JP2014030086A - Microwave/quasi-millimeter wave band oscillator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To minimize effects on resonance and oscillation frequencies even when a substrate changes in dielectric constant, and efficiently lay out a circuit on the substrate.SOLUTION: An open end of a cylinder 22 with a closed opposite end is connected onto a resin substrate 1 with a conductive adhesive 21 and two probes 23, 24 comprising coplanar lines are arranged on the substrate 1 from an outer circumference to a center of the cylinder 22 to provide a surface-mounted cavity resonant circuit, and the two probes 23, 24 are connected to an amplification element 27 via transmission lines 25, 26 comprising coplanar lines. The two probes 23, 24 are led out from positions on the circumference of the cylinder 22 apart from each other by an angle of zero degrees (parallel positions), so that the probes 23, 24 and the transmission lines 25, 26 have minimum lengths satisfying an oscillation condition.

Description

  The present invention relates to a microwave / quasi-millimeter wave band oscillator, and more particularly to a self-oscillation type oscillator in which a resonance circuit and an oscillation circuit are formed on a resin substrate.

  FIG. 6 shows a configuration of a conventional high-frequency oscillator (Patent Document 1 below). As shown in FIG. 6, a dielectric resonator 2 and a first micro are formed on a dielectric substrate 1 (surface). A resonance circuit (resonator) composed of the strip line 3 and the second microstrip line 4 is formed, and for this resonance circuit, a transistor 5, bias resistors 6 and 7, an oscillation control capacitor 8 and a DC power supply terminal as an oscillation circuit. Vcc is provided, and an output terminal is connected to the collector of the transistor 5 through an output load resistor 9 and a capacitive coupling unit 10. A GND surface is formed on the back side of the substrate 1.

  According to the above configuration, the dielectric resonator 2 and the first microstrip line 3 and the second microstrip line 4 are coupled to each other at a desired frequency based on the resonance frequency of the dielectric resonator 2. Oscillates.

  FIG. 7 shows another example of a conventional oscillator (using a pattern resonance circuit). In the example of FIG. 7, a copper film 12 is provided on the substrate 1. The first input / output line 13, the second input / output line 14, and the pattern resonance unit 15, which are coplanar lines, are formed as resonance circuits (a line made of a copper film in the region H from which the copper film 12 is removed). 13 and 14 and the resonance part 15 are provided). In addition, an amplifier 16 connected to the first input / output line 13 and the second input / output line 14 is arranged as an oscillation circuit, and these circuits are entirely covered with a casing 17 and also on the back side of the substrate 1. A GND surface is formed. Even with such a configuration, a desired oscillation frequency can be obtained based on resonance using the pattern resonance unit 15.

JP 2008-35351 A

  However, in the conventional oscillator, when a thermosetting resin high-frequency substrate excluding Teflon (registered trademark) is used as the substrate 1, the resin surface of the substrate 1 is gradually exposed from the surface by being exposed to air. It is known that the dielectric constant changes due to oxidation.

  FIG. 8A shows the configuration of a part of the oscillator of FIG. 6, where the first microstrip line 3 and the second microstrip line 4 are provided on the surface of the substrate 1, and the back surface of the substrate 1. A ground (GND) 19 is provided on the surface of the substrate 1. When the surface of the substrate 1 on which the microstrip lines 3 and 4 are present is exposed to air, the oxidation proceeds from the surface. As shown in FIG. As the time elapses, the equivalent dielectric constant increases.

  Also in the case of the oscillator of FIG. 7, the dielectric constant of the pattern resonance circuit portion of the hatched portion of FIG. In the case of using this pattern resonance circuit, when the resonance circuit has a low Q and the resonance circuit itself is made of a resin substrate, the resonance frequency, that is, the oscillation frequency gradually changes during storage or operation ( For example, there is a problem that the frequency range permitted by the Radio Law is deviated in several years.

  As shown in FIG. 6, when the dielectric resonator 2 is used, since the resonance circuit has a high Q, the change in the dielectric constant (for example, a change of about 100 MHz in 5 years) is gentle. Since 2 is bonded to the substrate, the resonance frequency itself is susceptible to substrate oxidation.

  Further, in the case of the oscillators of FIGS. 6 and 7, since the GND 19 is provided on the entire back surface of the substrate 1, there is a disadvantage that a circuit cannot be arranged on the back surface.

  The present invention has been made in view of the above problems, and the object thereof is to reduce the influence on the resonance frequency and the oscillation frequency as much as possible even when there is a change in the dielectric constant of the substrate. It is an object of the present invention to provide a microwave / quasi-millimeter wave band oscillator that can be efficiently arranged.

In order to achieve the above object, the invention according to claim 1 is a microwave / quasi-millimeter wave band oscillator in which an oscillation circuit and a resonance circuit are arranged on a resin substrate. A cylindrical body having one end open and the other end closed. A surface mount type cavity resonance circuit in which the open end is connected to the substrate, and two probes composed of coplanar lines are arranged from the outer periphery to the center of the cylindrical body on the substrate, and 2 of the cavity resonance circuit. A coplanar transmission line connecting the two probes to the oscillation circuit, and taking out the two probes from the cylinder to the oscillation circuit side at an angular position of less than 180 degrees of the circumference of the cylinder, The probe and the transmission line have the shortest length that satisfies the oscillation condition.
According to a second aspect of the present invention, a circuit is formed on the back side of the substrate on which the cylindrical body is disposed.

  According to the above configuration, since a surface-mounted cavity resonance circuit having a simple structure and a high Q is used, and resonance is mainly performed in a cylindrical cavity, the resonance frequency of the resonance circuit is caused by a change in the dielectric constant of the substrate. The structure is not easily affected. In addition, the angle at which the two probes (input / output probes) are taken out from the cylindrical body to the oscillation circuit side is a position that is less than 180 degrees of the circumference of the cylindrical body, for example, 90 degrees or 0 degrees (parallel position), Since the length of the probe and the transmission line is the shortest length that satisfies the oscillation condition, the influence on the oscillation frequency can be eliminated. That is, in the oscillator, it is necessary to match the phase of the entire transmission line including the probe so that the oscillation condition is satisfied, and the longer the transmission line, the wider the range affected by the oxidation of the substrate. In the present invention, by making the length of the probe and the transmission line as short as possible to satisfy the oscillation condition, it is possible to reduce the change in the dielectric constant due to the oxidation of the substrate and reduce the influence on the oscillation frequency. Become.

  According to the microwave / quasi-millimeter wave oscillator of the present invention, since the resonance circuit has a high Q and resonance occurs in the cylindrical cavity, even if a change in the dielectric constant occurs in the substrate, it has an effect on the resonance frequency. The phase change between the probe and the transmission line (feedback line) can be minimized, the influence on the oscillation frequency can be reduced, and an oscillator with excellent frequency stability can be obtained over a long period of time. It becomes possible.

  Further, since the probe portion is composed of a coplanar line and the cylindrical body is connected to the ground pattern of the coplanar line, a necessary circuit can be efficiently arranged on the back surface of the substrate excluding the probe portion.

1 shows a configuration of a microwave / quasi-millimeter wave oscillator according to a first embodiment of the present invention, in which FIG. (A) is a top view and FIG. (B) is a side view. 1 is an overall perspective view of an oscillator according to a first embodiment. The operation of the cylindrical body in the oscillator according to the first embodiment is shown, in which FIG. (A) is a perspective view, FIG. (B) is a view from the top, and FIG. (C) is a view from the side. The structure of the microwave sensor using the oscillator of 1st Example is shown, A figure (A) is a top view, A figure (B) is a side view, A figure (C) is a bottom view, A figure (D) is a perspective view. . The structure of the microwave / quasi-millimeter wave band oscillator concerning the 2nd example is shown, and Drawing (A) is a top view and Drawing (B) is a BB sectional view of Drawing (A). It is a circuit diagram which shows the structure of the conventional high frequency oscillator. The other example of a structure of the conventional oscillator is shown, A figure (A) is a top view, A figure (B) is a side view. FIG. 5A is a diagram illustrating the state of substrate oxidation in a conventional oscillator, and FIG. 5B is a graph illustrating the state of substrate oxidation, and FIG.

  FIGS. 1 to 4 show the configuration of a microwave / quasi-millimeter wave band oscillator according to the first embodiment of the present invention. In FIGS. A copper film (conductive film) 12 is formed on the surface), and a metal cylinder 22 (with a conductive adhesive (or solder or the like) 21 such as a silver paste is formed on the copper film 12 (the ground pattern). 1A is connected). The cylindrical body 22 in FIG. The cylindrical body 22 has an upper surface closed and a lower surface opened, and the open end is bonded to the copper film 12.

  Further, a first probe (input / output probe) 23 and a second probe (input / output probe) 24, which are coplanar lines, are formed in the cylindrical body 22 on the substrate 1, and the first probe 23 performs the first transmission. The line 25 and the second probe 24 are connected to an amplifying element (FET or the like) 27 on the substrate 1 via the second transmission line 26. The first transmission line 25 and the second transmission line 26 are also coplanar lines. That is, the cylindrical body 22 and the first probe 23 and the second probe 24 constitute a surface mount type cavity resonance circuit (resonator). In the other circuit (line) to the amplification element 27 and the terminal 28, An oscillation circuit is configured, and the resonance circuit and the oscillation circuit are connected by the first and second transmission lines 25 and 26. Reference numeral 29 denotes a through hole that connects the back surface ground (GND) and the front surface ground (copper film 12).

  In the first embodiment, the first probe 23 and the second probe 24 are taken out from the cylindrical body 22 at a position separated by 0 degrees. That is, these probes 23 and 24 can be taken out from a position 180 degrees apart on the circumference of the cylindrical body, for example, as indicated by a dotted arrow F, but in the embodiment, the first probe 23 and the first transmission line The length 25 and the lengths of the second probe 24 and the second transmission line 26 are the shortest length satisfying the oscillation condition (for example, one wavelength of the transmission signal), so that they are taken out at 0 degree, that is, at a parallel position. I have to. Thus, by shortening the lengths of the probes 23 and 24 and the transmission lines 25 and 26, the area of the substrate 1 on which they are arranged can be reduced.

FIG 3 has resonant modes in the cavity resonance circuit using the cylinder 22 is shown, FIG. 3 (B), the utilizing manner, for example, resonance of the fundamental mode of the TM ₀₁₀ of (C) Yes. In such a cavity resonance circuit, resonance is mainly performed by the cylindrical body 22, and the resonance frequency is substantially determined by the inner diameter of the cylindrical body 22. Therefore, the influence of the change in the dielectric constant of the substrate 1 on the resonance frequency is extremely high. Becomes smaller.

  FIG. 4 shows a configuration example of a microwave sensor in which the oscillator of FIG. 1 is incorporated. In this example, the resonance circuit and the oscillation circuit incorporated in the substrate 1 are covered with a casing 31, and the back surface of the substrate 1 is covered. Is provided with a patch-like antenna 32. The patch antenna 32 is connected to the input / output circuit on the front surface side of the substrate 1 through the through-hole 33. In the embodiment, as shown in FIG. A plurality of antennas 32 are arranged together with the ground 34.

  According to the first embodiment, since the surface mount type cavity resonance circuit is used, the resonance Q becomes high, and the resonance is performed in the cylindrical cavity, so that the dielectric constant of the substrate 1 changes over time. However, the resonance frequency of the resonance circuit is not easily affected. Further, the angle at which the first and second probes 23 and 24 are taken out from the cylindrical body 22 is set to 0 degree, and the lengths of the probes 23 and 24 and the transmission lines 25 and 26 are set to the shortest length that satisfies the oscillation condition. Therefore, the influence on the oscillation frequency due to the change in dielectric constant can be eliminated.

  That is, in the oscillator, it is necessary to match the phases of the first probe 23 and the transmission line 25 and the second probe 24 and the transmission line 26 (feedback line) so that the oscillation condition is satisfied. The oscillation frequency also changes slightly when the phase of is shifted. On the other hand, as the transmission lines 25 and 26 become longer, lines are formed in a wider area on the substrate 1, and the change in dielectric constant due to oxidation of the resin substrate 1 is promoted. Therefore, in the embodiment, the lengths of the probes 23 and 24 and the transmission lines 25 and 26 are set to the shortest length (for example, one wavelength) that satisfies the oscillation condition, and the change in the dielectric constant due to the oxidation of the substrate is reduced. The influence on the oscillation frequency is reduced.

  Furthermore, the probes 23 and 24 and the transmission lines 25 and 26 are formed by coplanar lines, and the cylindrical body 22 is connected to the ground pattern 12 of the coplanar lines. Such a circuit can be arranged efficiently.

  FIG. 5 shows the configuration of the second embodiment in which the probe take-out angle is 90 degrees. As shown in FIG. 5, the second embodiment includes the first probe 35 and the second probe 36. The cylindrical body 22 is formed at a position 90 degrees apart in the circumferential direction, and the first transmission line 37 and the second transmission line 38 are provided in the same direction with respect to the first probe 35 and the second probe 36. The lengths of the first probe 35 and the first transmission line 37 and the lengths of the second probe 36 and the second transmission line 38 are set to the shortest length that satisfies the oscillation condition. A transmission line 39 as another circuit such as an antenna is formed on the back surface of the substrate 1.

  Even with such a configuration, the area of the substrate 1 on which the probes 35 and 36 and the transmission lines 37 and 38 are arranged can be reduced, and the influence on the resonance frequency and the oscillation frequency can be reduced. It becomes possible to use it.

  By using the oscillator of the present invention together with a homodyne mixer, a microwave / millimeter wave band Doppler sensor or the like can be configured with a simple structure, and applied to detection of moving objects using microwaves, speed measurement, and the like. Can do.

1 ... substrate 12 ... copper film,
16, 27 ... Amplifying element, 21 ... Conductive adhesive (or solder),
22 ... Cylinder,
23, 35 ... first probe, 24, 36 ... second probe,
25, 37 ... first transmission line, 26, 38 ... second transmission line,
29,33 ... through hole,
32: Patch antenna.

Claims (2)

In a microwave / quasi-millimeter wave band oscillator in which an oscillation circuit and a resonance circuit are arranged on a resin substrate,
A surface mount in which the open end of a cylindrical body whose one end is open and the other end is closed is connected to the substrate, and two probes comprising coplanar lines are arranged from the outer periphery to the center of the cylindrical body on the substrate. Mold cavity resonant circuit,
A coplanar transmission line connecting the two probes of the cavity resonance circuit to the oscillation circuit, and
The two probes are taken out from the cylindrical body to the oscillation circuit side at an angular position of less than 180 degrees on the circumference of the cylindrical body so that the probe and the transmission line have the shortest length that satisfies the oscillation condition. A microwave / quasi-millimeter wave oscillator.   2. The microwave / quasi-millimeter wave band oscillator according to claim 1, wherein a circuit is formed on the back side of the substrate on which the cylindrical body is disposed.

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