JP2011114376A - Microwave receiver - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress a reflective power to a prestage amplifier in a microwave receiver having a plurality of amplifiers, while destruction and deterioration of a poststage amplifier thereof is prevented via a small protection circuit when a microwave signal of large power is inputted. <P>SOLUTION: The protection circuit is inserted and connected between an output end of the prestage amplifier and an input end of the poststage amplifier in the microwave receiver according to the present invention. The protection circuit includes a transmission line, a first resistor, a diode, a second resistor, and a third resistor. The transmission line is of about 1/4 wavelength at its operating frequency from its input terminal to its output terminal. One end of the first resistor is connected to the input terminal. A cathode terminal is connected to the other end of the first resistor, and an anode terminal of the diode is grounded. The second resistor is connected between a bias terminal and the cathode terminal of the diode, The third resistor is connected between the cathode terminal of the diode and a gate bias circuit. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a receiver mainly used in the VHF band, UHF band, microwave band and millimeter wave band.

  In a conventional microwave receiver having a plurality of amplifiers, a limiter circuit that can be applied as a part of the microwave receiver in order to prevent destruction and deterioration of the subsequent amplifier when a high-power microwave signal is input. It is set as the structure which provides. (For example, see Patent Document 1)

Japanese Patent Laying-Open No. 2005-51364 (page 6, FIG. 1)

  For example, when the conventional microwave receiver has two amplifiers, a limiter circuit is connected between the front-stage amplifier and the rear-stage amplifier. When a low-power microwave signal is input to this circuit, no current flows through the diode of the limiter circuit, and a quarter-wavelength transmission line is connected between the input terminal and output terminal of the limiter circuit. The microwave signal input to the input terminal is output to the output terminal without causing a large loss.

  On the other hand, when a high-power microwave signal is input to this circuit, a current flows through the diode, and when the output terminal side is viewed from the input terminal, a grounded quarter-wave transmission line is connected. Since it is configured, it is open (open) in the vicinity of the center frequency. When the terminator side is viewed from the input terminal, a grounded terminator is connected. Accordingly, only the grounded terminator is connected to the input terminal, and the input power is not output to the output terminal, but is consumed by the terminator, and reflection to the input terminal is also suppressed. .

  However, in the conventional microwave receiver, the protection circuit needs to be designed independently of the amplifier, and there are a number of parts such as diodes of the protection circuit, and there is a problem that the circuit becomes large.

  The present invention has been made in order to solve the above-described problems, and in a microwave receiver having a plurality of amplifiers, it is a small-sized protection circuit and a subsequent amplifier when a high-power microwave signal is input. The purpose is to suppress the reflected power to the preamplifier and to prevent the destruction and deterioration of the amplifier.

  The microwave receiver according to the present invention includes an amplifier that forms a front-stage amplifier and a rear-stage amplifier, a gate bias circuit of the rear-stage amplifier, a bias terminal that applies a bias to the rear-stage amplifier via the gate bias circuit, A microwave receiver including a protection circuit inserted and connected between a front-stage amplifier and the rear-stage amplifier, wherein the protection circuit uses a frequency from an output terminal of the front-stage amplifier to an input terminal of the rear-stage amplifier. And a transmission line having about a quarter wavelength, a first resistor having one end connected to the output end of the preceding amplifier, a cathode terminal connected to the other end of the first resistor, and an anode terminal being grounded A diode, a second resistor connected between the bias terminal and the cathode terminal of the diode, and between the cathode terminal of the diode and the gate bias circuit It is characterized in that it has a third resistor connected in series, the.

  According to the present invention, the protection circuit having a reduced number of components using only one diode is provided to prevent destruction and deterioration of the rear-stage amplifier when a high-power microwave signal is input, and to the front-stage amplifier. There is an effect that it is possible to obtain a small microwave receiver capable of suppressing the reflected power.

BRIEF DESCRIPTION OF THE DRAWINGS It is a structure explanatory drawing for demonstrating the structure of the microwave receiver concerning Embodiment 1 of this invention. It is a figure for demonstrating operation | movement of the microwave receiver concerning Embodiment 1 of this invention. It is a figure for demonstrating operation | movement of the microwave receiver concerning Embodiment 1 of this invention. It is a figure for demonstrating operation | movement of the microwave receiver concerning Embodiment 1 of this invention. It is a figure for demonstrating operation | movement of the microwave receiver concerning Embodiment 1 of this invention. It is a configuration explanatory diagram for explaining the configuration of a microwave receiver according to a second embodiment of the present invention. It is a figure for demonstrating operation | movement of the microwave receiver concerning Embodiment 2 of this invention. It is a figure for demonstrating operation | movement of the microwave receiver concerning Embodiment 2 of this invention. It is a block diagram for demonstrating the structure of the microwave receiver concerning Embodiment 3 of this invention. It is a figure for demonstrating operation | movement of the microwave receiver concerning Embodiment 3 of this invention.

Embodiment 1 FIG.
FIG. 1 is a configuration explanatory diagram for explaining the configuration of a microwave receiver according to Embodiment 1 of the present invention. In the following description of the embodiments, the case of having two amplifiers will be described as an example in order to simplify the configuration. In the figure, 1 is an input terminal, 2 is an output terminal, 3 is a 1/4 wavelength transmission line, 4 is a diode, 5 is a first resistor, 6 is a second resistor, 7 is a third resistor, 8 Is a pre-stage amplifier, 9 is a post-stage amplifier, 10 is an input matching circuit of the post-stage amplifier 9, 11 is an output matching circuit of the post-stage amplifier 9, 12 is a transistor of the post-stage amplifier 9, 13 is a gate bias circuit of the post-stage amplifier 9, and 14 is a post-stage This is the gate bias terminal of the amplifier 9. The protection circuit includes a quarter-wavelength transmission line 3, a first resistor 5, a second resistor 6, a third resistor 7, and a diode 4, and the quarter-wavelength transmission line 3 is connected to the preamplifier 8. The first resistor 5 and the third resistor 7 are connected in series between the gate bias terminal 14 of the rear amplifier 9 and the gate bias circuit 13, and the second resistor 6 is connected to one end of the second amplifier 6. Is connected between the first resistor 5 and the third resistor 7, the other end is connected between the preamplifier 8 and the quarter-wavelength transmission line 3, and the diode 4 has one end connected to the first resistor. 5 and the third resistor 7, and the other end is grounded.

  Next, the operation will be described. It is assumed that a voltage Vg for operating the transistor 12 is applied to the gate bias terminal 14. As shown in FIG. 2, when a high-power microwave signal is not input, no current flows through the diode 4 and the diode 4 is open. At this time, there is no voltage drop in the gate bias circuit 13 and the voltage Vg is applied to the transistor 12. Therefore, the transistor 12 can perform a desired operation. In addition, when the second resistor 6 side is expected from the output side of the preamplifier 8, it is also opened. Therefore, as shown in FIG. 3, the configuration is equivalent to a configuration in which the transmission line 3 having a quarter wavelength is connected between the front-stage amplifier 8 and the rear-stage amplifier 9, and the microwave signal output from the front-stage amplifier 8 is The signal is input to the subsequent amplifier 9 without causing a large loss.

  On the other hand, when a high-power microwave signal is input, a current flows through the diode 4. As shown in FIG. 4, when a large power is input and a current Igg flows through the diode 4, the voltage applied to the transistor 12 due to the voltage drop becomes Vgg (= Vg−R3 * Igg) and becomes deeper than Vg. For this reason, the transistor 12 does not operate, and the impedance in anticipation of the post-amplifier 9 side is close to a short circuit. At this time, when the rear amplifier 9 side is viewed from the front amplifier 8, the grounded transmission line 3 with a quarter wavelength is connected, so that it is open near the center frequency. Further, since the diode 4 is short-circuited, the output side of the preamplifier 8 is equivalently grounded via the second resistor 6. Therefore, as shown in FIG. 5, the output side of the pre-stage amplifier 8 is equivalent to a configuration in which only a grounded resistor is connected, and the power output from the pre-stage amplifier 8 is not input to the post-stage amplifier 9, and the second stage Therefore, the reflection to the preamplifier 8 is also suppressed. In this way, it is possible to prevent the front-stage amplifier 8 and the rear-stage amplifier 9 from being destroyed or deteriorated.

From the above, there is an effect that the number of diode parts can be reduced as compared with the conventional case.
In general, if a resistor connected between the gate bias terminal and the gate bias circuit is shared, there is no need to newly provide a resistor for configuring the protection circuit, and the number of parts of the protection circuit can be reduced and the size can be reduced. It is possible to obtain a microwave receiver.

Embodiment 2. FIG.
FIG. 6 is an explanatory diagram for explaining the configuration of the microwave receiver according to the second embodiment of the present invention. In the figure, 1 to 6 and 8 to 14 are the same as in FIG. 1, and 15 is a coil. The protection circuit includes a quarter-wave transmission line 3, a first resistor 5, a second resistor 6, a coil 15, and a diode 4, and the quarter-wave transmission line 3 includes a front-stage amplifier 8 and a rear-stage amplifier 9. The first resistor 5 and the coil 15 are connected in series between the gate bias terminal 14 of the post-stage amplifier 9 and the gate bias circuit 13, and one end of the second resistor 6 is the first resistor 5. And the other end is connected between the pre-stage amplifier 8 and the quarter-wave transmission line 3, and the diode 4 has one end connected between the first resistor 5 and the coil 15. The other end is grounded.

  Next, the operation will be described. It is assumed that a voltage Vg for operating the transistor 12 is applied to the gate bias terminal 14. The operation is the same as that described in the first embodiment. When a high-power microwave signal is not input, no current flows through the diode 4 and the diode 4 is open. At this time, there is no voltage drop in the gate bias circuit 13 and the voltage Vg is applied to the transistor 12. Therefore, the transistor 12 can perform a desired operation. In addition, when the second resistor 6 side is expected from the output side of the preamplifier 8, it is also opened. Therefore, the configuration is equivalent to a configuration in which the transmission line 3 having a quarter wavelength is connected between the front-stage amplifier 8 and the rear-stage amplifier 9, and the microwave signal output from the front-stage amplifier 8 does not cause a large loss. It is input to the post-amplifier 9.

  On the other hand, when a high-power microwave signal is input, a current flows through the diode 4. Although the current Igg flows through the diode 4, the voltage drop is caused by the loss of the coil 15 because the coil 15 is used instead of the third resistor 7 in the second embodiment. Although the loss of the coil is small compared to the resistance, the current Igg is generally large, causing a voltage drop. Due to this voltage drop, the transistor 12 does not operate, and the impedance expecting the post-amplifier 9 side becomes close to a short circuit. At this time, when the rear amplifier 9 side is viewed from the front amplifier 8, the grounded transmission line 3 with a quarter wavelength is connected, so that it is open near the center frequency. Further, since the diode 4 is short-circuited, the output side of the preamplifier 8 is equivalently grounded via the second resistor 6. Therefore, as shown in FIG. 5, the output side of the pre-stage amplifier 8 is equivalent to a configuration in which only a grounded resistor is connected, and the power output from the pre-stage amplifier 8 is not input to the post-stage amplifier 9, and the second stage Therefore, the reflection to the preamplifier 8 is also suppressed. In this way, it is possible to prevent the front-stage amplifier 8 and the rear-stage amplifier 9 from being destroyed or deteriorated.

  From the above, there is an effect that the number of parts of the diode can be reduced as compared with the conventional case.

  Further, in the first embodiment, the resistance value between the gate bias terminal 14 and the transistor 12 is the sum of the first resistor 5 and the third resistor 7 as shown in FIG. By using the coil 15 as shown, the sum of the resistance value of the first resistor 5 and the loss of the coil 15 is obtained. When the resistor 7 or the coil 15 that is opened when the bias terminal 14 side is viewed from the bias circuit 13 is selected, the loss of the coil 15 may be smaller than the resistance value of the resistor 7, so that the resistance value is large. This also has the effect of preventing thermal runaway caused by.

Embodiment 3 FIG.
FIG. 9 is an explanatory diagram for explaining the configuration of the microwave receiver according to the third embodiment of the present invention. In the figure, 1 to 6 and 8 to 15 are the same as or correspond to those in FIG. The protection circuit includes a quarter-wavelength transmission line 3, a first resistor 5, a second resistor 6, a third resistor 7, a coil 15, and a diode 4. The first resistor 5 and the third resistor 7 are connected in series between the gate bias terminal 14 of the post-stage amplifier 9 and the gate bias circuit 13, and are connected between the amplifier 8 and the post-stage amplifier 9. One end is connected to the coil 15, the other end is connected between the preamplifier 8 and the quarter-wave transmission line 3, and the other end of the coil 15 is connected to the first resistor 5 and the third resistor 7. One end of the diode 4 is connected between the second resistor 6 and the coil 15 and the other end is grounded.

  Next, the operation will be described. It is assumed that a voltage Vg for operating the transistor 12 is applied to the gate bias terminal 14. The operation is the same as that described in the first embodiment. When a high-power microwave signal is not input, no current flows through the diode 4 and the diode 4 is open. At this time, there is no voltage drop in the gate bias circuit 13 and the voltage Vg is applied to the transistor 12. Therefore, the transistor 12 can perform a desired operation. In addition, when the second resistor 6 side is expected from the output side of the preamplifier 8, it is also opened. Therefore, the configuration is equivalent to a configuration in which the transmission line 3 having a quarter wavelength is connected between the front-stage amplifier 8 and the rear-stage amplifier 9, and the microwave signal output from the front-stage amplifier 8 does not cause a large loss. It is input to the post-amplifier 9.

  On the other hand, when a high-power microwave signal is input, a current flows through the diode 4. Although the current Igg flows through the diode 4, the voltage drop due to the first resistor and the third resistor also occurs in the third embodiment. For this reason, the transistor 12 does not operate, and the impedance in anticipation of the post-amplifier 9 side is close to a short circuit. At this time, when the rear amplifier 9 side is viewed from the front amplifier 8, the grounded transmission line 3 with a quarter wavelength is connected, so that it is open near the center frequency. Further, since the diode 4 is short-circuited, the output side of the preamplifier 8 is equivalently grounded via the second resistor 6. Therefore, as shown in FIG. 5, the output side of the pre-stage amplifier 8 is equivalent to a configuration in which only a grounded resistor is connected, and the power output from the pre-stage amplifier 8 is not input to the post-stage amplifier 9, and the second stage Therefore, the reflection to the preamplifier 8 is also suppressed. In this way, it is possible to prevent the front-stage amplifier 8 and the rear-stage amplifier 9 from being destroyed or deteriorated.

  From the above, there is an effect that the number of parts of the diode can be reduced as compared with the conventional case.

  Further, when the coil 15 is viewed from between the diode 4 and the second resistor 6 as shown in FIG. 10, the gate bias terminal 14 can be opened in the protection circuit when a large power is input. There is also an effect that the influence of the load on the side is reduced.

  Here, in the first to third embodiments, the impedance of the input terminal or the output terminal in the protection circuit is set to 50Ω that is generally used.

  Next, the case where the configuration as the protection circuit in the first to third embodiments is viewed as a part of the output matching circuit of the front-stage amplifier 8 or the part of the input matching circuit of the rear-stage amplifier 9 will be described.

  In these cases, it is not necessary to set the impedance of the input terminal or output terminal in the protection circuit to 50Ω, which is generally used, and can be set according to the input matching circuit or the output matching circuit. There is an effect.

  1 input terminal, 2 output terminal, 3/4 wavelength transmission line, 4 diode, 5 first resistor, 6 second resistor, 7 third resistor, 8 preamplifier, 9 postamplifier, 10 input matching Circuit, 11 output matching circuit, 12 transistor, 13 gate bias circuit, 14 gate bias terminal, 15 coil.

Claims (6)

An amplifier forming a front-stage amplifier and a rear-stage amplifier;
A gate bias circuit of the post-stage amplifier;
A bias terminal for applying a bias to the subsequent amplifier through the gate bias circuit;
A protection circuit inserted and connected between the front-stage amplifier and the rear-stage amplifier;
A microwave receiver comprising:
The protection circuit is
A transmission line of about a quarter wavelength at a use frequency from the output terminal of the front-stage amplifier to the input terminal of the rear-stage amplifier;
A first resistor having one end connected to the output end of the pre-stage amplifier;
A diode having a cathode terminal connected to the other end of the first resistor and an anode terminal grounded;
A second resistor connected between the bias terminal and the cathode terminal of the diode;
A third resistor connected in series between the cathode terminal of the diode and the gate bias circuit;
A microwave receiver comprising: An amplifier forming a front-stage amplifier and a rear-stage amplifier;
A gate bias circuit of the post-stage amplifier;
A bias terminal for applying a bias to the subsequent amplifier through the gate bias circuit;
A protection circuit inserted and connected between the front-stage amplifier and the rear-stage amplifier;
A microwave receiver comprising:
The protection circuit is
A transmission line of about a quarter wavelength at a use frequency from the output terminal of the front-stage amplifier to the input terminal of the rear-stage amplifier;
A first resistor having one end connected to the output end of the pre-stage amplifier;
A diode having a cathode terminal connected to the other end of the first resistor and an anode terminal grounded;
A second resistor connected between the bias terminal and the cathode terminal of the diode;
A coil connected in series between the cathode terminal of the diode and the gate bias circuit;
A microwave receiver comprising: An amplifier forming a front-stage amplifier and a rear-stage amplifier;
A gate bias circuit of the post-stage amplifier;
A bias terminal for applying a bias to the subsequent amplifier through the gate bias circuit;
A protection circuit inserted and connected between the front-stage amplifier and the rear-stage amplifier;
A microwave receiver comprising:
The protection circuit is
A transmission line of about a quarter wavelength at a use frequency from the output terminal of the front-stage amplifier to the input terminal of the rear-stage amplifier;
A first resistor having one end connected to the output end of the pre-stage amplifier;
A diode having a cathode terminal connected to the other end of the first resistor and an anode terminal grounded;
A second resistor having one end connected to the bias terminal;
A coil connected in series to the other end of the second resistor and the cathode terminal of the diode;
A third resistor connected in series between the other end of the second resistor and the gate bias circuit;
A microwave receiver comprising: 4. The microwave according to claim 1, wherein circuit element values constituting the protection circuit are set to values at which the protection circuit independently obtains a predetermined input / output impedance. 5. Receiving machine. The circuit element value constituting the protection circuit is set to a value for obtaining a predetermined input / output impedance as a part of an output matching circuit of the pre-stage amplifier to which the protection circuit is inserted and connected. The microwave receiver of any one of 1-3. The circuit element value constituting the protection circuit is set to a value for obtaining a predetermined input / output impedance as a part of an input matching circuit of the post-stage amplifier to which the protection circuit is inserted and connected. The microwave receiver of any one of 1-3.

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