JP2008236174A - Dc cut circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a DC cut circuit which can surely cut a direct current, can be used in a microwave band and a millimeter-wave band and can be manufactured, in a simple structure and at low cost. <P>SOLUTION: The DC cut circuit 1 is provided with a dielectric substrate 2, an input stripline 3, an output stripline 4, a resonator electrode 5 and a ground electrode 6. The input and output striplines 3 and 4 are formed on the surface 20 of the dielectric substrate 2, while their opened end parts 32 and 42 are located at a central part. The opened end parts 32 and 42 of the input and output striplines 3 and 4 are a prescribed distance separated from each other, face each other and have a gap G between the opened end parts 32 and 42. The resonator electrode 5 is set to a length that is about 1/2 the wavelength of the dielectric substrate 2 and is formed in the dielectric substrate 2 so as to face the gap G. The resonator electrode 5 also is formed, in such a manner that both opened end parts 51 and 52 overlap the opened end parts 32 and 42. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a DC cut circuit applied to a high frequency circuit such as a high frequency amplifier.

In an amplifier or the like of a mobile communication device, a DC cut circuit that cuts a DC (direct current) component such as a direct current bias from an input / output signal and extracts only a high frequency component within a band is used.
As this type of DC cut circuit, for example, as disclosed in Patent Document 1 and Patent Document 2, input strip lines and output strip lines are arranged in parallel on the same plane, or resonator electrodes are arranged. There is a configuration in which an input stripline and an output stripline are arranged in parallel so that a signal is input from the input stripline and an in-band signal is extracted from the output stripline.
Further, for example, as in the techniques disclosed in Patent Document 3 and Patent Document 4, the input strip line and the output strip line are arranged with a predetermined gap in the length direction on the same plane, and the resonator electrode Are arranged below or above the gap between the input stripline and the output stripline, and the input stripline, the output stripline and the resonator electrode are shielded from above and below by a plurality of ground conductors. There are also things.

JP 62-263701 A JP 05-083007 A JP-A-10-224108 JP 05-152804 A

However, the conventional techniques described above have the following problems.
The technology disclosed in Patent Document 1 and Patent Document 2 has a simple configuration in which strip lines are arranged or strip lines and resonator electrodes are arranged. In such a DC cut circuit, in order to increase the resonance frequency, it is necessary to increase the capacitance value by increasing the opposing area between the strip lines or between the strip line and the resonator electrode and by narrowing the gap. However, in this DC cut circuit, since the strip lines and the resonator electrodes are arranged side by side, the facing area is small, and therefore the gap must be narrowed in order to increase the capacitance value. Therefore, in order to be able to use in the microwave band and the millimeter wave band, it is necessary to form a very narrow gap by using a highly accurate fine electrode wiring process. For this reason, there exists a problem that manufacturing cost is expensive.
On the other hand, in the techniques disclosed in Patent Document 3 and Patent Document 4, since the resonator electrode is arranged below or above the gap between the input stripline and the output stripline, the stripline and resonator The area facing the electrode can be increased. For this reason, even if these gaps are not extremely narrowed, a capacitance value having a desired size can be obtained and can be used in the microwave band and the millimeter wave band. However, since it has a triplate structure in which the input stripline, the output stripline, and the resonator electrode are shielded by sandwiching them from above and below by a plurality of ground conductors, it is structurally complicated and requires many manufacturing steps. There is a problem that the manufacturing cost is high.

  The present invention has been made in order to solve the above-described problems, and can directly cut a direct current and can be used in a microwave band and a millimeter wave band, and has a simple structure and low cost. An object of the present invention is to provide a DC cut circuit that can be manufactured easily.

In order to solve the above-described problem, a DC cut circuit according to the invention of claim 1 is an input that is located on the surface of the dielectric substrate with the dielectric substrate and an end opposite to the signal input end as an open end. An output strip line located on the surface of the dielectric substrate with the end opposite to the strip line and the signal output end being an open end and the open end being opposed to the open end of the input strip line Is located inside the dielectric substrate, and when viewed from the back side of the dielectric substrate, one open end overlaps with the open end of the input strip line and the other open end is the open end of the output strip line. With a predetermined distance to the gap between the open end of the input strip line and the open end of the output strip line, and has a length of about one half of the wavelength in the dielectric substrate at the resonance frequency. Resonator electrode It was configured to include the.
With this configuration, when a signal having a predetermined frequency is input from the input stripline, the signal is transmitted from the open end of the input stripline to the resonator electrode, and the resonator electrode resonates when the signal frequency is an in-band frequency. And the signal of this resonance frequency is output to an output strip line from an open end. Therefore, even if a DC signal is input to the input strip line, the resonator electrode does not resonate, and this DC signal is cut. The band of the signal that resonates at the resonator electrode is determined by the overlapping area between one open end of the resonator electrode and the open end of the input strip line, and between the open end of the other and the open end of the output strip line. It changes according to the overlapping area. Further, by reducing the distance between the resonator electrode and the input and output strip lines, the electromagnetic coupling between the both ends of the resonator electrode and the open ends of the input and output strip lines can be strengthened.

  According to a second aspect of the present invention, in the DC cut circuit according to the first aspect, the ground electrode is provided on the back surface of the dielectric substrate, and the input strip line and the output strip line are microstrip lines.

  According to a third aspect of the present invention, in the DC cut circuit according to the first or second aspect, ground electrodes are provided on both sides of the input stripline and the output stripline, respectively, and the input stripline, the output stripline, and the ground are provided. A coplanar line was constructed with the electrodes.

According to a fourth aspect of the present invention, in the DC cut circuit according to any one of the first to third aspects, the gap between the input stripline and the output stripline is widened, and the surface of the dielectric substrate is within the gap. One or more intermediate strip lines are discretely arranged so as to face the gap between the input strip line and the intermediate strip line, the gap between adjacent intermediate strip lines, and the gap between the intermediate strip line and the output strip line, respectively. By arranging a plurality of resonator electrodes in the dielectric substrate, the DC cut part has a multi-stage configuration.
With this configuration, it is possible to cut the DC signal more reliably.

According to a fifth aspect of the present invention, in the DC cut circuit according to any one of the first to fourth aspects, an external circuit for connecting the characteristic impedance of the input stripline and the output stripline to the input stripline and the output stripline The output impedance and the input impedance are matched.
With this configuration, it functions as a matching circuit by interposing between the transmission line and the external circuit.

The invention of claim 6 is the DC cut circuit according to any one of claims 1 to 5, wherein the branch path is provided in the middle of the resonator electrode, and a grounded termination resistor is connected to the tip of the branch path, An open stub having a length of about a quarter of the wavelength in the dielectric substrate at the resonance frequency is a part of the branch path, and is only about a quarter of the wavelength in the dielectric substrate from the branch point of the branch path. The configuration is such that it protrudes at a distant position.
With this configuration, the branch point of the branch path in the resonator electrode is opened with respect to the in-band signal, and the outflow of the signal to the branch path side is prevented. When the out-of-band signal flows into the branch path, it flows out to the outside through the grounded termination resistor.

  A high-frequency module according to a seventh aspect of the invention includes the DC cut circuit according to any one of the first to sixth aspects.

As described above in detail, according to the DC cut circuit of the present invention, a DC signal can be cut reliably.
In addition, since both open ends of the resonator electrode overlap with the open ends of the input and output strip lines, the distance between the resonator electrode and the input and output strip lines need not be extremely narrow. The desired capacitance value can be easily obtained by these overlapping portions, and as a result, a DC cut circuit that can be used in the microwave band and the millimeter wave band can be easily manufactured. In addition, since the area of the overlap between the open ends of the resonator electrodes and the open ends of the input and output strip lines can be easily increased, the DC cut circuit disclosed in Patent Document 1 or Patent Document 2 can be used. In comparison, the transmission frequency band can be made wider.
Furthermore, since the gap between the resonator electrode and the input and output strip lines can be easily narrowed by the electrode and dielectric layering technique, as in the DC cut circuit disclosed in Patent Document 1 and Patent Document 2, There is no need to use a highly accurate fine electrode wiring process. As a result, the DC cut circuit can be manufactured at low cost. In addition, in this way, by reducing the distance between the resonator electrode and the input and output strip lines, electromagnetic coupling between both open ends of the resonator electrode and the open ends of the input and output strip lines is achieved. Since it can be strengthened, in-band signals can be transmitted with low loss.
The DC cut circuit of the present invention is not a triplate structure like the DC cut circuits disclosed in Patent Document 3 and Patent Document 4, but input and output strip lines are provided on the surface of the dielectric substrate, and the resonator electrodes are provided. Since it is a simple structure arranged in the dielectric substrate so as to face the gap, it can be manufactured with few steps, and the manufacturing cost can be reduced correspondingly.

In particular, according to the fourth aspect of the present invention, it is possible to cut the DC signal more reliably.
Further, according to the invention of claim 5, since it can function as a matching circuit, a dedicated matching circuit is not required, and accordingly, a device incorporating this DC cut circuit can be reduced in size and cost. Can be achieved.

  According to the invention of claim 6, since the in-band signal is reliably propagated in the resonator electrode, and the out-of-band signal flows out through the branch path, the loss to the in-band signal can be reduced. In addition, it is possible to stabilize the cutoff characteristic for out-of-band signals.

  In addition, according to the high frequency module of the seventh aspect of the invention, it is possible to achieve stability, downsizing, and cost reduction of the entire apparatus, and to increase the transmission / reception frequency band.

  The best mode of the present invention will be described below with reference to the drawings.

  1 is a partially cutaway perspective view showing a DC cut circuit according to a first embodiment of the present invention, FIG. 2 is a plan view of the DC cut circuit, and FIG. 3 is a view of FIG. 4 is a cross-sectional view taken along the line A-A, and FIG. 4 is a perspective view of the overlapping state of the input and output strip lines and the resonator electrode as seen through from the back side of the dielectric substrate.

The DC cut circuit 1 of this embodiment includes a dielectric substrate 2, an input strip line 3, an output strip line 4, a resonator electrode 5, and a ground electrode 6, as shown in FIGS.
The input strip line 3 is a conductor having a width w3 for inputting a signal (see FIG. 4), and is patterned on the surface 20 of the dielectric substrate 2.
Specifically, the signal input end 31 of the input stripline 3 is located at the edge 20 a of the surface 20 of the dielectric substrate 2, and the open end 32 on the opposite side is located at the center of the surface 20. Yes.
The output strip line 4 is a conductor having a width w4 for outputting a signal (see FIG. 4), and is patterned on the surface 20 of the dielectric substrate 2 so as to face the input strip line 3. .
Specifically, the signal output end 41 of the output strip line 4 is located at the edge 20 b of the surface 20 of the dielectric substrate 2, and the open end 42 on the opposite side is the open end of the input strip line 3. In the state of facing to 32, the dielectric substrate 2 is located at the center of the surface 20.
The open ends 32 and 42 of the input and output strip lines 3 and 4 are opposed to each other by a predetermined distance, and have a gap G therebetween.

The resonator electrode 5 is a conductor electrode that resonates at a predetermined frequency, and is patterned inside the dielectric substrate 2 so as to face the gap G between the input and output strip lines 3 and 4.
Specifically, as shown in FIGS. 3 and 4, the resonator electrode 5 is a line open at both ends having a width w 5 and a length L, and is disposed at a depth d from the surface 20 of the dielectric substrate 2. The gap G between the open end portions 32 and 42 is opposed to the gap G. In addition, the length L of the resonator electrode 5 is set to about one half of the wavelength in the dielectric substrate 2 (hereinafter referred to as “λg”) at the resonance frequency.
Such a resonator electrode 5 overlaps the open ends 32, 42 of the input and output striplines 3, 4. That is, as shown in FIG. 4, when viewed from the rear surface 21 side of the dielectric substrate 2, one open end 51 overlaps the open end 32 of the input stripline 3 with a length D. The other open end 52 also overlaps the open end 42 of the output stripline 4 with a length D.

  As shown in FIGS. 1 and 2, the ground electrode 6 is provided on the entire back surface 21 of the dielectric substrate 2. Thus, the input and output strip lines 3 and 4 together with the ground electrode 6 constitute a microstrip line.

Next, the operation and effect of the DC cut circuit 1 of this embodiment will be described.
FIG. 5 is a cross-sectional view for explaining the operation and effect of the DC cut circuit 1.
As shown in FIG. 5, when a signal S within the band is input from the signal input end 31 of the input strip line 3, as indicated by an arrow, between the open end 32 and the open end 51 of the resonator electrode 5. Then, an electric field E is generated between the open end 52 and the open end 42 of the output strip line 4, and the input and output strip lines 3 and 4 and the resonator electrode 5 are electromagnetically coupled. As a result, the signal S is transmitted from the open end 32 of the input stripline 3 to the resonator electrode 5 so that the resonator electrode 5 resonates. Then, the signal S is input to the output strip line 4 from the open end 52, and is output from the signal output end 41 to an external circuit (not shown) or the like.
Therefore, even if a DC signal is input to the input strip line 3, the resonator electrode 5 does not resonate, and this DC signal is cut.

By the way, this DC cut circuit 1 forms a capacitance by overlapping the surfaces of the open ends 32 and 42 of the input and output strip lines 3 and 4 and the open ends 51 and 52 of the resonator electrode 5. Therefore, even if the distance d between the resonator electrode 5 and the input and output strip lines 3 and 4 is not extremely narrowed, a large capacitance value can be obtained by these overlapping portions. That is, the DC cut circuit 1 also functions as a filter for the signal S having a frequency in the microwave band or the millimeter wave band.
Further, by reducing the distance d between the resonator electrode 5 and the input and output strip lines 3 and 4, a larger capacitance value can be obtained and the resonator electrode 5 and the input and output strip lines 3 and 4 can be obtained. Since the electromagnetic coupling between the two can be strengthened, the DC cut circuit 1 can be used as a filter having a wide bandwidth, and the use of the DC cut circuit 1 enables low-loss transmission of the signal S. .

  Further, the DC cut circuit 1 stacks the electrodes and lines while laminating the dielectric substrate 2 layer, the resonator electrode 5 layer, and the input and output strip lines 3 and 4 on the ground electrode 6 layer. Since it can be manufactured only by forming a pattern, the distance d between the input and output strip lines 3 and 4 and the resonator electrode 5 can be easily reduced.

The inventors performed the following simulation in order to confirm the effect of the DC cut circuit 1.
FIG. 6 is a plan view for explaining the dimensions of the DC cut circuit used in the simulation, and FIG. 7 is a diagram showing the result of the simulation.
In this simulation, the dielectric substrate 2 having a relative dielectric constant of 8.8 was used, and the center frequency in the band was set to 60 GHz. That is, the resonator electrode 5 having a length L of 0.730 mm is used, the length D of the overlapping portion between the open ends 32 and 42 and the open ends 51 and 52 is 0.265 mm, and the input and output strip lines 3, The distance d between 4 and the resonator electrode 5 was set to 0.05 mm. First, as shown in FIG. 6 (a), the widths w3 and w4 of the input and output strip lines 3 and 4 and the width w5 of the resonator electrode 5 are set to be equal to 0.22 mm, and 0 to 100 GHz. The signal was swept to simulate the reflection coefficient and transmission coefficient for each frequency.
Then, as shown by the dashed reflection coefficient curve Sa11 in FIG. 7, the reflection coefficient is about “−45 (dB)” which is the lowest at about 60 GHz, the reflectance is low, and the bandwidth Wa is also 10 GHz or more. The width was secured, and broadening of the bandwidth was confirmed.
Further, as indicated by the broken transmission coefficient curve Sa21, the transmission coefficient is “0 (dB)” for a signal of 50 GHz or more, but becomes very small for a signal of less than 50 GHz and does not transmit a DC signal.
Next, as shown in FIG. 6 (b), the widths w3 and w4 of the input and output strip lines 3 and 4 are equally set to 0.22 mm, and the width w5 of the resonator electrode 5 is set to 0.07 mm. And simulated.
Then, as indicated by the solid reflection coefficient curve Sb11 in FIG. 7, although the center frequency is shifted slightly lower, a value almost equivalent to the reflection coefficient curve Sa11 was obtained.
As indicated by the solid transmission coefficient curve Sb21, the transmission coefficient is substantially the same as the transmission coefficient curve Sa21 of 50 GHz or higher, but is smaller than the transmission coefficient curve Sa21 for signals of less than 50 GHz. That is, it was confirmed that the transmission characteristics in the low frequency region can be improved by making the resonator electrode 5 thinner.

Next explained is the second embodiment of the invention.
FIG. 8 is a plan view showing a DC cut circuit according to the second embodiment of the present invention, and FIG. 9 is a cross-sectional view taken along the line BB in FIG.
The DC cut circuit 1-2 according to this embodiment is different from the first embodiment in that the DC cut circuit has a two-stage configuration.
In the first embodiment, the input and output strip lines 3 and 4 and the resonator electrode 5 constitute one DC cut portion. On the other hand, in this embodiment, as shown in FIGS. 8 and 9, the gap between the input stripline 3 and the output stripline 4 is widened, and an intermediate stripline 34 smaller than this gap is patterned in this gap. Formed. Then, the two resonator electrodes 5-1 and 5-2 are dielectrically arranged so as to face the gap G1 between the input stripline 3 and the intermediate stripline 34 and the gap G2 between the intermediate stripline 34 and the output stripline 4, respectively. It was arranged in the body substrate 2. In this way, the input strip line 3, the resonator electrode 5-1, and the intermediate strip line 34 constitute a first-stage DC cut portion, and the intermediate strip line 34, the resonator electrode 5-2, and the output strip line. 4 and the second-stage DC cut portion.

With this configuration, the DC signal is cut by the two-stage DC cut unit, so that the DC signal can be cut more reliably.
Further, since there are two resonator electrodes, double resonance occurs within the band, and the bandwidth of the pass frequency can be changed.

The inventors conducted the following simulation to confirm the effect of the DC cut circuit 1.
FIG. 10 is a diagram showing the results of simulation.
This simulation was performed under substantially the same conditions as the DC cut circuit shown in FIG.
As a result of the simulation, as shown by the transmission coefficient curve S21 in FIG. 10, the transmission coefficient is 40 GHz or more, and the transmission coefficient curve Sa21 of the DC cut circuit shown in FIG. However, it was confirmed that a signal of less than 40 GHz is significantly lower than the transmission coefficient curve Sa21.
Further, as shown by the reflection coefficient curve S11, it was confirmed that resonance occurred at two frequencies of about 45 GHz and about 60 GHz, and the bandwidth Wa was expanded to a width of about 20 GHz.
Since other configurations, operations, and effects are the same as those in the first embodiment, description thereof is omitted.

Next explained is the third embodiment of the invention.
FIG. 11 is a plan view showing a DC cut circuit according to a third embodiment of the present invention, and FIG. 12 is a cross-sectional view showing the DC cut circuit.
In this embodiment, the characteristic impedance of the input and output strip lines 3 and 4 is made to coincide with the output impedance and input impedance of an external circuit connected to the input and output strip lines 3 and 4. And different from the second embodiment.
That is, when an input impedance or an output impedance is set to 10Ω in an FET used for a high-frequency power amplifier or the like, it is necessary to provide a matching circuit between the 50Ω transmission line and the FET.
In such a case, the DC cut circuit 1-3 of this embodiment can also function as a matching circuit.
For example, the output strip line 4 can be changed by changing the width and length of the output strip line 4 to which the input terminal of the FET 100 having an input impedance of 10Ω is connected as in the DC cut circuit 1-3 shown in FIGS. Is set to 10Ω. Then, the characteristic impedance of the input strip line 3 to which a 50Ω transmission line (not shown) is connected is set to 50Ω.
By adopting such a configuration, since the DC cut circuit 1-3 can function as a matching circuit, a dedicated matching circuit is not required, and accordingly, a device in which the DC cut circuit 1-3 is incorporated. Can be reduced in size and cost.
In the case of a DC cut circuit to which the output side of the FET 100 is connected, the characteristic impedance of the input strip line 3 is set to 10Ω, and the characteristic impedance of the output strip line 4 is naturally set to 50Ω.
Other configurations, operations, and effects are the same as those in the first and second embodiments, and thus description thereof is omitted.

Next explained is the fourth embodiment of the invention.
FIG. 13 is a plan view showing a part of the DC cut circuit according to the fourth embodiment of the present invention.
The DC cut circuit 1-4 of this embodiment is different from the first to third embodiments in that it has a damping circuit.
As shown in FIG. 13, the damping circuit 7 is formed on the side of the resonator electrode 5.
Specifically, the branch path 70 was branched from the center side of the resonator electrode 5 at a right angle to the resonator electrode 5, and the grounded termination resistor 71 was connected to the tip of the branch path 70. Then, an open stub 72 having a length of about λg / 4 was protruded from a branch point P1 of the branch path 70 at a site P2 at a distance of about λg / 4.

With this configuration, when the in-band signal S is input to the resonator electrode 5 from the input stripline 3,
Since the open stub 72 having a length of λg / 4 protrudes from the branch point P1 of the branch path 70 to the portion P2 of about λg / 4, the branch point P1 becomes open with respect to the signal S. S flows from the resonator electrode 5 into the output strip line 4 without flowing into the branch path 70 side. On the other hand, when the out-of-band signal S ′ is input to the resonator electrode 5 from the input stripline 3, the signal S ′ flows into the branch path 70 because the resonator electrode 5 is in a non-resonant state. Since the grounded termination resistor 71 is connected to the tip of the branch path 70, the signal S ′ is consumed by the termination resistor 71 and lost without being reflected at the tip of the branch path 70.
Therefore, according to the DC cut circuit 1-4 of this embodiment, the in-band signal S is reliably propagated in the resonator electrode 5 and the out-of-band signal S ′ flows out through the branch path 70. The loss for the in-band signal S can be reduced, and the cutoff characteristic for the out-of-band signal S ′ can be stabilized. As a result, it functions as a stabilization circuit outside the band of an active circuit such as an amplifier.

The inventors conducted the following simulation to confirm the effect of the DC cut circuit 1.
FIG. 14 is a diagram showing the results of simulation.
In this simulation, the dielectric substrate 2 having a relative dielectric constant of 8.8 was used, and the center frequency in the band was set to 60 GHz. That is, the resonator electrode 5 having a length L of 0.750 mm is used, the length of the overlapping portion between the open ends 32 and 42 and the open ends 51 and 52 is 0.25 mm, and the input and output strip lines 3 and 4 are used. The distance d between the resonator electrode 5 and the resonator electrode 5 was set to 0.05 mm. First, as shown in FIG. 6A, the widths of the input and output strip lines 3 and 4, the width of the resonator electrode 5, the width of the branch path 70, and the width of the open stub 72 are equally 0.1 mm. Set to. Further, the distance between the branch points P1 and P2 and the length of the open stub 72 were set to 0.35 mm and 0.42 mm, respectively. Under such conditions, sweeping was performed with a signal of 0 to 100 GHz, and the magnitude of the reflection coefficient and the transmission coefficient for each frequency were simulated.
At the same time, the signal was swept with a signal of 0 to 100 GHz under the condition excluding the damping circuit 7, and the magnitude of the reflection coefficient and the transmission coefficient for each frequency were simulated.
Then, a result as shown in FIG. 14 was obtained. That is, there was almost no difference between the reflection coefficient curve Sa11 indicated by a broken line when the damping circuit 7 was removed and the reflection coefficient curve Sb11 indicated by a solid line when the damping circuit 7 was provided.
On the other hand, the transmission coefficient curve Sb21 indicated by the solid line when the damping circuit 7 is provided is transmitted in a low frequency region of 30 GHz or less as compared with the transmission coefficient curve Sb21 indicated by the broken line when the damping circuit 7 is excluded. It shows that the coefficient has decreased significantly. As a result, the inventors confirmed that by providing the damping circuit 7, the DC cut circuit can function as a stabilization circuit outside the band of the active circuit.
Other configurations, operations, and effects are the same as those in the first to fourth embodiments, and thus description thereof is omitted.

Next explained is the fifth embodiment of the invention.
15 is a plan view showing a DC cut circuit according to a fifth embodiment of the present invention, and FIG. 16 is a cross-sectional view taken along the line CC in FIG.
The DC cut circuit 1-5 of this embodiment is different from the first to fourth embodiments in that a coplanar line is configured.
Specifically, as shown in FIGS. 15 and 16, ground electrodes 6 and 6 are provided on both sides of the input and output strip lines 3 and 4, respectively, and the input and output strip lines 3 and 4 and the ground electrode are provided. The coplanar line was composed of 6 and 6.
Of course, the ground electrode 6 may also be provided on the back surface 21 of the dielectric substrate 2 as indicated by a broken line in FIG.
Other configurations, operations, and effects are the same as those in the first to fourth embodiments, and thus description thereof is omitted.

Next explained is the sixth embodiment of the invention.
FIG. 17 is a block diagram showing a high-frequency module according to the sixth embodiment of the present invention.
As shown in FIG. 17, the high-frequency module of this embodiment is configured by combining an antenna block 81, a duplexer block 82, a transmission block 83, a reception block 84, and an oscillation block 85.

The antenna block 81 is a block that transmits a transmission radio wave and receives a reception radio wave, and includes an antenna 81a. The duplexer block 82 is a block for switching the antenna 81a to the transmission state or the reception state by the duplexer 82a. The transmission block 83 is a block that is connected to the duplexer block 82 and outputs a high-frequency signal S toward the antenna block 81, and includes a mixer 83a, a band-pass filter 83b, and a power amplifier 83c. On the other hand, the reception block 84 is a block that is connected to the duplexer block 82 and receives the high-frequency signal S received by the antenna block 81, and includes a low noise amplifier 84a, a band pass filter 84b, and a mixer 84c. The oscillation block 85 is connected to the transmission block 83 and the reception block 84, and oscillates a local oscillation signal LO having a predetermined frequency from the local oscillator 85a to the mixers 83a and 84c.
With this configuration, a baseband intermediate frequency signal IF modulated by a baseband unit (not shown) is input to the high frequency module via the input terminal 83A, is up-converted to the high frequency signal S by the transmission block 83, and is transmitted from the antenna 81a to the radio wave. As sent. The intermediate frequency signal IF received by the antenna 81a and down-converted by the reception block 84 is output from the output terminal 84A to a baseband unit (not shown) and demodulated by the baseband unit.

Such a high frequency module includes the DC cut circuit 1 (1-2 to 1-5) of any one of the first to fifth embodiments.
The DC cut circuit 1 is attached to any or all of the power amplifier 83c, the low noise amplifier 84a, the mixers 83a and 84c, and the local oscillator 85a.
FIG. 18 is a block diagram showing a state in which the DC cut circuit is attached to the power amplifier 83c.
As shown in FIG. 18, the amplifier such as the power amplifier 83c is operated by the DC bias voltage from the bias circuits 85 and 85. Therefore, the DC cut circuit 1 (1-2 to 1-5) is interposed between the bias circuit 85 and the band pass filter 83b or the duplexer 82a which are external circuits. As a result, the DC cut circuit 1 (1-2 to 1-5) cuts the DC bias voltage from the bias circuits 85 and 85, thereby preventing outflow to an external circuit.
In FIG. 18, reference numeral 86 denotes a matching circuit.

Here, the inventors performed a simulation on the gain and stabilization coefficient (K-factor) exhibited by the DC cut circuit attached to the power amplifier 83c shown in FIG.
FIG. 19 is a diagram showing the gain of the DC cut circuit obtained by the simulation of the power amplifier shown in FIG. FIG. 20 is a diagram showing the stabilization coefficient of the DC cut circuit obtained by the simulation of the power amplifier shown in FIG.
Specifically, the inventors simulated how the gain and the stabilization coefficient differ depending on whether the DC cut circuit has the damping circuit 7 applied in the fourth embodiment, and FIG. The result of FIG. 20 was obtained.
In FIG. 19, as is clear from the gain curve Sa1 (dashed line) indicating the gain of the DC cut circuit without the damping circuit 7 and the gain curve Sa2 (solid line) indicating the gain of the DC cut circuit having the damping circuit 7, the damping is performed. Regardless of the presence or absence of the circuit 7, the gain in the vicinity of 60 GHz is almost equal.
On the other hand, in FIG. 20, a stabilization coefficient curve Sb1 (dashed line) showing the gain of the DC cut circuit without the damping circuit 7 and a gain curve Sb2 (solid line) showing the stabilization coefficient of the DC cut circuit with the damping circuit 7 are shown. As is clear from the above, the DC cut circuit having the damping circuit 7 has higher stability in the 10 to 20 GHz band.
As a result, it was confirmed that by attaching the damping circuit 7 to the DC cut circuit, the stability of the 10 to 20 GHz band can be improved without reducing the gain of the 60 GHz band.

As described above, the DC cut circuit 1 (1-2 to 1-5) is a high frequency module attached to any or all of the power amplifier 83c, the low noise amplifier 84a, the mixers 83a and 84c, and the local oscillator 85a. As a result, it is possible to achieve stability, downsizing, and cost reduction of the entire apparatus, and to increase the bandwidth of the transmission / reception frequency.
Other configurations, operations, and effects are the same as those in the first to fifth embodiments, and thus description thereof is omitted.

In addition, this invention is not limited to the said Example, A various deformation | transformation and change are possible within the range of the summary of invention.
For example, in the second embodiment, the input and output strip lines 3 and 4, the intermediate strip line 34, and the two resonator electrodes 5 constitute a two-stage DC cut section, but the number of DC cut sections is arbitrary. It is. Accordingly, a plurality of intermediate strip lines 34 are discretely arranged between the input and output strip lines 3 and 4, and the gap between the input strip line 3 and the intermediate strip line 34, the gap between adjacent intermediate strip lines 34, and the intermediate By arranging the plurality of resonator electrodes 5 so as to face the gaps between the strip line 34 and the output strip line 4, a multi-stage DC cut portion can be configured.
Of course, the damping circuit 7 applied to the fourth embodiment may be provided in each resonator electrode 5 of the multi-stage DC cut unit.

1 is a perspective view showing a part of a DC cut circuit according to a first embodiment of the present invention. It is a top view of a DC cut circuit. It is arrow AA sectional drawing of FIG. FIG. 5 is a perspective view of an overlapping state of input and output strip lines and resonator electrodes as seen through from the back side of a dielectric substrate. It is sectional drawing for demonstrating the effect | action and effect of DC cut circuit. It is a top view for demonstrating the dimension of the DC cut circuit used for simulation. It is a diagram which shows the result of simulation. It is a top view which shows the DC cut circuit based on 2nd Example of this invention. It is arrow BB sectional drawing of FIG. It is a diagram which shows the result of simulation. It is a top view which shows the DC cut circuit based on 3rd Example of this invention. It is sectional drawing which shows DC cut circuit. FIG. 10 is a plan view showing a DC cut circuit according to a fourth embodiment of the present invention, partially broken away. It is a diagram which shows the result of simulation. It is a top view which shows the DC cut circuit based on 5th Example of this invention. It is CC sectional view taken on the line of FIG. It is a block diagram which shows the high frequency module which concerns on 6th Example of this invention. It is a block diagram which shows the example which applied the DC cut circuit to the high frequency amplifier. It is a diagram which shows the gain of the DC cut circuit obtained by simulation of the power amplifier shown in FIG. It is a diagram which shows the stabilization coefficient of the DC cut circuit obtained by simulation of the power amplifier shown in FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1,1-2 to 1-5 ... DC cut circuit, 2 ... Dielectric board | substrate, 3 ... Input stripline, 4 ... Output stripline, 5,5-1, 5-2 ... Resonator electrode, 6 ... Ground electrode 7 ... Damping circuit, 20 ... Front side, 20a, 20b ... Edge, 21 ... Back side, 31 ... Signal input end, 32, 42, 51, 52 ... Open end, 34 ... Intermediate strip line, 41 ... Signal output End part 70 ... Branching path 71 ... Terminating resistor 72 ... Open stub 100 ... FET Wa = Bandwidth d ... Spacing D ... Length G, G1, G2 ... Gap, w3-w5 ... Width

Claims (7)

A dielectric substrate;
An input strip line located on the surface of the dielectric substrate with an end opposite to the signal input end as an open end,
An output strip line positioned on the surface of the dielectric substrate in a state where the end opposite to the signal output end is an open end and the open end is opposed to the open end of the input strip line. ,
Located inside the dielectric substrate and viewed from the back side of the dielectric substrate, one open end overlaps the open end of the input strip line and the other open end is the open end of the output strip line In a state of being overlapped with the open strip portion of the input strip line and the open end portion of the output strip line with a predetermined interval, and having a length of about one half of the wavelength in the dielectric substrate at the resonance frequency. A DC cut circuit comprising: a resonator electrode having a thickness. The DC cut circuit according to claim 1,
A ground electrode is provided on the back surface of the dielectric substrate, and the input strip line and the output strip line are microstrip lines.
DC cut circuit characterized by the above. In the DC cut circuit according to claim 1 or 2,
Ground electrodes were provided on both sides of the input strip line and output strip line, respectively, and the input strip line and output strip line and the ground electrode constituted a coplanar line.
DC cut circuit characterized by the above. The DC cut circuit according to any one of claims 1 to 3,
Increase the gap between the input stripline and output stripline,
One or more intermediate strip lines are discretely arranged in the gap on the surface of the dielectric substrate,
A plurality of the resonator electrodes are disposed on the dielectric substrate so as to face the gap between the input stripline and the intermediate stripline, the gap between adjacent intermediate striplines, and the gap between the intermediate stripline and the output stripline, respectively. By arranging in, the DC cut part has a multi-stage configuration,
DC cut circuit characterized by the above. The DC cut circuit according to any one of claims 1 to 4,
The characteristic impedance of the input stripline and the output stripline is matched with the output impedance and input impedance of an external circuit connected to the input stripline and the output stripline.
DC cut circuit characterized by the above. The DC cut circuit according to any one of claims 1 to 5,
A branch path is provided in the middle of the resonator electrode,
Connect a grounded termination resistor to the tip of the branch,
An open stub having a length of about a quarter of the wavelength in the dielectric substrate at the resonance frequency is a part of the branch path, and is about a quarter of the wavelength in the dielectric substrate from the branch point of the branch path. Projected at a position 1 away from
DC cut circuit characterized by the above. The DC cut circuit according to claim 1 is provided.
A high-frequency module characterized by that.

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