CIRCUIT-ARRANGEMENT FOR SUPER-REGENERATIVE RECEPTION Filed July 9 1951 fOE.

INVENTOR Adrionus Johannes Wilhelmus Mcm'e Von %i% AGE United States Patent CIRCUIT-ARRANGEMENT FOR SUPER- REGENERATIV E RECEPTION Adrianus Johannes Wilhelmus Marie van Overbeek, Eindhoven, Netherlands, assignor to Hartford National Bank and Trust Company, Hartford, Conn., as trustee Application July 9, 1951, Serial No. 235,706

Claims priority, application Netherlands July 19, 1950 8 Claims. (Cl. 25020) This invention relates to circuit-arrangements for superregenerative reception, wherein the quenching frequency is produced in the same tube in which the damping of the signal input-circuit is reduced.

In such circuit-arrangements it is known to use tubes having a plurality of electrodes, one of which is a secondary emission electrode. It has been proposed to use a socalled dynatron, i. e. a tube which comprises a cathode, an anode and, in addition, two grids, in which the voltages applied are such as to produce a negative resistance between the anode and the cathode. In a known arrangement, the circuit wherein the quenching frequency occurs is connected between the anode and the cathode of such a tube, and the circuit wherein the incoming signal occurs is connected between the firstcontrol grid and the cathode. The damping of the latter circuit is controlled through the use of a back-coupling capacitor connected between the anode and the first control grid. In this circuit, it is necessary for the different voltages to be adjusted such that the anode current can alternately reverse its direction of flow.

Furthermore, it is known in a dynatron circuit-arrangement for regenerative reception, to connect the circuit for the quenching frequency and that for the signal frequency in series between the anode and the cathode. In this arrangement, the quenching frequency controls. the tube by periodically displacing the working point on the anode current-anode voltage characteristic curve beyond a maximum or a minimum of this curve, the adjustment of the voltages being rather critical.

This invention is directed to a circuit-arrangement for super-regenerative reception, wherein the quenching frequency is produced in the same tube in which damping reduction of the signal input-circuit is also effected. This tube has a cathode, an anode, and at least two control grids and a secondary-emission electrode. The circuit for the quenching oscillations and the signal input-circuit are both connected between the secondary-emission electrode and the cathode so that their damping can be reduced .by the negative resistance set up betweenthese electrodes. The signal input-oscillation is supplied to one control grid while the quenching frequency is supplied to the other control grid.

The signal input-circuit is preferably connected between the first control grid (viewed from the cathode) and the cathode. The circuit wherein thequenching frequency is operative is arranged such that the quenching frequency substantially exclusively influences the second control grid.

As is customary, a load or an amplifier may be connected to an impedance included in the anode circuit. Furthermore, it is advantageous to provide a screen-grid between the two control grids, a screen-grid being preferably also arranged between the second control grid and the anode, or the secondary emission electrode. The quenching frequency circuit and the signal input-circuit may be connected either in parallel or in series between the secondary-emission electrode and the cathode. As a rule, the series-connection is optimum.

In order that the invention may be readily carried into eifect, it will now be described in detail with reference to the accompanying drawing, in which two embodiments thereof are represented by way of example.

In the drawing:

Fig. l is a schematic diagram of a first preferred embodiment of the invention; and

Fig. 2 is a schematic diagram of a second preferred embodiment of the invention.

In Figure 1, the reference numeral 1 denotes a circuit to which is supplied an ultra high frequency oscillation. This circuit is coupled tothe signal input circuit 2, which is tuned to the incoming frequency of the super-regenerative receiving circuit-arrangement. Circuit 3 is tuned to the quenching oscillation, the frequency of which, as is usual, is much lower than the signal frequency and, in general, only a small fraction thereof. The circuit 3 is connected by way of a capacitor 15 to the secondary-emission electrode 10 of a discharge tube 4 and is connected to circuit 2 through capacitor 14. Both circuits and the cathode 5 of tube 4 are grounded. In addition to the said two electrodes, the tube 4 comprises a first control grid 6, a first screen grid 7, a second control-grid 8, a second screen grid 9, and an anode 11. The two screw-grids are interconnected to a point of positive voltage. The first control-grid 6 is connected by way of a capacitor 12 to the upper end of circuit 2 and through a resistor 13 to the cathode. The second control-grid 8 is connected through a capacitor 19 to the secondary-emission electrode and through a high resistor 21 to a point of negative potential, the secondary-emission electrode being connected through a high resistor 16 to a point of positive potential. The output voltage may be taken from a high resistor 17 included in the anode circuit through terminals 20. A capacitor 18, which represents a short-circuit to the highfrequency signal currents, is connected in parallel with the resistor 17. The end of resistor 17 disconnected from the anode is connected to a point of positive potential. As is customary in circuit-arrangements using secondaryemission tubes, the potential of the last-mentioned point is chosen to be larger than the potentials supplied to the secondary emission electrode and the screen-grids.

The circuit-arrangement operates as follows:

The voltages set up at the electrodes of the tube are so chosen as to produce a certain negative resistance between the secondary-emission electrode 10 and the cathode. Consequently, oscillations will occur in circuit 3, the frequency of which is determined by the tuning proper to this circuit. The tendency for the initiation of these oscillations is stimulated because the secondary-emission electrode is connected through the capacitor 19 to the second control grid 8. In this manner an apparent negative resistance approximately of 2000 ohms is produced across circuit 3, this resistance being mainly determined by the mutual conductance of the tube in relation to. the grid 8 as the resistance is substantially the converse of this mutual conductance. Since circuit 2 is connected through capacitor 14 to the secondary-emission electrode 10, its damping is also greatly reduced and this reduction is still enhanced as the circuit is also connected to the first control grid 6 through the capacitor 12. The apparent negative resistance produced across this circuit corresponds substantially to the converse of the mutual conductance of the tube in regard to the grid 6. In a practical embodiment this negative resistance was 200 ohms. Hence, it is obvious that oscillations produced in circuit 2 will very rapidly attain .a particular maximum amplitude. Owing, however, to the presence of the capacitor 19 and the second control grid 8, the damping of circuit 2 is periodically increased with the frequency of the quenching oscillation to a value such that the oscillations produced decrease rapidly to a very low amplitude. As in all circuit-arrangements for super-regenerative reception, the time in which the oscillations in circuit 2 increase to a particular amplitude, depends upon the intensity of the signal oscillation in circuit 1, with the result that an oscillation, with which the signal oscillation is modulated, will appear in the anode-circuit of the tube. This modula tion-oscillation may be taken from an impedance connected in the anode-circuit.

The capacitor 15 is a blocking capacitor which may have a comparatively high capacity. The value of the capacitor 14 should not be excessively high, since otherwise the circuit 3 might constitute a short-circuit in relation to circuit 2. In the circuit-arrangement described, it is furthermore possible to connect the second screengrid 9 through a capacitor 26, as shown, to the secondaryemission electrode 10. In this event it is, of course, necessary to include a high impedance 27 in the lead connecting this electrode to the supply.

Figure 2 shows a circuit-arrangement according to the invention, which is different from that shown in Fig. 1, in that the quenching frequency circuit 3 and the signal input circuit 2 are connected in series between the secondary emission-electrode and the cathode. This circuitarrangement is more advantageous than that depicted in Fig. 1 in as much as the circuit for the quenching frequency is no longer connected in parallel with the signal input circuit and the latter is influenced to a lesser degree by the former. The circuit 3 has a very low impedance in regard to the signal input oscillation and, conversely, the circuit 2 has a very low impedance in regard to the quenching oscillation. Consequently, oscillations will be produced in the circuit 3 due to the apparent negative resistance between the grid 8 and the cathode, so that the damping of circuit 2 will periodically attain high negative and high positive values.

In the circuit-arrangement shown in Fig. 2, it may be advantageous to connect the screen-grid 7 to the point joining circuits 2 and 3, as shown; in this case the positive voltage for this grid must be supplied through a high impedance 28. Alternatively, just as in the circuit-arrangement shown in Fig. 1, the second screen-grid may be connected through a capacitor to the secondary-emission electrode 10.

What we claim is:

1. In a super-regenerative circuit wherein a quenching oscillation modulates a regenerated oscillatory signal derived from an applied signal, an electron discharge tube having an anode, a secondary-emission electrode, first and second control grids and a cathode, a first network tuned to said signal and coupled between one of said grids and said cathode, a second network tuned to the frequency of the quenching oscillations and coupled between said secondary-emission electrode and said cathode, means coupling said secondary-emission electrode to said one of said grids to effect regeneration to an extent producing oscillations of said signal, means coupling said second network to the other of said grids to effect periodic quenching of said oscillatory signal at the frequency of said second network whereby said oscillatory signal is modulated therewith, and output means coupled to said anode to obtain said modulated oscillatory signal.

2. A circuit as set forth in claim 1 wherein said electron discharge tube further includes first and second screen grids, said first screen grid being interposed between said first and second control grids, said second screen grid being interposed between said second control grid and said secondary-emission electrode.

3. In a super-regenerative circuit wherein a quenching oscillation modulates a regenerated oscillatory signal derived from an applied signal, an electron discharge tube having an anode, a secondary-emission electrode, first and second control grids, first and second screen grids, and a cathode, said first screen grid being interposed between said first and second control grids, said second screen grid being interposed between said second control grid and said secondary-emission electrode, a first network tuned to said signal and coupled between said first control grid and said cathode, a second network tuned to the frequency of the quenching oscillations and cod,- pled between said secondary-emission electrode and said cathode, means coupling said secondary-emission electrode to said first control grid to effect regeneration to an extent producing oscillations of said signal, means coupling said second network to said second control grid to effect periodic quenching of said oscillatory signal at the frequency of said second network whereby said oscillatory signal is modulated therewith, and output means coupled to said anode to obtain said modulated oscillatory signal.

4. A circuit as set forth in claim 3 wherein said second screen grid is connected to said secondary-emission electrode.

5. In a super-regenerative circuit wherein a quenching oscillation modulates a regenerated oscillatory signal derived from an applied signal, an electron discharge tube having an anode, a secondary-emission electrode, first and second control grids and a cathode, a first network tuned to said signal and'coupled between said first control grid and said cathode, a second network tuned to the frequency of the quenching oscillations and coupled between said secondary-emission electrode and said cathode in serial connection with said first network, means coupling said secondary-emission electrode to said first control grid to efiect regeneration to an extent producing oscillations of said signal, means coupling said second network to said second control grid to effect periodic quenching of said oscillatory signal at the frequency of said second network whereby said oscillatory signal is modulated therewith, and output means coupled to said anode to obtain said modulated oscillatory signal.

6. A circuit as set forth in claim 5 wherein said tube further includes a first screen grid interposed between said first and second control grids and coupled to a connecting point common to said first and second networks.

7. In a super-regenerative circuit wherein a quenching oscillation modulates a regenerated oscillatory signal derived from an applied signal, an electron discharge tube having an anode, a secondary-emission electrode, first and second control grids and a cathode, a first network tuned to said signal and coupled between said first grid and said cathode, a second network tuned to the frequency of the quenching oscillations and coupled between said secondary-emission electrode and said cathode in parallel connection with said first network, means coupling said secondary-emission electrode to said first grid to effect regeneration to an extent producing oscillations of said signal, means coupling said second network to said second grid to effect periodic quenching of said oscillatory signal at the frequency of said second network whereby said'oscillatory signal is modulated therewith, and output means coupled to said anode to obtain said modulated oscillatory signal.

8. A circuit as set forth in claim 7 wherein said output means includes an impedance and wherein said modulated oscillatory signal is developed across said impedance.

References Cited in the file of this patent UNITED STATES PATENTS 2,030,120 Rust et al. Feb. 11, 1936 2,093,781 Roberts Sept. 21,1937 2,160,663 Jensen May 30, 1939

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