CN1369135A - Analog filter - Google Patents
Analog filter Download PDFInfo
- Publication number
- CN1369135A CN1369135A CN00811283A CN00811283A CN1369135A CN 1369135 A CN1369135 A CN 1369135A CN 00811283 A CN00811283 A CN 00811283A CN 00811283 A CN00811283 A CN 00811283A CN 1369135 A CN1369135 A CN 1369135A
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- filter
- analog filter
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- inductance
- node
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H7/00—Multiple-port networks comprising only passive electrical elements as network components
- H03H7/01—Frequency selective two-port networks
- H03H7/17—Structural details of sub-circuits of frequency selective networks
- H03H7/1741—Comprising typical LC combinations, irrespective of presence and location of additional resistors
- H03H7/1758—Series LC in shunt or branch path
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H11/00—Networks using active elements
- H03H11/02—Multiple-port networks
- H03H11/04—Frequency selective two-port networks
- H03H11/08—Frequency selective two-port networks using gyrators
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H11/00—Networks using active elements
- H03H11/46—One-port networks
- H03H11/48—One-port networks simulating reactances
- H03H11/50—One-port networks simulating reactances using gyrators
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H7/00—Multiple-port networks comprising only passive electrical elements as network components
- H03H7/01—Frequency selective two-port networks
- H03H7/0115—Frequency selective two-port networks comprising only inductors and capacitors
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H7/00—Multiple-port networks comprising only passive electrical elements as network components
- H03H7/01—Frequency selective two-port networks
- H03H7/075—Ladder networks, e.g. electric wave filters
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H7/00—Multiple-port networks comprising only passive electrical elements as network components
- H03H7/01—Frequency selective two-port networks
- H03H7/17—Structural details of sub-circuits of frequency selective networks
- H03H7/1716—Comprising foot-point elements
- H03H7/1725—Element to ground being common to different shunt paths, i.e. Y-structure
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Networks Using Active Elements (AREA)
- Filters And Equalizers (AREA)
Abstract
The invention relates to an analog filter (IF) including at least one filter stage (FSTi) having an input terminal (INi), an output terminal (OUTi) and an impedance network (INET') connected between said input and output terminals (INi, OUTi) and ground (GND), said impedance network (INET') having arranged three impedance elements (La, Lb, Lc, G2, G3, G4) in a Delta-configuration, such that a first node (N1i) of the Delta-configuration is connected to the input terminal (INi), a second node (N2i) of the Delta-configuration is connected to the output terminal (OUTi) and the third node (N3i) is connected to ground (GND). Optionally, a capacitive network (CNET) is inserted between said third node (N3i) and ground (GND). Using the star-delta transformation parasitic nodes, in particular purely resistive nodes in the filter transfer function when gyrators are used to replace inductances, are avoided since each inductance connection node (N1i, N2i, N3i) is respectively connected to a capacitive element (C1, CNET, C5).
Description
Invention field
The present invention relates to a kind of analog filter, present invention is specifically related to need high accuracy and accurate make at sheet (on-chip) IF filter.The analog filter that the present invention considered can be the passive filter that only uses passive components such as coil and electric capacity.Yet analog filter of the present invention also can be an active analog filter (gyrator-C or gm-C filter) of replacing inductance with gyrator.
Background of invention
Fig. 1 represents a kind of typical structure of conventional filter circuit.Filter circuit comprises at least one filter stage FSTi, and can a plurality of filter stage FST1 of cascade ... FSTi...FSTI.Typical filter is fed by a source S, and ends in termination impedance T.Basically, add a utmost point if each filter stage FSTi is a filter transfer function, the exponent number of filter transfer function is exactly I.As everyone knows, the filter transfer function of analog filter is to count the multinomial of I and represent by have a plurality of zero points and multiplicity of poles in composite plane.Yet, when the filter transfer function of Design Theory is applied to the multiple filter of employing such as electric capacity and inductance true parts such as (coils), the ghost effect meeting distorts filter transfer function, and can cause undesirable analog filter performance.
This ghost effect is the result who produces internal node, and these nodes do not belong to the filter transfer function (filter topologies) of Design Theory.In addition, when forming the pure resistance node, network transformation can produce extra internal node.That is to say to have the characteristic of hope in order to make filter, mathematic(al) manipulation can change zeros of transfer functions/limit structure, and can produce different characteristics thus.Yet particularly under the situation of pure resistance node, any parasitic capacitance all can increase undesirable limit and/or zero point in filter transfer function.
Therefore, the parts of use must have value very accurately, or can adopt the automatic tuning circuit of resonator (filter) parts to reduce parasitic influence, and particularly those wish the noncompensable influence of parts with existing.This automatic tuning for example is to realize with gyrator-C or gm-C filter.
Therefore, wish all the time to design a kind of like this filter, the change of its component values and/or ghost effect can not produce the extra node that did not have originally in real transfer function, in order to avoid cause unstable or different performance of filters.
The explanation of prior art
The design of analog filter is very advanced in practice, has various technological means can realize the hope filter transfer function of being scheduled to.Typical design is from comprising the basic lowpass prototype filter circuit of at least one filter stage FST1.Fig. 2 a represents an example of this filter stage.Capacitor C 1 is connected between the ground GND and input IN1 of filter stage FST1, and capacitor C 5 is connected between the ground GND and output OUT1 of filter stage FST1.Also be provided with a termination resistance R5 in addition, and the source S of a current source I and resistance R 1 formation offered the input of filter stage FST1.
In filter stage FST1, exist one to form a capacitance network by capacitor C 3, and its be connected GND, and impedance network, for example be inductance L 2 with Y-connection, L3, the inductance network that L4 constitutes, it is connected capacitor C 3 and input and output side IN1, between the OUT1.Although inductance network L1, L2, L3 exists all the time, and the filter circuit of having removed capacitance network is also arranged, and that is to say, and capacitor C 3 only is a line over the ground.
Shown in Fig. 3 a, can provide a plurality of filter stage FST1 that have basic structure shown in Fig. 2 a separately, FST2, FST3.Filter stage FST1, FST2, FST3 are cascades, inductance L 41 separately, L22; L42, L23 is connected in series.Certainly the circuit of Fig. 3 a also can reduce into the filter of Fig. 3 b, with coil L41, L22; L42, L23 are merged into a single inductance L ', L " forms the filter circuit of Fig. 3 b.Adopt this cascaded filter level just can realize the filter circuit of predetermined order.
From the primary filter design of a filter stage shown in Fig. 2 a, the someone advises with a kind of means its tectonic transition one-tenth not being had the resonator group of the ground connection of solitary parasitism (can increase new not wishing limit or zero point) recently.Filter stage FST1 to Fig. 2 a takes the logical prototype conversion of the typical conventional belt of typical band logical conversion can formation shown in Fig. 2 b.Basically, Fig. 2 c represents to be used for realizing a kind of typical gyrator of Fig. 2 b, and coil has wherein been replaced by the gyrator shown in Fig. 4 a (vide infra).Fig. 2 c is the logical variation of band that is used for realizing the gyrator of Fig. 2 a among Fig. 4 b basically.
The inventor has studied and this reconfiguration has been become the logical conversion of band of ground connection gyrator group, finds that the filter transfer function of structure of this institute conversion is more stable, because it does not have above-mentioned solitary parasitism.
Yet, the inventor also finds, if the structure to Fig. 2 a adopts the logical conversion of the band that comprises the gyrator shown in Fig. 2 c, connect inductance L 2, the node P of L3 and L4 will form the pure resistance node, that still can cause filter does not wish form, because the filter transfer function of Shi Xianing has departed from the filter transfer function of Design Theory in practice.
If to Fig. 4 a, the filter circuit inductance L 2 that the active filter circuit of the employing gyrator structures shown in the 4b is realized, L3, L4 adopt the logical conversion of band, just can obtain the pure resistance node.After Fig. 4 b being with logical conversion, in the gyrator circuit of the logical conversion of band of Fig. 2 c undesirable pure resistance node can appear.
Yet even avoid gyrator and do not utilize gyrator to realize coil really, after the logical conversion of band, the inventor has still found undesirable solitary parasitism in the filter circuit of Fig. 2 b, for example is over the ground or to the parasitic capacitance of gas circuit parts.As the result of the logical conversion of band, this solitary parasitism is equivalent to problematic extra pure resistance node under the situation of the logical coil of gyrator band.How the authenticity of this point and star impedance network realize just having only coil or have only electric capacity or coil and electric capacity, have nothing to do.Whether no matter whether the capacitor C 3 among Fig. 2 a (or Fig. 2 b, 2c, 3a, 3b, corresponding elements among the 4b) exists, or adopt and connect over the ground directly that also all it doesn't matter.
A kind of active filter circuit can be known from for example summary of Japan Patent JP08196642.Wherein,, can obtain a stabilized frequency characteristic, and can in first grade structure, regulate a Q value with a transconcluctance amplifier for the change of parasitic capacitance.Stabilized frequency characteristic herein is to utilize extra tuning circuit to obtain.
In addition, US5,192,884 have described a kind of active filter with differential type voltage control source.The conversion meeting that above-mentioned document does not disclose any kind causes extra pure resistance node.
Summary of the invention
As mentioned above, for fear of ghost effect, when adopting the network theory technology of leading to routines such as conversion such as band to come the design simulation filter, the inventor has found that can cause solitary parasitism (in the filter of the logical conversion of the revolution of the nothing shown in Fig. 2 b type band) or extra resistance nodes (in the filter of the logical conversion of the revolution type band shown in Fig. 2 c) in filter transfer function.
For this reason, the purpose of this invention is to provide a kind of analog filter, wherein in filter transfer function, can not cause solitary parasitism or extra pure resistance node with one or more above-mentioned filter stage.
Solution
This purpose is to realize with the analog filter with at least one filter stage, described filter stage has an input, an output and be connected a impedance network between above-mentioned input and output side and the ground, above-mentioned impedance network has three impedance components arranging according to triangular construction, make the first node of triangular construction be connected to input, the Section Point of triangular construction is connected to output, and the 3rd node is connected to ground.
Preferably, between above-mentioned the 3rd node and ground, insert another network.
Preferably, above-mentioned impedance network comprises the mixture of three inductance taking triangular construction or three electric capacity or inductance/capacitance.
Preferably, above-mentioned another network comprises an electric capacity or an inductance, or electric capacity-inductance network in parallel or series connection.
Three impedor triangular construction do not have extra pure resistance node according to analog filter of the present invention, because can guarantee that all inductor terminals all are connected on the electric capacity.So just can in filter transfer function, not cause undesirable pole.
The inductance of impedance network can be realized with coil or paired gyrator.
Below to be explained with reference to the drawings embodiments of the invention.Yet it should further be appreciated that the present invention is not limited only to described embodiment, can also realize various modifications and changes.Particularly, present invention includes the embodiment that requires respectively in the claims and/or the independent various characteristics combination of describing form in specification.
Brief description
Fig. 1 represents to have the essential structure of a kind of analog filter IF of a plurality of filter stage FSTi;
Fig. 2 a represents to have a kind of typical conventional lowpass prototype filter of single filter stage FST1;
A kind of typical conventional belt of Fig. 2 b presentation graphs 2a leads to the prototype conversion;
Fig. 2 c represents to realize with gyrator a kind of typical case of the circuit of Fig. 2 b;
Fig. 3 a, 3b represent a kind of structure of multiple filter, and wherein each filter stage has the basic structure shown in Fig. 2 a;
Fig. 4 a, 4b are illustrated in and adopt gyrator to replace the structure of a kind of conventional simulation filter of coil among Fig. 2 a;
Fig. 5 represents the essential structure according to filter circuit of the present invention;
Fig. 6 represents an embodiment according to the analog filter of Fig. 5;
Fig. 7 a, 7b represent to be used for the circuit that comprises a kind of triangular construction of multiple filter; And
Fig. 8 a, 8b represent a kind of active filter, have wherein replaced the inductance among Fig. 6 with gyrator.
Detailed description of the invention
Fig. 5 represents the theory diagram according to analog filter of the present invention, has wherein only used a filter stage FSTi.Yet if apply the present invention to each filter stage in the multiple filter circuit, following explanation stands good.
Analog filter has an input INi, an output OUTi and be connected to ground GND and the input INi and output OUTi an impedance network INET.As mentioned above, between impedance network INET and ground GND, insert another network C NET (dotting) alternatively, just directly do not have under the situation of direct line over the ground at INET and GND.Another network C NET can be a capacitance network, and impedance network can be the pure inductance network.Yet whether with INET is made of irrelevantly inductance and/or electric capacity, and important problem is that impedance will be taked a kind of star interconnection.
In addition, first capacitor C 1 can be connected between input INi and the ground GND, and second capacitor C 5 can be connected between output OUTi and the ground GND.Resistance R 1 and R5 are as source and termination impedance.All parts C1, C5, R1, R2 are optional according to principle of the present invention.
As an example, suppose that lowpass prototype filter shown in Figure 5 has the impedance network INET that is made of inductance network, the inductance L 2 that comprises Y-connection, L3, L4, and also having by capacitance network is another network C NET that capacitor C 3 constitutes, and adopts band to lead to conversion-form with a kind of star-delta-conversion structure of impedance shown in Figure 6 (inductance) network INET ' according to the present invention-replacements.Can be applied to any star impedance network INET according to star-delta transformation of the present invention, impedance L1 just, L2, L3 itself can be made up of the in parallel and/or impedance network that constitutes that is connected in series of inductance and/or electric capacity.
Should be able to find out that also the electric capacity that dots among Fig. 6 only is a kind of selection, if replace this electric capacity with direct connection over the ground, it is suitable that the present invention remains.
In addition, constitute the INET network generally speaking in general impedance (promptly only being inductance and/or electric capacity) by Y-connection, triangle-structure La, Lb, the impedance of Lc also is general impedance, just inductance and/or electric capacity certainly.That is to say, all impedance L1 of primitive network INET, L2, L3 can be impedance networks itself, therefore, the impedance La of the impedance network INET ' of conversion, Lb, the general impedance network of Lc.
Generally adopting star-delta transformation in power engineering, for example is the triangular construction that the Y-connection of stator coil is transformed into stator coil in motor, and this is that those skilled in the art is known.As shown in Figure 6, star-delta transformation causes a kind of structure, wherein three inductance or impedance component La generally speaking, Lb, Lc is arranged to triangular construction, make the first node N1i of triangular construction be connected to input INi, the Section Point N2i of triangular construction is connected to output OUTi, and the 3rd node N3i is connected to capacitance network CNET, this capacitance network CNET still can be made of a capacitor C 3 shown in Fig. 2 a, or is directly connected to ground (if saving capacitor C 3).
As mentioned above, first node N1i is connected to capacitor C 1, and Section Point N2i is connected to capacitor C 5, and the 3rd node N3i is connected to capacitor C 3 or capacitance network CNET or is directly connected to ground, and this depends on the type of filter circuit.
Since star-delta transformation, impedance (for example being inductance) La, Lb, Lc can obtain following value:
As mentioned above, if impedance L1, L2, L3 are inductance, and the impedance of conversion is inductance just certainly.If they are electric capacity, La, Lb, Lc are exactly electric capacity, and if they are mixtures of coil and/or electric capacity, impedance La, Lb, Lc also can be the mixtures of coil and/or electric capacity.
Therefore, the present invention is not specifically limited at any specific impedance network INET, INET ' (as long as INET is a star configuration, and INET ' is a triangular construction), and another network is optional.No matter under any circumstance, star-delta transformation of the present invention can both be eliminated (the gyrator structure) parasitic node and (is not under the situation about being realized by gyrator at inductance) solitary parasitism, so just can eliminate the instability problem of filter transfer function.
Only there is filter coefficient to disperse (coefficient spread) and size to increase along with this conversion, because impedance La, Lb, the value of Lc can increase significantly owing to this conversion as shown in formula (1).
Star-delta transformation can also be applied to the multilevel simulation filter shown in Fig. 7 a or the 7b.Comparison diagram 7 and Fig. 3, Fig. 3 a, all Y-connections among the 3b have all been replaced by the triangular construction of coil.So just make multiple filter also can possess advantage of the present invention.
To replace such as the such active parts of gyrator for example be each inductance element in the filter circuit of Fig. 6 if use, and as Fig. 8 a, the active filter shown in the 8b also can be benefited from star-delta transformation of the present invention.Therefore, also can be configured to gyrator-C or gm-C active filter, wherein, eliminate the solitary parasitism node by star-delta transformation to prototype filter.
Industrial applicibility
The present invention can be applied to have the mould of any type of the Y-connection of coil and/or electric capacity Intend wave filter, and be not limited only to realize impedance network and replace electric capacity with gyrator with inductance Active filter. No matter the filter circuit with star impedance network INET of any type has There is not another CNET from star-delta transformation of the present invention, to benefit.
In addition, the present invention can also have and different embodiment mode described herein, the technology of this area Personnel obviously can also make the present invention various according to above explanation and claims Modifications and changes. Particularly, the present invention can be included in the specification claim and distinguish The various features of describing.
Label in claims is only used for clearly purpose rather than will limits right and want The scope of asking.
Claims (10)
1. an analog filter (IF), comprise at least one filter stage (FSTi), described filter stage has an input (INi), an output (OUTi) and be connected described input and output side (INi, an impedance network OUTi) and (GND) (INET ')
It is characterized in that
Described impedance network (INET ') be furnished with three impedance component (La according to triangular construction, Lb, Lc, G2, G3 G4), makes the first node (N1i) of triangular construction be connected to input (INi), the Section Point of triangular construction (N2i) is connected to output (OUTi), and the 3rd node (N3i) is connected to ground (GND).
2. according to the analog filter (IF) of claim 1, it is characterized in that between described the 3rd node (N3i) and ground (GND), inserting another network (CNET).
3. according to the analog filter (IF) of claim 1, it is characterized in that described impedance network (INET ') comprise three inductance taking triangular construction (La, Lb, Lc) or the mixture of three electric capacity or inductance/capacitance.
4. according to the analog filter (IF) of claim 3 or 2, it is characterized in that described another network (CNET) comprises an electric capacity or an inductance, or electric capacity-inductance network in parallel or series connection.
5. according to the analog filter (IF) of claim 1, it is characterized in that a filter stage (FSTi) and be connected described input (IN1) and ground between (GND) input capacitance (C1) and be connected described output (OUT1) with the output capacitance (C5) between (GND).
6. according to the analog filter (IF) of claim 3, it is characterized in that described inductance element be coil (L2, L4, L3).
7. according to the analog filter (IF) of claim 3 or 6, it is characterized in that described inductance element is that (G1, G2 G3) constitute by paired gyrator respectively.
8. according to the analog filter (IF) of claim 4, it is characterized in that described capacitance network (CNET) comprises at least one electric capacity (C3).
9. according to the analog filter (IF) of claim 1, it is characterized in that described analog filter is a kind of gyrator-C or gm-C filter.
10. according to the analog filter (IF) of claim 1, it is characterized in that described analog filter is that band is logical, low pass, high pass, band resistance and all-pass filter, or the combination of described filter.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19936430.3 | 1999-08-03 | ||
| DE19936430A DE19936430A1 (en) | 1999-08-03 | 1999-08-03 | Analog filter |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN1369135A true CN1369135A (en) | 2002-09-11 |
Family
ID=7916970
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN00811283A Pending CN1369135A (en) | 1999-08-03 | 2000-07-10 | Analog filter |
Country Status (6)
| Country | Link |
|---|---|
| EP (1) | EP1201030A1 (en) |
| JP (1) | JP2003506946A (en) |
| CN (1) | CN1369135A (en) |
| AU (1) | AU6157500A (en) |
| DE (1) | DE19936430A1 (en) |
| WO (1) | WO2001010021A1 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102829853A (en) * | 2012-08-22 | 2012-12-19 | 中联重科股份有限公司 | Transmitter, multistage filter and weighing system |
| CN106936136A (en) * | 2017-04-24 | 2017-07-07 | 李清远 | A kind of all-pass wave filtering harmonic elimination structure and control method for medium voltage network system |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102010029152A1 (en) | 2010-05-20 | 2011-11-24 | Continental Teves Ag & Co. Ohg | Active insulation filter |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH04233312A (en) * | 1990-12-28 | 1992-08-21 | Sharp Corp | Microwave active filter circuit |
| US5917387A (en) * | 1996-09-27 | 1999-06-29 | Lucent Technologies Inc. | Filter having tunable center frequency and/or tunable bandwidth |
| AU2111699A (en) * | 1998-01-21 | 1999-08-09 | Kmy Instruments Llc | Passive programmable wide-range filter |
-
1999
- 1999-08-03 DE DE19936430A patent/DE19936430A1/en not_active Ceased
-
2000
- 2000-07-10 JP JP2001514538A patent/JP2003506946A/en not_active Withdrawn
- 2000-07-10 EP EP00947963A patent/EP1201030A1/en not_active Withdrawn
- 2000-07-10 CN CN00811283A patent/CN1369135A/en active Pending
- 2000-07-10 WO PCT/EP2000/006537 patent/WO2001010021A1/en not_active Application Discontinuation
- 2000-07-10 AU AU61575/00A patent/AU6157500A/en not_active Abandoned
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102829853A (en) * | 2012-08-22 | 2012-12-19 | 中联重科股份有限公司 | Transmitter, multistage filter and weighing system |
| CN106936136A (en) * | 2017-04-24 | 2017-07-07 | 李清远 | A kind of all-pass wave filtering harmonic elimination structure and control method for medium voltage network system |
| CN106936136B (en) * | 2017-04-24 | 2018-03-27 | 韶关市佰瑞节能科技有限公司 | A kind of all-pass wave filtering harmonic elimination structure and control method for medium voltage network system |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2003506946A (en) | 2003-02-18 |
| WO2001010021A1 (en) | 2001-02-08 |
| AU6157500A (en) | 2001-02-19 |
| EP1201030A1 (en) | 2002-05-02 |
| DE19936430A1 (en) | 2001-04-12 |
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