JP5172392B2 - Gunn diode voltage controlled oscillator - Google Patents

Description

  The present invention relates to an oscillator using a microwave or millimeter-wave Gunn diode, and more particularly to a Gunn diode voltage controlled oscillator which has a wide modulation width and an improved linearity of modulation characteristics.

  FIG. 4 shows a surface view (a) and a cross-sectional view (b) of a gallium arsenide (GaAs) surface-mount type Gunn diode 200 having a mesa structure used in a microwave or millimeter wave band oscillator. A first semiconductor layer 23 made of high-concentration n-type GaAs, an active layer 24 made of low-concentration n-type GaAs, and a high-concentration n-type GaAs are formed on a semiconductor substrate 22 made of high-concentration n-type GaAs by MBE or MOCVD. The second semiconductor layer 25 is sequentially stacked, and has a mesa structure in order to reduce the area of the electron travel space. 26 is an insulator, 27 is an anode electrode, 28 is a cathode electrode, 29 is an anode bump formed by conductive protrusions, and 30 is a cathode bump formed by conductive protrusions. The insulator 26 is formed in a cylindrical shape by boron implantation from the upper surface to the boundary between the active layer 24 and the first semiconductor layer 23, the anode electrode 27 is separated from the cathode electrode 28, and the inner side surrounded by the insulator 26 is formed. A functional part of a Gunn diode is formed by the active layer 24 and the second semiconductor layer 25. In FIG. 4, six cylindrical portions surrounded by the insulator 26 are formed, and Gunn diode function portions are formed below the six anode electrodes 27. The anode bumps 29 are respectively formed on the upper surfaces of all of the six anode electrodes 27, and the cathode bumps 30 are three on one side so that a group of anode bumps 29 are sandwiched from both sides of the upper surface of the cathode electrode 28. A total of six are formed. This type of surface-mount type Gunn diode is disclosed in Patent Document 1.

  In addition to the surface-mount type Gunn diode as described above, it has a Gunn diode functional part composed of the first semiconductor layer 23, the active layer 24 and the second semiconductor layer 25, and the cathode electrode on the semiconductor substrate side. In some cases, the Gunn diode element is formed and assembled into a pill type package and used as a pill type Gunn diode.

  FIG. 5 is a partial cross-sectional view of a Gunn diode voltage controlled oscillator configured by mounting the Gunn diode 200 of FIG. 4 on an oscillation circuit 100 formed of a microstrip line. FIG. 6 is an overall perspective view of a Gunn diode voltage controlled oscillator constituted by a microstrip line. In the oscillation circuit 100, an output signal line 12 constituted by a microstrip line and an open stub line 17 constituting a resonator are formed on the upper surface of a dielectric substrate 11, and the open stub line 17 is sandwiched from both sides. The surface ground electrode 13 for two Gunn diodes is formed, and the back surface ground electrode 14 is formed on the back surface, and each surface ground electrode 13 and the back surface ground electrode 14 are electrically connected by the via hole 15 penetrating the dielectric substrate 11. It has been made. On the output signal line 12, a Gunn diode bias electrode 16 for supplying power to the Gunn diode 200 is formed. The Gunn diode 200 is mounted such that the central anode bump 29 is connected to the signal line 12 and the open stub line 17 and the cathode bumps 30 on both sides are connected to the surface ground electrodes 13 for the Gunn diodes on both sides.

In the varactor diode 300, an anode bump (not shown) connected to the anode is installed near the open stub line 17, and a cathode bump ( (Not shown) is mounted so as to be connected to the back-open stub line 21 installed in the vicinity of the transmission line 18. A surface ground electrode 19 for varactor diode is formed on the transmission line 18, and a bias electrode 20 for varactor diode is formed on the back-open stub line 21. A modulation voltage is applied to the bias electrode 20, and the oscillation frequency is modulated by changing the capacitance value of the varactor diode 300, thereby constituting a Gunn diode voltage controlled oscillator. This type of voltage-controlled Gunn diode oscillation circuit is disclosed in Patent Document 2. Although 31 is a heat radiation base, illustration was abbreviate | omitted in FIG.
JP 2003-152246 A Japanese Patent Laid-Open No. 2002-9551

  Such a conventional Gunn diode voltage controlled oscillator has a problem that a sufficient modulation width and good linearity cannot be obtained. An object of the present invention is to provide a Gunn diode voltage controlled oscillator having a wide modulation width while maintaining good linearity.

In order to achieve the above object, the invention according to claim 1 of the present application includes a signal electrode made of a microstrip line formed on the surface of a dielectric substrate, a first bias electrode for power supply connected to the signal electrode, An open stub line disposed at one end of the signal electrode, two first surface ground electrodes disposed across the signal electrode in the vicinity of the oven stub line, and an entire back surface of the dielectric substrate. The formed back surface ground electrode, the two first front surface ground electrodes, the two first via holes penetrating the dielectric substrate respectively connecting the back surface ground electrode, and the other end of the signal electrode An oscillation signal output unit disposed in the unit, one of an anode or a cathode formed in the center of the bottom surface, and the other electrode formed on both sides of the bottom surface, the one electrode being A surface-mounted Gunn diode connected to the signal electrode and the other electrode connected to the surface ground electrode, a transmission line coupled to the open stub line at high frequency, and a second connected to the transmission line A surface ground electrode, a second via hole penetrating the dielectric substrate connecting the second surface ground electrode and the back surface ground electrode, a back-open stub disposed near the transmission line, A second bias electrode for applying a modulation voltage to be connected to the back-open stub, and a varactor diode having one of an anode and a cathode connected to the transmission line and the other electrode connected to the back-open stub. in Gunn diode voltage controlled oscillator comprising a varactor diode modulation circuit consisting of the Barakutadai Comprises two over de modulation circuit, wherein the open stub line has a branching portion that branches into two, wherein one of the two varactor diodes modulation circuit, a high-frequency manner and branched one open stub line from the branch portion And the other of the two varactor diode modulation circuits is coupled with the other open stub branched from the branch section at a high frequency, and the two varactor diode modulation circuits are applied as the modulation voltage applied increases. When the modulation increase width is further increased and the modulation voltage to be applied is further increased, the modulation increase width is decreased, and one of the two varactor diode modulation circuits increases the modulation voltage to be applied. Accordingly, the modulation voltage is applied in a voltage range in which the modulation increase width increases, and the other changes as the modulation voltage to be applied increases. Modulating the oscillation frequency by applying the modulation voltage in a voltage range in which the increase width becomes small, and applying the modulation voltage to the two varactor diode modulation circuits independently and simultaneously. It is characterized by.

The invention according to the claims 2, in the Gunn diode voltage controlled oscillator of claim 1, wherein the width of the open stub line and the high-frequency coupled to the transmission line, the different for each said varactor diode modulation circuit, wherein The modulation characteristics of the two varactor diode modulation circuits are different from each other .

  The Gunn diode voltage controlled oscillator according to the present invention has a structure including a varactor diode modulation circuit coupled at high frequency to each of at least two open stub lines, and the modulation characteristics of one varactor diode modulation circuit and the other varactor diode By combining the modulation characteristics of the modulation circuit, it is possible to obtain a characteristic having a wide modulation width while maintaining linearity as compared with a case where only one varactor diode modulation circuit is provided.

  The modulation characteristics of the varactor diode modulation circuit can be easily adjusted by changing the degree of coupling with the open stub electrode by changing the width of the transmission line on which the varactor diode is mounted. Also, using two varactor diodes with almost equal characteristics, one is used as a varactor diode modulation circuit that is used in a voltage range with a small applied voltage, and the other is combined as a varactor diode modulation circuit that is used in a voltage range with a large applied voltage. Can be easily adjusted.

  Hereinafter, the Gunn diode voltage controlled oscillator of the present invention will be described in detail.

  FIG. 1 is an explanatory diagram of an embodiment of a Gunn diode voltage controlled oscillator according to the present invention using a surface mount Gunn diode 200. As shown in FIG. 4, the Gunn diode 200 is a surface-mounted Gunn diode in which an anode bump 29 is projected at the center of the bottom surface and a cathode bump 30 is formed on both sides. The Gunn diode 200 is an output diode composed of a microstrip line. The signal line 12 and the open stub line are mounted as described later.

The oscillation circuit has a good semi-insulating property with a specific resistance of 10 ⁶ Ω · cm or more and a thermal conductivity of 140 W / mK or more such as aluminum nitride (AlN), silicon (Si), silicon carbide (SiC), diamond, etc. This substrate is a dielectric substrate 11, and a gun for supplying power to the output signal line 12, the surface ground electrode 13 for the Gunn diode, the open stub line 17, and the Gunn diode 200 on the surface of the dielectric substrate 11. A bias electrode 16 for the diode is formed. The open stub line 17 branches into two in the middle and is connected again to one at the end, and is installed near one of the branch parts of the open stub line 17 at a high frequency and in the vicinity of the transmission line 18A. The back-open stub line 21A, the varactor diode bias electrode 20A for applying a modulation voltage to the varactor diode 300A, and the varactor diode surface ground electrode 19A are formed. Further, for the varactor diode for applying the modulation voltage to the transmission line 18B coupled to the other of the branch portions of the open stub line 17 in high frequency, the back open stub line 21B installed near the transmission line 18B, and the varactor diode 300B. Bias electrode 20B and surface ground electrode 19B for the varactor diode are formed. Each front surface ground electrode 13, 19 </ b> A, 19 </ b> B is connected to the back surface ground electrode 14 through a via hole 15 penetrating the dielectric substrate 11.

  The Gunn diode 200 is mounted such that the central anode bump 29 is connected to the signal line 12 and the open stub line 17, and the cathode bumps 30 on both sides are connected to the surface ground electrodes 13 for the Gunn diodes on both sides. The varactor diode 300A is mounted such that an anode bump (not shown) connected to the anode is connected to the transmission line 18A, and a cathode bump (not shown) connected to the cathode is connected to the back-open stub line 21A. 1 varactor diode modulation circuit. Further, the varactor diode 300B is mounted such that an anode bump (not shown) connected to the anode is connected to the transmission line 18B, and a cathode bump (not shown) connected to the cathode is connected to the back-open stub line 21B. A second varactor diode modulation circuit is configured.

  In the Gunn diode voltage controlled oscillator having such a configuration, a bias voltage is applied to the Gunn diode 200 via the Gunn diode bias electrode 16, and a bias voltage is applied to the varactor diode 300A via the varactor diode bias electrode 20A. At the same time, by applying a bias voltage to the varactor diode 300B via the varactor diode bias electrode 20B, the oscillation frequency of the output signal of the Gunn diode 200 can be modulated by the two varactor diode modulation circuits.

  In this embodiment, the modulation voltage applied to one varactor diode modulation circuit and the modulation voltage applied to the other varactor diode modulation circuit are set as follows.

  FIG. 2 shows a first varactor diode modulation circuit (displayed as a first modulation circuit) mounted with a varactor diode 300A and a second varactor diode modulation circuit (displayed as a second modulation circuit) mounted with a varactor diode 300B. It is a graph which shows a modulation characteristic. As can be seen from FIG. 2, the oscillation frequency changes as the modulation voltage applied to the varactor diode increases. As the modulation voltage is gradually increased from 0 V, the modulation increase width (the oscillation frequency width that changes when the voltage is increased from a predetermined voltage to a constant width) gradually increases as the modulation voltage increases. It can be seen that there is a region where the modulation increases, and when the modulation voltage increases to some extent, there is a region where the modulation increase width gradually decreases as the modulation voltage increases.

  The present invention provides a Gunn diode voltage controlled oscillator having good linearity and a wide modulation width by using a combination of varactor diode modulation circuits having different modulation characteristics with different modulation increase widths. doing. In particular, the open stub line 17 is branched, and each of the branched parts is provided with a varactor diode modulation circuit and connected to one at the end of the open stub line 17, so that transmission of each varactor diode modulation circuit is performed. The degree of coupling between the lines 18A and 18B and the open stub line 17 increases. As a result, compared with a Gunn diode voltage controlled oscillator that does not branch the open stub line 17, the modulation width is greatly widened. By applying a voltage to each varactor diode modulation circuit as described later, good linearity is obtained. It is done.

  As an example, in the case of the varactor diode modulation circuit having the modulation characteristics shown in FIG. 2, the voltage applied to each varactor diode modulation circuit is in the range of 0 to 10 V, where the modulation increase width gradually increases. The range of ˜15 V is a region where the modulation increase width is gradually reduced. Therefore, a configuration is adopted in which a modulation voltage of 0 to 10 V is applied to the first varactor diode modulation circuit, and a modulation voltage of 10 to 15 V is simultaneously applied to the second varactor diode modulation circuit. Specifically, when a modulation voltage of 0, 1, 2, 3,... 10 V is applied to the first varactor diode modulation circuit, 10.0, 10.5, The modulation voltages were applied independently and simultaneously so as to be 11.0, 11.5.

  FIG. 3 is a graph showing the modulation characteristics of the Gunn diode voltage controlled oscillator when the two varactor diode modulation circuits shown in FIG. 2 are used. In FIG. 3, the modulation voltage indicates the modulation voltage applied to the first varactor diode modulation circuit. As shown in FIG. 3, when the modulation voltage is changed in the range of 0 to 10V (the modulation voltage of the second varactor diode modulation circuit is changed in the range of 10 to 15V), the modulation width is 332 MHz, linearity The result was 3.92%. For comparison, when only the first varactor diode modulation circuit shown in FIG. 1 is used (modulation voltage 0 to 10 V), the modulation width is 151 MHz and the linearity is 6.62%. Similarly, the second varactor diode is used. When only the modulation circuit is used (modulation voltage 0 to 10 V), the modulation width is 170 MHz and the linearity is 7.06%. Further, the modulation width of the Gunn diode voltage controlled oscillator that does not branch the open stub line 17 is 250 MHz, and the structure of the present invention increases the degree of coupling between the open stub line 17 and each varactor diode modulation circuit. It can be seen that the modulation width is greatly widened, and that linearity is also greatly improved by applying a voltage to each varactor diode modulation circuit as described above.

  The present embodiment is not limited to the case where there are two varactor diode modulation circuits and the case where the open stub line 17 branches into two. By increasing the number, the modulation width can be improved and the linearity can be increased. And further fine adjustment of the oscillation frequency. Further, the varactor diode modulation circuit is not limited to one having different modulation characteristics as shown in FIG. 2, and may have substantially the same modulation characteristics, and the modulation voltage to be applied according to the modulation characteristics. May be appropriately set so that a desired frequency characteristic can be obtained.

  Furthermore, the width of the transmission line coupled with one open stub line at a high frequency is different from the width of the transmission line coupled with the other open stub line at a high frequency, thereby coupling with the open stub line. When the degree is different, the modulation characteristic can be easily adjusted.

It is explanatory drawing of the Gunn diode voltage control oscillator which is an Example of this invention. It is a figure explaining the modulation characteristic of the varactor diode modulation circuit of the Example of this invention. It is a figure explaining the modulation characteristic of the Gunn diode voltage controlled oscillator which is an example of the present invention. It is explanatory drawing of the conventional Gunn diode. It is a partial sectional view of a conventional Gunn diode voltage controlled oscillator. It is explanatory drawing of the conventional Gunn diode voltage control oscillator.

Explanation of symbols

100: Oscillator circuit, 200: Gunn diode, 300A, 300B, 300C: Varactor diode, 11: Dielectric substrate, 12: Signal line, 13: Surface ground electrode for Gunn diode, 14: Back surface ground electrode, 15: Via hole 16: Bias electrode for Gunn diode, 17: Open stub line, 18, 18A, 18B: Transmission line, 19, 19A, 19B: Surface ground electrode for varactor diode, 20, 20A, 20B: Bias for varactor diode Electrode, 21, 21A, 21B: Back-open stub line, 22: Semiconductor substrate, 23: First semiconductor layer, 24: Active layer, 25: Second semiconductor layer, 26: Insulator, 27: Anode electrode, 28 : Cathode electrode, 29: anode bump, 30: cathode bump, 31: heat dissipation base

Claims (2)

A signal electrode made of a microstrip line formed on the surface of the dielectric substrate, a first bias electrode for power supply connected to the signal electrode, and an open stub line arranged at one end of the signal electrode Two first surface ground electrodes arranged with the signal electrode in the vicinity of the oven stub line, a back surface ground electrode formed on the entire back surface of the dielectric substrate, and the two first surfaces. Two first via holes penetrating the dielectric substrate for connecting the ground electrode and the back surface ground electrode, respectively, an output portion of an oscillation signal disposed at the other end of the signal electrode,
One of an anode and a cathode formed in the center of the bottom surface and the other electrode formed on both sides of the bottom surface, the one electrode being connected to the signal electrode and the other electrode being A surface-mount type Gunn diode connected to each of the surface ground electrodes;
A transmission line coupled to the open stub line at a high frequency, a second surface ground electrode connected to the transmission line, and the dielectric substrate connecting the second surface ground electrode and the back surface ground electrode. A second via hole, a back-open stub disposed in the vicinity of the transmission line, a second bias electrode for applying a modulation voltage connected to the back-open stub, and either an anode or a cathode In a Gunn diode voltage controlled oscillator comprising a varactor diode modulation circuit comprising a varactor diode connected to the transmission line and having the other electrode connected to the back-open stub .
Two varactor diode modulation circuits are provided, and the open stub line has a branching portion that branches into two,
One of the two varactor diode modulation circuits is coupled with one open stub line branched from the branch portion at a high frequency, and the other of the two varactor diode modulation circuits is the other open stub branched from the branch portion. With high frequency,
The two varactor diode modulation circuits have a modulation characteristic that the modulation increase width increases as the applied modulation voltage increases, and the modulation increase width decreases when the applied modulation voltage is further increased,
One of the two varactor diode modulation circuits applies the modulation voltage in a voltage range in which the modulation increase width increases as the modulation voltage to be applied increases, and the other increases the modulation voltage to be applied. Accordingly, by applying the modulation voltage in a voltage range in which the modulation increase width becomes small, and applying the modulation voltage to the two varactor diode modulation circuits independently and simultaneously, the oscillation frequency is reduced. A Gunn diode voltage controlled oscillator characterized by modulating . The Gunn diode voltage controlled oscillator of claim 1,
The Gunn diode voltage characterized in that the modulation characteristics of the two varactor diode modulation circuits are different from each other because the width of the transmission line coupled to the open stub line at high frequency is different for each varactor diode modulation circuit Controlled oscillator.

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