JP5937826B2 - Wireless module - Google Patents

Description

  The present invention relates to a wireless module.

  Conventionally, a first transmission line including a short-circuit point and a plurality of adjustment points at one end, and a part or all of the first transmission line are arranged in parallel, opposite to the short-circuit point of the first transmission line. A second transmission line including a short-circuit point and a plurality of adjustment points on the side, the short-circuit point of the first transmission line and the short-circuit point of the second transmission line are connected, and the first and second transmission lines There has been a circuit having a matching circuit that is matched by connection of opposing adjustment points (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 10-224119

  By the way, the conventional circuit has a problem that the end of the second transmission line opposite to the short-circuit point is an open stub, so that the signal deteriorates when transmitting a high-frequency signal.

  Accordingly, an object of the present invention is to provide a wireless module in which signal degradation is suppressed.

A wireless module of one aspect of the present invention includes a substrate, an antenna, a line having a characteristic impedance that is formed on one surface of the substrate, has one end connected to the antenna, and impedance-matched to the antenna, an amplifier connected to the other end of the line is formed along the longitudinal direction of the line on the one surface of the substrate, viewed contains a pad which is held at ground potential, said pad, A plurality of lines are formed along the longitudinal direction of the line .

  A unique effect that a wireless module in which signal degradation is suppressed can be provided.

It is a perspective view which shows the wireless module of embodiment. 1 is a diagram illustrating a wireless module 100. FIG. It is a figure which shows the equivalent circuit of the radio | wireless module 100 of embodiment. It is a figure which shows the Smith chart obtained by simulation about the wireless module 100 of embodiment. It is a figure which shows the Smith chart obtained by simulation about the wireless module 100 of embodiment. It is a figure which shows the equivalent circuit of the radio | wireless module 100 of embodiment. It is a figure which shows the characteristic of S21 parameter of the radio | wireless module 100 of embodiment. It is a figure which shows the characteristic of S21 parameter of the radio | wireless module 100 of embodiment. It is a figure which shows the characteristic of S21 parameter of the radio | wireless module 100 of embodiment. It is a top view which shows the radio | wireless module 100A of the 1st modification of embodiment. It is a top view which shows the radio | wireless module 100B of the 1st modification of embodiment.

  Embodiments to which the wireless module of the present invention is applied will be described below.

<Embodiment>
FIG. 1 is a perspective view illustrating a wireless module according to an embodiment. Here, an XYZ coordinate system is defined as an orthogonal coordinate system as shown in FIG.

  The wireless module 100 according to the embodiment includes a substrate 101, a line 102, pads 103A to 103E, a ground pattern 104, an antenna 105, a resist 106, a PA (Power Amplifier) 107, a capacitor 108, and a resistor chip 109.

  As the substrate 101, for example, a FR-4 (Flame Retardant Type 4) standard substrate in which a glass cloth base material is impregnated with an epoxy resin can be used. For example, the substrate 101 may include a filler such as carbon fiber instead of the glass cloth base material, or may be formed of only an epoxy resin without including the glass cloth base material. The substrate 101 may be a Teflon (registered trademark) glass substrate or a flexible substrate formed of polyimide resin or the like.

  The line 102 is formed on one surface of the substrate 101 (the upper surface in FIG. 1). The line 102 is formed, for example, by patterning a copper foil formed on one surface of the substrate 101.

  The line 102 forms a microstrip line by forming a ground pattern on one surface of the other surface (the lower surface in FIG. 1) of the substrate 101. The length (length in the longitudinal direction (X-axis direction)) from one end 102A to the other end 102B of the line 102 is equal to or shorter than the half (λe / 2) of the effective length (λe) of the used wavelength of the wireless module 100. The reason for setting the length of the line 102 to be set to λe / 2 will be described later.

  A PA 107 is connected to one end 102 A of the line 102, and an antenna 105 is connected to the other end 102 B of the line 102 via a capacitor 108.

  The pads 103A to 103E are formed at equal intervals on the side of the line 102 along the longitudinal direction of the line 102. The pads 103A to 103E are connected to the ground pattern 104 by vias (not shown) and are held at the ground potential.

  The pads 103A to 103E are formed by patterning a copper foil formed on one surface of the substrate 101, for example. The pads 103 </ b> A to 103 </ b> E may be formed simultaneously with the line 102 by patterning a copper foil formed or pasted on the entire surface of one surface of the substrate 101.

  The ground pattern 104 is formed by, for example, forming or sticking a copper foil on the entire other surface of the substrate 101.

  The antenna 105 is formed at the end on the X axis positive direction side of one surface of the substrate 101. The antenna 105 illustrated in FIG. 1 is a T-shaped monopole antenna. However, the antenna 105 may have any shape as long as communication as the wireless module 100 is possible. An inverted F-type antenna may be used.

  The antenna 105 is formed, for example, by patterning a copper foil formed on one surface of the substrate 101. The antenna 105 may be formed at the same time as the line 102 and the pads 103A to 103E by patterning a copper foil formed or pasted on the entire surface of one surface of the substrate 101.

  The resist 106 is formed on one surface of the substrate 101 from above the line 102, the pads 103 </ b> A to 103 </ b> E, and the antenna 105. As the resist 106, for example, a film made of polyamide or polyimide can be used.

  The resist 106 includes openings 111 to 115 formed on the line 102 at equal intervals along the X axis, openings 121 to 125 formed on the pads 103A to 103E, respectively, and a capacitor 108. An opening 131 for connection between the other end 102 </ b> B of the line 102 and the antenna 105 is formed.

  The openings 111 to 115 and the openings 121 to 125 are formed so that the positions in the X-axis direction coincide with each other. Further, the pads 103A to 103E are positioned so as to be exposed from the openings 121 to 125, respectively.

  Although not shown in FIG. 1, the resist 106 is also formed with an opening for connecting one end 102 </ b> A of the line 102 and the PA 107.

  The PA 107 is connected to a filter (not shown) and an RF (Radio Frequency) circuit, and a transmission signal output from the RF circuit is input through the filter. A transmission signal input to the PA 107 is transmitted to the antenna 105 through the line 102 and the capacitor 108 and radiated from the antenna 105.

  The capacitor 108 is connected between the other end 102 </ b> B of the line 102 and the T-shaped base 105 </ b> A of the antenna 105, and is provided to block a direct current component.

  The resistor chip 109 connects the portion exposed from the opening 111 of the line 102 and the pad 103A. The resistor chip 109 includes, for example, a portion exposed from the opening of the line 102, a portion exposed from the opening 111 of the line 102 by applying cream solder on the pad 103A and reflowing the cream solder, Connected to the pad 103A.

  For example, a resistor chip 109 having a resistance value of 0Ω can be used. Further, instead of the resistor chip 109, an element having an inductance component or an element having a capacitance component may be connected as a reactance element.

  The resistor chip 109 is connected to a portion exposed from the opening 111 of the line 102 and the pad 103A in order to adjust the characteristic impedance of the line 102.

  The resistor chip 109 may be connected between the portion exposed from the opening 112 of the line 102 and the pad 103B, and between the portion exposed from the opening 113 of the line 102 and the pad 103C, the opening of the line 102. It may be connected between the portion exposed from 114 and the pad 103D, or between the portion exposed from the opening 115 of the line 102 and the pad 103E.

  That is, the resistor chip 109 can be connected to five locations in the X-axis direction, and a plurality of resistor chips 109 may be connected to a plurality of five locations.

  The antenna 105 has an impedance of 50Ω, for example, and the line 102 is set to have a characteristic impedance of 50Ω that is impedance matched with the antenna 105 in order to reduce the total transmission loss of the transmission signal.

  On the other hand, the impedance of the PA 107 is, for example, about 10Ω or 20Ω.

  Therefore, it is difficult to achieve impedance matching between the antenna 105 and the PA 107.

  For this reason, in the wireless module 100 of the embodiment, the pads 103A to 103E that are held at the ground potential are provided along the line 102, and the line 102 and the pads 103A to 103E are connected by the resistor chip 109. The characteristic impedance is adjusted to improve the impedance matching between the PA 107 and the antenna 105.

  FIG. 2 is a diagram illustrating the wireless module 100, and FIG. 2A illustrates a state in which the resist 106, the PA 107, the capacitor 108, and the resistor chip 109 are removed. FIG. 2B illustrates a lower surface side of the wireless module 100 illustrated in FIG.

  As shown in FIG. 2A, pads 103 </ b> A to 103 </ b> E are formed along the line 102. In addition, a base portion 105A of the antenna 105 is located in the vicinity of the other end 102B of the line 102. The state illustrated in FIG. 2A corresponds to a state in which the copper foil formed or attached to one surface of the substrate 101 is patterned to form the line 102, the pads 103A to 103E, and the antenna 105.

  As shown in FIG. 2B, a ground pattern 104 is formed on the other surface of the substrate 101.

  FIG. 3 is a diagram illustrating an equivalent circuit of the wireless module 100 according to the embodiment.

  In FIG. 3, portions of the line 102 exposed at the openings 111 to 115 of the resist 106 are shown as taps 141 to 145.

  Further, the input port of the PA 107 is denoted by reference numeral 151, and the input port corresponding to the base portion 105 </ b> A (see FIGS. 1 and 2) of the antenna 105 is denoted by reference numeral 152.

  In FIG. 3, the pad 103A and the tap 141 are connected by the resistor chip 109 indicated by a solid line, but this is the same as the state shown in FIG. The resistor chip 109 may be connected between the pad 103B and the tap 142, the pad 103C and the tap 143, the pad 103D and the tap 144, or the pad 103E and the tap 145, as indicated by a broken line.

  Next, a simulation result performed with the use frequency of the wireless module 100 set to 2.45 GHz will be described. Since the effective wavelength at 2.45 GHz is about 60 mm, the length from one end 102A of the line 102 to the other end 102B is set to 30 mm.

  The length from the one end 102A to the tap 141 was 5 mm, the length between each of the taps 141 to 145 was 5 mm, and the length from the tap 145 to the other end 102B was 5 mm.

  4 and 5 are diagrams illustrating Smith charts obtained by simulation for the wireless module 100 of the embodiment.

  The Smith chart was obtained by measuring the S11 parameter at the input ports 151 and 152 while changing the frequency from 2 GHz to 3 GHz with a 50Ω resistor connected to the input port 151 shown in FIG.

  The Smith chart shown in FIG. 4A is a characteristic obtained in a state where the resistor chip 109 is not connected to any of the pads 103A to 103E and the taps 141 to 145. The Smith chart shown in FIG. 4B shows characteristics obtained in a state where the resistor chip 109 is connected between the pad 103 </ b> A and the tap 141. The Smith chart shown in FIG. 4C shows characteristics obtained in a state where the resistor chip 109 is connected between the pad 103B and the tap 142. FIG.

  Further, the Smith chart shown in FIG. 5A shows characteristics obtained in a state where the resistor chip 109 is connected between the pad 103C and the tap 143. The Smith chart shown in FIG. 5B shows characteristics obtained in a state where the resistor chip 109 is connected between the pads 103C and 103D and the taps 143 and 144, respectively. The Smith chart shown in FIG. 5C shows characteristics obtained in a state where the resistor chip 109 is connected between the pad 103D and the tap 144. The Smith chart shown in FIG. 5D shows characteristics obtained in a state where the resistor chip 109 is connected between the pad 103E and the tap 145.

  Thus, it has been found that the Smith chart changes depending on where the resistor chip 109 is connected to the pads 103A to 103E and the taps 141 to 145.

  4 and 5, FIGS. 4B, 4 </ b> C, 5 </ b> A, 5 </ b> C, and 5 </ b> D are pads 103 </ b> A to 103 </ b> E and taps 141 to 145. The results of connecting the resistor chips 109 in order are shown, and it can be seen that the 2 GHz to 3 GHz impedance of the line 102 can be made to make one round (360 degrees) around 50Ω.

  Therefore, it can be seen from these figures that the impedance of 2 GHz to 3 GHz of the line 102 can be made to make one turn (360 degrees) around 50Ω by adjusting the position where the resistor chip 109 is connected to the line 102.

  For this reason, even if the antenna 105 and the PA 107 are connected to the line 102, the characteristic impedance of the line 102 can be optimized by connecting the resistor chip 109 to a position where an optimum impedance is obtained.

  Here, the Smith charts of FIGS. 4 and 5 are obtained by setting the length of the line 102 to half (λe / 2) of the effective length (λe) of the used wavelength.

  Accordingly, in order to adjust the impedance of the line 102 in a state where the antenna 105 and the PA 107 are connected to the line 102, the length of the line 102 is half the effective length (λe) of the used wavelength (λe / 2). It ’s enough. That is, the length of the line 102 may be a length that is equal to or less than half (λe / 2) of the effective length (λe) of the used wavelength.

  Next, the S21 parameter obtained by the simulation for the wireless module 100 of the embodiment will be described.

  FIG. 6 is a diagram illustrating an equivalent circuit of the wireless module 100 according to the embodiment.

  In FIG. 6, as in FIG. 3, portions of the line 102 exposed at the openings 111 to 115 of the resist 106 are shown as taps 141 to 145. Further, the input port of the PA 107 is denoted by reference numeral 151, and the input port corresponding to the base portion 105 </ b> A (see FIGS. 1 and 2) of the antenna 105 is denoted by reference numeral 152.

  The S21 parameter was measured with an XΩ resistor connected to the port 151 and a 50Ω resistor connected to the port 152. As XΩ, 10Ω or 50Ω is used. A resistance of 50Ω corresponds to the antenna 105.

  In addition, the board | substrate 101 used the thickness of 0.5 mm of FR-4 specification, the width | variety of the track | line 102 was set to 1 mm, and the characteristic impedance was set to 50 (ohm). In this state, the difference in S21 parameter depending on the presence / absence of the resistor chip 109 and the position where the resistor chip 109 is connected was obtained by simulation.

  7 to 9 are diagrams illustrating characteristics of the S21 parameter of the wireless module 100 according to the embodiment.

  In FIG. 7, when X = 10Ω and the resistor chip 109 is connected between the pad 103E and the tap 145, and when X = 50Ω, the resistor chip 109 is connected between the pads 103A to 103E and the taps 141 to 145. This is the result obtained when the resistor chip 109 is not connected between the pads 103A to 103E and the taps 141 to 145 with X = 10Ω.

  Of these, when X = 10Ω and the resistor chip 109 is connected between the pad 103E and the tap 145, the pad 103A and the tap 141 are connected by the resistor chip 109, and the impedance of the line 102 is adjusted by the resistor chip 109. This is the case.

  When X = 50Ω and the resistor chip 109 is not connected between the pads 103A to 103E and the taps 141 to 145, the characteristic impedances of the line 102 and the port 151 are matched. Further, when X = 10Ω and the resistor chip 109 is not connected between the pads 103A to 103E and the taps 141 to 145, the PA 107 having a resistance value of 10Ω is connected to the line 102.

  In FIG. 8, when X = 10Ω and the resistor chip 109 is connected between the pad 103C and the tap 143, and when X = 50Ω, the resistor chip 109 is connected between the pads 103A to 103E and the taps 141 to 145. This is the result obtained when the resistor chip 109 is not connected between the pads 103A to 103E and the taps 141 to 145 with X = 10Ω.

  When X = 10Ω and the resistor chip 109 is connected between the pad 103C and the tap 143, the pad 103C and the tap 143 are connected by the resistor chip 109 and the impedance of the line 102 is adjusted by the resistor chip 109. .

  The remaining two cases are the same as in FIG.

  FIG. 9 shows a case where the resistor chip 109 is connected between the pad 103A and the tap 141 with X = 10Ω, and the resistor chip 109 is connected between the pads 103A to 103E and the taps 141 to 145 with X = 50Ω. This is the result obtained when the resistor chip 109 is not connected between the pads 103A to 103E and the taps 141 to 145 with X = 10Ω.

  When the resistance chip 109 is connected between the pad 103A and the tap 141 with X = 10Ω, the pad 103A and the tap 141 are connected with the resistance chip 109 and the impedance of the line 102 is adjusted with the resistance chip 109. .

  The remaining two cases are the same as in FIG.

  As shown in FIG. 7, when the S21 parameter is compared with X = 10Ω and the presence or absence of the resistor chip 109, the value of the S21 parameter when the resistor chip 109 is connected is about 2.25 GHz to about 2.6 GHz. It was found that it exceeded the value of the S21 parameter when the chip 109 was not connected. When the resistor chip 109 is connected, the value of the S21 parameter is maximum at about 2.45 GHz, and a value close to the case of X = 50Ω is obtained.

  8 and 9, it can be confirmed that the value of the S21 parameter changes when the resistor chip 109 is connected at X = 10Ω, but it exceeds that when the resistor chip 109 is not connected at X = 10Ω. There wasn't.

  As described above, in the case of X = 10Ω, it can be seen that the value of the S21 parameter can be improved by selecting the location where the resistor chip 109 is connected, and the deterioration of the signal when the signal is transmitted through the line 102 can be reduced. It was.

  When the resistor chip 109 is connected in the equivalent circuit shown in FIG. 6, the S21 parameter shown in FIG. 7 is the best, so that the resistor chip 109 is connected between the pad 103E and the tap 145. It has been found that the characteristic impedance of the line 102 is optimized.

  As described above, for example, when communication is performed using a frequency of 2.45 GHz for a wireless local area network (LAN), the resistor chip 109 is connected to the pad 103E when the resistor chip 109 is connected with the equivalent circuit illustrated in FIG. It has been found that the characteristic impedance of the line 102 can be optimized by connecting between the line and the tap 145.

  FIG. 10 is a plan view showing a wireless module 100A according to a first modification of the embodiment. In FIG. 10, the resist 106 is omitted.

  The wireless module 100A includes ground patterns 200A and 200B on one surface of the substrate 101. The ground patterns 200A and 200B are formed on both sides of the line 102, and construct a coplanar line with the line 102. The ground patterns 200 </ b> A and 200 </ b> B have the same dimension in the X-axis direction as the line 102.

  The PA 107 (see FIG. 1) is connected to one end 102A of the line 102 and a portion 202 located near the one end 102A in the ground pattern 200A.

  The capacitor 108 (see FIG. 1) is connected to the other end 102B of the line 102 and the base portion 105A of the antenna 105.

  In such a wireless module 100A, the ground pattern 104 may be formed on the other surface of the substrate 101, similarly to the wireless module 100 shown in FIG. When forming the ground pattern 104 on the other surface of the substrate 101, for example, the ground patterns 104 and 200 may be connected by vias penetrating the substrate 101.

  When the ground pattern 104 is formed in addition to the ground patterns 200A and 200B, the line 102 constructs the ground pattern 104 and the microstrip line, and therefore the distance in the Y-axis direction between the ground patterns 200A and 200B is If the width in the Y-axis direction is W, 5 W is set.

  FIG. 11 is a plan view showing a wireless module 100B according to a first modification of the embodiment. In FIG. 10, the resist 106 is omitted.

  A wireless module 100B illustrated in FIG. 11 illustrates a state in which the resist 106, the PA 107, the capacitor 108, and the resistor chip 109 are not connected, as in FIG.

  The wireless module 100B includes a pad 303 instead of the pads 103A to 103E of the wireless module 100 illustrated in FIG.

  The pad 303 has a shape in which the pads 103A to 103E shown in FIG. The pad 303 is connected to the ground pattern 104 formed on the other surface of the substrate 101 by vias 304A to 304E, and is held at the ground potential.

  If the resistor chip 109 is connected to an arbitrary position of the pad 303, the characteristic impedance of the line 102 is optimized even if the PA 107 and the antenna 105 are connected to the line 102, as in the wireless module 100 shown in FIG. can do.

  Note that the vias 304A to 304E that connect the pad 303 to the ground pattern 104 may be formed at, for example, the center positions of the pads 103A to 103E shown in FIG.

  As described above, the pad 303 is formed continuously in the X-axis direction, but since a plurality of vias 304A to 304E are formed from one end 303A to the other end 303B in the X-axis direction, the one end 303A to the other end 303B are formed. No matter where the resistor chip 109 is connected, an open stub is hardly formed, and deterioration of a high frequency signal can be suppressed.

  The wireless module of the exemplary embodiment of the present invention has been described above, but the present invention is not limited to the specifically disclosed embodiment, and does not depart from the scope of the claims. Various modifications and changes are possible.

100, 100A, 100B Wireless module 101 Substrate 102 Line 103A-103E Pad 104, 200A, 200B Ground pattern 105 Antenna 106 Resist 107 PA
108 Capacitor 109 Resistor Chip 111-115 Opening 121-125 Opening 131 Opening

Claims (7)

A substrate,
An antenna,
A line having a characteristic impedance that is formed on one surface of the substrate and has one end connected to the antenna and impedance-matched to the antenna;
An amplifier connected to the other end of the line;
Is formed along the longitudinal direction of the line on the one surface of the substrate, viewed contains a pad which is held at ground potential,
A plurality of the pads are formed along the longitudinal direction of the line . A resist layer formed on one surface of the substrate;
Together formed the first opening above the pad of the resist layer, wherein an upper portion of the position corresponding to the pad second opening of the line is formed, according to claim 1, wherein the radio module. Further comprising, according to claim 1 or 2 radio module according to the resistance or reactance element connecting the said pad line. A ground pattern formed on the other surface of the substrate;
The line is to build the ground pattern and the microstrip line, a wireless module of any one of claims 1 to 3. The pad is a part of a ground pattern formed on the one surface of the substrate;
The line is to build the ground pattern and the coplanar line, wireless module of any one of claims 1 to 4. Radio module which capacitors are inserted in series, according to any one of claims 1 to 5 between the line and the antenna. The wireless module according to any one of claims 1 to 6 , wherein a length of the line in a longitudinal direction is not more than a half of an effective length of a used wavelength.

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