GB2172762A - Improvements in electrical transfer filters - Google Patents
Improvements in electrical transfer filters Download PDFInfo
- Publication number
- GB2172762A GB2172762A GB08507367A GB8507367A GB2172762A GB 2172762 A GB2172762 A GB 2172762A GB 08507367 A GB08507367 A GB 08507367A GB 8507367 A GB8507367 A GB 8507367A GB 2172762 A GB2172762 A GB 2172762A
- Authority
- GB
- United Kingdom
- Prior art keywords
- filter
- operational amplifier
- output
- fed
- amplifier
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- 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
- H03H11/12—Frequency selective two-port networks using amplifiers with feedback
- H03H11/1217—Frequency selective two-port networks using amplifiers with feedback using a plurality of operational amplifiers
- H03H11/1252—Two integrator-loop-filters
Abstract
A bi-Quad double integrator loop filter has the following transfer function: <IMAGE> where S= 2ROOT -1 w, and wherein 2<A<3 7<B<9 1<C<2 2.5<D<4. Preferred values are A=2.37, B=7.99, C=1.67, and D=3.26. A preferred transfer filter is especially suited to use in a noise attenuating device. <IMAGE>
Description
SPECIFICATION
Improvements in electrical transfer filters
Field of the invention
This invention relates two an electrical transfer filter, i.e. an active filter having a Laplace transfer function selected to provide for transmission of an electrical signal therethrough in accordance with inter-related magnitude and phase shift characteristics.
Background to the invention
Concurrent U.K. Patent Application No. describes an active acoustic attenuation device in which a -microphone and a loudspeaker are coupled via an amplifier means which, in a preferred arrangement, incorporates a transfer filter adapted to facilitate production of a cancallation signal which maximises noise attenuation at the loudspeaker.
Object of the invention
It is an object of this invention to provide a transfer filter having characteristics which make it particularly suitable for use in the noise attenuating device above referred to. However, the transfer filter of this invention is not limited to use in the said noise attenuating device.
The invention
According to the invention, there is provided an electrical transfer filter characterised by the
Laplace transfer function:
A.10 9SZ+B.10 5S+1
C.10 9S2+D.10 105+1 where S V71 w, and wherein 2 < Ac3 7 < B < 9 ltC < 2 2.5 < D < 4
In one particular example of the filter:
A=2.37 B=7.99 C=1.67 D=3.26.
The particular transfer filter is especially suited to use in the noise attenuating device hitherto referred to.
A preferred construction of filter comprises a first operational amplifier with resistive feedback fed with the input signal and the output of which is fed to a second operational amplifier with capacitive feedback, the output of which is in turn fed to a third operational amplifier with capacitive feedback, the output of the second operational amplifier also being fed to a fourth operational amplifier with resistive feedback, and the output of the fourth operational amplifier being fed back to the first operational amplifier and fed on to a fifth operative amplifier with resistive feedback, which last-mentioned amplifier provides the output and is also fed at its input with the outputs of the first and third operational amplifiers, the output of the third operational amplifier also being fed back to the first operational amplifier.
Description of drawings
A practical example of transfer filter in accordance with the invention will now be described by way of example with reference to the accompanyaing drawings, in which:
Figure 1 is a circuit diagram of-the filter; and
Figures 2A and 2B are graphs respectively showing the magnitude and phase shift characteristics of the filter.
Description of embodiment
The circuit shown in Fig. 1 is apparent from the drawing, and comprises operational amplifiers IC1 to IC5 connected in circuit with a plurality of feedback paths utilising resistors R1 to R12 and capacitors C1, C2. Resistors R2, R8 and R11, the capacitors C1 and C2, respectively provide feedback from output to-input at the respective amplifiers IC1, IC4, CS, IC2 and IC3.
The 9V power supply (positive and negative) at each amplifier is also indicated. The input (x) to the circuit is also shown, together with the output (y).
The component values are as follows:
K ohm R1 27.4
R2 56.2
R3 27.4
R4 15.0 R5 15.0
R6 47.5
R7 33.2
R8 10.0
R9 10.0
R10 51.1 R11 33.2
R12 24.0
nF C1 3.9 C2 3.9
The operational amplifiers are typically Texas Instruments type TL071 or equivalent.
The filter shown in Fig. 1, given the absolute component values specified above, has the transfer function:
2.37.10 9 S2+7.99.1015 S+1 Y= x 1.67.10 9S2+3.26.10 5S+1 wherein S=jw and j'= V71.
Figs. 2A and 2B show the filter transfer function characteristics for magnitude and phase shift, respectively.
The detailed circuit shown in Fig. 1 may be modified, especially in respect of the component values, within limits which maintain the same general transfer function, in accordance with the ranges hereinbefore set forth.
Claims (5)
1. An electrical transfer filter characterised by the Laplace transfer function
A.10 9S2+B.10 5S+1
C.10 9 S2+D.10 5 S+1 where S=fft w, and wherein 2 < A < 3 7 < B < 9
1 < C < 2 2.5 < D < 4.
2. A filter as claimed in claim 1, wherein A=2.37, B=7.99, C=1.67, and D=3.26.
3. A filter as claimed in claim 7 or 2, comprising a first operational amplifier with resistive feedback (to which the input signal can be fed) the output of which is fed to a second operational amplifier with capacitive feedback, and to a fourth operational amplifier with resistive feedback, and a percentage of the output of the fourth operational amplifier is fed back to an input of the first operatipnal amplifier, the fourth output signal also serving as an input signal to a fifth operational amplifier having resistive feedback, the last-mentioned amplifier providing the output signal from the filter, and wherein a percentage of each of the output signals for the first and third operational amplifiers is fed to the input of the fifth operational amplier and a percentage of the third operational amplifier output signal fed back to an signal of the first operational amplifier.
4. A filter as claimed in claim 1 or 2 in combination with a noise attenuating device.
5. An electrical transfer filter constructed arranged and adapted to operate substantially as herein described with reference to and as illustrated in the accompanying drawings.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08507367A GB2172762A (en) | 1985-03-21 | 1985-03-21 | Improvements in electrical transfer filters |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08507367A GB2172762A (en) | 1985-03-21 | 1985-03-21 | Improvements in electrical transfer filters |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB8507367D0 GB8507367D0 (en) | 1985-05-01 |
| GB2172762A true GB2172762A (en) | 1986-09-24 |
Family
ID=10576389
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08507367A Withdrawn GB2172762A (en) | 1985-03-21 | 1985-03-21 | Improvements in electrical transfer filters |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2172762A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NL9002309A (en) * | 1989-10-23 | 1991-05-16 | Gold Star Electronics | FEED CHAIN OF THE FEEDBACK TYPE. |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1246634A (en) * | 1968-09-18 | 1971-09-15 | Rft Messelektronik Dresden Veb | Active rc filter with transfer zeros |
| GB1297058A (en) * | 1969-03-11 | 1972-11-22 | ||
| GB1345200A (en) * | 1970-12-04 | 1974-01-30 | Wandel & Goltermann | Circuit for equalising a transmission system |
| GB2016233A (en) * | 1977-10-26 | 1979-09-19 | Feistal K H | Network having a variable transfer function |
| GB2049331A (en) * | 1979-05-08 | 1980-12-17 | Rockland Systems Corp | Filter using a state-variable biquadratic transfer function circuit |
-
1985
- 1985-03-21 GB GB08507367A patent/GB2172762A/en not_active Withdrawn
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1246634A (en) * | 1968-09-18 | 1971-09-15 | Rft Messelektronik Dresden Veb | Active rc filter with transfer zeros |
| GB1297058A (en) * | 1969-03-11 | 1972-11-22 | ||
| GB1345200A (en) * | 1970-12-04 | 1974-01-30 | Wandel & Goltermann | Circuit for equalising a transmission system |
| GB2016233A (en) * | 1977-10-26 | 1979-09-19 | Feistal K H | Network having a variable transfer function |
| GB2049331A (en) * | 1979-05-08 | 1980-12-17 | Rockland Systems Corp | Filter using a state-variable biquadratic transfer function circuit |
Non-Patent Citations (2)
| Title |
|---|
| ELECTRONICS 9 DEC. 1968 PP98-106 * |
| GHAUSI & LAKER MODERN FILTER DESIGN PRENTICE HALL PP233-242 * |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NL9002309A (en) * | 1989-10-23 | 1991-05-16 | Gold Star Electronics | FEED CHAIN OF THE FEEDBACK TYPE. |
Also Published As
| Publication number | Publication date |
|---|---|
| GB8507367D0 (en) | 1985-05-01 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |