JP2001251101A - High frequency switch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high frequency switch in which an inductance component due to a bonding wire, etc., is sufficiently canceled and an insertion loss is small even in a high frequency range. SOLUTION: This switch is provided with 1st and 2nd switch elements 102 and 103 whose one ends are respectively connected to a common node A, a 1st capacitor 301 connected between the node A and a 1st terminal P1, a 2nd capacitor 303 connected between the other end of the 1st switch element 102 and a 2nd terminal P2, a 3rd capacitor 304 connected between the other end of the 2nd switch element 103 and a 3rd terminal P3, and a coil 305 connected between the terminals P2 and P3.

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 single pole double throw (S) using a semiconductor device.
single Pole Double Throw: S
More specifically, the present invention relates to a high-frequency switch of PDT), and more specifically, an inductance component due to a bonding wire or the like is sufficiently canceled, an insertion loss is small even in a high frequency band, and a difference between the entire high-frequency switch circuit and the ground potential is provided. The present invention relates to a high-frequency switch in which parasitic capacitance components are sufficiently canceled.

[0002]

2. Description of the Related Art Conventionally, a single-pole double-throw switch using a diode has been known as a switch for switching a high-frequency signal.

FIG. 8 is a circuit diagram showing a single-pole double-throw switch 800.

As shown in FIG. 8, a single pole double throw switch 800 is composed of two diodes 8 having cathodes connected in common.
01, 802, and one of the diodes is brought into a conductive state, whereby the node J-
One between K and between nodes J-L is made conductive at a high frequency, and the other is made non-conductive. Diode 8
The control of conduction / non-conduction of 01, 802 is performed by whether or not a bias current is supplied. That is, when a bias current flows in the forward direction, the area between the anode and the cathode is turned on at a high frequency, and the bias current is stopped.
It turns off in terms of high frequency.

[0005] Such a single-pole double-throw switch 800 generally has good switch characteristics at a frequency of about several tens of MHz. It is known that isolation characteristics are degraded. This is mainly due to the series inductance parasitic on the package and the residual capacitance of the element turned off.

As means for reducing such characteristic deterioration in the quasi-microwave band, for example, Japanese Patent Application Laid-Open No. 9-30 / 1990
A method disclosed in Japanese Patent Publication No. 7303 is known.

FIG. 9 is a circuit diagram showing a circuit 900 in which the high-frequency characteristics of a single-pole double-throw switch 800 are improved by the method disclosed in Japanese Patent Application Laid-Open No. 9-307303.

In the single-pole double-throw switch 900 shown in FIG. 9, a capacitor 901 is inserted between the anode K of the diode 801 and the terminal P2.
The capacitor 902 is connected between the anode L of
Are inserted, and a coil 903 is inserted between the terminal P2 and the terminal P3. Here, terminals P1, P2
And P3 are nodes on the printed circuit board.

For simplicity, FIG. 9 does not show a bias circuit for controlling conduction / non-conduction of the diodes 801 and 802, but actually, the bias circuit (not shown) allows the diodes 801 and 802 to be controlled by the bias circuit (not shown). One of the switches 802 is turned on and the other is turned off.

FIG. 10 is a circuit diagram equivalently showing a case where the diode 801 is turned on and the diode 802 is turned off in the single pole double throw switch 900 shown in FIG.

In FIG. 10, a conducting diode 801 is equivalently represented by a resistance component 1001, and a non-conducting diode 802 is equivalently represented by a capacitance component 1002. Also,
The inductance components 1004, 1005, and 1007 are based on bonding wires, and the inductance components 1003, 1006, and 1008 are based on lead frames.

Here, the capacitor 901 performs a series resonance with the inductance component 1005 and the inductance component 1006 at a specific frequency and cancels the series resonance, and the capacitor 902 functions as an inductance component 1007 and an inductance It acts in series resonance with the component 1008 to cancel it. The coil 903 is a non-conductive diode (in FIG. 10, the capacitance component 10
02 corresponds to this. ) And at a specific frequency, parallel resonance occurs to improve the isolation characteristics to the terminal P3.

FIG. 11 is an equivalent circuit diagram of the circuit shown in FIG. 10 from which the portion canceled by resonance as described above is omitted.

As shown in FIG.
1 and the inductance component 1005 and the inductance component 1006 are canceled by series resonance,
A short circuit occurs between the terminal P2 and the node K, and it appears that only the coil 903 exists between the terminal P3 and the node K. Further, a capacitance component 1002 exists between the terminal P3 and the node J. Only seems to exist. Note that the resistance component 1001 is usually 1 Ω or less and can be ignored. As a result, the terminal P2 and the node J are short-circuited, and the terminal P3 and the node J are not connected. , Coil 903 and capacitance component 1002 in parallel.

[0015]

The single-pole, double-throw switch 900 configured as described above can be used to switch a signal of a relatively low frequency band, for example, a signal of about 2 GHz, even if the signal has the number of quasi-microwave bands. Although it exhibits good characteristics to some extent, when the frequency is higher than this, for example, in the switching of a signal of about 5 GHz, the influence of the inductance components 1003 and 1004 cannot be ignored. For this reason, matching cannot be performed accurately in the target frequency band, and the inductance component 1003,
There is a problem that the effect of 1004 appears as an increase in insertion loss.

Further, when such a single-pole double-throw switch is mounted on a printed circuit board, parasitic capacitance generated between a ground pattern formed on the back surface of the printed circuit board, a shield case covering the printed circuit board, and the like causes There is a problem that the entire switch circuit is mismatched in capacitance.

Accordingly, an object of the present invention is to provide a high-frequency switch in which an inductance component due to a bonding wire or the like is sufficiently canceled and insertion loss is small even in a high frequency band.

It is another object of the present invention to provide a high-frequency switch in which a parasitic component between the entire high-frequency switch circuit and the ground potential is sufficiently canceled.

[0019]

SUMMARY OF THE INVENTION The object of the present invention is as follows.
A high-frequency switch including a common signal terminal and a plurality of switching signal terminals, and electrically connecting the common signal terminal and any one of the plurality of switching signal terminals, to cancel an inductance component parasitic on the common signal terminal. This is achieved by a high frequency switch in which a capacitor is connected to said common signal terminal.

According to the present invention, since the capacitor for canceling the inductance component parasitic on the common signal terminal is provided, the insertion loss between the common signal terminal in the conductive state and the switching signal terminal is reduced. This is effective in switching signals in a high frequency band.

In a preferred embodiment of the present invention, the high-frequency switch includes a plurality of switching elements respectively corresponding to the plurality of switching signal terminals, and one ends of the plurality of switching elements are commonly connected to the common signal terminal. The other ends of the plurality of switching elements are respectively
It is connected to the corresponding switching signal terminal.

In a further preferred embodiment of the present invention, the plurality of switching elements are integrated on one die.

In a further preferred aspect of the present invention, the inductance component exists between the one ends of the plurality of switching elements and the common signal terminal,
The capacitor plays a role in canceling such an inductance component.

In a further preferred aspect of the present invention, the inductance component includes a parasitic inductance component due to a bonding wire derived from the die, and the capacitor plays a role of canceling at least the inductance component.

In a further preferred aspect of the present invention, the inductance component includes a parasitic inductance component due to a lead frame that electrically connects the one end of the plurality of switching elements and the common signal terminal, and the capacitor includes It plays a role of at least canceling out such an inductance component.

In a further preferred aspect of the present invention, the capacitor is connected between the one ends of the plurality of switching elements and the common signal terminal.

In a further preferred aspect of the present invention, the plurality of switching elements are constituted by diodes.

According to a further preferred aspect of the present invention, the plurality of switching elements are constituted by transistors.

According to another aspect of the present invention, there is provided a high-frequency switch including a common signal terminal and a plurality of switching signal terminals, and electrically connecting the common signal terminal and any one of the plurality of switching signal terminals. A coil for canceling a parasitic capacitance component generated between the common signal terminal and the ground potential is achieved by a high-frequency switch connected between the common signal terminal and the ground potential.

According to the present invention, since the coil for canceling the parasitic capacitance component generated between the ground potential and the ground potential is provided, the parasitic capacitance component between the entire high-frequency switch circuit and the ground potential is sufficiently canceled. Therefore, it is possible to prevent the entire switch circuit from being mismatched in capacity.

In a preferred embodiment of the present invention, the high-frequency switch includes a plurality of switching elements respectively corresponding to the plurality of switching signal terminals, and one ends of the plurality of switching elements are commonly connected to the common signal terminal, The other ends of the plurality of switching elements are respectively
It is connected to the corresponding switching signal terminal.

In a further preferred embodiment of the present invention, the plurality of switching elements are integrated on one die.

In a further preferred aspect of the present invention, the parasitic capacitance component is generated between a ground pattern or a shield case formed on a printed circuit board,
The coil plays a role of canceling out such a parasitic capacitance component.

[0034] In a further preferred aspect of the present invention, a capacitor is further provided between the one end of the plurality of switching elements and the common signal terminal.

The object of the present invention is also to provide a first switching element and a second switching element each having one end connected to a common node, and a second switching element connected between the common node and a first terminal. 1 capacitor, a second capacitor connected between the other end of the first switching element and a second terminal, and between a second end of the second switching element and a third terminal. A third capacitor connected;
This is also achieved by a high-frequency switch including a coil connected between the second terminal and the third terminal.

In a preferred embodiment of the present invention, the high frequency switch further includes a coil connected between the first terminal and a ground potential.

[0037] In a further preferred aspect of the present invention, the high-frequency switch further comprises means for turning on the first switching element and means for turning on the second switching element.

[0038]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a drawing showing a single pole double throw switch body 100 according to a preferred embodiment of the present invention.

As shown in FIG. 1, the high-frequency switch body 100 includes a die 101 on which two diodes 102 and 103 are formed, and three lead frames 105 and 10.
6, 107 and these lead frames 105, 106,
There are provided three bonding wires 108, 109, 110 for electrically connecting the 107 and the die 101. Here, die 101, bonding wires 108, 10
9, 110 and lead frames 105, 106, 10
7 is enclosed in a package 104. The cathodes of the diodes 102 and 103 are commonly connected on the die 101.

Here, the common connection point is a node J, the anode of the diode 102 is a node K, and the anode of the diode 103 is a node L. Also, the lead frame 10
The electrical nodes on 5, 106 and 107 are nodes A, B and C, respectively. In the present embodiment, the die 101
Is constituted by one semiconductor chip made of silicon. That is, two diodes are integrated in one die.

FIG. 2 is a circuit diagram equivalently showing each conductive path in the package 104 of the single pole double throw switch body 100.

The inductance component 20 shown in FIG.
2, 203 and 205 are formed by bonding wires 108, 109 and 110, respectively, and inductance components 201, 204 and 206 are formed by
This is based on the lead frames 105, 106, and 107.

With respect to the single-pole double-throw switch body 100, the parasitic inductance component and the residual capacitance of the turned-off element are canceled, and the entire single-pole double-throw switch body 100 and the ground pattern formed on the printed board are removed. What canceled the parasitic capacitance between
4 is a high-frequency switch 300 according to the embodiment of the present invention shown in FIG. In FIG. 3, the terminals P1, P
2. P3 is an electric node on the printed circuit board.
That is, the package 104 is mounted on a printed board, and is electrically connected to wiring (not shown) formed on the printed board via the lead frames 105, 106, and 107. For convenience, in the following description, the terminal P1 may be referred to as a “common signal terminal” and the terminals P2 and P3 may be referred to as “switching signal terminals”.

As shown in FIG. 3, the single-pole double-throw switch 300 includes a capacitor 301 connected between the node A and the terminal P1, a coil 302 connected between the terminal P1 and the ground potential, A capacitor 303 connected between the node B and the terminal P2; a capacitor 304 connected between the node C and the terminal P3; and a coil 305 connected between the terminal P2 and the terminal P3. ing. That is, the single-pole double-throw switch 300 according to the present embodiment is formed by adding the various components as described above to the single-pole double-throw switch main body 100 shown in FIG. That is, in the present embodiment, in addition to the single pole double throw switch body 100 (package 104), the capacitors 301, 303,
Each of the coils 304 and coils 302 and 305 is also a single (discrete) electronic component, and these components are mounted on a printed circuit board (not shown), and are connected as shown in FIG. A double throw switch 300 is formed.

Although the bias circuit is omitted in FIG. 3, if a bias circuit is added to the circuit, a circuit as shown in FIG. 4 is obtained. The bias circuit brings one of the diode 102 and the diode 103 into a conductive state and the other into a non-conductive state.
By applying a voltage equal to or higher than the threshold voltage of the diode to the terminal CT1 and applying a voltage equal to or lower than the threshold voltage of the diode to the terminal CT2, a bias current flows in the diode 102 in the forward direction, and the anode-cathode Are turned on at a high frequency, while the diode 10
No bias current flows through 3, and the device 3 is turned off in terms of high frequency. A diode that has been turned on at a high frequency by the bias circuit can be considered as a resistor equivalently, and a diode that has been turned off at a high frequency can be considered as a capacitor equivalently. In the present embodiment, the resistors 401 and 40 constituting the bias circuit
2403 are separately mounted as components on the printed circuit board.

FIG. 5 shows that in the single-pole double-throw switch 300, the diode 102 is turned on and the diode 1 is turned on.
03 is an equivalent circuit in the case where a non-conductive state is obtained.

As shown in FIG.
At a desired frequency (for example, 5 GHz), and performs a series resonance with the parasitic inductance components 201 and 202 of the nodes A and J, and plays a role of canceling them. Further, the capacitor 303 performs a series resonance with the inductance component 203 and the inductance component 204 at a desired frequency, and functions to cancel the resonance. Accordingly, it appears that only the resistance component 501 exists between the terminals P1 and P2 that are in a conductive state at a high frequency, and the inductance components 201, 202, 203, and 204 are almost canceled. Moreover, the resistance component 501 is usually 1 Ω or less, typically about several tens mΩ, and this can be ignored. As a result, the terminal P1 and the terminal P2 are considered to be short-circuited. Can be.

The capacitor 304 performs a series resonance with the inductance component 205 and the inductance component 206 at a desired frequency to cancel the resonance, and the coil 305 includes a non-conductive diode (in FIG. 5, , And capacitance component 502) at a specific frequency. Thereby, the isolation characteristics between the terminals P1 and P3 are improved. This is the same as the conventional case.

The case where the diode 102 is conducting and the diode 103 is non-conducting has been described above, but the same applies to the case where the diode 102 is non-conducting and the diode 103 is conducting. . That is, even when any one of the switching signal terminals P2 and P3 is connected to the common signal terminal P1 at a high frequency, good insertion loss characteristics and isolation characteristics can be obtained.

On the other hand, the coil 302 plays a role of canceling a capacitance component generated between the ground potential and the entire circuit. That is, as described above, the terminal P1 and the terminal P2 in a conductive state can be regarded as being in a short-circuit state. Therefore, only by inserting the correction coil 302 only in the P1 terminal side, the P2 side is simultaneously connected. Will be compensated. Conversely, when the terminal P1 and the terminal P3 are on, the coil 302 also compensates for the terminal P3.

As described above, the capacitor 301 and the coil 3
02 play different roles from each other. That is, the capacitor 301 has the inductance components 201 and 202.
, And the coil 302 plays a role of canceling a capacitance component generated between the ground potential and the entire circuit.

According to this embodiment, since the inductance components 201 and 202 parasitic on the common signal terminal P1 are canceled by the capacitor 301, the common signal terminal P1
Insertion loss between the selected switching signal terminal P2 and the selected switching signal terminal P2 is particularly effective in switching signals in a high frequency band, and is generated between the entire single pole double throw switch 300 and the ground potential. The parasitic capacitance component is coil 3
02, the single pole double throw switch 30
The parasitic capacitance component between 0 and the ground potential is sufficiently canceled, and the entire circuit is prevented from being capacitively mismatched.

The present invention is not limited to the above embodiments, and various modifications can be made within the scope of the invention described in the claims, and these are also included in the scope of the present invention. It goes without saying that it is a thing.

For example, in the above embodiment, the capacitor 301 and the coil 302 are provided, but in the present invention, it is not always necessary to provide both the capacitor 301 and the coil 302. That is, if there is almost no capacitance component between the ground potential and the entire circuit, or if the effect is small, the coil 3 is connected to the terminal P1 side.
By adding only the capacitor 301 without adding “02”, only the parasitic inductance components 201 and 202 may be canceled. Conversely, although the influence of the parasitic inductance components 201 and 202 is small, the ground potential and circuit If the effect of the capacitance component on the whole is large, the capacitance component may be canceled only by adding only the coil 302 without adding the capacitor 301 to the terminal P1 side.

In the above embodiment, the diodes 102 and 103 are used as the switching elements. However, the present invention is not limited to this.
As shown in (1), field effect transistors (FETs) 602 and 603 may be used as switching elements. In this case, as shown in FIG.
Control of conduction / non-conduction is performed by the voltage applied to the gates of 2,603. Specifically, by applying a voltage sufficiently higher than the pinch-off voltage to the gate of the transistor to be turned on, the drain-source is turned on at a high frequency, and conversely, to the gate of the transistor to be turned off, By applying a gate bias sufficiently lower than the pinch-off voltage, the device is turned off at a high frequency. Further, a switching element other than the field effect transistor may be used.

Further, in the above embodiment, a single pole double throw switch using two diodes 102 and 103 whose cathodes are commonly connected has been described, but the present invention is not limited to this. For example, the present invention can be applied to a single-pole double-throw switch using two diodes whose anodes are commonly connected. Furthermore, the number of diodes to be used is not limited to two, and the present invention can be applied to a high-frequency switch using three or more diodes.

In the above embodiment, the desired high-frequency switch is obtained by mounting various components such as the single-pole double-throw switch body 100 and the coil on the printed circuit board. The single-pole double-throw switch body 100 and the coil 30
Various components such as 2,305 may be connected by aerial wiring to obtain a desired high-frequency switch.

Further, in the above embodiment, the single pole double throw switch body 100 in which the two diodes 102 and 103 are integrated in one die 101 is used, but the present invention is not limited to this. For example, each diode may be a separate component.

In the above embodiment, the two diodes 102 and 103 are made of a die 101 made of silicon.
However, the present invention is not limited to this. For example, two diodes 102 and 103 may be integrated in a die made of GaAs.

[0061]

According to the present invention, it is possible to provide a high-frequency switch in which an inductance component due to a bonding wire or the like is sufficiently canceled and insertion loss is small even in a high frequency band.

Further, according to the present invention, it is possible to provide a high-frequency switch in which a parasitic capacitance component between the entire high-frequency switch circuit and the ground potential is sufficiently canceled.

[Brief description of the drawings]

FIG. 1 is a drawing showing a single-pole double-throw switch body used in a high-frequency switch according to an embodiment of the present invention.

FIG. 2 is a circuit diagram equivalently showing the inside of a package.

FIG. 3 is a circuit diagram showing a high-frequency switch according to the embodiment of the present invention.

FIG. 4 is a circuit diagram showing a state in which a bias circuit is added to the high-frequency switch shown in FIG. 3;

FIG. 5 is a circuit diagram equivalently showing the high-frequency switch shown in FIG. 3;

FIG. 6 is a circuit diagram showing an example in which a field effect transistor is used instead of the diode used in the high frequency switch shown in FIG.

FIG. 7 is a circuit diagram showing a state in which a bias circuit is added to the high-frequency switch shown in FIG. 6;

FIG. 8 is a circuit diagram showing a conventional single-pole double-throw switch.

FIG. 9 is a circuit diagram showing a conventional single-pole double-throw switch.

FIG. 10 is a circuit diagram equivalently showing the conventional high-frequency switch shown in FIG. 3;

FIG. 11 is a simplified circuit diagram of the circuit diagram shown in FIG. 10;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 100 Single pole double throw switch body 101 Die 102,103 Diode 104 Package 105-107 Lead frame 108-110 Bonding wire 201-206 Inductance component 300 Single pole double throw switch 301,303,304 Capacitor 302,305 Coil 602,603 Electric field Effect transistor

Claims (17)

[Claims] A high-frequency switch that includes a common signal terminal and a plurality of switching signal terminals, and electrically connects the common signal terminal and any one of the plurality of switching signal terminals; A high-frequency switch, wherein a capacitor for canceling the inductance component is connected to the common signal terminal. A plurality of switching elements respectively corresponding to the plurality of switching signal terminals, one ends of the plurality of switching elements are commonly connected to the common signal terminal,
The high frequency switch according to claim 1, wherein the other ends of the plurality of switching elements are respectively connected to corresponding switching signal terminals. 3. The high frequency switch according to claim 2, wherein said plurality of switching elements are integrated in one die. 4. The high-frequency switch according to claim 2, wherein the inductance component exists between the one ends of the plurality of switching elements and the common signal terminal. 5. The high-frequency switch according to claim 3, wherein the inductance component includes a parasitic inductance component caused by a bonding wire derived from the die. 6. The high frequency according to claim 3, wherein the inductance component includes a parasitic inductance component due to a lead frame that electrically connects the one end of the plurality of switching elements and the common signal terminal. switch. 7. The high-frequency switch according to claim 2, wherein the capacitor is connected between the one ends of the plurality of switching elements and the common signal terminal. . 8. The device according to claim 1, wherein said plurality of switching elements are constituted by diodes.
The high-frequency switch according to any one of the above. 9. The high-frequency switch according to claim 1, wherein said plurality of switching elements are constituted by transistors. 10. A high-frequency switch comprising a common signal terminal and a plurality of switching signal terminals, wherein said high-frequency switch electrically connects said common signal terminal and any one of said plurality of switching signal terminals. A high frequency switch, wherein a coil for canceling a generated parasitic capacitance component is connected between the common signal terminal and the ground potential. 11. The plurality of switching signal terminals each include a corresponding plurality of switching elements, one ends of the plurality of switching elements are commonly connected to the common signal terminal, and the other ends of the plurality of switching elements are connected to each other. The high-frequency switch according to claim 10, wherein each of the high-frequency switches is connected to a corresponding switching signal terminal. 12. The high frequency switch according to claim 11, wherein the plurality of switching elements are integrated on one die. 13. The high-frequency switch according to claim 11, wherein the parasitic capacitance component is generated between a ground pattern or a shield case formed on a printed circuit board. 14. The high-frequency device according to claim 11, wherein a capacitor is provided between said one end of said plurality of switching elements and said common signal terminal. switch. 15. A first switching element and a second switching element each having one end connected to a common node, and a first switching element connected between the common node and a first terminal.
And a second capacitor connected between the other end of the first switching element and a second terminal, and a second capacitor connected between the other end of the second switching element and a third terminal. A high-frequency switch comprising: a third capacitor; and a coil connected between the second terminal and the third terminal. 16. The high frequency switch according to claim 15, further comprising a coil connected between the first terminal and a ground potential. 17. The high-frequency device according to claim 15, further comprising: means for turning on said first switching element and means for turning on said second switching element. switch.