EP0440661A1 - A high-frequency band-pass filter. - Google Patents
A high-frequency band-pass filter.Info
- Publication number
- EP0440661A1 EP0440661A1 EP89908824A EP89908824A EP0440661A1 EP 0440661 A1 EP0440661 A1 EP 0440661A1 EP 89908824 A EP89908824 A EP 89908824A EP 89908824 A EP89908824 A EP 89908824A EP 0440661 A1 EP0440661 A1 EP 0440661A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- resonator
- bandpass filter
- input
- output
- length
- 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.)
- Granted
Links
- 239000003990 capacitor Substances 0.000 claims description 20
- 238000005516 engineering process Methods 0.000 claims description 18
- 239000000758 substrate Substances 0.000 claims description 6
- 238000013016 damping Methods 0.000 abstract description 7
- 230000008878 coupling Effects 0.000 description 24
- 238000010168 coupling process Methods 0.000 description 24
- 238000005859 coupling reaction Methods 0.000 description 24
- 230000005540 biological transmission Effects 0.000 description 5
- 230000035699 permeability Effects 0.000 description 5
- 230000008901 benefit Effects 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 2
- 239000004020 conductor Substances 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 230000008859 change Effects 0.000 description 1
- 238000005094 computer simulation Methods 0.000 description 1
- 238000005530 etching Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000004088 simulation Methods 0.000 description 1
- 230000003313 weakening effect Effects 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
- H01P1/00—Auxiliary devices
- H01P1/20—Frequency-selective devices, e.g. filters
- H01P1/201—Filters for transverse electromagnetic waves
- H01P1/203—Strip line filters
- H01P1/20327—Electromagnetic interstage coupling
- H01P1/20354—Non-comb or non-interdigital filters
- H01P1/20363—Linear resonators
Definitions
- the present invention relates to a high-frequency bandpass filter according to the preamble of patent claim 1.
- a generic high-frequency bandpass filter is already known from the textbook "Zinke / Brunswig: Textbook of High Frequency Technology, Volume 1, 3rd Edition, Springer-Verlag 1986, page 209, Figure 4.14 / 9".
- This known high-frequency band-pass filter is a so-called interdigital filter with capacitively shortened resonator inner conductors.
- an input line resonator, a center line resonator and an output line resonator lie parallel to one another in such a way that a coupling between the input line resonator nator and the center line resonator and a coupling between the center line resonator and the output line resonator occurs.
- This coupling is a so-called coupling of parallel lines.
- a desirable shift of the next pass band which in the case of lambda half-resonators is twice the resonance frequency, to higher frequencies, so that good attenuation at the first harmonic of the center frequency occurs of the passband can be achieved.
- the degree of coupling of this known interdigital filter cannot be increased arbitrarily and thus the damping at the resonance frequency cannot be reduced to low damping values without undesired direct coupling of the input resonator to the output resonator, which in turn inhibits the characteristics of the Inter ⁇ digital filter would affect.
- a bandpass filter with parallel coupled lambda half resonators is also known from the textbook on radio frequency technology cited above, page 207, Figure 4.14 / 6.
- the known bandpass filter is implemented using strip technology or micro-strip technology and comprises a plurality of lambda half-strip line resonators on a substrate, which are mutually offset in the longitudinal direction by lambda quarters.
- Such a high-frequency band-pass filter structure has large external dimensions. Furthermore, such an unabridged high-frequency bandpass filter cannot be tuned and has a relatively low attenuation at the first harmonic.
- FIG. 1 a high-frequency bandpass filter using stripline technology is known, which has an input coupling line, two center resonators and an output coupling line.
- the input coupling line and the output coupling line are each designed as idling lines and capacitive coupling elements, which are arranged parallel to one another and unaligned in the direction of their longitudinal extension, that is to say arranged at the same height.
- the two center resonators are designed as U-shaped, capacitively shortened lambda half resonators, the ends of which are connected to the ground potential and the center of which are each connected to a capacitor.
- the high-frequency bandpass filter according to the invention prevents a direct coupling of the input resonator to the output resonator by means of their arrangement which is offset in the longitudinal direction of the central resonator, as a result of which a high degree of coupling can be achieved, with a through loss of only 1 to 2.5 dB. of the pass-through frequency is possible without the usual wave formation of the attenuation curve in the frequency range with such a high degree of coupling.
- the high-frequency bandpass filter according to the invention not only shows the very high passband attenuation just mentioned, but also has, depending on the degree of coupling and bandwidth of the passband, an attenuation of up to -70 dB at the first harmonic.
- An important advantage of the filter according to the invention is that its characteristics can be simulated by computer, which is not the case with many known filter structures or can only be carried out approximately with considerable effort.
- the filter according to the invention is suitable for tuning capacitors with adjustable capacitance values or trimmers and can be constructed compactly and inexpensively using microstrip technology. Because of its low pass-through attenuation, the field of application of the line filter according to the invention not only appears to be limited to frequency processing, but it also seems to be possible in principle to use the filter according to the invention also in the power range.
- FIG. 2 shows a computational simulation of the damping curve of the embodiment according to FIG. 1;
- FIG. 3 shows a measurement result of the damping curve of the embodiment according to FIG. 1.
- the third-order high-frequency bandpass filter which is designated in its entirety by reference number 1, comprises an input resonator 2, a center resonator 3 and an output resonator 4.
- the resonators 2, 3, 4 are designed as line resonators in strip technology or microstrip technology on a substrate by means of the etching technology which is conventional per se.
- the substrate has a thickness of approximately 1.5 mm with a relative permeability or effective dielectric constant
- the input resonator 2 is coupled to the central resonator 3 in parallel.
- the center resonator 3 is in turn coupled to the output resonator 4 in parallel.
- the mutually turned ends 5, 6 of the input resonator 2 and the output resonator 4 are connected to ground.
- the two ends 7, 8 of the center resonator 3 are connected to ground.
- the center of the center resonator 3 is connected to ground via a first adjustable capacitor 9.
- the opposite ends 10, 11 of the input resonator 2 and the output resonator 4 are also connected to ground via a second or third adjustable capacitor 12, 13.
- the input resonator 2 is parallel to the center resonator 3 between one end 7 and the center 14 of the center resonator 3.
- the output resonator 4 is parallel to the center resonator 3 between the center 14 of the center resonator 3 and the other end 8 thereof Offset of the input resonator and the output resonator largely prevents an undesired, direct coupling from the input resonator to the output resonator, which would lead to a weakening of the damping outside the pass frequency.
- the center resonator 3 in conjunction with the first capacitor 9 assigned to it forms a shortened lambda half-line resonator, the length of which, by suitable selection of the capacitance value of the first capacitor, is likewise from 10 to 30%, but preferably approximately 16%, of the length of a lambda Half resonator is set.
- the capacitance value of the first capacitor 9 corresponds with approximately 2% accuracy to twice the capacitance value of the second or third capacitor 12, 13.
- the ratio of the capacitance values results from the line lengths.
- the lengths can be changed independently of one another within certain limits, which is accompanied by a corresponding change in the capacitance values.
- the outer line elements 2, 4 can be shifted slightly parallel to the middle line 3, which facilitates the placement of the middle capacitor 9.
- the input resonator 2 is connected to an input connection line 15 by means of a direct tap.
- the output resonator 4 is connected to an output connection line 16 by means of a direct tap.
- any other coupling can be used in deviation from the exemplary embodiment shown.
- the computational attenuation curve shows a transmission loss of less than -1 dB and an attenuation of -65 dB at twice the transmission frequency
- FIG. 3 shows the actually measured attenuation curve of the embodiment of the high-frequency band-pass filter according to the invention with the above-mentioned direction
- the computed attenuation curve according to FIG. 2 coincides relatively well with that actually measured Attenuation curve according to FIG. 3.
- a transmission loss of -1.2 dB was achieved at the transmission frequency f of 400 MHz.
- the attenuation curve shown in FIG. 3 shows that a very high degree of coupling is achieved at the pass frequency f without the wave formation of the attenuation curve in the frequency range which is usual with such high degrees of coupling being accepted must be taken, as occurs in filters with two resonators coupled in parallel.
- the illustrated embodiment of the bandpass filter according to the invention has a very wide tuning range from 360 MHz to 960 MHz with an approximately constant quality.
- a decisive advantage of the high-frequency bandpass filter according to the invention is that its damping behavior can be simulated with little effort using programs known per se. B. is not possible with an interdigital filter with more than two resonators.
- Preferred areas of application of the filter according to the invention are in the field of frequency processing technology at frequencies between approximately 50 MHz and 10 GHz. It is also conceivable to use the filter according to the invention as an output filter for transmitters with low power to suppress harmonics.
Landscapes
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Control Of Motors That Do Not Use Commutators (AREA)
Abstract
Filtre passe-bande haute fréquence comportant un résonateur d'entrée, un résonateur central et un résonateur de sortie couplés en parallèle. Le résonateur d'entrée et le résonateur de sortie sont des résonateurs quart d'onde à capacité diminuée. Pour améliorer les caractéristiques d'amortissement, le résonateur central se présente sous la forme d'un résonateur demi-onde à capacité diminuée. Le résonateur d'entrée s'étend sur une première partie de la longueur du résonateur central. Le résonateur de sortie s'étend sur une deuxième partie de la longueur du résonateur central.A high frequency bandpass filter comprising an input resonator, a central resonator and an output resonator coupled in parallel. The input resonator and the output resonator are quarter wave capacitance reduced resonators. To improve the damping characteristics, the central resonator is in the form of a half-wave resonator with reduced capacity. The input resonator extends over a first part of the length of the central resonator. The output resonator extends over a second part of the length of the central resonator.
Description
Claims
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AT89908824T ATE95341T1 (en) | 1988-10-18 | 1989-08-01 | HIGH FREQUENCY BANDPASS FILTER. |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE3835480A DE3835480A1 (en) | 1988-10-18 | 1988-10-18 | HIGH FREQUENCY BAND PASS FILTER |
DE3835480 | 1988-10-18 |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0440661A1 true EP0440661A1 (en) | 1991-08-14 |
EP0440661B1 EP0440661B1 (en) | 1993-09-29 |
Family
ID=6365389
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP89908824A Expired - Lifetime EP0440661B1 (en) | 1988-10-18 | 1989-08-01 | A high-frequency band-pass filter |
Country Status (4)
Country | Link |
---|---|
US (1) | US5136269A (en) |
EP (1) | EP0440661B1 (en) |
DE (2) | DE3835480A1 (en) |
WO (1) | WO1990004861A1 (en) |
Families Citing this family (15)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2246670B (en) * | 1990-08-03 | 1995-04-12 | Mohammad Reza Moazzam | Microstrip coupled lines filters with improved performance |
DE4213195C2 (en) * | 1992-04-22 | 1995-01-19 | Rohde & Schwarz | Multi-circuit line filter |
EP0600118B1 (en) * | 1992-12-01 | 1998-05-27 | Siemens Aktiengesellschaft | Voltage-controlled microwave oscillator |
US5442330A (en) * | 1993-12-27 | 1995-08-15 | Motorola, Inc. | Coupled line filter with improved out-of-band rejection |
KR20010094784A (en) * | 2000-04-06 | 2001-11-03 | 윤종용 | Radio filter of combline structure with capacitor recompense circuit |
KR100392682B1 (en) * | 2001-02-26 | 2003-07-28 | 삼성전자주식회사 | Radio filter of combline structure with frequency cut off circuit and method |
JP2005117433A (en) * | 2003-10-08 | 2005-04-28 | Eudyna Devices Inc | Filter |
JP4230467B2 (en) * | 2005-02-25 | 2009-02-25 | 日本電波工業株式会社 | High frequency filter using coplanar line type resonator. |
KR100675393B1 (en) * | 2005-02-25 | 2007-01-29 | 삼성전자주식회사 | Parallel coupled-line filter miniaturized by using lumped capacitors and grounding and fabrication method thereof |
CN101361219B (en) * | 2006-09-28 | 2012-05-30 | 株式会社村田制作所 | Dielectric filter, chip element, and chip element manufacturing method |
JP5464864B2 (en) * | 2009-02-25 | 2014-04-09 | 京セラ株式会社 | Filter circuit and wireless communication module and wireless communication device using the same |
JP5936133B2 (en) * | 2011-01-28 | 2016-06-15 | 国立大学法人電気通信大学 | Transmission line resonator, bandpass filter using transmission line resonator, duplexer, balanced-unbalanced converter, power distributor, unbalanced-balanced converter, frequency mixer, and balanced filter |
US10249582B2 (en) * | 2016-12-19 | 2019-04-02 | Nxp Usa, Inc. | Radio frequency (RF) devices with resonant circuits to reduce coupling |
US10581132B2 (en) * | 2017-05-11 | 2020-03-03 | Eagantu Ltd. | Tuneable band pass filter |
CN110679033A (en) | 2017-05-11 | 2020-01-10 | 伊根图有限公司 | Compact band-pass filter |
Family Cites Families (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB1358980A (en) * | 1971-06-15 | 1974-07-03 | Ferranti Ltd | Microwave filters |
FR2510326A1 (en) * | 1981-07-24 | 1983-01-28 | Thomson Csf | LINEAR RESONATOR PASSER FILTER OPEN TO THEIR TWO ENDS |
FR2540294B1 (en) * | 1983-01-31 | 1985-10-04 | Thomson Csf | MICROWAVE FILTER WITH LINEAR RESONATORS |
JPS61177001A (en) * | 1985-01-31 | 1986-08-08 | Maspro Denkoh Corp | Microwave filter |
FR2613557A1 (en) * | 1987-03-31 | 1988-10-07 | Thomson Csf | FILTER COMPRISING CONSTANT DISTRIBUTED ELEMENTS ASSOCIATING TWO TYPES OF COUPLING |
FR2613538A1 (en) * | 1987-03-31 | 1988-10-07 | Thomson Csf | Microwave filter |
JPH02146801A (en) * | 1988-11-28 | 1990-06-06 | Fujitsu Ltd | Band pass filter whose center frequency is variable |
-
1988
- 1988-10-18 DE DE3835480A patent/DE3835480A1/en not_active Withdrawn
-
1989
- 1989-08-01 DE DE89908824T patent/DE58905789D1/en not_active Expired - Fee Related
- 1989-08-01 WO PCT/EP1989/000902 patent/WO1990004861A1/en active IP Right Grant
- 1989-08-01 EP EP89908824A patent/EP0440661B1/en not_active Expired - Lifetime
-
1991
- 1991-02-22 US US07/660,560 patent/US5136269A/en not_active Expired - Fee Related
Non-Patent Citations (1)
Title |
---|
See references of WO9004861A1 * |
Also Published As
Publication number | Publication date |
---|---|
DE58905789D1 (en) | 1993-11-04 |
WO1990004861A1 (en) | 1990-05-03 |
DE3835480A1 (en) | 1990-04-19 |
US5136269A (en) | 1992-08-04 |
EP0440661B1 (en) | 1993-09-29 |
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