DE1088165B - Impedance-inverting network containing active switching elements - Google Patents

Description

GERMAN

There is often a great deal of interest in the rule and Decelerating devices via two adjustable impedances whose product remains constant at all frequencies. The reverse impedance of a given impedance can always easily be realized at a certain, unchangeable frequency. Against it are impedance inversions of precisely prescribed ratio in a wide frequency range with circuit arrangements, which only contain passive switching elements, difficult to reach. However, it can be Use active quadrupoles with advantage for the construction of circuit arrangements that operate in a wide frequency range Impedance inversions should cause within narrow tolerance limits.

It is known that the impedance - R \ jZ appears at the input terminals of a T-element, the series branches of which are realized by resistors R ₀ and the shunt branch by the negative resistance - R ₀ , when this T-element is connected to the output side with the Impedance Z is terminated. In contrast, the invention is based on the object of converting an impedance Z into an impedance R \ jZ. This task is on. can be released by a T-element terminated with the impedance Z , whose series branches are formed by negative resistors - R ₀ and whose shunt branch consists of the resistor R ₀ . However, it is difficult to insert the usual tube circuits used to produce negative resistances into the ungrounded series branches of branch circuits. The invention provides a way of obviating these difficulties. The circuit arrangement according to the invention is based on the idea of locating two active, impedance-converting quadrupoles which contain tube circuits that can be connected to earth on one side, of which the tube circuit of the one active quadrupole, with appropriately selected output-side shading, the quadrupole input impedance R% \ Z + R ₀ results, which is converted into the impedance R \ jZ by the input impedance -R _{0 of} the second active quadrupole, which is connected to the first active quadrupole in a so-called front series circuit. :

The arrangement according to the invention thus belongs to the class of impedance-inverting networks which contain active switching elements and which produce the impedance RIjZ at their input terminal pair when their output terminal pair is connected to the impedance Z. According to the invention, this impedance conversion is achieved in detail in that the inverted impedance appearing at the input terminal pair of the impedance-inverting network is the sum of the input resistances of two four-pole active switching elements containing active switching elements connected to one another on the input side by four-pole series connection
impedance inverting network

Applicant:

Compagnie Industrielle des Telephones, Paris

Representative: Dipl.-Ing, H. Leinweber, patent attorney,
Munich 2, Rosental 7

Claimed priority:
France, 16 August 1955

Robert Leroy, Paris,
has been named as the inventor

of which the one quadrupole, which has the impedance - R ₀ at its input terminal pair, is terminated on the output side by an impedance consisting of passive switching elements, while the other quadrupole, which produces the impedance RIjZ + R ₀ at its input terminal pair, on the output side via two series impedances with a spar bridge circuit connected is. The two bridge arm impedances of this bridge circuit are formed by two series-connected impedances of half the size of the impedance Z to be inverted.

The elements of the arrangement according to the invention, which form negative impedances, can be in any be carried out in a known manner.

As an example, an embodiment of the invention is described below in which the active Four-pole by a bridge circuit to be found in literature with a differential transformer and a Amplifier tube are realized. The cross arm of this bridge circuit is created by the grid-cathode route the amplifier tube is formed, while the primary winding halves of the differential transformer as series branches serve, whose secondary winding belongs to the anode circuit of the amplifier tube, whose anode external resistance Realized by the bridging branch.

Fig. 1 shows the circuit diagram of an arrangement with. an impedance, which in certain circumstances is quite is equivalent to the parallel connection of an impedance and an impedance with a changed sign;

Fig. 2 shows a known circuit of a four-pole · · all lock and

Fig. 3 shows the circuit diagram of the embodiment of Inversion device according to the invention with such an all-lock. '. ■ "_-

009 589/361

In the following it will be shown in detail, -Z ₁ , in such a way that between the points ft and q the

that with the active impedance illustrated by FIG. 1 [Z ₀ , -Z ₁

Z ₀ · (- Z ₁ ) where is below

is measurable.
Z ₀ , —Ζ-Λ which results from the parallel

Four-pole at the terminal pair ft-q the impedance "° - ¹ t ¹ ^ t ₊ Y τ ¹ A ^{l! L} T a \ Ia

* rr 2 f _Zo - _Zl \ circuit of the impedances Z ₀ and -Z ₁ resulting

occurs when the pair of terminals mn with 5 understand _{impedance value} ^z o · (- ^ ₁₎

the impedance Z ₁ and the pair of terminals ft-q with the ^F Z ₀ - Z ₁

Impedance Z _{0 is} connected. Incidentally, you notice that it is easy to

This fact affects the arrangement according to -jj.jj.-i ² ι · · t_j.

of the invention in the case of the application of active resistance components - ^ to compensate if it does not

Networks according to FIG. 1 in such a way that io is negligible. In this case, the quadrupole is connected to the input of the impedance Riss + -K _{0. The} place of Z _{1 is} the impedance
should be measurable, this impedance value on the one hand by ₍ 2

Shading of the four-pole input terminals with the Z _{1 -Z 1} - - ^ -, (6)

Resistance R ₀ , on the other hand, is achieved by shading the four-pole output terminals, 15 which is always possible if one chooses the winding sense of the transformer that the equation is such that k is negative.

R ₀ - (R ₀ Z) It should now be the resistance of the primary winding of the

Roß + -Ro ⁼ D / ο _i_ 7, transformer T must be taken into account.

⁰ ^ ⁰ ^> Let X _{1 be} the inductance of this winding and M die

is satisfied. A correction will be made later on. The mutual inductance between the primary and the moving assumption that the differential transformer has secondary windings.

of arrangements according to FIG. 1 look like an ideal equation (3) is then to be replaced by

Transformer behavior is thus the output terminal pair U * = (Z ₁ + T ₁ + 3 ω L ₁ ) J ₁ + j co MJ ₉ ; (7)

of the active quadrupole in question of the arrangement \ 1 1 1 1 ./ 1 /./ 1 1 y j ν> \ j

according to the invention with the impedance R ₀ -f- Z ab- 25 ω denotes the angular frequency of the connect to the terminals ft . and q applied voltage.

If one looks at FIG. 1, one sees that between From equation (2), one can in the

the terminals ft and q on the one hand an impedance Z ₀ and equation (7) J ₂ , on the other hand, replace the series connection of an impedance Z ₁ and the drawn value with its from equation (2). This gives
the primary winding of a transformer T in parallel 30
are switched. Z ₀ and Z ₁ are tj g with their one terminal

laid on earth. The middle point K of the primary winding - = - = -Z ₁ = - == - ^ r = . (8th)

of the transformer T is with the grid 2 of a pentodeö J ¹ j _ω - 1 j ω - 1

with practically infinitely high internal resistance

bond, the cathode 1 of which is connected to earth. The secondary 35 as long as ω MS / 2 is large compared to one, applies

winding of the transformer T is in the circle of. tj 1 2L

Anode 3 of the tube switched. 4 denotes the braking -γ- ^ --Z ₁ = j ^. (9)

grid of the tube and 5 its screen grid. Ji 'j _ω ^{Mi} M ά}

Let J _{1 be} the current in the primary winding of the Trans- 2 Y ₁

formator from ft to q and T ₇ , the current in the anode 40 _, ", . ,, i / LT ■ ±. i_ j. t_j. j- -r> ■%.

circle of the tube 6. Since M = yi ^ and Ä = j / ^, the relationship exists

Let U be the voltage difference at the terminals ft and q. 2L ₁ 2

The potential of point K and consequently that of MS ~ kS '

". ,," -cjj. -j. U + Z ₁ J ₁ Introducing

Grid 2 against earth is thus ■ · «

MS j 2L ₁ .

If 5 is the steepness of the tube 6, we get 7 = 27 " Ψ = ~ ( ¹⁰ )

Jp - S 2 · (2) can be said about the circuit of FIG. 1 that

at their terminals ft and q for a direction of winding des

If one assumes, as a first approximation, that the trans- 50 transformer T, of the negative values of M

formator speaks the properties of an ideal transformer, the impedance JjZ ₀ , -Z ₁ I can be measured if the

one obtains: terminals m and η with the impedance

J ₁ = -kj ₉ . (3) _z " _{= Zi +} _ _r l_ _{+ φ} (H)

Here h is the transformation ratio of the transformer. 55

Inserting the value of J ₁ into equation (2) results in: be connected.

jj 2 'B ^e * Application to a rule or equalizer

- = - = -Z ₁ - = - 7-. (4) there is an interest in the circuit, the same impedance Z

Ji with the controllable elements at the same time in the circuit

^ p and k are much larger to accept than one, to use ^{6o md} ™ ^inversion apparatus according to the invention *. This is achieved if the means is such that the controllable impedance Z point is accessible without any further 2 .. further by connecting the inversion device £ 5 "^ I ι 'with the impedance Z by an all-lock.

and that ^6s * £ ^ "^ ^ ^ze IGT embodiment, a Allsperre in

jj known form. Between the input terminals α and b

-γ-cz - Z ₁ . (5) the circuit are two impedances? and 8 from

Ji 2

tv τ j τ jj · π · ·· · π JT value —- placed in series. One output terminal is

The impedance Z ₁ and the primary winding of the trans- 2 0 t> ο &

formator T together are thus equal to an impedance 70 directly to terminal b and the other output

Terminal c is connected to point e via the primary winding of an ideal transformer 9 with a transformation ratio of -1. The secondary winding of this transformer is connected in parallel with the impedance 8 between the input terminal α and the center point e.

Let I ₂ be the input current at terminals c and d. It is easy to see that a current I ₁ + I _{2 flows} between points b and e in the impedance 7, while a current I ₁ -I _{2 flows} in the impedance 8. The voltage at terminals a, b has a value ZI ₁ and the voltage at terminals cd has a value

| - (ii + h) - ~ {hh) = ZI ». .

3 shows the inversion device in a schematic representation according to the invention.

This arrangement, at whose terminals p and q the inversion result occurs, contains in series the input circuits of two four-pole terminals Q ₁ and Q _{2 of the} same structure as the four-pole pole p qmn according to FIG. 1.

The input terminals fi-r of the quadrupole Q ₁ are connected to the resistor R ₀ and its output terminals M ₁ - ^ n via a resistor R ₁ and a capacitor γ _Λ to the terminals dc of a quadrupole Q ₃ , which together with the two halves - the given

Impedance Z to be converted, an all-block forms which the all-lock according to FIG. 2 is similar. Of the

Resistor R ₁ has the value R ₀ +

M ₁

on. With L ₁

is the inductance of the primary winding of the transformer T ₁ , M ₁ is the mutual inductance of this transformer and S _{1 is} the steepness of the tube P ₁ . On the other hand, the capacitor y has _x

a capacity that is the same. With T ₁ of the resistance of the primary winding of the transformer T ₁ is designated.

Under these circumstances the measurable input impedance of the quadrupole Q _{1 is} equal to R \\ Z + R ₀ .

Furthermore, a resistor R ₃ equal to aR ₀ (cc> 0) is connected to the input terminals rq of the quadrupole Q ₂ , and the output terminals m _% -n of the same are connected to the series connection of a resistor

2 L ₂

M ₂ S ₂ M ₂ S ₂

and a capacitor connected to -. The index »2«

2 -I ι (

1 - (- a
the capacity γ ₂ =

characterizes the parameters of the transformer T ₂ and the tube P ₂ .

Thus between the terminals φ and r of the quadrupole Q _{1 there is} an impedance || i? ₀ , - (R ₀ + Z) || and an impedance between the terminals r and q of the quadruple terminal Q ₂

ll ^{ai? t} "- TT ^

As a result, between the terminals p and q of the overall circuit of the four- _{terminal network ^ 1} and Q _2, an impedance of the given impedance Z, which is reversed with respect to R * and is connected to the terminals α and δ of the four- terminal network Q ₃ , arises.

The arrangement according to the invention can in particular be used to reverse impedances perform that contain thermistors or inductors whose value depends on the intensity of a magnetic Depends on the field. For example, in transmission systems with coaxial lines, weather-related attenuation distortions are automatically compensated Equalizer application that has a bridged T-element, the series branches of which contain active resistances and whose shunt branch is made up of resistors and capacitors, while the bridging branch consists of inductances, the value of which depends on a magnetic field generated by a Control current is influenced. When using the inversion device according to the invention one can achieve that the shunt of this bridged T-link has a reverse impedance of that of the bridging branch. In this case, the division of the switching elements prepares the bridging branch no difficulty in two parts; it is enough to use the windings of the controllable inductors and to split the resistors connected to them into two halves.

Claims (1)

Claim: Impedance-inverting network containing active switching elements, which converts an impedance Z connected to its output terminal pair into an impedance RIjZ occurring at its input terminal pair, characterized in that the inverted impedance appearing at the input terminal pair of the impedance-inverting network is the sum of the input resistances of two input terminals interconnected, active switching elements containing quadrupoles (Q ₁ and Q ₂ ) , of which the one quadrupole having the impedance - R ₀ at its input terminal pair is terminated on the output side by an impedance (γ, R ₂ ) consisting of passive switching elements, while the other quadrupole, which produces the impedance R \\ Z + R ₀ at its input terminal pair, is connected on the output side via two series impedances (γ, R ₁ ) to a spar bridge circuit, the two bridge branch impedances of which are connected by two series-connected impedances of ha Is formed over the size of the impedance Z to be inverted. Considered publications: French Patent No. 886,452;
Journal of The Institution of Electrical Engineers, Vol. 65, 1927, pp. 373-376. 1 sheet of drawings