EP3568913A1 - Systèmes, dispositifs et procédés de filtre accordable - Google Patents

Systèmes, dispositifs et procédés de filtre accordable

Info

Publication number
EP3568913A1
EP3568913A1 EP18738587.7A EP18738587A EP3568913A1 EP 3568913 A1 EP3568913 A1 EP 3568913A1 EP 18738587 A EP18738587 A EP 18738587A EP 3568913 A1 EP3568913 A1 EP 3568913A1
Authority
EP
European Patent Office
Prior art keywords
resonator
band
tunable
tunable filter
coupling
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Withdrawn
Application number
EP18738587.7A
Other languages
German (de)
English (en)
Other versions
EP3568913A4 (fr
Inventor
Jørgen BØJER
Peter Dam MADSEN
Arthur S. Morris
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Wispry Inc
Original Assignee
Wispry Inc
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Priority claimed from US15/402,982 external-priority patent/US10320357B2/en
Application filed by Wispry Inc filed Critical Wispry Inc
Publication of EP3568913A1 publication Critical patent/EP3568913A1/fr
Publication of EP3568913A4 publication Critical patent/EP3568913A4/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • 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
    • H03H7/0153—Electrical filters; Controlling thereof
    • 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
    • H03H7/175—Series LC in series path
    • 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
    • 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
    • H03H7/1766—Parallel LC in series path
    • 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
    • H03H7/1775—Parallel LC in shunt or branch path
    • 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
    • H03H7/46—Networks for connecting several sources or loads, working on different frequencies or frequency bands, to a common load or source
    • H03H7/466—Networks for connecting several sources or loads, working on different frequencies or frequency bands, to a common load or source particularly adapted as input circuit for receivers
    • 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
    • H03H2007/013—Notch or bandstop filters
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H2210/00—Indexing scheme relating to details of tunable filters
    • H03H2210/01—Tuned parameter of filter characteristics
    • H03H2210/012—Centre frequency; Cut-off frequency
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H2210/00—Indexing scheme relating to details of tunable filters
    • H03H2210/02—Variable filter component
    • H03H2210/025—Capacitor
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H2250/00—Indexing scheme relating to dual- or multi-band filters

Definitions

  • the subject matter disclosed herein relates generally to electromagnetic tunable filters and methods for the fabrication thereof. More particularly, the subject matter disclosed herein relates to systems, devices, and methods for tunable filters that are configured to support multiple frequency bands, such as within the field of cellular radio communication.
  • tunable single resonance filters the performance has not been satisfactory for some cellular systems due to the loss of the tuning resonator and the associated tradeoff between pass-band and stop-band attenuation.
  • tunable multiresonance filters have also been reported to have problems in that they have not been small enough, they have not had the power handling capability, or they were too complex or unrepeatable for proper integration in hand-held cellular equipment.
  • the problem with tunable systems is to make it cost effective and small while at the same time meeting system requirements (e.g., 3GPP standards).
  • duplex self-interference arises from the high power of the transmitter challenging the linearity of the receiver that can be setup with high gain to deal with comparatively low power reception levels.
  • receiver and transmitter antennas i.e., systems where transmitter and receiver have separate antennas so some duplex isolation is created between the antennas
  • receiver and transmitter antennas cannot be physically spaced apart by significant distances.
  • Locating the transmitter and receiver antennas in close proximity introduces further equipment requirements and/or other considerations, though.
  • a filter is required in the receive path that primarily rejects the transmit frequency to avoid overstearing or suppress intermodulation products in the receiver.
  • notch filtering at transmitter frequency in the receiver chain can be used.
  • a filter is required in the transmit branch that primarily rejects the transmitter noise at the receive frequency.
  • a duplex filter can be used for co-use of the same antenna for transmitter and receiver.
  • band application In addition to providing isolation between transmission and reception signals, another issue in frequency-domain duplexing for cellular applications (e.g., LTE band application) is with bands that switch from having the reception frequency higher than the transmission frequency to having the reception frequency below the transmission frequency.
  • bands 1 to 25 have reception frequency above transmission frequency (i.e., positive duplex spacing), but bands 1 3,14, 20 and 24 have the reverse order (i.e., negative duplex spacing) so that the reception frequency is below the transmission frequency.
  • Configuring a system to allow for operation using both kinds of band spacing can further require yet additional filters and switches.
  • filters have had a design constraint on component height of less than 1 mm so it could be placed together with RF transceiver integrated circuitry, digital processing integrated circuitry, and multimedia processing integrated circuitry.
  • adaptive filter having an input node and an output node can comprise a first resonator connected between the input node and a signal node, a second resonator connected between the signal node and the output node, and one or more coupling elements connected between the signal node and a ground.
  • the first resonator and the second resonator can be selectively tunable to define a reject band configured to block signals having frequencies within a first signal band between the input node and the output node, and the one or more coupling elements can be selectively tunable to define a pass band configured to pass signals having frequencies within a second signal band between the input node and the output node.
  • the one or more coupling elements can be tunable both to (1 ) a first mode at which a coupling impedance of the one or more coupling elements is tuned such that the pass band has a minimum pass band insertion loss at frequencies that are less than frequencies within the reject band and to (2) a second mode at which the coupling impedance of the one or more coupling elements is tuned such that the pass band has a minimum pass band insertion loss at frequencies that are greater than frequencies within the reject band.
  • a method for adjusting a tunable filter can include connecting a first resonator between an input node and a signal node, connecting a second resonator between the signal node and an output node, and connecting one or more coupling element between the signal node and a ground, wherein the first resonator, the second resonator, and the one or more coupling elements are electrically tunable.
  • the method can further include selectively adjusting a tuning setting of one or more of the first resonator or the second resonator to define a reject band configured to block signals having frequencies within a first signal band between the input node and the output node.
  • the method can further include selectively adjusting a tuning setting of the one or more coupling element to define a pass band configured to pass signals having frequencies within a second signal band between the input node and the output node.
  • selective adjusting a tuning setting of the one or more coupling elements can comprise selectively tuning the one or more coupling elements among (1 ) a first mode at which a coupling impedance of the one or more coupling elements is tuned such that the pass band has a minimum pass band insertion loss at frequencies that are less than frequencies within the reject band and (2) a second mode at which the coupling impedance of the one or more coupling elements is tuned such that the pass band has a minimum pass band insertion loss at frequencies that are greater than frequencies within the reject band.
  • Figures 1 through 8 each illustrate electrical schematics of configurations of a tunable filter according to embodiments of the presently disclosed subject matter
  • Figures 9 through 15 each illustrate graphs of frequency responses of a tunable filter according to embodiments of the presently disclosed subject matter at a variety of tuning states;
  • Figure 16 is a graph of inductor Q vs. inductor diameter of a tunable filter according to an embodiment of the presently disclosed subject matter
  • Figure 17 is a graph of attenuation vs. inductor coil diameter of a tunable filter according to an embodiment of the presently disclosed subject matter
  • Figure 1 8 is a smartphone floor plan according to an embodiment of the presently disclosed subject matter
  • Figure 19 illustrates schematic representations of antenna duplex systems incorporating tunable filters according to embodiments of the presently disclosed subject matter
  • Figure 20 illustrates a schematic representation of an antenna configuration incorporating a tunable filter according to an embodiment of the presently disclosed subject matter
  • Figure 21 illustrates a schematic representation of examples of various base stations and communication links for use with a tunable filter according to an embodiment of the presently disclosed subject matter
  • Figure 22 illustrates a schematic representation of an antenna duplex system incorporating tunable filters according to an embodiment of the presently disclosed subject matter.
  • the present subject matter provides systems, devices, and related methods that use tunable filters that can tune over a wide frequency range and at the same time minimize pass band attenuation and maximize stop band attenuation.
  • Such filter systems, devices, and methods can bring down the size of a tunable solution, make it more cost efficient, and at the same time solve the issue of removing unwanted interference (e.g., from a transmitter in the wireless communication terminal).
  • the term filter should be understood widely as any hardware that generates a frequency selective frequency response and can discriminate between receive and transmit frequency response (e.g., greater than about 8 dB).
  • one configuration for a tunable filter can include a first resonator, generally designated 1 10, and a second resonator, generally designated 120, connected between a first port P1 and a second port P2.
  • first resonator 1 10 includes a first capacitive element 1 1 2 connected between first port P1 and a ground
  • second resonator 1 20 includes a second capacitive element 1 22 and a second inductive element 124 (i.e., a two-terminal conductive element characterized by its ability to store magnetic field energy by having a (varying) current running between its terminals) connected in a series arrangement between second port P2 and a ground.
  • a second inductive element 124 i.e., a two-terminal conductive element characterized by its ability to store magnetic field energy by having a (varying) current running between its terminals
  • the capacitive elements can be electrically tunable capacitors.
  • the capacitive elements of the resonators can be variable capacitors implemented using any of a variety of technologies (e.g., ferroelectric, paraelectric, MEMS, and/or solid-state technologies) such that a variable and/or switchable capacitance (e.g., between about 0.7 and 1 .1 pF) is achieved by varying an electric or magnetic field.
  • a variable and/or switchable capacitance e.g., between about 0.7 and 1 .1 pF
  • one terminal of the variable capacitor e.g., a high parasitic side
  • tunable filter 100 can provide a notch filter with low Q tunable components that has adequate performance for cellular and wireless systems.
  • one terminal of the capacitor of each of the resonators can be connected to the terminal of the resonator that is connected to the signal path (i.e., in communication with one of first port P1 or second port P2).
  • the signal path i.e., in communication with one of first port P1 or second port P2.
  • an internal/direct connection can be provided in the capacitor technology substrate, although this arrangement can make the resonators more susceptible to a parasitic load from the capacitor parasitics.
  • tunable filter 1 00 can be extended to include both a number of resonators (i.e., two or more) discussed above as well as a number of coupling elements to combine the advantages of a coupled resonator band reject filter comprising inductive and capacitive elements.
  • tunable filter 100 can again comprise first resonator 1 10 and second resonator 120.
  • first resonator 1 10 can include a series connection of one or more capacitive element 1 12, which can be configured to couple an electric field, and one or more inductive element 1 14, which can have a fixed inductance (e.g., about 44 nH), and which can be configured to resonate with capacitive element 1 1 2.
  • second resonator 1 20 can include a series connection of one or more capacitive element 122 and one or more inductive element 124.
  • tunable filter 100 can further comprise one or more coupling element 130, which can provide low insertion loss (e.g., less than about 5-7 dB) within a pass band.
  • Coupling element 130 can be provided in any of a variety of configurations, but with each case comprising at least an impedance element with two terminals that is connected by a conductive material to a signal node of both of first resonator 1 10 and second resonator 1 20 so as to create coupling between the resonators.
  • a total pass band loss in tunable filter 100 can be less than about 5-7 dB at the desired duplex frequency (e.g., for a filter in a receive signal path, a pass band loss of less than about 5-7 dB at the receive frequency).
  • coupling element 130 can provide simultaneous conjugate impedance matching to the impedance at first resonator 1 10 and at second resonator 120. Specifically, by programming the impedance of coupling element 130, the frequency at which the simultaneous conjugate match occurs can be altered, which can thereby alter the frequency of the passband.
  • the impedance element of coupling element 130 includes a capacitive element.
  • the impedance element of coupling element 130 can include a variable capacitor, with changes in the capacitance (e.g., between about 0.7 and 2.8 pF) being achieved by varying an electric or magnetic field (e.g. a MEMS capacitor).
  • the impedance element of coupling element 130 includes an inductive element (i.e., characterized by its ability to store magnetic field energy by having a (varying) current running between its terminals).
  • the inductive element of coupling element 1 30 can have a fixed inductance (e.g., about 20 nH).
  • coupling element 130 can be a variable impedance element configured for changing the coupling impedance by varying an electric or magnetic field.
  • coupling element 130 comprises a first coupling capacitive element 1 32 connected between first port P1 and second port P2.
  • a coupling inductive element 134 can be provided in series with first coupling capacitive element 132 between first port P1 and second port P2.
  • a combined impedance response of the series connected inductive and capacitive elements can in majority be equal to the impedance response known from a series LC circuit and as such can have a low impedance at resonance.
  • the configuration shown in Figure 3 further comprises a second coupling capacitive element 133 connected in parallel with first coupling capacitive element 132.
  • first coupling capacitive element 132 can be a variable capacitor (e.g. a MEMS variable capacitor), where the inductance of coupling inductive element 134 can be effectively tuned by adjusting the capacitance of first coupling capacitive element 132.
  • the filter notch or reject band frequencies can be controlled by tuning one or both of first capacitive element 1 1 2 or second capacitive element 122.
  • the pass band characteristics can be determined by the configuration of inductive elements and capacitive elements in coupling element 130, with these characteristics being programmable by tuning the value of first coupling capacitive element 132.
  • the combined impedance of those elements can be selectively either primarily inductive or primarily capacitive at the desired bands of operation (i.e., RX and TX frequency).
  • 1 /(juC m i n can be greater than r ⁇ ⁇ _, and 1/((joCmax) can be less than 1 /r ⁇ ⁇ _, where ⁇ is the signal pass band frequency, L is the inductance value, C max is the maximum tunable capacitance, C m i n is the minimum tunable capacitance, and r is a constant larger than 1 (e.g., 1 .33).
  • the impedance elements can be capable of making a variable frequency response between the input (i.e., first port P1 ) and the output (i.e., second port P2).
  • the pass band and matching can be moved relative to the notch frequency.
  • the pass band can be moved to either side of the notch, thereby allowing both positive and negative frequency duplex spacings.
  • tunable filter 100 can still be configured to minimize a total pass band loss (e.g., total loss of less than about 5-7 dB) and maximize a reject band attenuation (e.g., attenuation of more than about 15-18 dB) at corresponding duplex frequencies.
  • tunable filter 1 00 can again comprise a first resonator 1 10 in communication with a first port P1 , a second resonator 120 in communication with a second port, and one or more coupling element in communication with both of first resonator 1 1 0 and second resonator 120.
  • tunable filter 100 according to the embodiments shown in Figures 5 through 8 can be configured such that first resonator 1 10 and second resonator 1 20 are connected in a series arrangement between first port P1 and second port P2, and one or more coupling element 130 is connected to a node between the series connection of first resonator 1 10 and second resonator 120.
  • first resonator 1 10 can provide maximum isolation at the notch frequency between first port P1 and a third terminal T3.
  • second resonator 120 can provide maximum isolation at the notch frequency between a fourth terminal T4 and second port P2.
  • the reject band attenuation can be more than about 15-18 dB.
  • coupling element 130 serves as a variable impedance network to optimize total power transfer between first port P1 and second port P2 at the desired pass band frequency (e.g., pass band loss of less than about 5-7 dB).
  • the frequency of the resonators and of the coupling element can be varied by controlling and electric or magnetic field (e.g., as in MEMS devices, semiconductor switched impedance networks, or field modulated dielectrics (BST)).
  • each of Figures 6 through 8 illustrate configurations of tunable filter 100 in which first resonator 1 10 includes a first capacitive element 1 12 and a first inductive element 1 14 connected in parallel with each other between first port P1 and third terminal T3.
  • second resonator 120 includes a second capacitive element 122 and a second inductive element 124 connected in parallel with each other between fourth terminal T4 and second port P2.
  • the particular configurations shown in Figures 6 through 8 differ, however, in the particular arrangement of coupling element 130.
  • coupling element 130 in the configuration illustrated in Figure 6 includes a single coupling capacitive element 132 (e.g., a tunable capacitor) that is connected between a signal node of both of first resonator 1 10 and second resonator 120 (i.e., in communication with both of third terminal T3 and fourth terminal T4) and a ground.
  • coupling element 130 includes a coupling capacitive element 132 (e.g., a tunable capacitor) and a coupling inductive element 134 connected in parallel with one another between the signal node and ground.
  • coupling element 130 is illustrated as including a single coupling inductive element 134 connected between the signal node and ground.
  • first resonator 1 1 0, second resonator 120, and/or coupling element 130 can be electrically tunable (e.g., by using variable or switchable capacitors).
  • tunable filter 100 can provide a variable frequency distance between pass- and reject-bands while still having a small size compared to conventional filter configurations for use in cellular and wireless handheld components.
  • the inclusion of coupling element 130 allows tunable filter 100 to provide a notch filter with tunable capacitors, even in configurations where the tunable capacitors exhibit high levels of parasitic capacitance to the signal ground.
  • the tunable reject band characteristics and tunable pass band characteristics enable tunable filter 1 00 to be programmed such that minimum pass band insertion loss can be either at the higher-frequency-side of the reject band or at the low-frequency-side of the reject band.
  • tunable filter 100 is well suited for use in a wireless communication system, such as in a cellular communication system.
  • tunable filter 1 00 can be used in the mobile terminal of a cellular communication system, such as in the transmission path or in the reception path of a mobile terminal having separate antennas and branches for reception and transmission.
  • tunable filter 100 can be tuned for operation in any of a variety of frequency bands.
  • Figure 9 shows a frequency response of tunable filter 100 when used in 3GPP LTE band number 3 (curve including measurements m8, m9, m10, and m1 1 ), band number 2 (curve including measurements m4, m5, m12, and m13), band number 1 (curve including measurements ml , m2, m6, and m7), and band number 7 (curve including measurements m13, m14, m15, and m16).
  • band number 3 curve including measurements m8, m9, m10, and m1 1
  • band number 2 curve including measurements m4, m5, m12, and m13
  • band number 1 curve including measurements ml , m2, m6, and m7
  • band number 7 curve including measurements m13, m14, m15, and m16.
  • Figure 10 illustrates examples of frequency responses of tunable filter 100 when operating as a tunable receive (RX) filter for positive duplex spacing in 3GPP LTE band number 12 (curve including measurements m3, m4, m5, and m12), band number 5 (curve including measurements ml , m2, m6, and m7), and band number 8 (curve including measurements m13, m14, m15, and m1 6).
  • Figure 1 1 illustrates examples of frequency responses of tunable filter 1 00 when operating as a tunable RX filter for negative duplex spacing.
  • Figure 1 2 illustrates examples of frequency responses of tunable filter 1 00 when operating as a tunable RX filter for both positive duplex spacing in 3GPP LTE band number 5 (curve including measurements ml , m2, m6, and m7), band number 8 (curve including measurements m13, m14, m15, and m16), and band number 12 (curve including measurements m3, m4, m5, and m12), and negative duplex spacing in 3GPP LTE band number 13 (curve including measurements m8, m9, ml 0, and ml 1 ).
  • the function of the one or more of tunable filter 100 can be to define tunable reject band characteristics and tunable pass band characteristics.
  • tunable filter 100 can be configured to be tunable such that a minimum pass band insertion loss can be programmed to be at either of a higher frequency side of the reject band when in a first duplexing mode or a lower frequency side of the reject band when in a second duplexing mode.
  • tunable filter 100 can be tunable such that a pass band is provided at frequencies above the reject band (i.e., "positive" duplex spacing, such as is shown in Figure 10) or at frequencies below the reject band (i.e., "negative” duplex spacing, such as is shown in Figure 1 1 ).
  • tunable filter 100 can be configured to have a total path band loss of less than 7 dB and a reject band attenuation of more than 18 dB at corresponding duplex frequencies, (i.e., if the filter is a receive filter, it can have pass band loss of less than 7 dB at the receive frequency and have attenuation at the transmit frequency of more than 1 8 dB)
  • Tunable reject band characteristics can be monitored as a change of notch frequency in the S21 transmission characteristics. Likewise, tunable pass band characteristics can be seen in the S21 transmission, but the pass band is more significantly monitorable with respect to a moving notch or notches (i.e., reject band) in the S1 1 reflection characteristics. Both curves are illustrated in Figure 13, which shows examples of pass band tuning for fixed notch frequency setting (S21 transmission at top and S1 1 reflection at bottom). It is noted that the pass band tuning is most noticeable in its reflection response.
  • Figures 14 and 15 illustrate example embodiments of pass band tuning for a fixed notch frequency setting. In particular, Figure 14 illustrates S21 transmission, and Figure 1 5 illustrates S1 1 reflection.
  • tuning the value of a capacitance in coupling element 130 can move the pass band and matching frequency from a higher frequency to a lower frequency (e.g., from right to left in Figures 14-15) as the capacitance increases, which can move the pass band from one side of the transmission notch to the other side of the transmission notch.
  • tunable filter 100 can be operable to provide a desired filter response in both "positive” and “negative” duplexing modes. (See, e.g., Figure 12)
  • the capacitive elements in either resonator and/or in the coupling element can comprise variable capacitors as discussed above.
  • Such variable capacitor can be controlled by varying and electric field or current.
  • the variable capacitors are produced using semiconductor technology like CMOS, SOI (Silicon On Insulator), PHEMT, micro-electro-mechanical systems (MEMS) technology, or tunable ceramics (e.g., BST).
  • CMOS complementary metal oxide
  • SOI Silicon On Insulator
  • PHEMT micro-electro-mechanical systems
  • MEMS micro-electro-mechanical systems
  • tunable ceramics e.g., BST.
  • adjusting the capacitance of such variable capacitors can be achieved using electro mechanical actuation (e.g. MEMS), or electric field actuation (e.g., pin diodes, tunable dielectrics like BST).
  • the capacitances can be adjusted using electrical semiconductor switches connected to an array of capacitances.
  • the electrical semiconductor switches can be based on voltage field switching (e.g., PHEMT, JFET, CMOS) or current switching (e.g., bipolar transistors like GaAs HBT).
  • the variable capacitances can be programmable either using serial bus (e.g., SPI, RFFE, I2C) or programmable registers that control the capacitance value of the variable capacitor through semiconductor devices (e.g., transistors, gates, ADC's).
  • the variable capacitances can be programmable to an integer number of discrete capacitance settings.
  • the variable capacitances can be programmable according to a binary weighting scheme, or they can be programmable according to a linearly weighting scheme.
  • the inductive elements in either resonator and/or in the coupling element
  • the inductive elements can have an outer conductor turns diameter or effective conductor winding aperture (e.g., x, y) that is larger than about 0.7 mm.
  • the inductive elements can be implemented using a number of turns of a single piece of wound wire of conductive material (e.g., copper, aluminum, gold, silver).
  • the inductive elements can be implemented using loops of bond wire by the use of wire bond technology (e.g., to form a helix-like structure).
  • the inductive elements can be implemented as a ladder inductor using mechanically shaped, etched, printed, or laser direct structuring (LDS) structures.
  • LDS laser direct structuring
  • the inductive elements can be implemented using a section of dielectric (e.g., ceramic) coax (e.g., squared or circular).
  • the inductive elements can be SMD/SMT components that are manufactured for use with SMD/SMT soldering processes.
  • first resonator 1 10 and second resonator 120 can be configured such that magnetic coupling between the inductive elements of each is reduced.
  • the inductive elements of each resonator can be separated as far as possible from each other.
  • the inductive elements can be placed at an angle close to 90 degrees (i.e., between about 45 deg and 135 deg) so as make the magnetic field of the two inductive elements as orthogonal as possible to further reduce the magnetic coupling between the resonators.
  • a first conductor connecting from first resonator 1 10 to a first terminal of coupling element 1 30 can be arranged such that it is substantially perpendicular to a second conductor connecting from second resonator 1 20 to a second terminal of coupling element 130 to minimize coupling between input and output.
  • a third conductor connecting from first port P1 to the first terminal of coupling element 130 can be substantially perpendicular to a fourth conductor connecting from second port P2 to the second terminal of coupling element 130 so as to minimize coupling between the input and output.
  • the shared path of the first and third conductors can have an impedance due to its electrical length that it is less than the impedance of a coupling capacitive element 132 at the frequencies of operation (i.e., at signal and reject frequencies). This ensures a low pass band loss (e.g., less than about 5-7 dB) and a corresponding high reject band isolation (e.g., attenuation of more than about 15-18 dB).
  • tunable filter 100 it can be implemented into a module or onto a printed circuit board or printed wire board.
  • tunable filter 1 00 can be implemented using module technology characterized by having a common carrier (e.g., a wafer as used for planar circuit semiconductors, such as a silicon wafer; a wafer as used for processing MEMS devices; or a "strip" that is commonly used for packaging and modules, where this strip can be manufactured using package laminate processing, Printed Circuit Board (PCB) technology, or build up board processing) in which components of multiple modules are integrated or mounted and interconnected.
  • a common carrier e.g., a wafer as used for planar circuit semiconductors, such as a silicon wafer; a wafer as used for processing MEMS devices; or a "strip" that is commonly used for packaging and modules, where this strip can be manufactured using package laminate processing, Printed Circuit Board (PCB) technology, or build up board processing
  • the modules can be singulated by dividing the common carrier (e.g., using SAW or routing) into individual modules, while prior to the singulation the modules can be over molded or by other means enclosed to either shield or create a regular top surface.
  • a circuit can use connections of solder balls, solder paste, and/or wire bonding.
  • the capacitive elements e.g., first capacitive element 1 12, second capacitive element 122, first coupling capacitive element 132, second coupling capacitive element 133) can all be constructed in a single fabrication flow.
  • the capacitive elements can all reside on a common substrate (e.g., a semiconductor die).
  • the inductive elements and capacitive elements can be assembled and connected in a module or other hybrid assembly.
  • connection points can be provided to which external inductors can be connected to complete the tunable filter frequency characteristics.
  • the inductive elements and capacitive elements can be mounted on the same side of a given circuit laminate, or the inductive elements and capacitive elements can be mounted on opposite sides of the circuit laminate.
  • the inductive elements can be mounted on an edge of the circuit laminate (e.g., for edge mounting).
  • the circuit laminate can be further soldered to a system printed circuit board that connects multiple modules (e.g., PA, filters, transceivers, power supplies), and such a system printed circuit board can be part of a cellular phone or modem.
  • tunable filter 1 00 within a cellular phone
  • one or more of tunable filter 100 can be incorporated in a phone such that a greater relative height of tunable filter 100 (e.g., higher than 1 mm) can be allowed, thereby allowing resonator components in tunable filter 100 to be likewise higher.
  • This additional clearance can be desirable at frequencies below 1 GHz to achieve a high enough Q for tunable filters.
  • tunable filter 100 can provide a combined solution that makes it acceptable to place tunable filter 1 00 in a location on the phone board that allows higher building height (e.g., having a height that exceed about 1 .0 mm), therefore allowing the use of higher-diameter inductors to increase inductor Q and thereby make tunable frequency filter characteristics acceptable to system requirements.
  • tunable filter 100 can be placed on a printed circuit board in a compartment of a phone having a compartment higher than 1 mm, which can allow tunable filter 1 00 to have a height of 1 mm or more.
  • tunable filter 100 can be located on a PCB in a compartment of the phone not having vertical overlap with the region in which that the display is located.
  • tunable filter 100 can be located on a PCB in a compartment of the phone not having vertical overlap with the region in which the battery is located.
  • inductor diameter Figure 1 6
  • a resulting improvement of notch improvement vs. inductor diameter Figure 17
  • An exemplary smartphone floor plan showing combined tunable filter/antenna modules, an RF transceiver TRX, a digital signal processor/micro controller unit DSP/MCU, and a multimedia controller MMC is illustrated in Figure 18.
  • a first receive tunable filter 100a-1 , a second receive tunable filter 100a-2, and a transmit tunable filter 100b are arranged around the periphery of the system in locations where there is improved vertical clearance to allow for the use of larger resonators.
  • tunable filter 1 00 can be implemented in a wireless communication system, such as in a cellular communication system, to make a wireless frequency division duplex system that adapts filter responses to a selected radio communication requirement.
  • a wireless communication system such as in a cellular communication system
  • conventional solutions require that the system switch between multiple filters (i.e., in a matched system e.g. 50 ohm) to allow for adjustments in the frequency ranges that are passed or blocked.
  • Figure 19 illustrates two antenna duplex systems into which embodiments of tunable filter 1 00 can be implemented to serve multiple frequency bands without requiring multiple filters.
  • a first tunable filter 100a and a second tunable filter 1 00b can be provided in communication with each of a reception antenna Rx ANT and a transmission antenna Tx ANT, respectively.
  • the first and second tunable filters 100a and 100b can be tuned to provide minimum pass band attenuation and maximum stop band attenuation for the respective antennas.
  • configuration (b) in Figure 19 illustrates an embodiment in which a first tunable filter 100a and a second tunable filter 100b are implemented with a multiband antenna.
  • Adjustments to the tuning state of first and second tunable filters 1 00a and 100b can again adjust the operating frequencies for both the reception and transmission, respectively, and they can further adapt their filter characteristics to both positive and negative receive-to-transmit duplex spacings.
  • This configuration thus allows the resonators of first and second tunable filters 100a and 100b to be reused for both negative and positive duplex spacings.
  • first and second tunable filters 100a and 1 00b can be configured for tuning the signal path frequency response between one or more inputs and outputs.
  • the "sign" of the duplex spacing can be calculated (or looked up).
  • the pass band of first tunable filter 100a can be set to be below the transmit band frequency. Otherwise, the pass band can be set to be above the transmit band frequency.
  • the reject band of second tunable filter 100b can be set to the receive band frequency (or as close to the reception band as the transmit band insertion loss allows). Again, if the duplex spacing is "negative,” the pass band of second tunable filter 100b can be set to be above the receive band frequency. Otherwise, it can be set to be below the receive band frequency.
  • the spacing between desired rejection and pass bands will be near enough to each other that the edges of the rejection and pass bands may be in the filter frequency response transition region between the reject notch and low insertion regions of the filter, In this case, a tradeoff in tuning setting can be made between the achieved rejection at the edge of the rejection band and the achieved insertion loss at the edge of the passband. It may be that he reject band of first tunable filter 100a can be set to the transmit band frequency, but if not, it can be set as close to the transmit band as the resulting reception band insertion loss specification allows.
  • tunable filter 1 00 can tune over a wide frequency range by changing the characteristics of the filter.
  • tunable filter 100 can change reactive impedances within the filter circuit instead of switching at non-reactive impedances exterior to the filter circuit.
  • an antenna ANT is connected to a signal transfer block STB, tunable filter 100, and a signal processing chain SPC and is configured for communicating with a remote wireless communication unit.
  • the remote wireless communication unit can be a base station (e.g., a cellular base station).
  • the remote wireless communication unit can be a 3GPP base transceiver station BTS, although other units (e.g., NB and eNB) can be considered base stations according to this terminology.
  • Figure 21 illustrates examples of various base stations (e.g., BTS, NB, eNB) and communication links for 3GPP standards.
  • antenna ANT provides electromagnetic coupling of a transmission or receive signal towards a remote wireless communication unit either through direct coupling (e.g., self-radiating antenna) or through coupling to another metallic surface (e.g., terminal ground chassis).
  • antenna ANT can contain one or more signal path input/output and one or more connection points for load tuning.
  • antenna ANT can itself contain a matching circuit that optionally can be tunable.
  • Signal transfer block STB provides signal connections between the antenna ANT and tunable filter 100.
  • signal transfer block can include one or more of a fixed frequency filter (e.g., harmonic filter), an amplifier configured for amplifying levels between input and outputs, an electromagnetic coupling path (inductive or capacitive), a circuit for maximizing signal bandwidth, a conductive connection between inputs and outputs (e.g., short or transmission line type), or a combination thereof.
  • Signal processing chain SPC is one or both of the input to the signal path to a unit that either further process the receive signal or the output to the signal path that process the transmission signal.
  • the unit that process the receive signal can include one or more of a low noise amplifier (LNA), a frequency selection down conversion mixer, a variable gain amplifier (VGA), a system of signal selection filtering, an ADC system and a digital processing system (e.g., DSP).
  • the unit that process the transmission signal can include one or more of a digital processing system, an oscillator, a modulator, and one or more amplifier stages.
  • the system can be configured to communicate a modulated signal according to a wireless standard in accordance with a standardization body (e.g., 3GPP).
  • a standardization body e.g., 3GPP
  • configurations for tunable filter 100 can selectively allow signals to be passed at either side of the reject band.
  • tunable filter 100 can be tuned to have a reject band at either a transmit or receive frequency, and tunable filter 100 can be programmed to operate in either a first mode of operation in which the primary pass band at either the receive or transmit frequency is above the reject band frequency or a second mode of operation in which the primary pass band is below the receive or transmit frequency (i.e., reversible duplex order).
  • the pass band can be tunable to more than one frequency on one or more side of the reject band (i.e., tunable duplex spacing).
  • the reject band can likewise be tunable in frequency.
  • the variation of the impedance required to change the impedance and/or frequency characteristics can be achieved by applying a pseudo static electric or magnetic field.
  • a wireless system can include first tunable filter 100a and a first controller 150a incorporated into a receive signal path, which can further include one or more of an LNA, a frequency selection quadrature down conversion mixer, a VGA, a system of signal selection filtering, an ADC system, and a digital processing system (e.g., DSP).
  • first controller 150a can be connected in a signal link to an antenna, where the antenna receives signal from a base station and the output of first tunable filter 100a transfers the now filtered signal to a receive branch of the wireless device (e.g., LNA input).
  • a second tunable filter 100b and a second controller 150b can be incorporated into a transmit signal path.
  • second tunable filter 100b can receive a signal from the transmit branch of a wireless device (e.g., from a power amplifier (PA) pre-driver), and by means of a signal transfer path (e.g., a PA) can transfer the transmit signal to the antenna element that further transfers the signal to a base station.
  • a wireless device e.g., from a power amplifier (PA) pre-driver
  • PA power amplifier
  • a signal transfer path e.g., a PA
  • first tunable filter 100a and/or second tunable filter 100b can be configured to provide a tunable reject band and a tunable pass band relative to the respective reject band.
  • first controller and second controller 150a and 1 50b can comprise a digital control interface (e.g., a SPI, I2C or an RFFE interface), which can include a latch register and decoding and connection circuit capable of reading latch register information and apply this information to change the impedance of the variable elements in first tunable filter 100a or second tunable filter 100b, respectively.
  • a digital control interface e.g., a SPI, I2C or an RFFE interface
  • first tunable filter 100a and/or second tunable filter 100b can respond (e.g., based on UE downlink protocol stack information) to commands giving by a wireless base station controller. In this way, the respective one of first tunable filter 100a or second tunable filter 100b can set up the frequency response according the band assigned for receive or transmit.
  • first tunable filter 100a or second tunable filter 100b can set up the frequency response according to the physical frequency channel assigned for receive or transmit.
  • first controller 150a and/or second controller 150b is configured to set up the frequency response of the respective one of first tunable filter 1 00a and/or second tunable filter 100b according to the channel, frequency, or frequency band being scanned for power (e.g. searching for high power broadcast channels).
  • This information about channel or frequency can be taken either from the layered UE protocol stack (e.g., 3GPP channel numbers) or from somewhere in the processing chain that do translation of channel number to PLL setting. In this way, the respective one of first controller 150a or second controller 150b can set up the frequency response of the corresponding circuit or subcircuit according to the physical frequency channel assigned for receive or transmit, respectively.
  • the layered UE protocol stack e.g., 3GPP channel numbers
  • the respective one of first controller 150a or second controller 150b can set up the frequency response of the corresponding circuit or subcircuit according to the physical frequency channel assigned for receive or transmit, respectively.
  • Both of first controller and second controller 150a and 1 50b can receive control inputs from a master control unit 200 to control the communication protocols to and from the base station BTS.
  • a multimedia controller or applications processor 210 can be provided in communication with master control unit 200 to control the user operating system (e.g., with a graphical interface), user applications, or the like.
  • the DSP, master control unit 200, and multimedia controller or applications processor 210 can have shared hardware and processor(s).
  • tunable filter 1 00 can provide frequency-selective filtering response between its input and output terminals (e.g., first port P1 and second port P2 in the embodiments discussed above) according to the setting of a control unit provided in communication with tunable filter 100.
  • tunable filter 100 can be configured to provide tunable band reject characteristics and a programming mode allowing the primary reject frequency or frequencies to be moved (e.g., movable notch for suppressing duplex self-interferer).
  • tunable filter 100 can provide a tunable pass band characteristics and programming mode allowing the pass band frequency to be moved relative to the reject band frequency, and/or it can provide a tunable pass band characteristics allowing the primary pass band in one case to be above the primary reject band frequency and another mode allowing the primary pass band in this mode to be below the primary reject band frequency.
  • a method for operating a tunable filter to support multiple frequency bands is provided.
  • the method can be run by master control unit 200.
  • the method can involve, while searching for signal power, looking up a scan frequency.
  • the reject band of first tunable filter 100a can be tuned away from a PLL scan frequency, and first tunable filter 1 00a can further be programmed to align the pass band with the PLL scan frequency.
  • a scan can be performed at the scan frequency, and a next scan frequency can be looked up.
  • the pass- and reject-band settings can be reset again if the loss measured in first tunable filter 100a is too high at the scan frequency (or even as a default). Otherwise, the pass- and reject-band settings can be maintained for the next scan.
  • the method can involve looking up the receive band frequency, tuning the reject band of first tunable filter 100a away from the receive band frequency (or alternatively to the transmit band frequency), and programming the pass band of first tunable filter 100a to align with the receive frequency.
  • the method can involve receiving channel and band information from base station BTS.
  • Master control unit 200 can calculate (or look up) the sign of the duplex spacing (i.e., positive or negative spacing) and set the rejection band of first tunable filter 100a to the transmit frequency (e.g., as close to the receive frequency as the insertion loss allows). If the duplex spacing is negative (e.g., operating in bands 13, 14, 20, 24), the pass band of first tunable filter 100a can be set to be below the transmit frequency. Otherwise, the pass band of first tunable filter 100a can be set to be above the transmit frequency. In either case, these filter settings can be sent to first controller 150a.
  • the reject band of second tunable filter 100b can be set to the receive frequency (e.g., as close to the receive frequency as the insertion loss allows). If the duplex spacing is negative (e.g., operating in bands 13, 14, 20, 24), the pass band of second tunable filter 100b can be set to be above the receive frequency. Otherwise, the pass band of the second tunable filter 1 00b can be set to be below the receive frequency. In either case, these filter settings can be sent to second controller 150b.
  • first tunable filter 100a e.g., RX
  • second tunable filter 1 00b e.g., TX

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Control Of Motors That Do Not Use Commutators (AREA)
  • Filters And Equalizers (AREA)

Abstract

L'invention concerne des systèmes, des dispositifs et des procédés de filtres accordables qui sont configurés pour accepter plusieurs bandes de fréquence, comme dans le domaine des communications radio cellulaires et qui peuvent comporter un premier résonateur et un second résonateur configurés pour bloquer des signaux dans une ou plusieurs plages de fréquence, et un ou plusieurs éléments de couplage connectés à la fois au premier et au second résonateur. Le ou les éléments d'accouplement peuvent être configurés de manière à présenter de faibles pertes d'insertion dans une bande passante.
EP18738587.7A 2017-01-10 2018-01-05 Systèmes, dispositifs et procédés de filtre accordable Withdrawn EP3568913A4 (fr)

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US15/402,982 US10320357B2 (en) 2013-03-15 2017-01-10 Electromagnetic tunable filter systems, devices, and methods in a wireless communication network for supporting multiple frequency bands
PCT/US2018/012546 WO2018132314A1 (fr) 2017-01-10 2018-01-05 Systèmes, dispositifs et procédés de filtre accordable

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US10320357B2 (en) 2013-03-15 2019-06-11 Wispry, Inc. Electromagnetic tunable filter systems, devices, and methods in a wireless communication network for supporting multiple frequency bands
JP7313477B2 (ja) * 2019-05-08 2023-07-24 テレフオンアクチーボラゲット エルエム エリクソン（パブル） マルチバンドイコライザ
CN112564645B (zh) * 2021-02-18 2021-05-28 广州慧智微电子有限公司 一种多频低噪声放大器
CN113037240B (zh) * 2021-03-08 2022-06-24 电子科技大学 一种具有连续频率可调特性的宽可调范围带阻滤波器装置

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TWI239116B (en) * 2004-09-01 2005-09-01 Ind Tech Res Inst Dual-band bandpass filter
US7262677B2 (en) * 2004-10-25 2007-08-28 Micro-Mobio, Inc. Frequency filtering circuit for wireless communication devices
KR101350244B1 (ko) * 2010-01-28 2014-01-13 가부시키가이샤 무라타 세이사쿠쇼 튜너블 필터
FR2970129B1 (fr) * 2010-12-30 2013-01-18 Thales Sa Filtre variable par condensateur commute au moyen de composants mems
EP2974011A4 (fr) * 2013-03-15 2016-12-21 Wispry Inc Systèmes, dispositifs et procédés de filtres ajustables
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