JP4678127B2 - High frequency oscillator - Google Patents

Description

  The present invention relates to a high-frequency oscillator that oscillates a predetermined high-frequency signal, and in particular, a high-frequency oscillator in which a main part of an oscillation circuit is formed as an IC chip and a resonator that is connected to the IC chip is formed on a substrate on which the IC chip is mounted. It is about.

  Conventionally, a high-frequency oscillator, for example, a voltage-controlled oscillator, is a resonator that resonates at a predetermined frequency determined by an applied control voltage, and an oscillation that oscillates by amplifying a signal of the resonance frequency connected to the resonator Circuit. As a voltage controlled oscillator having such a configuration, there is a circuit configuration as shown in Patent Document 1.

  As a structure for realizing this circuit configuration, as shown in Patent Document 2, a resonator electrode pattern is formed by inner layer electrodes and upper and lower surface electrodes of a multilayer substrate, and each mounting component constituting an oscillation circuit is formed on this substrate. Some are equipped. Further, as shown in Patent Document 3, there is a structure in which an oscillation circuit other than a resonator is formed as an IC chip, and a resonator electrode pattern is formed on a substrate on which the IC chip is mounted.

An example of such a voltage controlled oscillator in which the part other than the resonator of the oscillator is formed as an IC chip will be described with reference to FIGS.
7A and 7B are perspective views showing a schematic configuration of a conventional voltage controlled oscillator, wherein FIG. 7A is a perspective view from the IC chip mounting surface side, and FIG. 7B is a perspective view from the facing surface side of FIG.
8A is a top view of the substrate of the voltage controlled oscillator shown in FIG. 7, and FIG. 8B is a bottom view of this substrate.
In the following, for simplicity of explanation, the surface shown in FIG. 8A is referred to as the front surface, and the surface shown in FIG. 8B is referred to as the back surface.

  As shown in FIGS. 7 and 8, a plurality of lands on which the IC chip 2 is mounted are formed on the surface of the dielectric substrate 1, and a resonator electrode pattern 11 having a predetermined shape including a microstrip line is formed. ing. The resonator electrode pattern 11 is electrically connected to the ground electrode 16 on the back surface through an electrode on one side from the surface to the side surface (the left back surface in FIG. 7A), and the other end is connected to the resonator connection terminal ( Res terminal) is conducted to the land where it is mounted. Further, a ground electrode pattern 13 is formed on the surface of the dielectric substrate 1, and one end thereof is electrically connected from this surface to the ground electrode 16 on the back surface through the electrode on the side surface (the right hand front surface in FIG. 7A). The other end is electrically connected to a land on which the ground terminal (GND2 terminal) of the IC chip 2 is mounted. Further, the midway portion of the resonator electrode pattern 11 is electrically connected to the land on which the emitter connection terminal (Emi terminal) of the oscillation transistor of the IC chip 2 is mounted by the wiring electrode pattern 12. Further, the land on which the oscillation transistor ground terminal (GND1 terminal) of the IC chip 2 is mounted is electrically connected to the ground electrode 16 on the back surface through the electrode pattern 14 and the through hole 15 having a conductor.

In addition, a metal case 3 including the IC chip 2 and covering substantially the entire surface is provided on the surface (front surface) of the dielectric substrate 1 on which the IC chip 2 is mounted.
JP-A-11-74727 JP 2000-307345 A JP-A-8-293728

In the voltage controlled oscillator having such a structure, a circuit as shown in FIG. 9 is configured.
FIG. 9 is an equivalent circuit diagram of the voltage controlled oscillator shown in FIG.
In the structure shown in FIGS. 7 and 8, since the voltage controlled oscillator is substantially grounded by the electrode near the side surface (the right rear surface in FIG. 7) of the dielectric substrate 1, as shown in FIG. between one end of the emitter side ground terminal of the oscillation transistor Tr1 (GND1 terminals) and the resonator electrode patterns 11 (L1), an inductor L _P by the wiring electrode patterns 14, the inductor L _TH by the through hole 15, the back surface a structure in which an inductor L _G by the ground electrode 16 are connected in series.

This voltage-controlled oscillator is a Colpitts type oscillator composed of an oscillation transistor Tr1, capacitors C3 and C6, and a resonator L1. , so that the resonators L1 and the inductor L _P, L _TH, synthetic inductor due to the series connection of the L _G is connected.

By the way, although the IC chip used for such a voltage controlled oscillator tends to be miniaturized, when the IC chip is miniaturized, the distance between the terminals is shortened and the width of the wiring electrode pattern tends to be narrowed. For this reason, the value of the aforementioned inductor L _P becomes large. Further, since the through hole 15 is formed of a conductor, the inductor L _TH also has a certain value, and the ground electrode 16 provided on the back surface has a relatively wide area. because the distance to the substantial ground point is long, the inductor L _G also will have a value of some degree.

Here, since these inductors are restricted to a certain extent due to the external shape of the oscillator and the configuration of the circuit pattern, it is difficult to control the value of the inductor to a predetermined value. For this reason, it is difficult to keep the L component of the Colpitts oscillator constant, which causes variations in oscillation frequency.
In addition, since a part of the wiring pattern of the oscillator is formed from the front surface to the back surface of the substrate, the wiring pattern becomes long, conductor loss occurs, and the C / N characteristics of the oscillation signal deteriorate.

  Furthermore, since the back side is mounted close to the module substrate on which this voltage controlled oscillator is mounted, electrical coupling occurs between the ground electrode and the electrode formed on the module substrate, and the constant of the Colpitts oscillator changes. The oscillation frequency may change. In addition, noise from the module substrate may propagate to the ground electrode on the back surface and affect the oscillation signal.

  Therefore, an object of the present invention is to provide an excellent C with a stable oscillation frequency by using a configuration in which an IC chip having an oscillator function including a portion excluding a resonator is mounted on a substrate on which a resonator electrode is formed. The object is to provide a high-frequency oscillator having a / N characteristic.

The present invention includes an IC chip that is mounted on a mounting substrate and includes at least an oscillation transistor and a buffer transistor, and a resonator electrode for adjusting an oscillation frequency formed on the surface of the mounting substrate. In the high-frequency oscillator, the IC chip is connected to the base of the oscillation transistor via a capacitor, and the oscillation circuit is connected to the emitter of the oscillation transistor via a capacitor. An oscillation circuit emitter terminal connected to the emitter of the oscillation transistor via the first resistance element; the mounting substrate includes a land to which the oscillation circuit ground terminal is connected; and a resonator connection terminal. and lands are connected, to have a plurality of lands on a surface including a land emitter terminal oscillator circuit is connected DOO And a through hole at a position shorter than the distance between the land to which the oscillation circuit ground terminal is connected and the end face of the mounting board, starting from the land to which the oscillation circuit ground terminal is connected. Is electrically connected to the land connected to the ground terminal for the oscillation circuit on the surface of the mounting substrate and the ground electrode provided on the back surface of the mounting substrate, and the resonator electrode formed on the surface of the mounting substrate has one end Is connected to the land to which the resonator connection terminal is connected , the other end is directly connected to the land to which the ground terminal for the oscillation circuit is connected, and an intermediate point between one end and the other end is connected to the mounting substrate. It is characterized in that it is connected to a land to which the emitter terminal for an oscillation circuit is connected through the formed branch line.

  In this configuration, one end of the resonator is grounded via the oscillation circuit ground terminal of the IC chip. Here, the oscillation circuit ground terminal is a terminal for grounding a high-frequency ground point of the oscillation circuit. For this reason, since the resonator is directly connected to the oscillation circuit, the electrode between the oscillation circuit ground terminal and the ground becomes an inductor between the oscillation circuit and the ground, and the inductor between the resonator and the ground. It becomes. As a result, these unstable inductors are not inserted into the high-frequency signal transmission path (the L portion of the Colpitts type oscillator) composed of the resonator and the oscillation circuit. Further, the gap between the resonator and the resonator connection terminal of the IC chip is shortened, and the conductor loss is reduced.

  Further, the present invention is characterized in that the mounting substrate is constituted by a laminated substrate including internal electrodes forming a plurality of layers, and at least a part of the resonator electrode is formed by the internal electrodes.

  In this configuration, the resonator electrode is formed in the mounting substrate, thereby reducing the surface area of the mounting substrate.

  According to the present invention, an unstable inductor or pattern electrode resistance due to the pattern electrode provided on the mounting substrate is not inserted into the high-frequency signal transmission path composed of the resonator and the oscillation circuit of the IC chip. In addition, it is possible to form a high-frequency oscillator having excellent oscillation characteristics and C / N characteristics.

  Further, according to the present invention, by forming the resonator electrode as an inner layer, a high-frequency oscillator having excellent C / N characteristics at a stable oscillation frequency can be formed in a small size.

A high-frequency oscillator according to a first embodiment of the present invention will be described with reference to FIGS. In the present embodiment, a voltage controlled oscillator will be described as an example of a high frequency oscillator.
1A and 1B are perspective views showing a schematic configuration of a voltage controlled oscillator according to the present embodiment, in which FIG. 1A is a perspective view from the IC chip mounting surface side, and FIG. 1B is a perspective view from the facing surface side of FIG. It is.
2A is a top view of the substrate of the voltage controlled oscillator shown in FIG. 1, and FIG. 2B is a bottom view of the substrate.
FIG. 3 is an equivalent circuit diagram of the voltage controlled oscillator of this embodiment.

  In the following, for simplicity of explanation, the surface shown in FIG. 2A is referred to as the front surface of the dielectric substrate 1, and the surface shown in FIG.

  As shown in FIGS. 1 and 2, electrodes are formed on the front surface and the back surface of the dielectric substrate 1, and a plurality of lands on which the IC chip 2 is mounted are formed on the front surface. A ground electrode 16 is formed on the substrate.

  The IC chip 2 has a plurality of terminals respectively mounted on the plurality of lands as shown below. Specifically, a control voltage signal input terminal Vc terminal, a drive voltage signal input terminal Vb terminal, a resonator connection terminal Res terminal, an oscillation transistor emitter connection terminal Emi terminal, and an oscillation transistor It has a GND1 terminal as a ground terminal, a GND2 terminal as a ground terminal through a capacitor of a Vb terminal as a drive voltage signal input terminal, and an OUT terminal as an oscillation signal output terminal. Here, since the GND1 terminal is a ground terminal for grounding the collector of the oscillation transistor at a high frequency via a capacitor, it corresponds to the “ground terminal for oscillation circuit” of the present invention.

  A resonator electrode pattern 11 is formed by a microstrip line on the surface of the dielectric substrate 1, one end of which is electrically connected to the Res terminal land of the plurality of lands, and the other end of which is for the GND1 terminal. Conducted to the land. Further, a wiring electrode pattern 12 is formed on the surface of the dielectric substrate 1 by a microstrip line for electrically connecting the midpoint of the resonator electrode pattern 11 and the Emi terminal land.

  Further, a through hole 15 penetrating through the dielectric substrate 1 and filled with a conductor is formed in the vicinity of the land for the GND1 terminal of the dielectric substrate 1, and the land for the GND1 terminal is a microstrip line wiring. The electrode pattern 14 and the through hole 15 are electrically connected to the ground electrode 16 on the back surface.

  In addition, arc-shaped cutouts are provided on two opposing end surfaces of the dielectric substrate 1 (the front surface of the right hand and the left back surface in FIG. 1A). An electrode is formed on the side surface, and an electrode is also formed around the notch on the surface of the dielectric substrate 1 so as to be electrically connected to the electrode. These electrodes are electrically connected to the ground electrode 16 on the back surface. Here, a ground electrode pattern 13 is formed on the surface of the dielectric substrate 1 to connect the GND2 terminal land and the electrode formed around the arc-shaped cutout portion.

  Further, a control voltage signal input electrode 101, a drive voltage signal input electrode 102, and an oscillation signal output electrode 103 are formed in three of the four corners of the dielectric substrate 1, and the remaining corners are NC. It is a terminal.

  The IC chip 2 is provided with the above-described terminals and, as shown in FIG. 3, except for the resonator L1 (resonator electrode pattern 11 in FIGS. 1 and 2), A circuit pattern is provided. Specifically, the cathode of the variable capacitance diode VD is connected to one end of the capacitor C1, and the Vc terminal is connected via the inductor L0. The anode of the variable capacitance diode VD is connected to the GND1 terminal, and the Vc terminal is also connected to the GND1 terminal via the capacitor C0. The other end of the capacitor C1 is connected to the base of the oscillation transistor Tr1 through the capacitor C2 and to the Res terminal.

  The emitter of the oscillating transistor Tr1 is connected to the Emi terminal via the resistor element R4, and is connected to the GND1 terminal via the capacitor C6. The emitter of the oscillation transistor Tr1 is connected to the base of the buffer transistor Tr2 via the capacitor C4. A feedback capacitor C3 is connected between the emitter and base of the oscillation transistor Tr1.

  The collector of the oscillation transistor Tr1 and the emitter of the buffer transistor Tr2 are connected to the GND1 terminal via the capacitor C5.

  The collector of the buffer transistor Tr2 is connected to the Vb terminal that is the drive voltage signal input terminal via the inductor L2, and is also connected to the OUT terminal that is the oscillation signal output terminal via the capacitor C7.

  The Vb terminal is connected to the GND2 terminal via the capacitor C8. Further, resistance elements R1, R2, and R3 are connected in series between the Vb terminal and the GND1 terminal, and the connection point of the resistance elements R1, R2 is connected to the base of the buffer transistor Tr2, and the resistance element R2 , R3 is connected to the base of the oscillation transistor Tr1.

  Such an IC chip 2 is mounted on a land formed on the dielectric substrate 1.

  With such a configuration, a voltage-controlled oscillator is formed by mounting the IC chip 2 including the oscillation circuit excluding the resonator portion on the dielectric substrate 1 on which the resonator electrode pattern 11 is formed. In the voltage controlled oscillator, as shown in FIG. 3, a capacitor C3 is connected between the emitter and base of the oscillation transistor Tr1, a capacitor C6 is connected between the emitter and collector, and a resonator L1 is connected between the base and collector. Therefore, a Colpitts type oscillator is constituted by these elements. The capacitor C5 is substantially in a very low impedance state, so the description of the connection relationship is omitted.

  When the voltage controlled oscillator having such a configuration is mounted on a module substrate on which another functional circuit is formed, the electrodes on the side and back surfaces of the dielectric substrate 1 are joined to the ground electrode of the module substrate with solder or the like. Secure the ground potential of the voltage controlled oscillator. Then, the drive voltage signal and the control voltage signal are supplied to the voltage controlled oscillator by electrically joining the Vb terminal, the Vc terminal, and the OUT terminal of the voltage controlled oscillator to the land on which the module board is mounted. An oscillation signal having a predetermined frequency is output by the resonator and the oscillation circuit.

With this configuration, as described above, one end of the resonator electrode pattern 11 is directly connected to the GND1 terminal land that is electrically connected to the emitter of the oscillation transistor Tr1 and the ground. wiring electrode patterns 14 of the surface, the through hole 15, and the inductor L _P by the rear surface of the ground electrode 16, L _TH, L _G is the base of the oscillation transistor Tr1 configuring the oscillator Colpitts - since it is not inserted between the collectors, these Thus, it is possible to configure a voltage controlled oscillator that oscillates stably at a desired oscillation frequency without being influenced by the inductor. In addition, since the base and the collector are not connected through a relatively long path including an electrode pattern, a through hole, and a ground electrode as in the conventional example, the occurrence of conductor loss due to these electrodes can be suppressed. A voltage-controlled oscillator having excellent / N characteristics can be configured.

  In addition, with such a configuration, even if noise propagates from the module substrate to the ground electrode on the back surface of the dielectric substrate, almost no noise is propagated to the surface of the dielectric substrate on which the oscillation circuit and the resonator electrode are formed. Thus, a voltage controlled oscillator having stable oscillation characteristics can be configured.

  As shown in FIG. 1, in the voltage controlled oscillator of this embodiment, a metal case 3 is installed on the surface side of the dielectric substrate 1 on which the IC chip 2 is mounted so as to cover the surface and the IC chip 2. ing. Since the metal case 3 is electrically connected to the electrode formed on the side surface of the dielectric substrate 1, the voltage controlled oscillator formed on the dielectric substrate 1 is suppressed from being affected by the signal from the external circuit. . As a result, a voltage controlled oscillator having further excellent oscillation characteristics can be configured.

Next, a voltage controlled oscillator according to a second embodiment will be described with reference to FIGS.
FIG. 4 is a perspective view showing a schematic configuration of the voltage controlled oscillator of the present embodiment. FIG. 5 is a top view of the substrate of the voltage controlled oscillator shown in FIG. FIG. 6 is an equivalent circuit diagram of the voltage controlled oscillator of this embodiment.

  The voltage controlled oscillator shown in FIGS. 4 and 5 has a resistance element 4 inserted in the middle of the wiring electrode pattern 12 of the voltage controlled oscillator shown in FIGS. 1 and 2, and other configurations are shown in FIGS. This is the same as the voltage controlled oscillator shown in FIG. If the resistance element 4 is R5 on the equivalent circuit diagram, and this is represented by the equivalent circuit diagram, the equivalent circuit diagram shown in FIG. 6 is obtained. As shown in the equivalent circuit diagram of FIG. 6, the voltage controlled oscillator according to the present embodiment has a resistance element R4 and a resistance element R5 connected in series between the emitter of the oscillation transistor Tr1 and the midpoint of the resonator L1. The other configurations are the same as those of the voltage controlled oscillator shown in the first embodiment. Here, the resistance element R5 is not formed in the IC chip 2, but is mounted on the surface of the dielectric substrate 1, so that the current flowing through the oscillation circuit is adjusted by changing the resistance value of the resistance element R5. can do.

  Therefore, with such a configuration, a plurality of types of current consumption and output levels can be obtained with one type of oscillation IC chip. That is, a plurality of types of voltage controlled oscillators can be formed with one type of IC chip.

  In each of the above-described embodiments, the resonator electrode is formed on the surface of the dielectric substrate. However, the resonator electrode may be formed of an inner layer electrode using a multilayer dielectric substrate. With such a structure, an IC chip can be mounted on the surface of the dielectric substrate, and a resonator electrode can be formed in the lower layer (inner layer), thereby reducing the shape of the voltage controlled oscillator.

  In each of the above-described embodiments, the voltage-controlled oscillator has been described as an example. However, if the high-frequency oscillator includes a resonator and an IC chip including an oscillation circuit other than the resonator, the above-described configuration is applied. And the effects described above can be achieved.

The perspective view which shows schematic structure of the voltage controlled oscillator of 1st Embodiment. Top view and bottom view of the substrate of the voltage controlled oscillator shown in FIG. 1 is an equivalent circuit diagram of the voltage controlled oscillator shown in FIG. The perspective view which shows schematic structure of the voltage controlled oscillator of 2nd Embodiment. Top view of the substrate of the voltage controlled oscillator shown in FIG. 4 is an equivalent circuit diagram of the voltage controlled oscillator shown in FIG. A perspective view showing a schematic configuration of a conventional voltage controlled oscillator The top view and bottom view of the substrate of the voltage controlled oscillator shown in FIG. 7 is an equivalent circuit diagram of the voltage controlled oscillator shown in FIG.

Explanation of symbols

1-dielectric substrate 2-IC chip 3-metal case 4-resistance element 11-resonator electrode 12-wiring electrode pattern 13-ground electrode pattern 14-wiring electrode pattern 15-through hole 16-ground electrode 101-control voltage signal Input electrode 102-driving voltage signal input electrode 103-oscillation signal output electrode

Claims (3)

An IC chip that is mounted on a mounting substrate and includes at least an oscillation transistor and a buffer transistor, and an oscillation frequency adjusting resonator electrode formed on the surface of the mounting substrate, the resonator electrode being the IC In a high-frequency oscillator that is connected to the chip,
The IC chip includes a resonator connection terminal connected to the base of the oscillation transistor via a capacitor, an oscillation circuit ground terminal connected to the emitter of the oscillation transistor via a capacitor, and an emitter of the oscillation transistor And an emitter terminal for an oscillation circuit connected via a first resistance element,
The mounting substrate has a plurality of lands including a land to which the oscillation circuit ground terminal is connected, a land to which the resonator connection terminal is connected, and a land to which the oscillation circuit emitter terminal is connected on the surface. And having a through hole at a position shorter than the distance between the land to which the oscillation circuit ground terminal is connected and the end surface of the mounting board, starting from the land to which the oscillation circuit ground terminal is connected, The through hole electrically connects a land to which the oscillation circuit ground terminal on the surface of the mounting substrate is connected and a ground electrode provided on the back surface of the mounting substrate,
The resonator electrode formed on the surface of the mounting substrate has one end connected to the land to which the resonator connection terminal is connected , and the other end directly connected to the land to which the oscillation circuit ground terminal is connected. And an intermediate point between the one end and the other end is connected to a land to which the oscillator circuit emitter terminal is connected via a branch line formed on the mounting substrate. High frequency oscillator.   The high-frequency oscillator according to claim 1, wherein all the resonator electrodes are formed on a surface of the mounting substrate. 3. The high frequency device according to claim 1, wherein a second resistance element is mounted on the branch line as a resistor connected in series between the resonator electrode and the oscillator circuit emitter terminal . 4. Oscillator.

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