JPH07202503A - High frequency switch - Google Patents

Abstract

PURPOSE:To provide the small-sized high frequency switch by incorporating a second strip line in a multilayered substrate and forming first and second diodes, a first strip line, etc., on the substrate. CONSTITUTION:This high frequency switch 10 includes a laminated body or the multilayered substrate. The first strip line electrodes and a second strip line electrode to be the first strip line, and the second strip line, are incorporated in the multilayered substrate. A first diode 44, a second diode 46, a chip inductor 48 to be an inductor, etc., are mounted on this multilayered substrate 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high frequency switch, and more particularly to a high frequency switch for switching a signal path in a high frequency circuit such as a digital mobile phone.

[0002]

2. Description of the Related Art A high-frequency switch, as shown in FIG.
In a digital mobile phone, etc., the connection between the transmission circuit TX and the antenna ANT and the reception circuit RX and the antenna ANT
Used to switch the connection with.

FIG. 7 is a circuit diagram showing an example of a high frequency switch which is the background of the present invention and to which the present invention is applied. The high frequency switch is connected to the antenna ANT, the transmission circuit TX and the reception circuit RX. The transmission circuit TX is connected to the first diode D via the first capacitor C1.
One anode is connected. The anode of the first diode D1 is grounded via the series circuit of the inductor L and the second capacitor C2. Further, a control terminal T is connected via a resistor R to an intermediate point between the inductor L and the second capacitor C2. A control circuit for switching the high frequency switch is connected to the control terminal T. Also, the first diode D
The cathode of No. 1 is connected to the antenna ANT via the third capacitor C3. The receiving circuit R is connected to the third capacitor C3 connected to the antenna ANT via a series circuit of a strip line SL and a fourth capacitor C4.
X is connected. The second diode D2 is provided at the midpoint between the strip line SL and the fourth capacitor C4.
The anode of is connected. And the second diode D
The second cathode is grounded.

When transmitting using the high frequency switch shown in FIG. 7, a positive voltage is applied to the control terminal T.
This voltage turns on the first diode D1 and the second diode D2. At this time, the direct current component is cut by the first to fourth capacitors C1 to C4, and the voltage applied to the control terminal T is applied only to the circuit including the first diode D1 and the second diode D2. ing. By turning on the first diode D1 and the second diode D2, the signal from the transmission circuit TX is sent to the antenna ANT, and the signal is sent from the antenna ANT. In the transmission signal of the transmission circuit TX, the strip line SL has the second diode D.
By being grounded by 2, the impedance resonates and the impedance seen from the connection point A to the receiving circuit RX side becomes very large, so that it is not transmitted to the receiving circuit RX.

On the other hand, at the time of reception, by applying no voltage to the control terminal T, the first diode D1
And the second diode D2 is turned off. Therefore, the reception signal is transmitted to the reception circuit RX, and the transmission circuit TX
Not transmitted to the side. In this way, the control terminal T
Transmission and reception can be switched by controlling the voltage applied to.

FIG. 8 is a plan view showing an example of a conventional high frequency switch having the circuit shown in FIG. The high-frequency switch 1 includes a substrate 2, and a coil electrode 3a serving as an inductor L and a strip line S are provided on one main surface of the substrate 2.
A stripline electrode 3b serving as L and a large number of lands are formed, and the first and second diodes 4 are formed on the coil electrode 3a, the stripline electrode 3b, and the land.
a and 4b, chip capacitors 5a, 5b, 5c and 5d, which are the first, second, third and fourth capacitors C1, C2, C3 and C4, and a chip resistor 6, which is a resistor R, are connected. There is.

[0007]

However, in the conventional high frequency switch 1 shown in FIG. 8, the length of the coil electrode 3a and the strip line electrode 3b is generally 1/4 of the wavelength of the transmission signal or the reception signal. The length is required, and depending on the dielectric constant of the substrate 2, it is required to be several tens of millimeters, and the portions related to the coil electrode 3a and the strip line electrode 3b occupy a large area on the substrate 2. Therefore, the high-frequency switch 1 has a problem in downsizing.

Therefore, a main object of the present invention is to provide a compact high frequency switch.

[0009]

The present invention is directed to a transmitter circuit,
A high frequency switch connected to a receiving circuit and an antenna for switching between a transmitting circuit and an antenna and a receiving circuit and an antenna, the anode being connected to the transmitting circuit side and the cathode being connected to the antenna side. 1
And a first strip line connected to the anode of the first diode or an inductor connected in parallel to the first diode, and a second strip line connected between the antenna and the receiving circuit. A second diode having an anode connected to the receiving circuit side and a cathode connected to the ground side, the second stripline being incorporated in the multilayer substrate, the first diode, the second diode, and the second diode. One strip line or the inductor is a high-frequency switch formed on the multilayer substrate.

[0010]

The second strip line is built in the multilayer substrate. Further, first and second diodes and a first stripline or inductor are formed on the multilayer substrate. Therefore, the area of the high frequency switch is reduced in a plan view.

[0011]

According to the present invention, a compact high frequency switch can be obtained.

The above-mentioned objects, other objects, features and advantages of the present invention will become more apparent from the detailed description of the embodiments below with reference to the drawings.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The high frequency switch of this embodiment is structurally characteristic, but the circuit itself is also characteristic.
The circuit of the high frequency switch of this embodiment will be described with reference to the drawings. This high frequency switch is used for switching transmission / reception of a digital mobile phone or the like. Therefore, the high frequency switch is connected to the antenna ANT, the transmission circuit TX and the reception circuit RX. Transmission circuit TX
Is connected to the anode of the first diode D1 via the first capacitor C1. The anode of the first diode D1 is grounded via the first strip line SL1 and the fourth capacitor C4. This first
The strip line SL1 may be replaced with an inductor. Further, the midpoint between the first strip line SL1 and the fourth capacitor C4 is connected to the first control terminal T1 via the first resistor R1.

The cathode of the first diode D1 has a second
Is connected to the antenna ANT via the capacitor C2. In addition, the inductor L1 and the seventh diode D1 are connected to the anode of the first diode D1 in parallel with the first diode D1.
A series circuit with the capacitor C7 is connected. further,
A sixth capacitor C6 is connected in parallel with the first diode D1.
And the second resistor R2 are respectively connected. Similar results can be obtained by connecting a resistor instead of the first strip line SL1 and the fourth capacitor C4 in the circuit example of FIG.

A second strip line SL2 is connected to the antenna ANT. The second strip line SL2 is connected to the receiving circuit RX via the third capacitor C3. In addition, the second strip line SL
The midpoint between the second capacitor C3 and the second capacitor C3 is grounded via the series circuit of the second diode D2 and the fifth capacitor C5. Furthermore, in parallel with the second diode D2,
The third resistor R3 is connected. This third resistor R3 is
The second control terminal T2 is connected via the fourth resistor R4.
Connected to.

When transmitting using the high frequency switch shown in FIG. 3, a positive voltage is applied to the first control terminal T1. The voltage applied to the first control terminal T1 is applied to the first diode D1 and the second diode D1.
2 is applied as a forward bias voltage, and these diodes D1 and D2 are turned on. Therefore, the transmission signal from the transmission circuit TX is transmitted from the antenna ANT and the second strip line SL2 is transmitted to the second strip line SL2.
Since it is grounded by the diode D2 and resonates and its impedance becomes infinite, it is not transmitted to the receiving circuit RX side.

During transmission, the first diode D1
And the second diode D2 is turned on, but these diodes have an inductance component. If such an inductance component exists, the impedance when the receiving circuit RX side is viewed from the connection point A between the antenna ANT and the second strip line SL2 does not become infinite. In order to eliminate such an influence of the inductance component, a series resonance circuit is formed by the inductance component of the second diode D2 and the fifth capacitor C5.
Therefore, the capacitance C of the fifth capacitor C5
Is the inductance component of the second diode D2, L _D ,
When the frequency used is f, it is expressed by the following equation. C = 1 / {(2πf) ² · L _D }

The capacitance C of the fifth capacitor C5
When the second diode D2 is turned on, a series resonance circuit is formed by setting the above condition to satisfy the condition of the receiving circuit RX side from the connection point A between the antenna ANT and the second strip line SL2. The impedance can be infinite. Therefore, the signal from the transmission circuit TX is not transmitted to the reception circuit RX, and the transmission circuit TX and the antenna ANT are transmitted.
The insertion loss between and can be reduced. further,
Good isolation can be obtained between the antenna ANT and the receiving circuit RX. When a voltage is applied to the first control terminal T1, the current is changed to the first, second, third, fourth and fifth capacitors C1, C2, C.
It is cut by 3, C4 and C5 and flows only to the circuit including the first diode D1 and the second diode D2, and does not affect other parts.

Further, when the high frequency switch shown in FIG. 3 is used for reception, the voltage application to the first control terminal T1 is stopped and the second control terminal T2 is applied.
A positive voltage is applied to. Second control terminal T2
The voltage applied to the first diode D1 and the second diode R1 is divided by the second resistor R2 and the third resistor R3.
Is applied as a reverse bias voltage to the diode D2. Thereby, the first diode D1 and the second diode D1
The diode D2 of is surely turned off, and the reception signal is transmitted to the reception circuit RX. At this time, since the diode has a capacitance component, the received signal is transmitted by the transmission circuit T.
It may leak to the X side. In order to prevent such a leakage of the received signal, as shown in FIG.
A parallel resonant circuit is formed by the capacitance component of, the inductor L1, and the sixth capacitor C6. Therefore,
The inductance L of the inductor L1 is represented by the following equation, where C is the combined capacitance of the first diode D1 and the sixth capacitor C6 and f is the operating frequency. L = 1 / {(2πf) ² · C}

By setting the inductance L of the inductor L1 to the above condition, the isolation between the transmission circuit TX and the antenna ANT can be improved. Therefore, the received signal does not leak to the transmitting circuit TX side, and the insertion loss between the antenna ANT and the receiving circuit RX can be reduced. The same effect can be obtained by using a high impedance transmission line instead of the inductor L1. In this embodiment, when a voltage is applied to the first and second control terminals T1 and T2, a seventh capacitor C is connected in series with the inductor L1 in order to prevent a current from flowing through the inductor L1.
7 is connected. It is needless to say that when the seventh capacitor C7 is connected, the above equation is corrected according to the capacitance thereof.

The inductance component and the capacitance component of the diode vary from one diode to another. In particular, due to the variation in capacitance, the resonance frequency of the parallel resonant circuit formed by the inductor L1 and the sixth capacitor C6 changes, which is disadvantageous. However, in the high frequency switch shown in FIG. 3, since the first diode D1 and the sixth capacitor C6 are connected in parallel, the combined capacitance thereof becomes large. For example, if the capacitance of the capacitor is C ₁ and the capacitance of the first diode D2 is C _D ,
The combined capacitance is C = C ₁ + C _D. The variation of the capacitance of the first diode D1 is C
_{Assuming DS} , the variation with respect to the total capacitance is C
It becomes _DS / (C ₁ + C _D ). When the sixth capacitor C6 is not connected, the ratio of variation with respect to the total capacitance is C _DS / C _D , and therefore the influence of the variation in capacitance can be reduced by connecting the sixth capacitor C6. Therefore, the high-frequency switch shown in FIG. 3 can obtain good and stable performance both during transmission and during reception.

Next, the structure of the high frequency switch of this embodiment will be described in detail with reference to FIGS. 1 and 2. The high frequency switch 10 includes a laminated body or a multilayer substrate 12. As shown in FIG. 2, the laminated body or the multilayer substrate 12 is formed by laminating a large number of dielectric layers and the like. A first ground electrode 16 is formed on substantially the entire surface of the bottommost first dielectric layer 14. Extraction electrodes 16a and 16b are formed from the first ground electrode 16 toward one of the opposite ends of the first dielectric layer 14, respectively. In this embodiment, extraction electrodes 16a and 16b are formed from the first ground electrode 16 toward one end and the other end of the first dielectric layer 14 in the longitudinal direction, respectively. A second dielectric layer 18 is formed on the first ground electrode 16.

A first stripline electrode 20 is formed on the second dielectric layer 18 in a meandering manner. One end and the other end of the first stripline electrode 20 are formed so as to be respectively arranged on one end side in the longitudinal direction of the second dielectric layer 18. A third dielectric layer 24 is formed on the first stripline electrode 20.

A second ground electrode 26 is formed on the third dielectric layer 24. Lead electrodes 26 a and 26 b are formed on the second ground electrode 26 at positions corresponding to the lead electrodes 16 a and 16 b of the first ground electrode 16. Via holes 28a and 28b are formed in the third dielectric layer 24. One via hole 28a is
The via hole 28b is formed at a position corresponding to one end of the first stripline electrode 20, and the other via hole 28b is formed at a position corresponding to the other end of the first stripline electrode 20. A fourth dielectric layer 30 is formed on the second ground electrode 26.

A second stripline electrode 32 is formed on the fourth dielectric layer 30 so as to meander. One end and the other end of the second stripline electrode 32 are formed so as to come to one end side in the longitudinal direction of the fourth dielectric layer 30, respectively. Via holes 34a and 34b are formed in the fourth dielectric layer 30 at positions corresponding to the via holes 28a and 28b. A fifth dielectric layer 36 is formed on the second stripline electrode 32.

A third ground electrode 38 is formed on the fifth dielectric layer 36. Lead electrodes 38a and 38b are formed on the third ground electrode 38 at positions corresponding to the lead electrodes 26a and 26b of the second ground electrode 26. Via holes 40a and 40b are formed in the fifth dielectric layer 36 at positions corresponding to the via holes 34a and 34b, and via holes 40c are formed at positions corresponding to both ends of the second stripline electrode 32, respectively. And 40d are formed. A sixth dielectric layer 42 is formed on the third ground electrode 38.

On the uppermost sixth dielectric layer 42,
Each land, first diode 44, second diode 4
6 and the chip inductor 48 that becomes the inductor L1 are formed. The first, second, third, fourth, fifth, sixth and seventh capacitors C1, C2, C are connected to those lands and the first and second diodes 44 and 46, respectively.
Chip capacitors 50, 52, 54, 56, 58, 60 and 62 which are 3, C4, C5, C6 and C7,
Chip resistors (or printing resistors) 64 that become the first, second, third and fourth resistors R1, R2, R3 and R4,
66, 68 and 70 are connected. The sixth dielectric layer 42 has via holes 72a, 72 at positions corresponding to the via holes 40a, 40b, 40c and 40d.
b, 72c and 72d are formed. These via holes 72a to 72d are formed so as to penetrate a predetermined land.

A laminated body or a multilayer substrate 12 is formed by integrating these plural dielectric layers.
At this time, the via holes 28b, 34b, 40b, 72b
And one end of the first stripline electrode 20, one end of the first chip capacitor 50, one end of the first diode 44, one end of the chip inductor 48, and the sixth chip capacitor 60 via the land 74. One end of
One end of the second chip resistor 66 is connected.

Further, the via holes 28a, 34a, 40
The other end of the first strip line electrode 20, one end of the first chip resistor 64, and one end of the fourth chip capacitor 56 are connected via a, 72a and the land 76.

Further, the second strip line electrode 32 is provided via the via holes 40c and 72c and the land 78.
One end of the second chip capacitor 52,
The other end of the diode 44 and the seventh chip capacitor 6
2, one end of the sixth chip capacitor 60 and the other end of the second chip resistor 66 are connected. Also, the seventh
The other end of the chip capacitor 62 of the
8 is connected to the other end.

Further, the second strip line electrode 32 is provided via the via holes 40d and 72d and the land 80.
Is connected to one end of the third chip resistor 68, one end of the second diode 46 (anode side), and one end of the third chip capacitor 54. Further, the other end of the third chip resistor 68 and one end of the fourth chip resistor 70 are connected via the land 82. Further, the other end (cathode side) of the second diode 46, one end of the fifth chip capacitor 58, and one end of the fourth chip resistor 70 are connected via the land 82.

Further, as shown in FIG. 1, eight external electrodes 84, 86, 8 are provided on the four side surfaces of the multilayer substrate 12.
8, 90, 92, 94, 96 and 98 are formed.
In this case, the multi-layered substrate 12 has three external electrodes 84, 86, 88 formed on one side surface portion in the width direction and three external electrodes 90, 92, 94 formed on the other side surface portion in the width direction. , One external electrode 96 is formed on one side surface portion in the longitudinal direction, and one external electrode 9 is formed on the other side surface portion in the longitudinal direction.
8 is formed.

The external electrode 84 is connected to the other end of the first chip capacitor 50. The external electrode 84 is connected to the transmission circuit TX. The external electrode 88 is connected to the other end of the third chip capacitor 54. This external electrode 88
Is connected to the receiving circuit RX. The external electrode 90 is the first
Is connected to the other end of the chip resistor 64. This external electrode 9
0 is connected to the control circuit via the first control terminal T1. The external electrode 92 is connected to the other end of the second chip capacitor 52. This external electrode 92
Is connected to the antenna ANT. The external electrode 94 is connected to the other end of the fourth chip resistor 70. The external electrode 94 is connected to another control circuit via the second control terminal T2.

The external electrodes 96 are the extraction electrode 16a of the first ground electrode 16, the extraction electrode 26a of the second ground electrode 26, and the extraction electrode 38a of the third ground electrode 38.
And the other end of the fourth chip capacitor 56. The external electrode 98 includes a lead electrode 16b of the first ground electrode 16 and a lead electrode 26b of the second ground electrode 26.
A lead electrode 38b of the third ground electrode 38, and a fifth electrode
Is connected to the other end of the chip capacitor 58. Therefore, the high frequency switch 10 shown in FIG. 1 has the circuit shown in FIG.

In the high frequency switch 10 shown in FIG.
And the first and second stripline electrodes 20 and 3 to be the second striplines SL1 and SL2.
2 is built in the laminated body or the multilayer substrate 12. further,
The first and second diodes 44 and 46 and the chip inductor 48 serving as the inductor L1 are provided in the multilayer substrate 1
Since it is mounted on the board 2, the area is reduced and the size is reduced in a plan view as compared with the case where these parts are mounted on one board. Therefore, it is possible to reduce the size of a digital mobile phone or the like using the high frequency switch 10 and increase the yield. In this embodiment, the chip inductor 48 serving as the inductor L1 is mounted on the surface of the multilayer substrate 12 and has the first and second strip lines SL1 and SL2 built therein. The strip line SL1 may be formed on the surface of the multi-layer substrate 12 to incorporate the inductor L1 therein.

Further, in the high frequency switch 10 shown in FIG. 1, as shown in FIG. 4, the laminated body or the multilayer substrate 12 may be covered, and the outer case 100 made of, for example, a metal and a resin material may be covered. Good. In this case, since the first and second stripline electrodes 20 and 32 are built in the laminated body or the multilayer substrate 12, it is unlikely to be adversely affected from the outside including the outer case 100.

Further, in the high-frequency switch 10 shown in FIG. 1, the first ground electrode 16, the second ground electrode 26 and the third ground electrode 26 and the third strip line electrodes 20 and 32 are sandwiched by a dielectric layer. Since the ground electrode 38 and the like are laminated, the stripline electrodes 20 and 32 can be formed to have a short length.
Further downsizing is possible.

Although the embodiment shown in FIG. 1 has the circuit shown in FIG. 3, the present invention is not limited to the circuit shown in FIG.
For example, it may be applied to the circuits shown in FIGS. In this case, as compared with the circuit shown in FIG. 7, in the circuit shown in FIG. 5, since the strip line and the diode are connected in two stages, the antenna ANT and the transmission circuit TX side and the reception circuit RX side are connected. Good isolation. In addition to the circuits shown in FIGS. 3, 5 and 7, the present invention provides another high frequency having a first strip line or inductor, a second strip line, and first and second diodes. It can also be applied to a switch circuit. Further, design modification within the scope of the present invention is free, such as by appropriately embedding capacitors and resistors formed on the laminated body or the multilayer substrate 12 inside.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention.

FIG. 2 is an exploded perspective view of a multilayer substrate of the high frequency switch of the embodiment shown in FIG.

FIG. 3 is a circuit diagram of the embodiment shown in FIG.

FIG. 4 is an illustrative view showing another embodiment of the present invention.

FIG. 5 is a circuit diagram showing another example of a high-frequency switch to which the present invention is applied.

FIG. 6 is a conceptual diagram showing the operation of a high frequency switch.

FIG. 7 is a circuit diagram showing an example of a high frequency switch which is the background of the present invention and to which the present invention is applied.

8 is a plan view showing an example of the high frequency switch shown in FIG. 7. FIG.

[Explanation of symbols]

10 High Frequency Switch 12 Multilayer Substrate 14 First Dielectric Layer 16 First Ground Electrode 16a, 16b, 26a, 26b, 38a, 38b Lead-out Electrode 18 Second Dielectric Layer 20 First Stripline Electrode 28a, 28b, 34a, 34b, 40a-40d, 7
2a to 72d via hole 24 third dielectric layer 26 second ground electrode 30 fourth dielectric layer 32 second stripline electrode 36 fifth dielectric layer 38 third ground electrode 42 sixth dielectric Layer 44 First diode 46 Second diode 48 Chip inductor 74,76,78,80,82 Land 84,86,88,90,92,94,96,98 External electrode 100 Outer case TX transmitter circuit RX receiver circuit ANT antenna T1 first control terminal T2 second control terminal

Claims (1)

[Claims] 1. A high-frequency switch connected to a transmission circuit, a reception circuit, and an antenna, for switching connection between the transmission circuit and the antenna and connection between the reception circuit and the antenna. A first diode having an anode connected to the antenna and having a cathode connected to the antenna; a first stripline connected to the anode of the first diode or an inductor connected in parallel to the first diode; A second strip line connected to the receiving circuit; and a second diode having an anode connected to the receiving circuit side and a cathode connected to the ground side, wherein the second strip line is a multilayer substrate. Embedded in the first diode, the second diode, and the first strip line. Others and the inductor,
A high frequency switch formed on the multilayer substrate.