JP2002319848A - Semiconductor switch circuit and semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor switch circuit that can prevent deterioration in the insertion loss performance and employ downsized semiconductor switch elements and to provide a semiconductor device. SOLUTION: By adding a 3rd capacitive element for impedance matching purpose to the semiconductor switch circuit in order to match the impedance at the operating frequency when viewing from 1st, 2nd and 3rd terminals with 50 ohms, the gate width of field effect transistors used for the semiconductor switch elements can be reduced. Thus, the semiconductor switch elements can be downsized and the deterioration in the insertion loss performance can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor switch circuit, and more particularly to a semiconductor switch circuit and a semiconductor device for switching a high-frequency signal from an ultrashort wave band to a quasi-microwave band.

[0002]

2. Description of the Related Art A semiconductor switch circuit using a semiconductor switch element as a switch circuit has been generally used for switching between transmission and reception in mobile communication such as a portable telephone. As one of the semiconductor switch circuits configured using a field effect transistor as the semiconductor switch element, an SPDT (Sing) having one input terminal and two output terminals is provided.
There is a semiconductor switch circuit called a “lePole Dual Through” switch.

FIG. 5 shows an example of such a semiconductor switch circuit. As shown in FIG. 5, in the semiconductor switch circuit, one end of the first inductance element 34 is connected to the first terminal 31 and the first inductance element 34
The other end of the first semiconductor switch element 35 is connected to one end of the first semiconductor switch element 35, the second terminal 32 is connected to one end of a second inductance element 36, and the other end of the second inductance element 36 is connected to the second semiconductor switch element 37. One end is connected. Further, one end of a third semiconductor switch element 38 is connected to a connection point between the other end of the first inductance element 34 and one end of the first semiconductor switch element 35, and a third inductance is connected to the other end of the third semiconductor switch element 38. One end of the element 39 is connected, one end of the first capacitor element 40 is connected to the other end of the third inductance element 39, and the other end of the first capacitor element 40 is connected to the ground. Further, the second inductance element 36
One end of the fourth semiconductor switch element 41 is connected to a connection point between the other end of the second semiconductor switch element 37 and one end of the second semiconductor switch element 37, and one end of a fourth inductance element 42 is connected to the other end of the fourth semiconductor switch element 41. Further, one end of a second capacitor element 43 is connected to the other end of the fourth inductance element 42, and the other end of the second capacitor element 43 is connected to the ground. Further, the other end of the first semiconductor switch element 35 and the other end of the second semiconductor switch element 37 are connected to each other, one end of a fifth inductance element 44 is connected to this connection point, and the other end of the fifth inductance element 44 is connected to the other end. Is connected to the third terminal 33. Further, the first terminal 31 is connected to a transmitting circuit, the second terminal 32 is connected to a receiving circuit, and the third terminal 33 is connected to an antenna.

Here, the first semiconductor switch element 35 and the fourth semiconductor switch element 41 are in a conductive state, and the second semiconductor switch element 37 and the third semiconductor switch element 38 are in a non-conductive state. 1 terminal 31 and 3rd
A conductive state is established between the terminals 33, and the second terminal 32 and the third terminal
Since the connection between the terminals 33 can be made non-conductive, the transmission signal input to the first terminal 31
Output from Further, the first semiconductor switch element 35 and the fourth semiconductor switch element 41 are in a non-conductive state, and the second semiconductor switch element 37 and the third semiconductor switch element 3 are not connected.
By making 8 a conductive state, the first terminal 31 and the third terminal 33 can be made non-conductive, and the second terminal 32 and the third terminal 33 can be made conductive.
The received signal input to the third terminal 33 is output from the second terminal 32.

In order to improve the isolation between the first terminal 31 and the second terminal 32, the first terminal 31 and the third terminal
A conductive state is established between the terminals 33, and the second terminal 32 and the third terminal
When the connection between the terminals 33 is made non-conductive, the first terminal 31
Is set such that the impedance of the series resonance circuit of the fourth inductance element 42 and the fourth capacitor element 43 becomes substantially zero in the frequency band of the transmission signal input to the transmission line. Similarly, when the connection between the first terminal 31 and the third terminal 33 is made non-conductive and the connection between the second terminal 32 and the third terminal 33 is made conductive, the reception signal input to the third terminal 31 The third inductance element 39 and the third
The impedance of the series resonance circuit of the capacitor element 40 is set to be substantially zero.

When a field effect transistor is used as a semiconductor switch element of a switch circuit, the first terminal 31, the second terminal 32, and the third terminal 33 are used to reduce the insertion loss of the semiconductor switch circuit. It was necessary to set the impedance at the working frequency to 50Ω.

[0007]

However, in order to match the impedance at the working frequency viewed from the first terminal 31, the second terminal 32 and the third terminal 33 to 50Ω, the gate width of the field effect transistor used must be reduced. It is necessary to increase the size, and there is a problem that the semiconductor switch element becomes large. Further, when the gate width of the field effect transistor is reduced in order to reduce the size of the semiconductor switch element,
Since the impedance at the operating frequency viewed from the terminal 31, the second terminal 32, and the third terminal 33 deviates from 50Ω, there is a problem that the insertion loss of the semiconductor switch circuit deteriorates.

The semiconductor switch circuit and the semiconductor device of the present invention have been made in view of the above-mentioned problems, and it is possible to solve these problems, prevent deterioration of insertion loss, and reduce the size of the semiconductor switch element. It is an object of the present invention to provide a semiconductor switch circuit and a semiconductor device that can be used.

[0009]

To achieve the above object, a switch circuit according to the present invention comprises a plurality of semiconductor switch elements, a plurality of inductance elements, and a plurality of capacitor elements, and has a first terminal and a first terminal. A function of switching between a conductive state and a non-conductive state between the three terminals;
In a semiconductor switch circuit having a function of switching between a conductive state and a non-conductive state between terminals, a first terminal is connected to a first terminal.
One end of the inductance element is connected and the first
One end of the first semiconductor switch element is connected to the other end of the inductance element, one end of the second inductance element is connected to the second terminal, and one end of the second semiconductor switch element is connected to the other end of the second inductance element. And the first
One end of a third semiconductor switch element is connected to a connection point between the other end of the inductance element and one end of the first semiconductor switch element, and one end of a third inductance element is connected to the other end of the third semiconductor switch element. One end of the first capacitor element is connected to the other end of the third inductance element, the other end of the first capacitor element is connected to the ground, and a connection point between the other end of the second inductance element and one end of the second semiconductor switch element. Is connected to one end of a fourth semiconductor switch element, one end of a fourth inductance element is connected to the other end of the fourth semiconductor switch element, and one end of a second capacitor element is connected to the other end of the fourth inductance element. The other end of the second capacitor element is connected to the ground, and the other end of the first semiconductor switch element is connected to the second semiconductor. The other ends of the switch elements are connected to each other, one end of the fifth inductance element and one end of the third capacitor element are connected to this connection point, and the third terminal is connected to the other end of the fifth inductance element. The other end of the element is connected to the ground.

Accordingly, the semiconductor switch circuit and the semiconductor device of the present invention provide a third capacitor for impedance matching in order to match the impedance at the operating frequency viewed from the first terminal, the second terminal and the third terminal to 50Ω. By adding the element, the gate width of the field effect transistor used for the semiconductor switching element can be reduced. This makes it possible to reduce the size of the semiconductor switch element and prevent deterioration of the insertion loss.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment, FIG. 1 A semiconductor switch circuit according to an embodiment of the present invention will be described below with reference to FIG.

As shown in FIG. 1, one end of a first inductance element 4 is connected to a first terminal 1 and a first semiconductor switch element 5 is connected to the other end of the first inductance element 4.
, One end of a second inductance element 6 is connected to the second terminal 2, and one end of a second semiconductor switch element 7 is connected to the other end of the second inductance element 6. Further, one end of the third semiconductor switch element 8 is connected to a connection point between the other end of the first inductance element 4 and one end of the first semiconductor switch element 5, and a third inductance is connected to the other end of the third semiconductor switch element 8. Element 9
, One end of the first capacitor element 10 is connected to the other end of the third inductance element 9, and the other end of the first capacitor element 10 is connected to the ground. Further, one end of the fourth semiconductor switch element 11 is connected to a connection point between the other end of the second inductance element 6 and one end of the second semiconductor switch element 7, and a fourth inductance is connected to the other end of the fourth semiconductor switch element 11. Element 1
2 is connected to one end of the second inductance element 1.
2 is connected to one end of a second capacitor element 13,
Further, the other end of the second capacitor element 12 is connected to the ground. Further, the other end of the first semiconductor switch element 5 and the other end of the second semiconductor switch element 7 are connected,
One end of the fifth inductance element 14 and one end of the third capacitor element 15 are connected to this connection point, the third terminal 3 is connected to the other end of the fifth inductance element 14, and the other end of the third capacitor element 15 is Connected to ground. Each inductance element is composed of an inductance component of a bonding wire and a parasitic inductance component such as a lead frame of a package. Further, the first terminal 1 is connected to a transmitting circuit, the second terminal 2 is connected to a receiving circuit, and the third terminal 3 is connected to an antenna. Further, the third capacitor element 15 has a role of an element for impedance matching.

Here, when a transmission signal is input to the first terminal 1 and is output from the third terminal 3, the first semiconductor switch element 5 and the fourth semiconductor switch element 11 are conductive and the second semiconductor switch element 11 is in the conductive state. The semiconductor switch element 7 and the third semiconductor switch element 8 are non-conductive. If the received signal is the third
In a reception state in which the signal is input to the terminal 3 and output from the second terminal 3, the first semiconductor switch element 5 and the fourth semiconductor switch element 11 are non-conductive, and the second semiconductor switch element 7 and the third semiconductor switch element 8 is a conduction state. At this time, when a field effect transistor is used as the semiconductor switch element, the semiconductor switch element in the conductive state has only a minute resistance component, and the semiconductor switch element in the non-conductive state has only the capacitance component of the field effect transistor.

In order to improve the isolation between the first terminal 1 and the second terminal 2, the first terminal 1 and the third terminal 3
Between the second terminal 2 and the third terminal 3 in a non-conductive state, the fourth inductance element 12 and the fourth capacitor in the frequency band of the transmission signal input to the first terminal 1. The impedance of the series resonance circuit of the element 13 is set to be substantially zero. Similarly, when the connection between the first terminal 1 and the third terminal 3 is made non-conductive and the connection between the second terminal 2 and the third terminal 3 is made conductive, the reception signal input to the third terminal 3 is changed. In the frequency band, the impedance of the series resonance circuit of the third inductance element 9 and the third capacitor element 10 is set to be substantially zero.
In mobile communication devices such as mobile phones, the transmission frequency and the reception frequency are the same or very close. Therefore, the impedance of each series resonance circuit of the semiconductor switch circuit is the same in both the transmission frequency and the reception frequency bands. Is almost zero. For this reason, in the transmission and reception states, the semiconductor switch excluding the third inductance element 9, the first capacitor element 10, the fourth inductance element 12, and the second capacitor element 13 forming the series resonance circuit is replaced with a semiconductor switch. It can be shown as an equivalent circuit of the circuit.

Next, FIG. 2 shows an equivalent circuit in a transmission state when a field effect transistor is used for each semiconductor switch element in the semiconductor switch circuit shown in FIG. The resistor 23 shown in FIG. 2 is a field-effect transistor resistance component of the first semiconductor switch element 5 shown in FIG. 1 in a conductive state, and the resistor 24 shown in FIG. 2 is a conductive component of the fourth semiconductor switch element 11 shown in FIG. This is a resistance component of a field effect transistor. Further, the capacitor 21 shown in FIG.
The capacitor 22 shown in FIG. 2 is the non-conductive field effect transistor capacitance component of the second semiconductor switch element 7 shown in FIG. 1. Further, the third inductance element 9, the first capacitor element 10, and the fourth inductance element 9 constituting the series resonance circuit portion of the semiconductor switch circuit shown in FIG.
The inductance element 12 and the second capacitor element 13
Since the impedance of the series resonance circuit becomes almost 0, FIG. 2 shows an equivalent circuit without these elements. Further, since the resistance 23 and the resistance 24, which are the resistance components of the field effect transistor in the conductive state, have very small resistance values, the resistance can be treated as a short-circuit state. Therefore, the equivalent circuit shown in FIG. 3 can be represented by an equivalent circuit.

Next, in the equivalent circuit shown in FIG. 3, the transmission frequency is 5.8 GHz, the first inductance element 4 and the fifth
When the inductance components of the inductance element 14 are each 1 nH, in order to maintain the respective input impedances as viewed from the first terminal 1 and the third terminal 3 at 50Ω, the capacitance 21 shown in FIG. 3 (the third semiconductor shown in FIG. The non-conductive field effect transistor capacitance component of the switch element 8 and the capacitor 22 (the third semiconductor switch element 8 shown in FIG. 1)
Non-conductive field effect transistor capacitance component) and the third
The combined capacitance with the capacitor 15 needs to be 0.52 pF. Here, the capacitance component C when the field effect transistor is in a non-conducting state can be expressed by a relational expression of C = A × Wg + B (Wg is the gate width of the field effect transistor, and A and B are the materials of the field effect transistor. Any constant that changes due to such as). For example, in the case of a semiconductor device in which the semiconductor switch circuit of this embodiment is formed on a GaAs substrate, A = 0.218 and B = 0.006. At the values of A and B, the combined capacitance is 0.52p
When F is all secured by the combined capacitance of the field effect transistors in the non-conductive state, the combined gate width Wg of the two field effect transistors is 2.33 mm.

Next, assuming that the impedance-matching third capacitor element 15 has a capacitance of, for example, 0.2 pF, the combined capacitance of the capacitance 21 and the capacitance 22, which are the capacitance components of the non-conductive field effect transistor. Is 0.3
2 pF is required. In order to make this combined capacitance 0.32 pF, the combined gate width Wg of the two field-effect transistors becomes 1.41 mm. Thereby, the gate width of the field effect transistor is increased from 2.33 mm to 1.41 mm.
It can be seen that it can be made smaller. Also, in the reception state, it can be shown as an equivalent circuit similar to the equivalent circuit in the transmission state, and similarly, the gate width of the field effect transistors used for the first semiconductor switch element 5 and the fourth semiconductor switch element 11 is also small. We can see that we can do it. Since the gate width of the field effect transistor can be reduced in this way,
The size of the semiconductor device constituted by the semiconductor switch circuit can be reduced. Further, since the impedance is matched to 50Ω, a low-loss semiconductor device can be obtained.

The gate width of each field-effect transistor used in the semiconductor switch element of the semiconductor switch circuit shown in FIG. 1 is selected to have a saturation current value larger than the maximum current value of a passing signal. .

Further, in the present embodiment, the semiconductor switching element is a field effect transistor and the third capacitor element 15 is added to match the input impedance viewed from each terminal. The semiconductor switch element of the semiconductor switch circuit described above only needs to have a capacitance component when the semiconductor switch element is off, and a semiconductor switch element other than a field effect transistor may be used. Further, in order to improve the withstand voltage of the field effect transistor used in the semiconductor switch element of the present embodiment, a semiconductor switch element in which two-stage field effect transistors are connected in series may be used.

[Second embodiment, FIG. 2] Hereinafter, a second embodiment of the present invention will be described.
A semiconductor switch circuit according to an embodiment will be described with reference to FIG.

As shown in FIG. 4, the second embodiment is almost the same as the first embodiment.
Is connected to a connection point between the other end of the third semiconductor switch 8 and one end of the third inductance element 9 and a connection point between the other end of the fourth semiconductor switch 11 and one end of the fourth inductance element 12. It is.

Here, when the connection between the first terminal 1 and the third terminal 3 is made conductive and the connection between the second terminal 2 and the third terminal 3 is made non-conductive, the signal is input to the first terminal 1. In the frequency band of the transmission signal, the impedance of the series resonance circuit of the fourth inductance element 12 and the fourth capacitor element 13 is almost zero.
It is set to be. Similarly, when the connection between the first terminal 1 and the third terminal 3 is made non-conductive and the connection between the second terminal 2 and the third terminal 3 is made conductive, the reception signal input to the third terminal 3 is changed. In the frequency band, the impedance of the series resonance circuit of the third inductance element 9 and the third capacitor element 10 is set to be substantially zero. Therefore, the other end of the third capacitor 15 is in the same state as that connected to the ground as in the first embodiment.
The same effects as in the first embodiment can be obtained.

Further, when a semiconductor device is manufactured using this semiconductor switch circuit, the wiring at the other end of the third capacitor 15 becomes easy, and the semiconductor device can be downsized.

In a communication system such as a PHS in which the transmission frequency and the reception frequency are the same, the frequency of the resonance circuit composed of the third inductance element 9 and the first capacitor element 10 and the fourth inductance element 12
Since the frequency of the resonance circuit composed of the second capacitor element 13 and the second capacitor element 13 is the same, the characteristics of the switch circuit can be obtained only by configuring one of the resonance circuits. Therefore, from the semiconductor switch circuit shown in FIG. 4, either the third inductance element 9 and the first capacitor element 10 constituting the resonance circuit, or the fourth inductance element 12 and the second capacitor element 13 constituting the resonance circuit A semiconductor switch circuit can be formed by removing one of the inductance element and the capacitance element that constitutes one of the resonance circuits, and a semiconductor device using the semiconductor switch circuit in which such an inductance element and a capacitor element are omitted one by one. In this case, the size of the semiconductor device can be further reduced.

[0025]

As described above, in the semiconductor switch circuit of the present invention, the impedance at the working frequency viewed from the first terminal, the second terminal, and the third terminal of the semiconductor switch circuit is 50Ω.
In order to match with the third,
A capacitor element is added. Thus, the gate width of the field effect transistor used for the semiconductor element can be reduced, so that the semiconductor device can be reduced in size and good switch characteristics with low loss can be obtained.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a semiconductor switch circuit according to a first embodiment.

FIG. 2 is an equivalent circuit diagram showing the semiconductor switch circuit of the present invention in a transmission state.

FIG. 3 is an equivalent circuit diagram further simplifying the equivalent circuit shown in FIG. 2;

FIG. 4 is a circuit diagram showing a semiconductor switch circuit according to a second embodiment.

FIG. 5 is a circuit diagram showing a conventional semiconductor switch circuit.

[Explanation of symbols]

1, 2, 3, 31, 32, 33 ---- Terminals 5, 7, 8, 11, 35, 37, 38, 41 ---- Semiconductor switch elements 4, 6, 9, 12, 14, 34, 36, 39, 42, 44 ---- Inductance element 10, 13, 15, 40, 43 ---- Capacitor element

Claims (6)

[Claims] A function of switching between a first terminal and a third terminal in a conducting state or a non-conducting state, comprising a plurality of semiconductor switch elements, a plurality of inductance elements, and a plurality of capacitor elements; In a semiconductor switch circuit having a function of switching between a conductive state and a non-conductive state between a second terminal and a third terminal, one end of a first inductance element is connected to a first terminal, and a second end is connected to the other end of the first inductance element. One end of the first semiconductor switch element is connected, one end of the second inductance element is connected to the second terminal, and one end of the second semiconductor switch element is connected to the other end of the second inductance element. One end of the third semiconductor switch element is connected to a connection point between the other end and one end of the first semiconductor switch element. The other end of the third inductance element is connected to one end of the third inductance element, the other end of the third inductance element is connected to one end of the first capacitor element, and the other end of the first capacitor element is connected to the ground. One end of the fourth semiconductor switch element is connected to a connection point between the other end of the second inductance element and one end of the second semiconductor switch element, and one end of the fourth inductance element is connected to the other end of the fourth semiconductor switch element; Further, one end of a second capacitor element is connected to the other end of the fourth inductance element, the other end of the second capacitor element is connected to the ground, and the other end of the first semiconductor switch element and the other end of the second semiconductor switch element are connected. The other ends are connected, and a fifth point
One end of the inductance element and one end of the third capacitor element are connected, the third terminal is connected to the other end of the fifth inductance element, and the other end of the third capacitor element is connected to the ground. Semiconductor switch circuit. 2. A semiconductor device comprising: a plurality of semiconductor switch elements; a plurality of inductance elements; and a plurality of capacitor elements, wherein a function of switching between a first terminal and a third terminal to a conductive state or a non-conductive state is provided. In a semiconductor switch circuit having a function of switching between a conductive state and a non-conductive state between a second terminal and a third terminal, one end of a first inductance element is connected to a first terminal, and a second end is connected to the other end of the first inductance element. One end of the first semiconductor switch element is connected, one end of the second inductance element is connected to the second terminal, and one end of the second semiconductor switch element is connected to the other end of the second inductance element. One end of the third semiconductor switch element is connected to a connection point between the other end and one end of the first semiconductor switch element. The other end of the third inductance element is connected to one end of the third inductance element, the other end of the third inductance element is connected to one end of the first capacitor element, and the other end of the first capacitor element is connected to the ground. One end of the fourth semiconductor switch element is connected to a connection point between the other end of the second inductance element and one end of the second semiconductor switch element, and one end of the fourth inductance element is connected to the other end of the fourth semiconductor switch element; Further, one end of a second capacitor element is connected to the other end of the fourth inductance element, the other end of the second capacitor element is connected to the ground, and the other end of the first semiconductor switch element and the other end of the second semiconductor switch element are connected. The other ends are connected, and a fifth point
One end of the inductance element is connected to one end of the third capacitor element, the other end of the fifth inductance element is connected to the third terminal, and the other end of the third capacitor element is connected to the other end of the third semiconductor switch. A semiconductor switch circuit, which is connected to a connection point at one end of an element and to a connection point between the other end of the fourth semiconductor switch and one end of a fourth inductance element. 3. The device according to claim 2, wherein one of the third inductance element and the first capacitor element or the one of the fourth inductance element and the second capacitor element is removed. Semiconductor switch circuit. 4. The semiconductor switch circuit according to claim 1, wherein said semiconductor switch element is a field effect transistor. 5. The semiconductor switch circuit according to claim 1, wherein said semiconductor switch element is a two-stage series connection of a field effect transistor. 6. The semiconductor device according to claim 1, wherein the inductance element of the semiconductor switch circuit is formed by wire bonding and an inductance component of a terminal.