DE3110076C2 - Electric filter circuit - Google Patents

Abstract

The invention relates to an electrical filter circuit, consisting of CTD elements unidirectional transmission behavior with one or more self-contained conductor loops that determine the frequency-dependent transmission behavior of the filter circuit and in which the individual conductor loops are coupled to each other via coupling circuits. The object of the invention is to implement such circuits in the manner of reactance branch circuits. This object is achieved according to the invention in such a way that at least one recharging capacity (C *) of a resonator (e.g. R ↓ 1) with at least one further recharging capacity (e.g. CΔ ↓ 2 and C ↓ 3) galvanically (LΔ ↓ 2, L ↓ 3) is connected, and this transfer capacity (CΔ ↓ 2 and C ↓ 3) to a filling and filling circuit ("fill and spill") of at least one other resonator (eg R ↓ 2 and R ↓ 3) that of a total transfer capacity (ΣC ↓ 1), which follows the transfer capacity (C *) of the resonator (R ↓ 1) with the galvanic lines (LΔ ↓ 2, L ↓ 3), one of the relative bandwidth of the resonator (R ↓ 1) the corresponding amount of charge is discharged via a transfer capacity (C ↓ 0 ↓ 1) into a sink (S ↓ 1) so that the total capacity (ΣC ↓ 1) from at least one filling and filling circuit with a charge source (e.g. Q ↓ 1 ) Charge is supplied, the amount of which is determined by the product of a recharging capacity (e.g. C ↓ 1), which follows a source (Q ↓ 1) and from the voltage addition a reloading capacity (e.g. ..

Description

The invention relates to an electrical filter circuit, consisting of CTD Charge Transfer Device = charge transfer device elements with unidirectional transfer behavior, with which a or several self-contained conductor loops are simulated, which determine the frequency-dependent transmission behavior of the filter circuit in which the individual conductor loop replicas are coupled to one another via coupling circuits.

Filter circuits of this type are given in DE-AS 31398. Also in DE-PS 24 53 669 specified electrical filter circuits which contain self-contained line loops as resonators and which are formed there as four-pole resonators are. Such a CTD filter circuit is also shown in FIG DE-PS 25 55 835 described in which a so-called two-pole resonator is used as a resonance-capable structure. In order to set up multiple electrical filter circuits, it is now necessary to couple such resonator circuits to one another. Walkthrough c for this purpose, for example, the German Auslegeschriften 27 04 318 and 28 08 604 are given. However, it turns out that certain technological Difficulties exist because, for example with the coupling circuit specified in DE-AS 28 08 604. Amplifiers present, the gain K with filters with no relative bandwidth 8 therefore becomes relatively large because the gain K is approximately inversely proportionally to the relative bandwidth B.

The invention is based on the object of providing coupling circuits for multi-element low-pass filters and band-pass filters to be specified from CDT line resonators. It should now be possible to dimension the low-pass filters or band-pass filters as reactance branch circuits which have selectable damping zero positions and damping pole points and which can be operated with a single clock frequency. The coupling formwork has the property from Z. B. dual converters or gyrators. The gain factors of the amplifiers required in the coupling elements should be less than or equal to | ± 1 | be, no amplifiers should occur in the CTD line loops forming the resonators. This object is achieved according to the invention for the electrical filter circuits mentioned in the introduction solved that at least one charge transfer capacity of a resonator is connected to at least one further charge transfer capacity via galvanic lines that this Transfer capacity to a filling and filling circuit ("ΠΙ1 and spill") belongs to at least one other resonator, that of a transfer total capacity, which is based on the transfer capacity of the resonator with the galvanic lines follows, an amount of charge corresponding to the relative bandwidth of the resonator is discharged via a transfer capacity into a sink that the total capacity is fed to at least one filling and filling circuit with a charge source charge, the amount of which is determined by the product of a charge reversal capacity that follows a source and the voltage state of a charge charge capacity of another resonator, and that the Total capacitance following a uniform charge withdrawal stage is inserted.

It is also important to consider the galvanic To design lines as aluminum conductor tracks or to manufacture them from conductively doped silicon.

The invention is explained in more detail below with the aid of exemplary embodiments. It shows in the drawing

F i g. I the concept with only one resonator Äi, F i g. 2 the coupling of three filter resonators /? I, /? ₂ and /? 3.

FIG. 3 gives the Si re-parameter equations for the arrangements according to FIG. 2, namely the expiring signal wave quantities v \ to v _} are shown. Depending on the incoming signal wave quantities u \ to U) and the respective associated coupling factors K _y or K ' _M and the associated capacitances of the CTD lines; F i g. 4 a possible equivalent circuit diagram of a line branching from non-unidirectional lines, e.g. B. coaxial lines, with W \ or W _{2 of} the wave resistance of the lines, z. B. W = 60 In D / d, is designated,

5 shows the scatter parameter equations of an arrangement according to the equivalent circuit diagram of FIG. 4,

F i g. 6 basic formulas for setting up a branching / branching circuit,

F i g. 7 a two-port circuit,

ί> 5 Fig. 8 to 11 Dimensioning formulas for the circuit Fig. 7th

In general, the following should first be noted. In the following, with the reference number /? ,, / ?; or Zf ₃ in itself

closed line loops from CTD-Rcsonatoren, as they are from the German patents 24 53 669 and 25 55 835 are known per se. This is indicated in each case by dashed lines these resonators are now essential for the operation of the present coupling circuits Elements drawn in, d. H. so capacity areas. which essentially cooperate with the associated coupling circuits.

Viewed in this way, FIG. 1 still recognizable an electrode area with the charge transfer capacity C ₁ another electrode area with the charge transfer capacity C * = C, to which two galvanic lines L Ί and L3 are brought. Finally, a total capacitance Σ Ci can be seen, which belongs to both the resonator and the branch line. From this total capacitance Σ Ci, charge is decoupled into a sink Si via a capacitance area Gn. In the course of the resonator Rt , a capacitance area Σ G - Coi. follows Such uniform charge removal stages are known per se from DE-OS 28 36 473 ~, so that they need not be discussed in detail here. Finally, in the resonator R, the actual resonator charge reversal capacity C follows again, and there are so many such resonator charge reversal capacities, ζ. Β. η = 4 ■ Clock frequency: band center frequency contained in the resonator R \ , as required for the dimensioning of a filter.

In FIG. 1 a charge source Qu can also be seen, which is followed by an electrode surface (not specifically designated), but a further galvanic line L \ opens into this electrode surface. In the course of this CTD line, there then follows a transfer capacity with the size d, which is coupled to the transfer capacity Σ Ci via the coupling factor K _t. Essentially analogous to this, a charge source Q '\ can be seen , from which charge is brought to a capacitance surface C'i via a capacitance electrode. Only this capacitance area C '\ is in galvanic connection with a line L \, for which the coupling factor K \ to the total capacitance Ci has a negative sign.

The associated dimensioning formulas are shown in FIG. 1 also indicated. Also, u \ denotes the incoming signal charge quantities and V ₁ denotes the outgoing signal charge quantities.

With regard to FIG. 2, 4 and 7 the following should be noted. Associated stages are also shown and identified as belonging together. Depending on the requirements the index of corresponding parts is designated by 2 or 3, so that the above Comments on F i g. 1 can be applied directly and analogously.

In particular, let us refer to FIG. 2 also referred to the routing of the galvanic lines. Thus, the line L \ electrically connects the capacitance C of the resonator 1 with the Umladekapazität C'2 of the resonator Ri, and the line L ₃ results in the Umladekapazität C) of the resonator Ry of the capacitance C = C * of the resonator R ₃ on the one hand performs a galvanic line L \ to the charge transfer capacity C \ of the resonator R \ and a galvanic line L ₂ to the charge transfer capacity C _{2 of} the resonator R-2. Finally, the charge transfer capacity C = C * of the resonator /? _{2 is} connected via the galvanic line L \ to the charge transfer capacity Ci of the resonator 1 and via din galvanic line L \ to the charge transfer capacity Cj of the resonator R _s .

In Fig. 7, the capacitance C is * connected to the resonator 1 via the line L ₂ with the Umladckapa / ität Ci upstream Umladekapazität further follows to the source Qi is electrically connected via the line L \ the Umladekapazität C * = C of the resonator Ri with transhipment capacity G.

In general, the physical mode of operation and the dimensioning of the coupling circuits described one more thing to say.

According to Fig. 1, 2, 7 is at least one charge transfer capacity C * of a resonator, z. B. R \, with one or more other reloading capacities, e.g. B. C'2 and C3 (Fig. 2), galvanic, e.g. B. each with the help of an aluminum line L'2, L ₃ connected to each of a "filling and filling circuit" z. B. with the sources Q'i and Ri of a further or more further resonators (Ri, Ri) belong. The method used here for generating positive or negative signal charges is described in the earlier patent application P 2 99 36 7315.
To the Fig. 1.2,7 also includes that of a capacity following the transfer capacity C *, z. B. from Σ G. a charge amount resulting from the transfer capacity Cm in a sink Si wire and further that the total capacity, ζ. Β. Σ G, following a uniform charge removal stage, e.g. B. Ai, is inserted, v / ln it is described in DE-OS 28 36 473 Da - as can be seen from the formulas in F i g. 6,9,11 results - the capacitance Σ Ci - Cop is greater than the resonator charge reversal capacity Cist (μ = 1,2,3), there would be an excess of uniform charge without a withdrawal stage, which would result in a shift in the operating point in the resonator.

In the same way as the coupling of the resonator R \ in the direction of the resonators Ri and A3 was described, the coupling of the resonator Ri in the direction of the resonators R \ and A3 as well as of Rj in the direction of R _x and Ri is to be carried out (Fig . 2). This shows how a two-port, F i g. 7, can win, as well as a "multiple goal" according to FIG. 2. The crossovers of the galvanic connecting lines that occur with a multi-port can be implemented.

F i g. ■ * gives the scattering parameter equations of the arrangement in Fig.2 and Fig.5 the scattering parameter equations of the equivalent circuit diagram F i g. 4 of a line branching desired as an example. With the relationships The remeasurement rules result from Fig. 1 with Fi & .6 for all transshipment capacities from the coefficient comparison of the equations in FIG. 3 and F i g. 5.

For the two-port in FIG. 7, the design rules in FIG. 9 result from the coefficient comparison of the equations in FIG. 8 - the pair of equations on the right is identical to F i g. 14 in DE-AS 28 08 604 - as well as further possible dimensioning rules in FIG. 11 from the coefficient comparison of the equations on the left in FIG. 8 with the equations in F i £. 10, which can be found with V ₃ = 0 from FIG. Let 5 win.

The demands made can be met with the proposed coupling links. So z. B. by Connection of a CTTC bipolar to connection 2 in

ω F i g. 2 - as described in DE-AS 27 04 318 - a Section of a filter circuit can be generated which is symmetrical to an attenuation zero point at a selectable distance each has a damping pole The CTD two-pole can consist of two resonators, which

b5 with a two-port according to FIG. 7 are coupled. / I are bridged circuits for pole generation with the three goal (Fig. 2) realizable, as it is described in DE-AS 28 08 604 and DE-AS 27 04 318.

31 IU U / b

As already mentioned in the introduction, the above coupling circuits described have the advantage that they have the properties of dual converters or gyrators and thus for the implementation of filtering circuits that follow the basic concept of reactance branch circuits can be used, with circuits with attenuation zeros and attenuation poles can be generated. In addition, they may also be available with just one Clock frequency can be operated.

For this purpose 3 sheets of drawings

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Claims (2)

Patent claims: 1. Electrical filter circuit, consisting of CTD Charge Transfer Device = charge transfer device elements unidirectional transfer behavior, with which one or more self-contained conductor loops are simulated, which determine the frequency-dependent transfer behavior of the filter circuit, in which the individual conductor loop simulations are coupled to one another via coupling circuits characterized in that at least one transfer capacity (C) of a resonator (z. B. R \) is connected to at least one further transfer capacity (z. B. C'i and Cj) via galvanic lines (L'i, LJ, that this transfer capacity (Ci and Cj belongs to in each case one filling and filling circuit ( "fill and spill") at least one other resonator (z. B. Ri and FJ that a charge-reversal SummenkapazitsU (Σ CtX on the Umladekapazität (C * ) of the resonator (R \) with the galvanic lines (L'i, LJ follows, one corresponds to the relative bandwidth of the resonator (Ri) nde charge amount is discharged via a transfer capacity (G> \) into a sink (S,) that the total capacity (Σ Ci) at least one filling and filling circuit with a charge source (z. B. Qi) charge is supplied, the amount of which is determined by the product of a transfer capacity (e.g. Ci) that follows one source (Q \) and the voltage state of a transfer capacity (e.g. C) of another Resonator ( e.g. Rt), and that di / total capacitance (e.g. Σ Ci) following a equal charge removal stage (Ai) is inserted. 2. Electrical filter circuit according to claim 1, characterized in that the galvanic lines (z. B. Lj, Lj) as aluminum conductor tracks and / or are formed as conductor tracks made of conductively doped silicon.