Source: http://www.google.com/patents/US7750756?ie=ISO-8859-1
Timestamp: 2014-11-24 03:57:20
Document Index: 232722792

Matched Legal Cases: ['Application No. 11', 'Application No. 2005', 'art 8', 'art 8', 'art 8', 'art 63', 'art 63', 'art 63', 'art 63', 'art 63', 'art 63', 'arts 63', 'art 30', 'art 8']

Patent US7750756 - Matching circuit - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inAdvanced Patent SearchPatentsThe present invention has for its object to provide a matching circuit with multiband capability which can be reduced in size, even if the number of handled frequency bands rises. The matching circuit of the present invention comprises a load having frequency-dependent characteristics, a first matching...http://www.google.com/patents/US7750756?utm_source=gb-gplus-sharePatent US7750756 - Matching circuitAdvanced Patent SearchPublication numberUS7750756 B2Publication typeGrantApplication numberUS 12/396,980Publication dateJul 6, 2010Filing dateMar 3, 2009Priority dateMay 20, 2005Fee statusLapsedAlso published asCN1866735A, CN100527611C, EP1724936A2, EP1724936A3, US7750757, US20060261911, US20090167458, US20090179711Publication number12396980, 396980, US 7750756 B2, US 7750756B2, US-B2-7750756, US7750756 B2, US7750756B2InventorsAtsushi Fukuda, Hiroshi Okazaki, Shoichi NarahashiOriginal AssigneeNtt Docomo, Inc.Export CitationBiBTeX, EndNote, RefManPatent Citations (4), Non-Patent Citations (1), Classifications (6), Legal Events (3) External Links: USPTO, USPTO Assignment, EspacenetMatching circuitUS 7750756 B2Abstract The present invention has for its object to provide a matching circuit with multiband capability which can be reduced in size, even if the number of handled frequency bands rises. The matching circuit of the present invention comprises a load having frequency-dependent characteristics, a first matching block connected with one end to the load with frequency-dependent characteristics, and a second matching block formed by lumped elements connected in series to the first matching block. And then, when a certain frequency band is used, matching is obtained with the series impedance of the first matching block and the second matching block. When a separate frequency band is used, a π-type circuit is constituted by connecting auxiliary matching blocks to both sides of the second matching block. Next, at the same frequency, by taking the combined impedance of this π-type circuit and a load whose characteristics do not depend on the frequency to be Z0, the influence of the second matching block is removed.
CROSS REFERENCE TO RELATED APPLICATION This application is a divisional and claims the benefit of priority under 35 U.S.C. �120 from U.S. Application No. 11/434,889, filed May 17, 2006 now abandoned the entire content of which is incorporated herein by reference, and claims the benefit of priority under 35 U.S.C. �119 of Japanese Patent Application No. 2005-148621, filed May 20, 2005.
Accompanying the diversification of services offered by means of radio communications, conversion to multiband capability for processing signals in a plurality of frequency bands is required of radio equipment. As an indispensable device included in radio equipment, there is the power amplifier. In order to carry out efficient amplification, there is a need to obtain impedance matching between the amplification element and its peripheral circuits, so a matching circuit is used. As an example of a conventional multiband power amplifier, technology as shown in Reference 1 (NTT DoCoMo Technical Journal, Vol. 10, No. 1: �Mobile Handsets�) is disclosed.
BRIEF SUMMARY OF THE INVENTION The matching circuit of the present invention has a first matching block, connected at one end to a load having an impedance with frequency-dependent characteristics and a second matching block formed by a lumped-parameter element connected in series to the first matching block. E.g., the second matching block matches the impedances of the signal source and the load in the lowest frequency band. Moreover, for the purpose of impedance matching in high frequency bands, it has a π-type circuit. A π-type circuit is a circuit in which respective switch elements and auxiliary matching blocks are connected to both ends of the second matching block.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing the configuration of a conventional 800 MHz/2 GHz band power amplifier
DETAILED DESCRIPTION OF THE INVENTION Embodiment 1 In FIG. 5, the basic configuration of a matching circuit of the present invention is shown. The matching circuit of the present invention is constituted by a first matching block 2 and a matching circuit part 8 consisting of lumped elements. Matching circuit part 8 is a π-type circuit constituted by a second matching block 3, switch elements 4 and 5, and auxiliary matching blocks 6 and 7. One end of first matching block 2 is connected to a first terminal P1 to which an element 1 (a load in this example) having an impedance ZL(f) with frequency-dependent characteristics is connected. To the other end of first matching block 2, one end of second matching block 3 is connected in series. The other end of second matching block 3 is connected, via a second terminal P2, to an element 9, e.g. a signal source, with an impedance Z0 whose impedance does not depend on the frequency. Also, to the terminal on the first matching block 2 side of second matching block 3, there is connected a series circuit of switch element 4 and auxiliary matching block 6. To the other end of second matching block 3, there is connected a series circuit of switch element 5 and auxiliary matching block 7. By being connected in this way, matching circuit part 8 becomes a π-type circuit.
Embodiment 2 FIG. 8 is an example where the basic structure of this invention, shown in FIG. 5, has been generalized so that it can be adapted to a plurality of frequency bands. This matching circuit is composed of first matching block 2, L-type blocks 43 a to 43 n, and shunt circuit blocks 46 a to 46 n. Each L-type block 43 i (i=a to n) is composed of a second matching block 40 i, a first switch element 41 i, and a first auxiliary matching block 42 i. One terminal of second matching block 40 a is connected to first matching block 2. Also, the other end of second matching block 40 a is connected to one terminal of second matching block 40 b. In this way, each second matching block 40 i is connected in series. First auxiliary matching block 42 i is connected, via first switch element 41 i, to the terminal of second matching block 40 i on the side of first terminal P1. In other words, an L-type circuit is formed by means of second matching block 40 i, first switch element 41 i, and first auxiliary matching block 42 i. To the second terminal P2 side of L-type block 43 n, there are connected in parallel shunt circuit blocks 46 a to 46 n. Each shunt circuit block 46 i (i=a to n) is composed of a second switch element 44 i connected in series and a second auxiliary matching block 45 i. Below, an explanation will be given on the operation and design method of a matching circuit in which three L-type blocks 43 a to 43 c and three shunt circuit blocks 46 a to 46 c are connected.
First, an explanation will be given for the case of frequency band f4. In the case of frequency band f4, first switch elements 41 a to 41 c and second switch elements 44 a to 44 c are all in a non-conducting state. Element 1 (impedance ZL(f4)) is connected, via three second matching blocks 40 a to 40 c connected in series, to element 9 (impedance Z0). Here, the impedance ZL(f) of element 1 changes with frequency. Also, element 9 is a signal source or the like, the impedance of which does not depend on the frequency. Here, second matching block 40 c is designed so that the combined impedance of element 1, first matching block 2, and second matching blocks 40 a and 40 b is converted to Z0. If second matching block 40 c is designed in this way, the impedance Z0 is matched at the second terminal P2 side end of second matching block 40 c. In the case of frequency band f3, switch element 41 c of L-type block 43 c and second switch element 44 a of shunt circuit block 46 a are chosen to be in a conducting state. In this case, since first auxiliary matching block 42 c and second auxiliary matching block 45 a are connected to both ends of second matching block 40 c, a π-type circuit is configured. Here, second matching block 40 b is designed so that the combined impedance due to element 1 (impedance ZL(f3)), first matching block 2, and second matching block 40 a is matched to Z0. If second matching block 40 b is designed in this way, the impedance seen from the second terminal P2 side of second matching block 40 b (the first terminal P1 side of second matching block 40 c) toward element 1 becomes Z0. Also, first auxiliary matching block 42 c and second auxiliary matching block 45 a are designed so that Eq. 2 is satisfied at frequency f3. By designing in that way, the impedance seen from the first terminal P1 side of second matching block 40 c (the second terminal P2 side of second matching block 40 b) toward element 9 also becomes Z0. In other words, it is possible to remove the influence of the impedance of second matching block 40 c, so the impedances are matched.
Embodiment 3 A matching circuit generalized by using π-type circuits was explained in FIG. 8, but it is also possible to configure a generalized matching circuit using T-type circuits. In FIG. 10, there is shown an embodiment of a matching circuit using two T-type circuits. This matching circuit is composed of first matching block 2, an L-type block part 63 a, an L-type block part 63 b, and a second matching block 60 c. One end of first matching block 2 is connected to a first terminal P1 at which it is connected to element 1. Also, the other end of first matching block 2 is connected to one end of a second matching block 60 a inside L-type block part 63 a. To the other end of second matching block 60 a, there is connected an auxiliary matching block 62 a via a first switch element 61 a. Moreover, the other end of second matching block 60 a is also connected to one end of a second matching block 60 b inside L-type block part 63 b. To the other end of second matching block 60 b, an auxiliary matching block 62 b is connected via a second switch element 61 b. In addition, the other end of second matching block 60 b is also connected to one end of second matching block 60 c. Here, L-type block part 63 a is composed of second matching block 60 a, first switch element 61 a, and auxiliary matching block 62 a. Also, L-type block part 63 b is composed of second matching block 60 b, second switch element 61 b, and auxiliary matching block 62 b. Also, T-type matching circuits 64 and 65 are composed of two L-type block parts 63 a and 63 b and one second matching block 60 c. T-type matching circuit 64 is composed of second matching blocks 60 a and 60 b, first switch element 61 a, and auxiliary block 62 a. Also, T-type matching circuit 65 is composed of second matching blocks 60 c and 60 b, second switch element 61 b, and auxiliary matching block 62 b. In this way, a matching circuit which matches impedances in three frequency bands is configured in two stages with T-type matching circuits 64 and 65.
Second matching block 60 b and second matching block 60 c are designed so that the combined impedance with element 1, first matching block 2, and second matching block 60 a becomes Z0. By designing second matching block 60 b and second matching block 60 c in this way, it is possible to match the impedances at second terminal P2 of second matching block 60 c. In the case of frequency band f2, switch element 61 b constituting T-type matching circuit 65 is in a conducting state. Second matching block 60 a is designed so that the combined impedance with element 1, having an impedance ZL(f2), and first matching block 2 is taken to be Z0. By designing second matching block 60 a in this way, the impedance seen from point D toward element 1 becomes Z0. Also, auxiliary matching block 62 b is designed so that the combined impedance of second matching blocks 60 b and 60 c, auxiliary matching block 62 b, and element 9 becomes Z0. If auxiliary matching block 62 b is designed in this way, the impedance seen from point D toward the element 9 side becomes Z0. Consequently, it is possible to match the impedances at point D. Also, even on the side of second terminal P2, the impedance seen toward element 1 is Z0. Consequently, the combined impedance of second matching blocks 60 c and 60 b and auxiliary matching block 62 b does not exert any influence on the matching condition. In other words, auxiliary matching block 62 b removes the influence of second matching blocks 60 c and 60 b at frequency f2.
Embodiment 4 An example showing a generalization of the T-type matching circuit explained in Embodiment 3 is shown in FIG. 11. The configuration up to the second-stage L-type block 63 b seen from first matching block 2 is identical to that of FIG. 10. On the second terminal P2 side of second-stage L-type block 63 b, L-type blocks are added. In FIG. 11, a total of N L-type blocks 63 a to 63 n are connected. To the other end of L-type block 63 n, one end of series second matching block 70 is connected, the other end of series second matching block 70 being connected to second terminal P2. N is an integer equal to or greater than 1. The matching circuit shown in FIG. 11 is a subordinate connection configuration of N T-type matching circuits and is capable of matching in N+1 frequency bands. The operation is the same as in FIG. 10.
Embodiment 5 Another T-type matching circuit embodiment is shown in FIG. 12. In FIG. 10, a T-type circuit was formed using second matching blocks of adjacent L-type blocks. FIG. 12 is an example in which a plurality of auxiliary matching blocks are connected, via switch elements, between two second matching blocks connected in series. This matching circuit is composed of first matching block 2 and T-type matching circuits 83 a, 83 b, and 83 c. T-type matching circuit 83 a is composed of second matching blocks 80 a and 80 b, a switch element 81 a, and an auxiliary matching block 82 a. One end of second matching block 80 a is connected to first matching block 2. The other end of second matching block 80 a is connected to one end of second matching block 80 b. Also, auxiliary matching block 82 a is connected, via switch element 81 a, between second matching block 80 a and second matching block 80 b. By this kind of connection relationship, second matching blocks 80 a and 80 b, switch element 81 a, and auxiliary matching block 82 a make up a T-type circuit. T-type matching circuit 83 b is composed of second matching blocks 80 c and 80 d, a switching element 81 b, and an auxiliary matching block 82 b. T-type matching circuit 83 c is composed of second matching blocks 80 c and 80 d, a second switching element 84, and an auxiliary matching block 85. Here, second matching blocks 80 c and 80 d are constituent parts of both T-type matching circuit 83 b and T-type matching circuit 83 c. With this configuration, auxiliary matching block 82 b is connected, via switch element 81 b, to the connection point of second matching block 80 c and second matching block 80 d. Moreover, auxiliary matching block 85 is also connected, via second switch element 84, to the connection point of second matching block 80 c and second matching block 80 d. One end of second matching block 80 c is connected to second matching block 80 b. Also, the other end of second matching block 80 d is connected to the second terminal P2 to which element 9 is connected.
Embodiment 6 As explained in Embodiment 5, in the case of connecting T-type matching circuits, there are cases in which, for two second matching blocks, a plurality of auxiliary matching blocks becomes necessary. In FIG. 13, there is shown a configuration example of a matching circuit using an additional auxiliary matching block. FIG. 13 shows a configuration example where a second switch element 90 and a second auxiliary matching block 91 have been connected in series with auxiliary matching block 82 b of FIG. 12. Having auxiliary matching blocks connected in series in two stages is done so that second matching blocks 80 c and 80 d constituting T-type matching circuit 83 b can handle two frequency bands.
Embodiment 7 In the explanations so far, the second matching blocks were explained as black boxes. In FIG. 14, there is shown a configuration example of second matching block 3 of FIG. 5. Second matching block 3 is constituted by an L-type circuit consisting of a series matching block 100, a switch element 101 for matching, and a matching element 102. One end of series matching block 100 is connected to first matching block 2. Matching element 102 is connected to the other end of series matching block 100 via switch element 101 for matching.
Embodiment 8 Another configuration of the second matching block is shown in FIG. 15. Second matching block 3 in FIG. 15 is constituted by a T-type circuit consisting of second matching blocks 60 a and 60 b, a switch element 110 for matching, and a matching element 111. Second matching block 60 a and second matching block 60 b are connected in series. One end of second matching block 60 a is connected to first matching block 2. The other end of second matching block 60 b is connected to second terminal P2. Matching element 111 is connected, via switch element 110 for matching, to the connection point of second matching block 60 a and second matching block 60 b. Switch element 110 for matching and matching element 111 are provided in order to increase the freedom in designing the second matching blocks and auxiliary matching block 7 and auxiliary matching block 6. Regarding the function, it is the same as in Embodiment 7.
Embodiment 9 Another configuration of the second matching blocks is shown in FIG. 16. FIG. 16 differs from FIG. 7 in the point that, on the second terminal P2 side of T-type matching circuit part 30, there are provided a switch element 120 form matching and a matching element 121. In the case of frequency f2, switch element 33 and switch element 120 for matching are e.g. made to conduct exclusively. Matching element 121 and second matching block 31 and 32 are designed so that the combined impedance with element 1 and first matching block 2 is chosen to be Z0. By configuring the circuit in this way, it is possible to increase the freedom in designing the second matching blocks.
Embodiment 10 In the same way as configuring second matching block 3 by using a plurality of elements, first matching block 2 may also be configured with a plurality of elements. A configuration example thereof is shown in FIG. 17. In this example, first matching block 2 is composed of a first series matching block 130 and an auxiliary matching block 131 connected to one end thereof. Further, auxiliary matching block 131 may be connected to either end of first series matching block 130. First series matching block 130 is connected to element 9 via matching circuit part 8.
Application Example An exemplification of the matching circuit which has been gradually explained this far is shown in FIG. 18. FIG. 18 is an example applied to an amplifying circuit operating in two frequency bands, the 2 GHz band and the 1 GHz band. On the input side of an FET 140, which is a power amplifier element, the matching circuit shown in FIG. 17 is connected, and on the input side, the matching circuit shown in FIG. 16 is connected. As for the matching circuit on the input side, first matching block 2 has become a first matching block 141. The output side matching circuit has, based on the matching circuit shown in FIG. 16, first matching block 2 configured with a first matching block 142.
Patent CitationsCited PatentFiling datePublication dateApplicantTitleUS5786737Feb 6, 1997Jul 28, 1998Mitsubishi Denki Kabushiki KaishaFor matching input/output impedances of an element to be evaluatedUS20070018758Mar 15, 2004Jan 25, 2007Ntt Docomo Inc.Matching circuitJPH06232657A Title not availableWO2004082138A1Mar 15, 2004Sep 23, 2004Atsushi FukudaMatching circuitNon-Patent CitationsReference1Koji Chiba, et al., "Mobile Terminals", NTT DoCoMo Technical Journal, vol. 4, No. 1, Apr. 1, 2002, pp. 15-20 (with English Translation and in the specification the title is written as "Mobile Handsets").Classifications U.S. Classification333/32International ClassificationH03H7/38Cooperative ClassificationH03H7/383, H04B1/0458European ClassificationH04B1/04C, H03H7/38BLegal EventsDateCodeEventDescriptionAug 26, 2014FPExpired due to failure to pay maintenance feeEffective date: 20140706Jul 6, 2014LAPSLapse for failure to pay maintenance feesFeb 14, 2014REMIMaintenance fee reminder mailedRotateOriginal ImageGoogle Home - Sitemap - USPTO Bulk Downloads - Privacy Policy - Terms of Service - About Google Patents - Send FeedbackData provided by IFI CLAIMS Patent Services©2012 Google