JPS6320041B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improving the performance of a transmitting/receiving switch that controls microwaves in a transmitting and receiving system using FETs formed on a semiconductor substrate. First, a conventional transmission/reception selector switch will be explained with reference to the drawings.

FIG. 1 shows an example of the configuration of a conventional transmission/reception changeover switch.

In the figure, 1 is a semiconductor substrate, 2 is a ground conductor, 3 is a main line of a microstrip line configured together with the ground conductor 2, 4a is a first sub-line, 4b is a second sub-line, and 5a is the first FET, 5b is the second FET, and 6a is the first FET constituting the first FET5a.
7a is the same first source electrode, 8a is the first gate electrode, and 6b is the second
A second drain electrode 7 constituting FET 5b of
b is the second source electrode, and 8b is the second source electrode.
The gate electrodes 9a and 9b are bias circuits composed of microstrip lines for applying bias voltages to the first gate electrode 8a and the second gate electrode 8b, respectively.

In the conventional transmission/reception switch, the tips of the first sub-line 4a and the second sub-line 4b are arranged opposite to each other on both sides of the tip of the main line 3, and the main line 3 and the first sub-line 4a are opposed to each other. A first FET 5a is arranged between the main line 3 and the second sub-line 4b, and a second FET 5b is arranged between the main line 3 and the second sub-line 4b.
The first drain electrode 6a constituting the main line 3
Similarly, the first source electrode 7a serves as a connection terminal with the first sub-line 4a, and the first drain electrode 6a and the first source electrode 7a also serve as a connection terminal with the first sub-line 4a. A first gate electrode 8a constituting the first FET 5a is formed between
The second drain electrode 6b constituting the FET 5b serves as a connection terminal with the main line 3, and also serves as a second drain electrode 6b.
The source electrode 7b serves as a connection terminal with the second sub-line 4b, and the second drain electrode 6b also serves as a connection terminal with the second sub-line 4b.
and the second source electrode 7b.
A second gate electrode 8b constituting the second gate electrode 8b is formed.

Here, it is assumed that the main line 3 constitutes a part of the antenna system, the first sub-line 4a constitutes a part of the transmitting system, and the second sub-line 4b constitutes a part of the receiving system.

Figure 2 is a diagram used to explain the characteristics of a typical FET, and shows the voltage and current characteristics between the drain electrode and the source electrode when the bias of the gate electrode is changed. In the figure, 10 and 11 are characteristic curves A and B when the bias of the gate electrode is zero and in the pinch-off state, respectively.
It is. For convenience of explanation, the voltage between the drain electrode and the source electrode is assumed to be V _DS and the current is assumed to be I _DS here. In this case, the resistance R _DS between the drain electrode and the source electrode is expressed as R _DS =V _DS /I _DS .

FIG. 3 shows an example of the configuration of a switch section using a general FET, including a conventional transmission/reception changeover switch.
In the figure, 1 is a semiconductor substrate, 2 is a ground conductor, 3a, 3b
is a transmission line of a microstrip line configured with ground conductor 2, 5 is FET, 6 is the drain electrode of FET 5, 7 is the source electrode of FET, 8 is FET 5
9 is a bias circuit consisting of a microstrip line for applying a bias voltage to the gate 8.

The switch part using conventional general FET is
An interdigital structure is formed between the drain electrode 6 and the source electrode 7, and a gate electrode 8 is formed in a bent structure within this interdigital structure.

The operation of the conventional transmission/reception changeover switch will be explained below using these figures.

Now, consider the case where microwaves are applied to the main line 3 in FIG. When a zero voltage is applied to the first gate electrode 8a via the bias circuit 9a and a pinch-off voltage is applied to the second gate electrode 8b via the bias circuit 9b, the characteristic curve A1 in FIG.
0 and the characteristic curve 11, the resistance between the first drain electrode 6a and the first source electrode 7a shows a small value, and the resistance between the second drain electrode 6b and the second source electrode 7b shows a small value. shows a large resistance.

Therefore, the microwave between the main line 3 and the first sub-line 4a becomes conductive, and the main line 3 and the second sub-line 4a become conductive.
The microwave communication between the sub line 4b and the sub line 4b is cut off.

On the other hand, when the voltage conditions applied to the first gate electrode 8a and the second gate electrode 8b are reversed, the main line 3 and the first sub-line 4a are similarly disconnected, and the main line 3 A conductive state is established between the line and the second sub-line 4b.

In this way, by changing the bias conditions for the first gate electrode 8a and the second gate electrode 8b, the voltage between the main line 3 and the first sub-line 4a and between the main line 3 and the second sub-line 4b, i.e. A transmit/receive switch that turns ON/OFF between the antenna system and the transmitting system and between the antenna system and the receiving system has been realized.

However, the following drawbacks are observed in the conventional transmission/reception selector switch. The reason is that when an attempt is made to improve the power durability characteristics in the disconnected state, the loss characteristics in the conductive state deteriorate. In order to improve the power durability of the conventional transmitting/receiving selector switch in the power-off state, that is, as shown in the characteristic curve B11 in Fig. 2.
In order to increase the breakdown voltage V _B of the FET, the first
The material of the semiconductor substrate 1 forming the FET 5a and the second FET 5b was changed. In this case, the unsaturated current I _F of the FET shown by the characteristic curve A10 in FIG. 2 decreased, leading to deterioration of the loss characteristics in the conductive state.

On the other hand, in the conventional transmission/reception switch, the first
The configuration of the FET 5a and the second FET 5b is shown in FIG. 3, that is, the width of the gate electrode 8 (referring to the total length of the bent part) is increased in the bent configuration, and the I _F is increased to increase the loss characteristics in the conductive state. was improving. However, in this configuration, the material of the semiconductor substrate 1 increases V _B and causes a decrease in _IF , so the width of the gate electrode 8 in the bent configuration becomes too wide in order to achieve the necessary _IF . .

In this case, the FET 5 was influenced by the bias circuit 9, and there was a limit to the improvement of loss characteristics.

In this way, it is difficult for conventional transmit/receive selector switches to have sufficiently good loss characteristics in the conductive state and power durability characteristics in the welded state, and they are usually configured with poor loss characteristics. There was also a problem in that heat generation due to the power of the microwave transmission system between the antenna system and the transmission system was also increasing.

In order to solve the above problem, this invention uses two FETs connected in series to control the receiving system, and aims to improve the loss characteristics and power resistance characteristics when the transmitting system is functioning. .

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 4 shows the configuration of a transmission/reception changeover switch in an embodiment of the present invention.

In the figure, 1 is a semiconductor substrate, 2 is a ground conductor, 3 is a main line of a microstrip line configured together with the ground conductor 2, 4a is a first sub-line, 4b is a second sub-line, and 5a is the first FET, 5b is the second FET, 5c is the third FET, and 6a is the first FET.
First drain electrode 7a forming FET 5a
is the same first source electrode, 8a is the first gate electrode, 6b is the second drain electrode constituting the second FET 5b, 7b is the second source electrode, 8b is the second gate electrode, 6c is the third drain electrode constituting the third FET 5c,
7c is also a third source electrode, 8c is a second gate electrode, and 9a and 9b are for applying a bias voltage to the first gate electrode 8a, second gate electrode 8b, and third gate electrode 8c, respectively. This is a bias circuit consisting of microstrip lines.

Here, it is assumed that the main line 3 constitutes a part of the antenna system, the first sub-line 4a constitutes a part of the transmitting system, and the second sub-line 4b constitutes a part of the receiving system.

In the transmission/reception changeover switch according to the present invention, the second sub-line 4b and the second
A third FET5c is formed between FET5b, and a second
The second source electrode 7b constituting the FET5b and the third drain electrode 6c constituting the third FET5c are formed as common connection terminals, and the third FET
The third source electrode 7c constituting the line 5c serves as a connection terminal with the second subline 4b, and also serves as a connection terminal with the second subline 4b.
A third gate electrode 8c constituting the third FET 5c is formed between the drain electrode 6c and the third source electrode 7c.

The operation of the transmission/reception selector switch of the present invention will be described below with reference to these figures.

First, a bias circuit 9 is connected to the first gate electrode 8a.
Applying zero voltage through a, the second gate electrode 8
When a pinch-off voltage is applied to the third gate electrode 8c and the third gate electrode 8c through the bias circuit 9b, as can be seen from FIG. A conductive state is established between the first sub line 4a and a disconnected state between the second drain electrode 6b and the third source electrode 8c, that is, between the main line 3 and the second sub line 4b. Become. In other words, the antenna system and the transmitting system are connected using microwaves, and the antenna system and receiving system are separated using microwaves.

On the other hand, if the application conditions of the first gate electrode 8a, the second gate electrode 8b, and the third gate electrode 8c are reversed, the connection between the main line 3 and the first sub-line 4a, that is, between the antenna system and the transmission The system becomes disconnected, and conduction occurs between the main line 3 and the second sub-line 4b, that is, the antenna system and the receiving system.

Therefore, by changing the bias conditions for the first gate electrode 8a, the second gate electrode 8b, and the third gate electrode 8c, the connections between the antenna system and the transmitting system and between the antenna system and the receiving system can be turned on and off. It has the same function as a conventional transmit/receive switch.

Next, the reason for improving the loss characteristics/power resistance characteristics of the transmission/reception selector switch according to the present invention will be explained.

First, we will discuss the power resistance characteristics. Generally, in a transmission/reception switch, large microwave power is applied only from the transmission system, and the characteristic curve B11 shown in Fig. 2
It is between the main line 3 and the second sub-line 4b that the breakdown voltage becomes a problem.

In this case, the main line 3 and the second sub line 4b
When the connection between the main line 3 and the second sub-line 4b, that is, the second drain electrode 6b and A voltage generated by microwaves is allowed up to 2×V _B between the third source electrode 7c and the third source electrode 7c.

Therefore, the transmission/reception switching switch according to the present invention can apply four times as much microwave transmission system power as the conventional transmission/reception switching switch even if the material of the semiconductor substrate 1 constituting the FET is the same.

Next, we will discuss the loss characteristics. Since the transmitting/receiving selector switch according to the present invention has significantly improved power resistance characteristics as described above, the material of the semiconductor substrate 1 has also been changed in the direction of increasing the unsaturated current I _F of the characteristic curve A10 shown in FIG. It will be done. In this case, the first
FET5a, second FET5b and third FET5c
The effect of having the configuration shown in FIG. 3 also increases. This is because the I _F of the FET is a relatively large value, and the necessary I _F can be achieved by increasing the width of the gate electrode 8 due to the folded configuration to such an extent that it is not affected by the bias circuit 9.

As a result, the transmission/reception switching switch according to the present invention has 1/3 times the loss between the main line 3 and the first sub-line 4a compared to the conventional transmission/reception switching switch, assuming the same power resistance characteristics. , the main line 3 and the 2nd line
The loss between the line and the sub line 4b is 2/3 times as large.

Therefore, heat generated by microwave transmission system power between the antenna system and the transmission system is also reduced.

In this way, in the transmitting/receiving switch according to the present invention, the transmitting/receiving switch according to the present invention has a
Since the FET section is composed of two FETs in series,
Improved power resistance/loss characteristics.

Although the above description has been given to a transmit/receive switch in which the FET electrodes are arranged in parallel, the present invention is not limited to this, and can also be applied to a transmit/receive switch in which the FET electrodes are arranged in a non-parallel manner. good.

As described above, in the transmitting/receiving selector switch according to the present invention, two FET sections connected to the receiving system are connected in series.
Since it is composed of FETs, it is effective in improving power durability and loss characteristics.

[Brief explanation of the drawing]

Figure 1 is a perspective view showing the configuration of a conventional transmission/reception switch, and Figure 2 is used to explain a general FET.
FIG. 3 is a perspective view showing the configuration of a switch section of a conventional transmission/reception selector switch, and FIG. 4 is a perspective view showing the configuration of a transmitter/receiver selector switch according to an embodiment of the present invention. In the figure, 1 is a semiconductor substrate, 2 is a ground conductor, 3 is a main line, 4a, 4b are first and second sub lines, 5a, 5
b, 5c are the first, second and third FETs, 6a,
6b, 6c are first, second and third drain electrodes; 7a, 7b, 7c are first, second and third source electrodes; 8a, 8b, 8c are first, second and third gates. Electrodes 9a and 9b are bias circuits. It should be noted that the same or corresponding parts in the figures are indicated by the same reference numerals.

Claims (1)

[Scope of Claims] 1. Tips of first and second sub-lines, also made of microstrip lines, are arranged opposite to each other on both sides of the tip of a main line made of microstrip lines formed on a semiconductor substrate. , and connecting the FET configured on the semiconductor substrate between the opposing main line and the first sub-line and between the main line and the second sub-line,
In addition, in a transmitting/receiving switch in which the main line constitutes a part of the antenna system, the first sub line constitutes a part of the transmitting system, and the second sub line constitutes a part of the receiving system, the main line and the first sub line constitute a part of the receiving system. connected between the sub-line of
The FET consists of one FET with a drain electrode and a source electrode as connection terminals, and the FET connected between the main line and the second sub-line consists of two FETs connected in series with a drain electrode and a source electrode as connection terminals. A transmitting/receiving switch characterized in that it is configured by connecting the FETs and is equipped with means for applying a bias voltage to the gate electrode of each FET. 2. The transmitter/receiver according to claim 1, wherein an interdigital configuration is formed between the drain electrode and source electrode of the FET, and the gate electrode of the FET is formed in a bent configuration within the interdigital configuration. Changeover switch.