GB837275A - Improvements in or relating to electric wave filters - Google Patents
Improvements in or relating to electric wave filtersInfo
- Publication number
- GB837275A GB837275A GB1428556A GB1428556A GB837275A GB 837275 A GB837275 A GB 837275A GB 1428556 A GB1428556 A GB 1428556A GB 1428556 A GB1428556 A GB 1428556A GB 837275 A GB837275 A GB 837275A
- Authority
- GB
- United Kingdom
- Prior art keywords
- filter
- circuits
- crystal
- band
- tuned
- 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.)
- Expired
Links
- 239000013078 crystal Substances 0.000 abstract 8
- 239000003990 capacitor Substances 0.000 abstract 2
- 230000009466 transformation Effects 0.000 abstract 1
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/46—Filters
- H03H9/54—Filters comprising resonators of piezoelectric or electrostrictive material
- H03H9/542—Filters comprising resonators of piezoelectric or electrostrictive material including passive elements
Landscapes
- Physics & Mathematics (AREA)
- Acoustics & Sound (AREA)
- Piezo-Electric Or Mechanical Vibrators, Or Delay Or Filter Circuits (AREA)
Abstract
837,275. Filter circuits. SIEMENS & HALSKE A.G. May 8, 1956 [May 9, 1955], No. 14285/56. Class 40 (8). One arm of a ladder-type filter having highpass, low-pass, band-stop or band-pass characteristics comprises a tuned element in the form of an electro-mechanical resonator (piezo-electric or magnetostrictive) and at least one further reactive element which gives the arm a secondary resonance, an adjacent arm having a tuned element which repeats this secondary resonance. In the band-pass filter shown the shunt arm contains a piezo-electric crystal element 1 in parallel with a parallel-resonant circuit 4 and the series arms contain parallel-resonant circuits 2 identical with the circuit 4. The attenuation peak produced by the crystal 1 may be arranged to determine the lower limit of the pass band whilst an adjacent attenuation peak at a frequency below that of the first peak is determined by the circuits 2, 4. The upper attenuation peak can be determined (or eliminated) by further parallel-resonant circuits 3 which may in some cases be simply inductors. Alternatively the attenuation peak produced by the crystal may determine the upper limit of the pass band in which case the tuned circuits 3 may be simply capacitors. In a further arrangement both the upper and lower limits are produced by crystal resonance in which case the circuits 2, 4 consist of crystal resonators. The filter may be designed so that the mid-shunt impedance of a half-section is given by the expression where Á is a constant, #2 and #1 are the limit frequencies, #α is the resonant frequency of the crystal filter and ## the resonant frequency of the tuned element in parallel with it. Where the circuit is in the form of a # network the shunt arms may include crystals resonant at frequencies which determine the limits of the filter band. Where the filter contains a number of sections it is not necessary for the resonant frequency of the third tuned elements to be exactly the same as the resonant frequency of the second tuned elements ; small deviations are permissible. The network may incorporate impedance transformation sections consisting of capacitors. Multi-electrode crystals may be used in some embodiments.
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DES43857A DE1125563B (en) | 1955-05-09 | 1955-05-09 | Electrical filter containing electromechanical elements in a branch circuit |
Publications (1)
Publication Number | Publication Date |
---|---|
GB837275A true GB837275A (en) | 1960-06-09 |
Family
ID=7484901
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB1428556A Expired GB837275A (en) | 1955-05-09 | 1956-05-08 | Improvements in or relating to electric wave filters |
Country Status (4)
Country | Link |
---|---|
DE (1) | DE1125563B (en) |
FR (1) | FR1149759A (en) |
GB (1) | GB837275A (en) |
NL (2) | NL113891C (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2008145659A1 (en) * | 2007-05-29 | 2008-12-04 | Epcos Ag | Multiband filter |
Family Cites Families (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US1795204A (en) * | 1927-01-03 | 1931-03-03 | American Telephone & Telegraph | Electrical wave filter |
FR657760A (en) * | 1927-07-19 | 1929-05-27 | Thomson Houston Comp Francaise | Improvements to electric filters |
-
0
- NL NL206956D patent/NL206956A/xx unknown
- NL NL113891D patent/NL113891C/xx active
-
1955
- 1955-05-09 DE DES43857A patent/DE1125563B/en active Pending
-
1956
- 1956-05-08 GB GB1428556A patent/GB837275A/en not_active Expired
- 1956-05-09 FR FR1149759D patent/FR1149759A/en not_active Expired
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2008145659A1 (en) * | 2007-05-29 | 2008-12-04 | Epcos Ag | Multiband filter |
US8384496B2 (en) | 2007-05-29 | 2013-02-26 | Epcos Ag | Multiband filter |
Also Published As
Publication number | Publication date |
---|---|
FR1149759A (en) | 1957-12-31 |
DE1125563B (en) | 1962-03-15 |
NL206956A (en) | |
NL113891C (en) |
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