DE1791037A1 - Filter circuit - Google Patents

Description

vine · ΗΛΓ-Ϊ3 RUSCHKE .-ir-fj. H '.: IM2 AGULAR S 982

. _: \ llt1Uiäte- »iktori3-Stt» Ät if 1791037

Telefonaktietolaget IM Ericsson, Stockholm 32 (Sweden)

ϊ i It activation

Simple piiter circuits have a transmission radio *

tion P on, for example

■ g *, -

■> 4- O

ie with a constant in the numerator and with a polynomial in the complex variable s « <f # jω in Henner. As is known per se, these pilter can for example consist of conductor networks with inductances and capacitors that are terminated by a resistor at one end and a voltage generator with a very low output impedance or a current generator with a very low output impedance at the other end high output impedance

109943/0529

be fed. In such udders the number of reactances is doh · the inductances and capacitances equal to the degree of the polynomial in the denominator. Filter with a transfer function F, which is also used in Numerators containing a polynomial can be done using conventional methods be set up in such a way that the conductor network has certain parallel resonance circuits instead of corresponding simple series elements is equipped or in such a way that the conductor network is equipped with mutual inductances in addition to simple inductances will determine what action is required when the numerator polynomial roots in the right half of the complex frequency plane having. This need additional reactances and in particular Having to provide mutual inductances must be viewed as a major disadvantage, and the present invention aims to eliminate this disadvantage *

line filter maintenance according to the invention has the im attached claim on the features listed.

The invention will now be described in detail. In the accompanying drawing, the
1 shows a circuit for a filter arrangement according to the invention

dung and the

2 shows a graph of the attenuation of the filter circuit and the time delay deviation as a function of the frequency _o

The filter circuit consists of a conductor network with the downstream inductances L1, L2, L3 and with the shunt capacitances 01, 02, 03 »At the right end, the conductor network is terminated by a resistor R, while the left end of the circuit is connected to an input signal source _{e Q} will «The capacitor 01 is on one side with the

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Connection point between the inductances L1 and L2 and on the other side with a signal source Oc ₁ β ■ connected. The capacitor QZ is connected on one side to the connection point between the inductances L2 and L3 and on the other side to a signal source et «e. The capacitor C3 is connected on one side to the connection point between the inductance L3 and the resistor R and on the other side is grounded.

The filter circuit after the Pigd should be in a telecommunications system can be used in which a transfer function F is required, which is graphically represented in FIG. 3 by the damping curve I and by the curve II of the time delay deviation as Function of the frequency f = <ΠΓ ~ is shown. this function F can be in analytical form with s * tf * + j «as the complex Angular frequency are represented, and in the present case is the transfer function is given by the equation below:

2.45s ⁴ + 503s ² +10395

s ^B + 2ts ⁵ + 210s ⁴ + 1260s ³ + 4725s + 10395s + Io395

From the function F given in this way, the transmission poles (3 the roots of the Henner polynomial) and the transmission zero values (3 the roots of the numerator polynomial) can be calculated, and the conductor network of the filter circuit is determined in detail from the now known poles, i.e. y and y ₂₁ are then known, where y is the admittance of a shunt element ρ of the total number of η shunt elements of the conductor network, while y ₂ ^ is part of the transmission admittance of the conductor network, which part is between the input terminal of the filter circuit (in Fig «1 left) and the shunt element y,« From the difference values of the admittance value part y ^, which values are for different

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integer values of ρ can be obtained within the interval 1 = r ρ = * η, and from the known transfer zero values for the transfer function, the various values for the quantity α ν are obtained, which represent the relationship between size and sign between a lifting element k from a connected signal source and a signal that is fed from the input signal source to the series elements of the FiIterschal device on the input side during operation ₀ Within the interval 1 "* k» m has k different integer values, where, m is the number of shunt elements The transfer function F for a filter circuit according to the invention can be expressed by the following equation:

k »m ^

1 + N ot. y, γ— j—

κ je ^ - y ₂₁ ; _k

For the circuit according to FIg, 1 is obviously m. »2 and η = 3. The various circuit elements of the circuit have the following values:

L1 »22.3 uH

12 «12 uH

L3 * 5.6 uH

Ci - 15.3 pF

C2 - 9 pF

03 * 1.9 p?

E β 1000 Ohm

oc ₁ «■ ■ - 0.46

and ot 2 * - 0.0037

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The invention is of course not limited to the circuit shown in "in which the inductances are connected in series and the capacitances are connected in series", which type of reactances, their number and the number of signal sources are completely determined by the transfer function that is implemented to be. in-band filter circuits, for example, pass the series elements from series resonant circuits, while the shunt elements consist of parallel resonant circuits. Furthermore, do not need the sources from separate units to exist, but they can z ₀ B "consist of parts of a voltage divider from the input signal source with voltages is supplied.

. Claim

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Claims (1)

Claim Filter circuit, consisting of a conductor network with reactances and a terminating resistor, the type and size of these reactances being determined by the transfer poles of the transfer function Έ of the filter arrangement, and signal sources being connected to one or more shunt elements in the conductor network, while a series element is connected to the The input side of the filter is to be connected to an input signal source, characterized in that the conductor network and the signal sources are dimensioned in such a way that the admittance of the conductor network and the said signals of the signal sources with regard to the magnitude and sign of the desired transfer function P of the filter circuit according to the following equation correspond ^{1 +} > ^dd τ— ν —r / ^y 21 ^j k where P C- y is the admittance of a shunt element ρ of the entire Number η of shunt elements of the conductor network the admittance of a shunt element es. k of m shunt elements of the conductor network that are connected to signal sources, 1098 4 3/0529 (V ₀₄ ) a part of the transmission admittance of the conductor network, which is located between the input of the multi-circuit and the siphon element ρ, (y ₂₁ ) _k a part of the transmission admittance of the conductor network, which is located between the input of the filter circuit and the siphon element k, k the relationship in terms of magnitude and sign between a signal supplied to the siphon element k from the connected signal source and a signal, that from the input signal source to the series elements of the Filter maintenance on the input side supplied during operation will, is, and, k, p, m, η are integers representing the relationships . . 'vSJtSn, le ^ p ^ n man suffice. 109843/0529 Blank page