JPH06164203A - Transmission / reception switching device - Google Patents

Abstract

(57) [Summary] (Modified) [Purpose] An object of the present invention is to reduce impedance mismatch in a transmission / reception switching device used in the microwave band and to obtain a transmission / reception switching device with good high frequency characteristics. [Structure] The quarter-wave transmission line is made into a lumped constant by using the coil 12 and the capacitors 13 and 14, and the capacitance of the capacitor 14 is reduced by the junction capacitance of the diode 7 to reduce the capacitance of the capacitor 14. A circuit is configured by the combined capacitance of the junction capacitance of the diode 7 and the diode 7. [Effect] With the above configuration, impedance mismatch caused by the presence of the capacitance of the diode is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a contactless transmission / reception switching device mainly used in a microwave band, in which deterioration of characteristics due to junction capacitance of a diode is suppressed.

[0002]

2. Description of the Related Art FIG. 8 is a diagram showing a conventional example of a transmission / reception switching device,
FIG. 9 is a diagram showing an equivalent circuit of FIG. In FIG. 8, 1 is a dielectric substrate made of alumina or the like, 2 is a microstrip transmission line provided on the dielectric substrate 1, 3 is a first diode mounted on the microstrip transmission line 2, and 4 is a first diode. 1/4 wavelength transmission line connected to the diode 3 and consisting of a microstrip line, 5 is a ground metal surface provided on the bottom surface of the dielectric substrate 1, and 6 is a ground connected to the ground metal surface 5 by side printing or the like. A conductor, 7 is a second diode connected between the quarter-wave transmission line 4 and the ground conductor 6, and 8 is a control terminal for supplying power to the first diode 3 and the second diode 7 during transmission. is there. Further, 9 is a transmission signal input terminal, 10 is a reception signal output terminal, and 11 is an antenna circuit connection terminal.

Next, the operation will be described with reference to FIG.
First, the operation during transmission will be described. Transmission / reception control terminal 8
When a positive voltage is applied to, the first diode 3 and the second diode 7 become conductive. Therefore, the transmission signal input from the transmission signal input terminal 9 is transmitted to the antenna circuit connection terminal 11 side through the first diode 3. At this time, 1 /
Since the reception signal output terminal 10 side of the 4-wavelength transmission line 4 is short-circuited by the second diode 7, the antenna circuit connection terminal 11 side of the 1 / 4-wavelength transmission line 4 is in an open state, and therefore the transmission signal is 1 / All the signals are transmitted to the antenna circuit connection terminal 11 without being transmitted to the 4-wavelength transmission line 4 side.

Next, the operation at the time of reception will be described. When the transmission / reception control terminal 8 is opened or a negative voltage is applied, the first diode 3 and the second diode 7 are turned off.
Therefore, the transmission signal input terminal 9 is the antenna circuit connection terminal 11
It becomes a state separated from. Further, the reception signal input to the antenna circuit connection terminal 11 is transmitted to the reception signal output terminal through the quarter wavelength transmission line 4. By the above operation, the transmission / reception signal can be switched. Note that reference numerals 15 and 16 in FIG. 9 denote the junction capacitance and the equivalent resistance of the second diode 7, respectively.

[0005]

Since the conventional transmission / reception switching device has the above-described structure, the junction capacitance of the second diode on the reception signal output terminal side becomes a non-negligible value in the microwave band, and therefore the matching is ensured. There is a problem that the high frequency characteristics are deteriorated because they cannot be obtained.

The present invention has been made in order to solve the above problems. The junction capacitance of the second diode is made a part of the quarter wavelength transmission line, or a stub is attached near the diode. It is an object of the present invention to obtain a transmission / reception switching device having excellent high frequency characteristics by correcting the junction capacitance of.

[0007]

In the transmission / reception switching device according to the present invention, a quarter wavelength transmission line is composed of a coil, a first capacitor and a second capacitor, and a second capacitor is
This is a capacitor having a capacitance as small as the junction capacitance of the diode.

In addition, a capacitor forming a quarter wavelength transmission line is replaced by a MIM (Metal-Insulator-Me).
tal) structure capacitors.

Further, the capacitor forming the quarter wavelength transmission line is formed of a comb-shaped capacitor.

Further, a stub is provided at a connection point between the quarter wavelength transmission line and the second diode.

[0011]

With the above configuration, the junction capacitance of the second diode acts as a part of the quarter wavelength transmission line.

Further, the stub acts to cancel the junction capacitance of the second diode.

[0013]

EXAMPLES Example 1. FIG. 1 shows an embodiment according to the present invention. FIG. 2 is a diagram showing an equivalent circuit of FIG. In FIG. 1, 1 to 3 and 5 to 11 are the same as or equivalent to the conventional example. Reference numeral 12 denotes a coil connected to a connection point between the first diode 3 and the antenna circuit connection terminal 11, and in the figure, an example of a coil configured by a microstrip line is shown. 13 is a first high-frequency chip capacitor connected between one end of the coil 12 and the ground conductor 5, and 14 is a second high-frequency chip capacitor connected between the other end of the coil 12 and the ground conductor 6. For chip capacitors. Further, in FIG. 2, 15 and 16 are second
And the junction capacitance and the equivalent resistance of the diode 7. In this embodiment, the capacitance of the second high-frequency chip capacitor 14 is smaller than the capacitance of the first high-frequency chip capacitor 13 by the junction capacitance 15 of the second diode 7.

Next, the operation will be described with reference to FIG.
First, the operation during transmission will be described. Transmission / reception control terminal 8
When a positive voltage is applied to, the first diode 3 and the second diode 7 become conductive. Therefore, the transmission signal input from the transmission signal input terminal 9 is transmitted to the antenna circuit connection terminal 11 side through the first diode 3. At this time, 1 /
Since the reception signal output terminal 10 side of the 4-wavelength transmission line 4 is short-circuited by the second diode 7, the antenna circuit connection terminal 11 side of the 1 / 4-wavelength transmission line 4 is in an open state, and therefore the transmission signal is 1 / All the signals are transmitted to the antenna circuit connection terminal 11 without being transmitted to the 4-wavelength transmission line 4 side.

Next, the operation at the time of reception will be described. When the transmission / reception control terminal 8 is opened or a negative voltage is applied, the first diode 3 and the second diode 7 are turned off.
Therefore, the transmission signal input terminal 9 is the antenna circuit connection terminal 11
It becomes a state separated from. Further, the reception signal input to the antenna circuit connection terminal 11 is transmitted to the reception signal output terminal through the quarter wavelength transmission line 4. By the above operation, the transmission / reception signal can be switched.

By the way, the values of the coil and the high-frequency chip capacitor that form the quarter-wave transmission line 4 are obtained by the equation 1.

[0017]

[Equation 1]

In the embodiment, the value of the coil 12 constituting the quarter wavelength transmission line 4 is made equal to L of the equation 1, and the value of the first high frequency chip capacitor 13 is made equal to C of the equation 1. Next, regarding the value of the second high-frequency chip capacitor, if the value of the second high-frequency chip capacitor is C2, then C2 may be a value obtained by the equation 2.

[0019]

[Equation 2]

That is, the 1/4 wavelength transmission line 4 is connected to the coil 1
2, the first high-frequency chip capacitor 13, the second high-frequency chip capacitor 13 and the second diode 7
The junction capacitance 15 of the second diode 7 and the junction capacitance 15 of the second diode 7 are part of the ¼ wavelength transmission line 4 reduce the influence of the junction capacitance of the diode and improve the high frequency characteristics. it can.

Further, the second high frequency chip capacitor 1
The total capacitance of 4 is the junction capacitance of the second diode 7
The case of replacing with 5 also constitutes an example of this embodiment.

Example 2. FIG. 3 shows a MIM (Metal-Insula) for a capacitor forming a quarter wavelength transmission line.
FIG. 4 is a diagram showing an example using a capacitor having a tor-metal structure, and FIG. 4 is a diagram showing an outline of a capacitor having a MIM structure. In FIG. 4, reference numeral 17 is a first electrode forming a capacitor having an MIM structure, 18 is a dielectric, 19 is a second electrode, and the dielectric 18 is sandwiched between the first electrode 17 and the second electrode 19. is there. Although the high frequency chip capacitor is used in the first embodiment, since it is connected by a gold wire or the like, the high frequency characteristics may deteriorate due to the inductance component. Therefore, by using the MIM structure capacitor, the deterioration of the characteristics can be reduced.

Example 3. FIG. 5 is a diagram showing an embodiment in which a comb-shaped capacitor is used as a capacitor forming a quarter wavelength transmission line, and FIG. 6 is a diagram showing an outline of the comb-shaped capacitor. In FIG. 6, reference numeral 20 is a first electrode finger that constitutes a comb-shaped capacitor, and 21 is a second electrode finger. Since the junction capacitance of the diode varies, it is necessary to finely adjust the electrostatic capacitance. The capacitance of the comb-shaped capacitor can be finely adjusted by adjusting the number or spacing of the first electrode fingers 20 and the second electrode fingers 21. Note that, in Examples 2 and 3, the second capacitor replaced with the junction capacitance 15 is also an example of the present case.

Example 4. FIG. 7 is a diagram showing an embodiment in which a stub is attached near the second diode. In the figure, 22 is a stub provided near the second diode. By making the stub inductive, the stub resonates with the junction capacitance of the second diode and acts so as to cancel the junction capacitance of the second diode.

[0025]

As described above, according to the present invention, 1/4
By configuring the wavelength transmission line with a coil and a high-frequency chip capacitor, reducing the electrostatic capacitance of the high-frequency chip capacitor by the junction capacitance of the diode, and making the junction capacitance of the diode part of the 1/4 wavelength transmission line. High frequency characteristics can be improved by eliminating impedance mismatch.

Further, a MIM (Metal-Insulator-) is used as a capacitor forming a quarter wavelength transmission line.
By using a capacitor of Metal structure,
Further, high frequency characteristics can be improved.

Further, by using a comb-shaped capacitor as the capacitor forming the 1/4 wavelength transmission line, the electrostatic capacitance can be finely adjusted. Since the variation in the junction capacitance of the diode can be absorbed, the high frequency characteristics can be further improved.

Further, by providing an inductive stub near the diode and causing it to resonate with the junction capacitance of the diode, high frequency characteristics can be improved.

[Brief description of drawings]

FIG. 1 is a diagram showing a structure of a transmission / reception switching device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing an equivalent circuit of Embodiment 1 of the present invention.

FIG. 3 is a diagram showing a structure of a transmission / reception switching device according to a second embodiment of the present invention.

FIG. 4 is an MIM (Metal-I) according to a second embodiment of the present invention.
It is a figure which shows the structure of the capacitor of a (nsulator-Metal) structure.

FIG. 5 is a diagram showing a structure of a transmission / reception switching device according to a third embodiment of the present invention.

FIG. 6 is a diagram showing a structure of a comb-shaped capacitor according to a third embodiment of the present invention.

FIG. 7 is a diagram showing the structure of a transmission / reception switching device according to a fourth embodiment of the present invention.

FIG. 8 is a diagram showing a structure of a conventional transmission / reception switching device.

FIG. 9 is a diagram showing a conventional equivalent circuit.

[Explanation of symbols]

1 Dielectric Substrate 2 Microstrip Transmission Line 3 First Diode 4 1/4 Wavelength Transmission Line 5 Ground Metal Surface 6 Ground Conductor 7 Second Diode 8 Transmission / Reception Control Terminal 9 Transmission Signal Input Terminal 10 Reception Signal Output Terminal 11 Antenna Circuit Connection terminal 12 Coil 13 First capacitor 14 Second capacitor 15 Junction capacitance of second diode 16 Equivalent resistance of second diode 17 MIM (Metal-Insulator-Me)
tal) First electrode of structure capacitor 18 Second electrode of MIM structure capacitor 19 Dielectric of MIM structure capacitor 20 First electrode finger of comb-shaped capacitor 21 Second electrode finger of comb-shaped capacitor 22 Stub

Claims (3)

[Claims] 1. A transmission signal input terminal, a first diode whose one end is connected to the transmission signal input terminal, and the first diode.
An antenna circuit connection terminal connected to the other end of the diode, a quarter wavelength transmission line having one end connected to a connection point between the first diode and the antenna circuit connection terminal,
A second diode connected between the other end of the / 4 wavelength transmission line and the ground conductor, and a reception signal output terminal connected to the connection point between the ¼ wavelength transmission line and the second diode. In a transmission / reception switching device configured, a first capacitor, in which the ¼ wavelength transmission line is connected between a connection point of the first diode and an antenna circuit connection terminal and a ground conductor, and a first capacitor 1. A transmission / reception switching device comprising a coil having one end connected to a coil, and a second capacitor connected between the other end of the coil and a ground conductor. 2. A transmission signal input terminal, a first diode whose one end is connected to the transmission signal input terminal, and the first diode.
An antenna circuit connection terminal connected to the other end of the diode, a quarter wavelength transmission line having one end connected to a connection point between the first diode and the antenna circuit connection terminal,
A second diode connected between the other end of the / 4 wavelength transmission line and the ground conductor, and a reception signal output terminal connected to the connection point between the ¼ wavelength transmission line and the second diode. In the configured transmission / reception switching device, the ¼ wavelength transmission line is connected between a connection point of the first diode and an antenna circuit connection terminal and a ground conductor, and a MIM (Metal).
-Insulator-Metal) structure or a comb-shaped first capacitor, a coil having one end connected to the first capacitor, a MIM structure connected between the other end of the coil and the ground conductor, or a comb-shaped second capacitor And a switching device. 3. A transmission signal input terminal, a first diode having one end connected to the transmission signal input terminal, and the first diode.
An antenna circuit connection terminal connected to the other end of the diode, a quarter wavelength transmission line having one end connected to a connection point between the first diode and the antenna circuit connection terminal,
A second diode connected between the other end of the / 4 wavelength transmission line and the ground conductor, and a reception signal output terminal connected to the connection point between the ¼ wavelength transmission line and the second diode. In the configured transmission / reception switching device, a stub is provided at a connection point between the ¼ wavelength transmission line and the second diode.