EP1782496B1 - Appareil et procede relatifs a des filtres a resonateurs annulaires a alimentation dedoublee et a fonction elliptique - Google Patents

Appareil et procede relatifs a des filtres a resonateurs annulaires a alimentation dedoublee et a fonction elliptique Download PDF

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Publication number
EP1782496B1
EP1782496B1 EP04779847A EP04779847A EP1782496B1 EP 1782496 B1 EP1782496 B1 EP 1782496B1 EP 04779847 A EP04779847 A EP 04779847A EP 04779847 A EP04779847 A EP 04779847A EP 1782496 B1 EP1782496 B1 EP 1782496B1
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European Patent Office
Prior art keywords
filter
coupling
resonators
ring
coupling extension
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EP04779847A
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German (de)
English (en)
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EP1782496A1 (fr
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Norman A. Luque
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Raytheon Co
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Raytheon Co
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    • 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
    • H01P1/20381—Special shape resonators
    • 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

  • a filter within an electrical circuit allows selected signals to "pass” while blocking other signals.
  • One type of filter is a bandpass filter.
  • a typical bandpass filter is an electrical device or circuit that allows signals in a specific frequency range to pass, but that blocks signals at other frequencies.
  • Bandpass filters are frequently used in electrical circuits in devices such as radio, television, cordless and cellular telephones, wireless communications systems, radar, sensors, and some types of manufacturing measurement and instrumentation systems. These devices transmit and receive signals using electromagnetic waves.
  • a primary function of a bandpass filter in a transmitter is to limit the bandwidth of the output spectrum.
  • a bandpass filter allows the receiver to receive a selected range of frequencies, while rejecting signals at unwanted frequencies.
  • a bandpass filter also optimizes the signal-to-noise (sensitivity) of a receiver.
  • well-designed bandpass filters having the optimum bandwidth for the mode and speed of communication being used, maximize the number of signals that can be transferred in a system, while minimizing the interference or competition among signals.
  • An example of an application of filters in electronics is in microwave communications, that is, wireless communications using signals in the microwave portion of the electromagnetic spectrum.
  • Conventional filter designs intended to operate at high frequencies include edge-coupled, surface acoustic wave (SAW), dielectric resonator and waveguide filters.
  • SAW surface acoustic wave
  • Another type of conventional filter used in microwave communications is a filter having two square loop resonators where the square loop resonators are positioned on either side of a core material where the loops are off-center from each other. This type of filter can be realized in two layers of a printed wiring board, for example. In operation, the square loop resonators cross-couple with each other thereby each influencing the electrical response of the other to produce a signal useful in microwave communications.
  • the response of this filter is controlled by varying the amount of offset in the relative positions of the resonators.
  • Examples of known filters are disclosed in WO 95/028746 and US 4264881 .
  • Another known filter is described in " Microstrip Rectangular Ring Bandpass Filter Elements for GSM" by Peixeiro, C published in Microwave Conference 2000 Asia-Pacific Sydney, NSW, Australia 3-6 December 2000, Pistcataway NJ, USA, IEEE, US, Pages 1273-1276 (ISBN: O-7803-6435-X ).
  • Embodiments of the present invention significantly overcome such deficiencies by providing techniques for filtering which use a novel filtering structure having a coupled ring resonator topology.
  • a novel filtering structure having a coupled ring resonator topology.
  • Such a structure is well-suited for bandpass filtering because it provides a high close-in rejection elliptic-response.
  • Such a structure yields filters that are small and narrow-band.
  • this topology is advantageous in that it can be realized using relatively inexpensive standard lithography techniques.
  • embodiments of the invention provide methods and apparatus that use ring resonator pairs placed orthogonally to feed lines in a filter circuit.
  • the feed lines are split in order to couple with two resonator pairs.
  • the resonators in each resonator pair couple with each other as well as with the feed lines.
  • Resonator placement in relation to other resonators and resonator coupling length are used to tune the filter circuit in order to pass selected frequencies.
  • Resonator placement in relation to feed lines and width of the resonator are also used to tune the filter circuit.
  • this topology effectively forms an Elliptic Function response bandpass filter with high close-in rejection capability.
  • these topologies of embodiments of the invention may be relatively inexpensively produced standard lithography techniques such as those used in printed wiring board manufacturing or in thin film manufacturing.
  • One such embodiment of a filter includes a first feed line having a first stem connected substantially perpendicularly to a first cross piece having a first coupling extension and a second coupling extension and a second feed line having a second stem connected substantially perpendicularly to a second cross piece having a third coupling extension and a fourth coupling extension where the first coupling extension is substantially parallel to the third coupling extension and the second coupling extension is substantially parallel to the fourth coupling extension.
  • the embodiment further includes four ring resonators located planar to the first and the second feed lines, two of the ring resonators being positioned between the first and the third coupling extensions and two other of the ring resonators being positioned between the second and the fourth coupling extensions such that the four ring resonators are coupled to the feed lines to form a first resonant circuit; a first 1 ⁇ 4 - wave transformer on said first stem (410) at a connecting point of said first cross piece; and a second 1 ⁇ 4 - wave transformer on said second stem at a connecting point of said second cross piece; wherein said feed lines are substantially centered on a mid-line that defines a bisecting line of said plane of said filter, said first pair positioned on one side of said mid-line and said second pair positioned on the other side of said mid-line.
  • the resonant circuit of this topology provides a well-defined passband where close-in frequencies can be blocked while passing a signal of a selected frequency.
  • each ring resonator is substantially one-quarter wavelength ( ⁇ /4) on each side providing a passband that is substantially centered on the selected frequency. Accordingly, the filter can be centered about a particular frequency by scaling the resonator lengths proportionally to wavelength.
  • each ring resonator is a square-shaped ring.
  • Square-shaped rings couple more effectively with the feed-lines and with each other than rounded ring resonators.
  • each side of the square-shaped rings is substantially one quarter wavelength ( ⁇ /4) of the selected center frequency.
  • the feed-lines, coupling extensions and ring resonators are conductive features of a signal layer on a substrate.
  • the bandpass filter formed using the disclosed inventive features is part of a circuit.
  • the bandpass filter further includes a fifth ring resonator between the first and the third coupling extensions and a sixth ring resonator between the second and the fourth coupling extensions. Additional resonators in the bandpass filter improve the definition of the passband.
  • the ring resonators are positioned relative to each other such that each the ring resonator affects resonance in adjacent resonators such that the passband of the bandpass filter is defined.
  • the positioning the ring resonators relative to each other effectively tunes the bandpass filter.
  • bandpass filter is configured to operate in the radio frequency region of the electromagnetic spectrum. In this way, the features of the bandpass filter are re-sized according to a selected frequency from the radio frequency range.
  • a first resonant circuit having ring resonators and a second resonant circuit having ring resonators as described above are connected in series. This is also referred to as “cascading" the filters.
  • the filters connected in series provide an even sharper passband than one filter alone.
  • a method embodiment of the invention includes acquiring an input signal; applying the input signal to an input of a filter in accordance with the invention, and conveying an output signal from the output.
  • Embodiments of the present invention provide mechanisms and techniques for a coupled ring resonator topology providing such filters. Further, the embodiments of the invention can be advantageously realized using relatively inexpensive standard lithography techniques such as the techniques used in printed wiring board manufacture or semiconductor manufacturing.
  • Embodiments of the present invention include two pairs of ring resonators. In one arrangement, the ring resonators are arranged side-by-side with respect to each other and orthogonally with respect to the input and output lines. In one arrangement, the resonators are square-ring resonators. The sides of each ring resonator are tuned to substantially ⁇ /4 of the frequency of circuit operation.
  • the input and output lines are split in order to couple to all ring resonators present in the arrangement.
  • Each ring resonator is placed in relation to the split feed in such a way that the ring and feed substantially form a ⁇ /4 coupler.
  • the Elliptic Function response achieved by one embodiment of the filter topology in the present invention allows for less than 10% bandwidth and higher rejection than an equivalent Chebyshev filter.
  • Figures 1 - 6 are presented to allow the reader to gain an understanding of filters and filter signal response, particularly, for filters used in high-frequency applications.
  • wireless communications for example, a wireless signal and a carrier wave are input to a signal mixer and their frequencies are changed.
  • spurious signals are unintentionally produced by the circuitry or the environment or a combination of both. Many times, the spurious signals are very close to the desired signal.
  • Figure 1 is a graph 100 of frequency versus signal in a conventional filter circuit where the graph shows a desired signal and spurious signals. In the graph, the horizontal axis is frequency measured in Hertz and the vertical axis is amplitude.
  • the selected pass frequency 105 is the signal having the largest amplitude signal.
  • spurious signals 110 close to the desired signal 105.
  • Conventional filters do not provide a bandpass filter that passes only a narrow band such that the desired signal is passed but the spurious signals, particularly the close spurious signals, are blocked.
  • Embodiments of the present invention enable one band of signal to be passed while other frequencies, even those close to the passed frequency, are blocked.
  • modem microwave systems require high-performance narrow-band bandpass filters having low insertion loss and high selectivity together with linear phase or flat group delay in the passband. These criteria are generally fulfilled by conventional filters having an Elliptic Function response. Generally the realization of Elliptic Function response filter characteristics requires cross-couplings between nonadjacent resonators.
  • Figure 2 is a top view of the elements on a substrate of a conventional 5-resonator edge-coupled bandpass filter that provides a Chebyshev filter response.
  • the elements are printed elements on a signal layer of a printed wiring board.
  • the elements are created using thin film techniques on a substrate.
  • the conventional bandpass filter of Figure 2 is constructed from a plurality of half-wave resonators, which are cascaded in an overlapping, edge-coupled fashion.
  • This conventional bandpass filter 150 has a first feed line 155-1 and a second feed line 155-2.
  • Each feed line 155 has a 1/4-wave transformer 160 connected to a 1/4-wave coupler 165.
  • Between the first feed line 155-1 and the second feed line 155-2 is a five-node resonator having five cascaded half-wave resonators, or waveguides 170-1, 170-2, 170-3, 170-4, 170-5 (collectively 170).
  • Each half-wave resonator 170 is 1/2-wave of a selected center frequency in length.
  • Each half-wave resonator 170 has a ground point at a point substantially in the center of the strip. Each half-wave resonator 170 further has an open at either end of the half-wave resonator 170. In Figure 2 , the ground and opens are indicated on half-wave resonator 170-1.
  • the half-wave resonator 170 are edge-coupled to each other as well as to the feed line 1/4-wave couplers 165. That is, the 1/4-wave coupler 165-1 of the first feed line 155-1 is edge-coupled to its adjacent half-wave resonator 170-1 and the second 1/4-wave coupler 165-2 is edge-coupled to its adjacent half-wave resonator 170-5.
  • the middle three resonators 170-2, 170-3, 170-4 are edge-coupled to the resonators 170-1, 170-5 on either side of them.
  • the middle point of each half-wave resonator that is, the ground, is the reference point.
  • the resonators 170 resonate only at a particular band of frequencies. Where each resonator 170 is a little offset, a wider band of pass frequencies is produced.
  • the resonators 170 interact with each other. If the gap between resonators 170 is large, the interaction between resonators decreases. If the gap between resonators 170 is small, each resonator pulls on the adjacent resonator(s).
  • Figure 3A shows a basic series resonator representation 200 for a resonator 170 of Figure 2 .
  • the resonator representation 200 for the half-wave resonator 170 includes an inductive component 205 and a capacitance component 210.
  • Figure 3B shows the amplitude-vs-frequency graph of the passband response of the half-wave resonator 170 for a conventional filter.
  • capacitors When capacitors are combined with inductors, it is possible to make circuits that have very sharp frequency characteristics.
  • Figure 4 is an output power-vs.-frequency graph 250 of a passband response curve of a hypothetical conventional bandpass filter.
  • Figure 4 is included here to show the expected signal response of conventional bandpass filters and to illustrate the elements of a filtered signal response including the type of response produced by the filter shown in Figure 2 .
  • Figure 4 shows a passband between the frequencies f 1 255 and f 2 260 and centered approximately around the resonant frequency f 0 265.
  • the cutoff frequencies, f 1 255 and f 2 260 are the frequencies at which the output signal power falls to half of the output signal power level at f 0 265.
  • the value of the difference between frequencies that is, (f 1 - f 2 ), defines the filter bandwidth.
  • the range of frequencies between frequencies f 1 255 and f 2 260 is the filter passband.
  • Figure 4 is included to show aspects of a desirable bandpass filter response curve. The leading and falling edges of the curve are called the skirts 270. Ideally, the skirts 270 of a bandpass filter response curve are steep, the bandwidth response 275 is flat and the knees 280 where the skirts meet the top of the curve are sharp.
  • the graph of Figure 4 is a typical response obtained when using prior art bandpass filters.
  • the passband response for filtering close-in spurious frequencies needs improvements in all aspects of the response curve.
  • FIG. 5A shows a part-representational, part-circuit diagram of the bandpass filter of Figure 2 presented here to model the coupled stripline bandpass filter of Figure 2 .
  • the feed lines 155 of Figure 2 are represented by the Vin 155-1' and Vout 155-2' leads.
  • Each resonator 170 of Figure 2 is here represented by resonator diagrams 170'.
  • Each circuit component is influenced by the adjacent components providing the response shown in Figure 5B .
  • Figure 5B shows an amplitude-vs-frequency graph of the output signal of a bandpass filter circuit of the type shown in Figure 5A .
  • the response curve (shown as a dotted line) is the result of the combined responses of each of the individual resonators in the circuit (shown as solid lines).
  • a prior art solution to increasing filter sharpness was to incorporate more resonators as in the bandpass filter shown in Figure 2 and represented in Figure 5A .
  • the circuit response shown in Figure 5B is similar to that shown in Figure 4 .
  • the filter sharpness is increased by the additional resonators, the electrical performance of the filter is degraded.
  • Figure 6 is a graph showing an example simulated passband response of the prior art filter of Figure 2 .
  • the graph of Figure 6 is an amplitude vs. frequency graph where amplitude is normalized in decibels.
  • the curve S 21 300 is the example simulated passband response of the prior art bandpass filter 150 of Figure 2 .
  • the skirts 305-1, 305-2 of the curve 300 are not very steep, and therefore it can be seen that the ability to block close-in frequencies with the bandpass filter 150 of Figure 2 would not be optimum.
  • the minimum bandwidth of the topology of the bandpass filter of Figure 2 is approximately 10% of the center frequency.
  • Narrower passbands translate into wider gaps between the half-wave resonators making the passband "shape" of this topology very sensitive to surrounding circuits and the environment.
  • additional half-wave resonators can be added to the design to increase the steepness of the filter's skirts. The addition of additional poles, however, degrades the performance and manufacturability (i.e., repeatability) of the filter.
  • the present invention employs ring resonators, which are placed orthogonally, that is, non-overlapping, between feed lines. Such a configuration provides a sharply defined passband having steep skirts, which improves its ability to block close-in spurious signals compared to earlier-disclosed filters.
  • FIG. 7 is a top view of the elements on a substrate of a coupled-ring bandpass filter according to principles of the present invention.
  • the coupled-ring bandpass filter is constructed from a plurality of rings placed orthogonally between the feed lines and coupled to the feed lines.
  • Coupling herein means electromagnetically-coupled, not necessarily physically coupled.
  • a typical range of operation for the filter is in the high-frequency range of the electromagnetic spectrum.
  • the range includes the radio frequency range (RF) which is generally defined as those frequencies less than 3 x 10 9 Hz, the microwave range which is generally defined as those frequencies between 3 x 10 9 Hz-3 x 10 10 Hz, and the millimeter-wave range which is generally defined as those frequencies between 3 x 10 10 Hz - 3 x 10 11 Hz.
  • RF radio frequency range
  • the elements shown in Figure 7 are realized as a microstrip circuit.
  • the elements are part of a signal plane layer on top of a core material and the core material has a ground plane at the back of the core material.
  • the ground plane in a microstrip is typically a metallization layer.
  • the elements shown in Figure 7 are realized as a stripline where the elements are part of a signal layer embedded in, for example, a multilayer printed wiring board.
  • On the outer sides of the core material, that is, the outsides of the structure are layers of metallization acting as ground planes.
  • the elements shown in Figure 7 are realized as a coplanar wave guide where the ground is located in the same plane as the elements. These arrangements may be manufactured using standard lithography techniques such as printed wiring board or thin film techniques.
  • the coupled-ring bandpass filter 400 of Figure 7 has a first feed line 405-1 and a second feed line 405-2.
  • one feed line is an input and other is an output, however, the circuit is symmetrical and so the input and output are, for the sake of simplicity, referred to by the same term.
  • the feed lines 405-1, 405-2 are substantially centered on a mid-line that defines a bisecting line of the plane of the circuit 400.
  • Each feed line 405 is split and has a stem 410 connected substantially perpendicularly to a cross-piece having two coupling extensions 420 that extend from either side of the stem 410.
  • each stem 410 has a 1/4-wave transformer 415.
  • a transformer in the present application is an impedance transformer and is a 1/4-wave element matching an impedance on one line with a different impedance on another line.
  • the coupling extensions 420-1 of the first feed line 405-1 are substantially parallel to the coupling extensions 420-2 of the second feed line 405-2.
  • the input coupling extensions form a first straight edge and the output coupling extensions form a second straight edge.
  • Each coupling extension 407 has a 1/4-wave transformer 425 and 1/4-wave couplers 430 where there is a transformer 425 between each pair of couplers 430 on each coupling extension 420.
  • each ring-shaped resonator 435 is positioned so that two of the resonators 435 are on one side of the mid-line 409 and two of the resonators 435 are positioned on the other side of the mid-line 409.
  • the ring-shaped resonators 435 have flattened areas to provide better coupling to the feed lines 405 and to each other, so each ring-shaped resonator 435 is generally square-shaped, that is, each resonator 435 has a square-shaped profile.
  • Each ring-shaped resonator 435 is substantially one quarter wave ( ⁇ /4) on each side.
  • the selected frequency is a resonant frequency around which the passband of the filter 400 is substantially centered.
  • the selected frequency is, essentially, the frequency to be passed by the bandpass filter 400.
  • Each ring-shaped resonator 435 has a theoretical open and a theoretical ground. Further, each ring-shaped resonator 435 is coupled to a first coupler 430-1 on the first feed line 405-1 and also to a second coupler 430-2 on the second feed line 405-2.
  • the ring-shaped resonators 435 are edge-coupled to each other as well as to the feed line 1/4-wave couplers 430.
  • the ring resonators 435 resonate only at a particular band of frequencies.
  • the ring resonators 435 interact in pairs. Each ring resonator 435 in a pair interacts with the adjacent resonator affecting the other resonator's resonant frequencies. Each ring resonator 435 is therefore slightly de-tuned providing a combined band of pass frequencies. If the gap 437 between the ring resonators 435 is large, the interaction between resonators 435 decreases. If the gap 437 between the ring resonators 435 is small, each resonator pulls strongly on the adjacent resonator. In this way, resonator placement is used to tune the bandpass filter. Other factors in tuning the filter include the overall length of the resonator and the placement of the resonator with respect to the feed lines. To a lesser degree than the other factors disclosed above, the width of the resonator line can be used to tune the filter.
  • alternative embodiments of the invention could include six ring resonators with three ring resonators on either side of the feed line stems forming triplets. Further alternative embodiments include eight ring resonators with four ring resonators on either side of the feed line stems forming four pairs of ring resonators, and so on. The scope of the invention is not limited to two pairs of ring resonators. Further alternate embodiments of the invention include resonators in which the ring is open. Specifically, the ring would have a gap in one side of the resonator; typically the side not coupled to an adjacent resonator or to a feed line. While the side of the ring resonator having the gap is "open," that side remains substantially ⁇ /4 long as do the other three sides of the resonator.
  • Figure 8 is a graph showing a simulated passband response of the coupled-ring resonator filter of Figure 7 when operating according to principles of the present invention.
  • the graph of Figure 8 is an amplitude vs. frequency graph where amplitude is normalized in decibels.
  • the S 21 curve 450 is the example simulated passband response of the bandpass filter 150 of Figure 7 .
  • the passband response shown in Figure 8 differs from the response of the prior art bandpass filters described above. As can be seen, the close-in skirts 455 of the curve 450 are steeper with respect to the prior art curve shown in Figure 6 . Therefore it can be seen that the ability to filter close-in frequencies with the bandpass filter 400 of Figure 7 would be improved over the prior art bandpass filters.
  • the passband is sharply defined.
  • the slopes of the lines through the cutoff frequencies are close to vertical.
  • the side lobes 460 in the graph are part of the rejection band of the filter.
  • the side lobes 460 are part of the ripple in the rejection band typical of Elliptic Response filters.
  • the passband can be further improved.
  • Figure 9 is a graph of an example tested passband response of a coupled-ring resonator of the type shown in Figure 7 .
  • the graph of Figure 9 is amplitude vs: frequency where amplitude is normalized in decibels.
  • the frequency axis shown in the graph of Figure 9 ranges from 23.85 GHz to 33.85 GHz.
  • the curve S 21 500 has its highest amplitude at 28.85 GHz, 2.5 dB below a reference amplitude of 0 dB.
  • the skirts 505 of the curve, the first skirt 505-1 between 27.15 GHz and 28.07 GHz and the second skirt 505-2 between 29.90 GHz and 30.60 GHz are steep, as predicted by the simulated passband response shown in Figure 8 .
  • the shape of the passband and skirts 500 has the characteristic Elliptic-Function response ripple in both the passband 510 and the stopband 515-2.
  • Figure 10 is a top view of two coupled-ring resonators in a cascade arrangement.
  • the coupled-ring resonator disclosed above can be cascaded in order to improve passband response.
  • the coupled-ring resonator filter 400 of Figure 7 having a input feed line 405-1 and an output feed-line 405-2 is connected in series to a second coupled-ring resonator filter 402 by connecting the output feed-line 405-2 of the first filter 400 to the input feed line 406-1 of the second filter 402.
  • the resulting passband response is shown in Figure 11 .
  • three or more coupled-ring resonator filters can be cascaded to increase rejection outside the passband.
  • Figure 11 is a graph showing an example simulated passband response for the cascade coupled-ring resonator filters 400, 402 of Figure 10 when operating according to principles of the present invention.
  • the graph of Figure 11 is amplitude vs. frequency graph where amplitude is normalized in decibels.
  • the curve S 21 550 is the example simulated passband response of the cascaded bandpass filters 400, 402 of Figure 10 .
  • the passband response shown in Figure 8 differs from the response of the prior art bandpass filters 150 described above.
  • the skirts 555 of the curve 550 are steep, and there is improved rejection of the close-in spurious signals 560 from the single coupled-ring filter 400 shown in Figure 7 . Therefore, it can be seen that the ability to filter close-in frequencies with the bandpass filter 400 of Figure 7 would be improved over the prior art bandpass filters 150.
  • FIG 12 is a flow chart of the assembly and operation of the filter 400 shown in Figure 7 .
  • a first feed line 405-1 and a second feed line 405-2 are provided for carrying signals.
  • a plurality of ring resonators 435 are provided to resonate in the filter circuit 400.
  • a plurality of coupling extensions 420 are also provided.
  • the coupling extensions 420 are physically attached to the feed lines 405 and signal-coupled to the resonators 435.
  • Each feed line 405 has two coupling extensions 420.
  • the ring resonators 435 are positioned between the coupling extensions 420 to form a resonant circuit 400 capable of filtering a signal.
  • a second resonant circuit 402 is provided in series with the first resonant circuit 400 established in steps 600.
  • the second resonant circuit 402 has a third and fourth feed lines where the third feed line is attached to the second feed line and receives the output signal of the first resonant circuit.
  • the filtered output of both circuits in series is available at the fourth feed line.
  • a signal is applied to the first feed line.
  • the first resonant circuit and then the second resonant circuit filter the signal.
  • a filtered signal is received at the fourth feed line.
  • Figure 13 shows a transmitter system including a filter according to principles of the present invention
  • Figure 14 shows a receiver system including a filter according to principles of the present invention.
  • the transmitter and receiver systems could be used in any frequency-dependent application including, for example, radio, television, radar, cordless and cellular telephones, satellite communications systems, and some types of test, measurement and instrumentation systems.
  • FIG 13 is a block diagram of a transmitter system 650 including a filter according to principles of the present invention.
  • the transmitter 650 has a signal source 655 attached to a filter 660 attached to an output device 665.
  • the filter 660 is configured and operates according to principles of the invention as disclosed above.
  • the signal source 655 provides a signal to the filter 660.
  • the filter 660 filters the signal and provides a filtered signal to the output device 665.
  • FIG 14 is a block diagram of a receiver system 700 including a filter according to principles of the present invention.
  • the receiver 700 has a signal receiving device 705 attached to a filter 710 attached to a filtered input receiver.
  • the signal receiving device 705 receives a signal to be filtered.
  • the signal receiving device 705 sends the signal to the filter 710.
  • the filter 710 filters the signal and sends the filtered signal to the filtered input receiver 715.
  • the coupled-ring resonator filter 400 provides a sharp Elliptic-Function cutoff at a frequency close-in to both edges of the passband.
  • the use of the inventive topology described above yields filters that are relatively small, narrow-band and provide high close-in rejection.
  • the topology of the couple-ring resonator filter 400 permits the practical realization of a narrowband (less than 10% bandwidth) and a relatively high-Q filters.
  • the inventive topology is also advantageous in that it can be realized using relatively inexpensive standard lithography processes such as thin film or printed substrate technologies.
  • coupled-ring resonator filters 400, 402 are described for use in high-frequency environments, it is possible to use the inventive filter topology in other frequency ranges.
  • the filters 400, 402 can effectively be re-sized to operate at lower frequencies. Different spacings between the resonators 435 and also between the resonators 435 and feed line couplers 420 can be made to achieve alternate bandpass characteristics.
  • the ring resonators could be rounded rings rather than square-shaped.
  • the coupling extensions could, in this embodiment be straight or could follow the contours of the ring resonators.
  • the feed line stem has a small split and each side of the split is connected to a coupling connection such that the coupling connections on a feed line are not physically connected to each other but rather to a side of the split which is then connected to the stem of the feed line.

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Claims (16)

  1. Filtre (400) comprenant :
    une première ligne d'alimentation (405-1) ayant une première tige (410) connectée sensiblement perpendiculairement à une première traverse ayant une première extension de couplage (420-1) et une deuxième extension de couplage ;
    une deuxième ligne d'alimentation (405-2) ayant une deuxième tige connectée sensiblement perpendiculairement à une deuxième traverse ayant une troisième extension de couplage (420-2) et une quatrième extension de couplage, où ladite première extension de couplage (420-1) est sensiblement parallèle à ladite troisième extension de couplage (420-2) et ladite deuxième extension de couplage est sensiblement parallèle à ladite quatrième extension de couplage ;
    quatre résonateurs annulaires (435) situés entre ladite première ligne d'alimentation (405-1) et ladite deuxième ligne d'alimentation (405-2), deux desdits résonateurs annulaires (435) pour former une première paire étant positionnés entre ladite première extension de couplage (420-1) et ladite troisième extension de couplage (420-2) et deux autres desdits résonateurs annulaires (435) pour former une deuxième paire étant positionnés entre ladite deuxième extension de couplage et ladite quatrième extension de couplage de sorte que lesdits quatre résonateurs annulaires (435) soient couplés aux dites lignes d'alimentation (405-1, 405-2) pour former un premier circuit résonnant ;
    un premier transformateur de quart d'onde sur ladite première tige (410) à un point de connexion de ladite première traverse ; et
    un deuxième transformateur de quart d'onde sur ladite deuxième tige à un point de connexion de ladite deuxième traverse ;
    dans lequel lesdites lignes d'alimentation (405-1, 405-2) sont sensiblement centrées sur une ligne médiane qui définit une ligne de bissection dudit plan dudit filtre (400), ladite première paire étant positionnée sur un côté de ladite ligne médiane et ladite deuxième paire étant positionnée sur l'autre côté de ladite ligne médiane.
  2. Filtre (400) selon la revendication 1, comprenant en outre un transformateur d'impédance (415) à un point de connexion de chaque tige (410) avec les extensions de couplage respectives (420-1, 420-2).
  3. Filtre (400) selon la revendication 1 ou 2, dans lequel au moins un résonateur annulaire (435) est un anneau de forme carrée.
  4. Filtre (400) selon la revendication 3, dans lequel chaque côté dudit anneau de forme carrée est sensiblement égal à un quart de longueur d'onde d'une fréquence centrale sélectionnée, la bande de passage du filtre passe-bande (400) étant sensiblement centrée sur ladite fréquence centrale sélectionnée.
  5. Filtre (400) selon la revendication 1, dans lequel chaque extension de couplage (420-1, 420-2) comprend un transformateur d'impédance (425) entre les coupleurs de quart d'onde (430) formés par les points de couplage (407) des parties de l'extension de couplage (420-1, 420-2).
  6. Filtre (400) selon l'une quelconque des revendications 1 à 5, dans lequel lesdites lignes d'alimentation (405-1, 405-2) et lesdits résonateurs annulaires (435) sont des caractéristiques conductrices d'une couche de signal d'un substrat.
  7. Filtre (400) selon l'une quelconque des revendications 1 à 6, comprenant en outre un cinquième résonateur annulaire entre lesdites première et troisième extensions de couplage (420-1, 420-2) et un sixième résonateur annulaire entre lesdites deuxième et quatrième extensions de couplage.
  8. Filtre (400) selon l'une quelconque des revendications 1 à 7, dans lequel lesdits résonateurs annulaires (435) sont positionnés l'un par rapport à l'autre de sorte que chaque dit résonateur annulaire (435) affecte la résonance des résonateurs adjacents (435) de façon qu'une bande de passage du filtre passe-bande soit définie de telle manière que le filtre passe-bande soit réglé.
  9. Filtre (400) selon l'une quelconque des revendications 1 à 8, configuré pour fonctionner dans la région de radiofréquences du spectre électromagnétique.
  10. Filtre (400) selon l'une quelconque des revendications 1 à 8, configuré pour fonctionner dans la région de micro-ondes du spectre électromagnétique.
  11. Filtre (400) selon l'une quelconque des revendications 1 à 8, configuré pour fonctionner dans la région d'ondes millimétriques du spectre électromagnétique.
  12. Filtre (400) selon l'une quelconque des revendications 1 à 6 et/ou des revendications 8 à 11, comprenant en outre un deuxième circuit résonnant en série avec ledit premier circuit résonnant, ledit deuxième circuit résonnant ayant :
    une troisième ligne d'alimentation ayant une troisième tige connectée à une cinquième extension de couplage et une sixième extension de couplage ;
    une quatrième ligne d'alimentation ayant une quatrième tige connectée à une septième extension de couplage et une huitième extension de couplage, où ladite cinquième extension de couplage est sensiblement parallèle à ladite septième extension de couplage et ladite sixième extension de couplage est sensiblement parallèle à ladite huitième extension de couplage ; et
    un deuxième ensemble de quatre résonateurs annulaires situés orthogonalement et planaires à ladite troisième ligne d'alimentation et ladite quatrième ligne d'alimentation, deux desdits résonateurs annulaires du deuxième ensemble étant positionnés entre ladite cinquième extension de couplage et ladite septième extension de couplage et deux autres desdits résonateurs annulaires du deuxième ensemble étant positionnés entre ladite sixième extension de couplage et ladite huitième extension de couplage de sorte que lesdits quatre résonateurs annulaires du deuxième ensemble soient couplés aux dites troisième et quatrième lignes d'alimentation pour former un deuxième circuit résonnant.
  13. Filtre (400) selon l'une quelconque des revendications 1 à 12, dans lequel ledit filtre (400) est un filtre passe-bande.
  14. Emetteur comprenant :
    un circuit de source de signal qui est configuré pour fournir un signal d'entrée ;
    un circuit de sortie qui est configuré pour envoyer un signal de sortie ; et
    le filtre (400) de la revendication 1.
  15. Récepteur comprenant :
    un circuit d'entrée qui est configuré pour recevoir un signal d'entrée ;
    un circuit de rendu qui est configuré pour rendre un signal de sortie ; et
    le filtre (400) de la revendication 1.
  16. Procédé pour filtrer un signal, le procédé comprenant les étapes consistant à :
    acquérir un signal d'entrée ;
    appliquer le signal d'entrée à une entrée du filtre (400) de la revendication 1 ; et
    transporter le signal de sortie à partir de la sortie.
EP04779847A 2004-07-30 2004-07-30 Appareil et procede relatifs a des filtres a resonateurs annulaires a alimentation dedoublee et a fonction elliptique Expired - Lifetime EP1782496B1 (fr)

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PCT/US2004/024913 WO2006022672A1 (fr) 2004-07-30 2004-07-30 Appareil et procede relatifs a des filtres a resonateurs annulaires a alimentation dedoublee et a fonction elliptique

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EP1782496B1 true EP1782496B1 (fr) 2010-04-28

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JP2008172455A (ja) * 2007-01-10 2008-07-24 National Institute Of Information & Communication Technology 帯域阻止フィルタ
US8902020B2 (en) 2009-07-27 2014-12-02 Avago Technologies General Ip (Singapore) Pte. Ltd. Resonator filter with multiple cross-couplings
US11211676B2 (en) * 2019-10-09 2021-12-28 Com Dev Ltd. Multi-resonator filters
CN114976540B (zh) * 2022-03-31 2023-11-03 南通大学 一种基于三线耦合结构的无反射带通滤波器

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Publication number Priority date Publication date Assignee Title
NL7314269A (nl) * 1973-10-17 1975-04-21 Philips Nv Microgolfinrichting voorzien van een 1/2 lambda resonator.
JPH0812961B2 (ja) * 1989-05-02 1996-02-07 株式会社村田製作所 並列多段型帯域通過フィルタ
CA2185666A1 (fr) * 1994-04-14 1995-10-26 Zhi-Yuan Shen Filtres a supraconducteurs haute temperature capables de traiter des courants eleves
US6825742B1 (en) * 2002-12-30 2004-11-30 Raytheon Company Apparatus and methods for split-feed coupled-ring resonator-pair elliptic-function filters

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JP4327876B2 (ja) 2009-09-09
JP2008508788A (ja) 2008-03-21
EP1782496A1 (fr) 2007-05-09
DE602004026933D1 (de) 2010-06-10
WO2006022672A1 (fr) 2006-03-02
ATE466387T1 (de) 2010-05-15

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