US2806154A - Circuit arrangement to change the characteristic curve of multi-electrode tubes - Google Patents

Description

Sept. 10, 1957 K. STEINBUCH CIRCUIT ARRANGEMENT TO CHANGE THE CHARACTERISTIC CURVE 0F MULTI-ELECTRODE TUBES Filed June 16, 1954 Fig. 1 Fig. 2

Fig. 3 Fig. 4

INVEN OR K. STEINBUCH ATTORNEY United States Patent CIRCUIT ARRANGEMENT TO CHANGE THE CHARACTERISTIC CURVE 0F MULTI-ELEC- TRODE TUBES Karl Steinbuch, Stuttgart-Bad Cannstatt, Germany, as-

signor to International Standard Electric Corporation,

This invention relates to' a novel biasing arrangement for an electron tube, and particularly to an arrangement for modifying the steepness of slope of the output waveform from the tube.

It is often necessary to change the normal characteristic curve of an electron tube by means of elements in the output circuit; negative feedback circuits serve this purpose. In this connection non-linear resistances such as rectifiers or varistors may also be used in the negative feedback path of the electron tube.

The present invention, however, provides a novel circuit arrangement to change the characteristic curve of multi-electrode tubes, by providing in the negative feedback circuit, in particular the cathode circuit, a circuit element having a descending current-voltage characteristic.

In accordance with this invention, the circuit element comprises a transistor.

Although the invention is not to be limited to the use of a transistor, to facilitate an understanding of the invention it will be described in connection with a transistor, reference being had to the accompanying drawing, in which:

Fig. 1 shows a transistor circuit of conventional design,

Fig. 2 the current-voltage diagram for the transistor of Fig. 1,

Fig. 3 an example of a circuit arrangement as provided by the invention,

Fig. 4 the current-voltage curve of the circuit arrangement of Fig. 3.

The arrangement shown in Fig. 1 is a point contact transistor having a current-voltage characteristic that descends in part.

The collector, or a junction point, is designated C. The emitter is denoted by E. Rb indicates the coupling resistance between the emitter base and ground represented by a point M.

It over a drop resistance Rv a voltage U is applied between the points C and M, then at these points a voltage U, and in the collector circuit a current J can be measured.

The current-voltage curve, Fig. 2,- is a function of the resistance Rb.

It can be seen that the characteristic is similar to that of a glow-discharge diode. The ignition-voltage Uz depends initially on resistance Rb and is of the order of from 10 to 20 volts. The burning-voltage Ubr is of the order of from 2 to 5 volts.

Patented Sept. 10, 1957 The behaviour however, of a transistor circuit is different from that of a glow-discharge diode since ignition and extinction in the transistor occur in small fractions of a microsecond.

In accordance with this invention, the descent of the voltage U from Uz to Ubr is used to advantage.

Fig. 3 represents a tube stage as provided by the invention. This arrangement comprises the electron tube V and a transistor circuit such as illustrated in Fig. l. The emitter E is connected directly to the cathode of this tube. Its base is joined to the cathode over resistance Rb. Collector C is connected to ground. Between collector C and the grid of V the voltage U is effective. Between collector C and the cathode of V the negative feedback voltage Uk arises.

The behavior of the arrangement shown in Fig. 3 will now be explained with the aid of Fig. 4.

For highly negative values of U, such as point 0, Fig. 4, the transistor diode constitutes a high negative feedback resistance. In the range OA, represented by a dashed curve, the slope there effective is small compared with the characteristic proper, S, shown by a solid line; that is, the characteristic which would be effective if no transistor circuit were provided. If now U increases toward values more positive, the ignition voltage is suddenly exceeded at A whereby the curve part A-B of infinite slope will result.

By virtue of this curve range the described circuit arrangement is a very simple solution to the problem of steepening the edges of impulses.

Conversely, when positive values of U are changed toward the negative region, a sudden change similar to the former will result, namely, from B to A.

It is thus possible to realize infinite slope by arranging circuit elements of descending current-voltage characteristic in the negative feedback path of tube stages. This provision is the main feature of the invention.

While I have described above the principles of my invention in connection with specific apparatus, it is to be clearly understood that this description is made only by way of example and not as a limitation of the scope of my invention as set forth in the objects thereof and in the accompanying claims.

What is claimed is:

1. A circuit arrangement for sharpening the flanks of impulses comprising an electron-discharge device having cathode, grid and anode electrodes, a crystal triode having emitter, collector and base electrodes, means coupling said base electrode of said crystal triode over a resistance to said cathode, means coupling said emitter electrode directly to said cathode, and means for applying an input signal between said grid and collector electrodes.

2. The arrangement according to claim 1 wherein said electron discharge device comprises a vacuum tube.

References Cited in the file of this patent UNITED STATES PATENTS

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