JPH07221504A - Filter circuit and mobile body communication equipment - Google Patents

Abstract

PURPOSE:To obtain a desired frequency characteristic having an attenuation pole with simple configuration by forming plural impedance sections with a bridged circuit network where components are arranged in a bridged T shape and including a strip line resonator for the impedance section at its longitudinal rod position. CONSTITUTION:A bridged impedance section 1 is formed by a parallel circuit comprising an inductor 2L2 and a series circuit comprising a capacitor C1/2 and an inductor 2L1. An arm impedance section 2(3) being one of two divided an upper side of the T shape is made up of a capacitor C3 and the capacitance of both arm divisions is equal to each other. A strip line resonator is connected to an arm impedance section 4 at a longitudinal rod position of the T shape, and the strip line resonator is expressed equivalently as a parallel resonance circuit comprising a capacitor 2C3 and an inductor L3/2 in the Figure. Thus, the frequency characteristic of the entire filter circuit is decided by effecting the frequency characteristic of mainly the strip line resonator and the frequency characteristic depending on other impedance sections, especially on the bridged impedance section with each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a filter circuit and a mobile communication device.

[0002]

2. Description of the Related Art For example, when there is a band in which passage is desired to be blocked in the immediate vicinity of a pass band, a filter circuit having an attenuation pole in frequency characteristics is appropriately used. For example, in a small mobile communication device such as a mobile phone device, the antenna is used for both transmission and reception, the transmission signal from the transmission circuit is given to the antenna via a demultiplexer, and the reception signal captured by the antenna is demultiplexed as described above. The frequency component of the received signal is removed from the transmitted signal by the transmitting filter circuit, and the received signal frequency is removed from the received signal by the receiving filter circuit. The component is removed.

To meet the demands for downsizing, reduction of insertion loss, steep attenuation characteristics, etc., conventionally, a filter circuit using a dielectric has been applied as a filter circuit having an attenuation pole in frequency characteristics. The first is a filter circuit using a short-circuited and open-ended λ / 4 long dielectric resonator made of ceramic, and the second is a λ / 4 long open-ended by providing a strip line on the dielectric substrate. It is a filter circuit which constitutes a resonance circuit composed of a circuit or a λ / 2 long tip short circuit and which is connected to an impedance element for providing an attenuation pole to this resonance circuit.

[0004]

However, in the case of a filter circuit using a dielectric resonator, since the dielectric itself constitutes the resonator, the manufacturing cost is high, and the size and weight are reduced. There is a limit in advancing, and from this point, it can be said that the latter filter circuit using the resonance circuit of the strip line configuration is preferable.

However, even in the latter filter circuit,
Even if an attempt was made to match the frequency characteristic with the intended one, such a configuration could not be accepted. A capacitor or inductor is connected in series to the stripline resonator as an impedance element that gives the attenuation pole.
It was difficult to obtain a value, and it was difficult to increase the amount of attenuation with such a configuration, and it was also difficult to achieve a steeper attenuation pole inclination. Therefore, when a large amount of attenuation is to be achieved or a steep attenuation slope is to be achieved, a plurality of filter circuits are connected in multiple stages, resulting in an increase in size.

Further, in the conventional mobile communication device,
Since a filter circuit in which it is difficult to obtain a desired attenuation characteristic with such a single unit is applied, there are problems such as an increase in the size of the structure around the demultiplexer and a difficulty in demultiplexing.

[0007]

In order to solve the above problems, the present invention provides a bridge T-shaped circuit network in which a plurality of impedance portions are arranged in a bridge T in a filter circuit using a stripline resonator. And the impedance part at the T-shaped vertical bar position includes the stripline resonator.

Further, in the mobile communication device of the present invention, such a filter circuit is applied as a filter circuit in the duplexer.

[0009]

In the filter circuit of the present invention, the frequency characteristic is centered on the stripline resonator which constitutes the impedance portion of the T-shaped vertical bar position, and the frequency characteristic determined by the other impedance portion, particularly the bridge impedance portion. Influence each other to determine the frequency characteristic of the entire filter circuit. Therefore, it is easy to realize a desired frequency characteristic with one filter circuit by appropriately selecting the impedance of each part including the stripline resonator. For example, if the attenuation pole in the frequency characteristic of the component centering on the stripline resonator and the attenuation pole in the frequency characteristic of the component centering on the bridge impedance part are matched, the frequency characteristic of the entire filter circuit is attenuated. It is possible to obtain a material having a desired damping characteristic such as a large quantity or a steep damping slope.

When a filter circuit capable of realizing such desired attenuation characteristics is applied to a filter circuit in a demultiplexer of a mobile communication device, the device can be downsized and the demultiplexing characteristic can be improved.

[0011]

【Example】

(A) First Embodiment Hereinafter, a first embodiment of the filter circuit according to the present invention will be described in detail with reference to the drawings. Here, FIG. 1 is a circuit diagram showing an equivalent circuit of a filter circuit using the stripline resonator of the first embodiment, and FIG. 2 is an exploded perspective view of the filter circuit.

In FIG. 1, the filter circuit of the first embodiment is constructed by a so-called bridge T-type network. Here, the bridge impedance unit 1 is composed of a parallel circuit of a series circuit of a capacitor C1 / 2 and an inductor 2L1 and an inductor 2L2. Each of the arm impedance portions 2 and 3 obtained by dividing the upper side of the T-shape into two parts is composed of capacitors C2 and C2 having the same value. A stripline resonator is connected to the arm impedance portion 4 at the T-shaped vertical bar position. In FIG. 1, the stripline resonator is equivalently represented by a parallel resonance circuit of a capacitor 2C3 and an inductor L3 / 2. There is.

The stripline resonator is λ / 2.
It may be a long tip open stripline resonator or a λ / 4 long tip shorted stripline resonator.

The filter circuit of the first embodiment is characterized in that it has the equivalent circuit configuration shown in FIG. 1, and the mounting method of each element thereof is arbitrary. For example, the mounting configuration shown in FIG. 2 is used. Can be applied.

In FIG. 2, the filter circuit has a two-layer structure, and the first and second layers are dielectric substrates 10 and 2, respectively.
It is configured around 0. In the mounted state, the two dielectric substrates 10 and 20 are bonded together via a dielectric adhesive.

A pair of terminals 11a and 11b are provided on the upper surface of the dielectric substrate 10 of the first layer.
Strip line 12 as a current path from a and 11b
a and 12b are extended. Bridge impedance part 1
The capacitor C1 / 2 is realized by the chip capacitor 13, and the inductors 2L1 and 2L2 are realized by the coils 14 and 15, respectively. One end of the chip capacitor 13 is connected to the strip line 12a, and the other end of the chip capacitor 13 is connected to one end of the coil 14 via a very short strip line 12c.
The other end of 4 is connected to the strip line 12b.
Further, both ends of the coil 15 are connected to the strip lines 12a and 12b, respectively. Further, the strip lines 12a and 12b are respectively connected to the regions to be the electrodes (pads) 16 and 17 of the capacitors C2 and C2 constituting the arm impedance portions 2 and 3 that divide the upper side of the T shape into two. ing.

On the upper surface of the second-layer dielectric substrate 20, a stripline resonator (2C3 and L3 / 2) constituting the T-shaped vertical bar arm impedance portion 4 is formed, for example, λ / 4.
A long tip shorting stripline 21 is provided. One end of the λ / 4 long tip short-circuit stripline 21 is connected to the region 22 which becomes the other common electrode (pad) of the above-mentioned two capacitors C2 and C2, and the λ / 4 long tip short-circuit stripline 21 is formed. The other end of is connected to a plating region described later and is grounded.

The upper surface of the first-layer dielectric substrate 10 is plated (including metallization; the same applies hereinafter) except for the portions where the above-mentioned components and regions are arranged and the peripheral portions thereof. The upper surface of the second-layer dielectric substrate 20 is also plated except for the portions where the above-mentioned components and regions are arranged and the peripheral portions thereof. The entire side surfaces of the dielectric substrates 10 and 20 of each layer are plated so as to be continuous with the plating area on the upper surface. Further, the entire lower surface of the second-layer dielectric substrate 20 is plated, for example. The plating area as described above is grounded.

The above-described mounting structure shown in FIG. 2 realizes the filter circuit having the bridge T-shaped network structure shown in FIG.

Next, the fact that the filter circuit having the bridge T-shaped network structure shown in FIG. 1 operates as a filter circuit having an attenuation pole is replaced with a lattice type circuit shown in FIG. 3 which is an equivalent circuit thereof. explain.

First, it will be explained that the filter circuit having the bridged T-shaped network structure shown in FIG. 1 is equivalent to the lattice type circuit shown in FIG. About Bartlet's 2 about axisymmetric circuit
According to the "equal division theorem", in order to obtain an equivalent circuit of a symmetric two-terminal pair circuit, an open impedance Zf and a short-circuit impedance Zs when the two-terminal pair circuit is cut in half are obtained, and a lattice having the elements is used. It is sufficient to create a shaped circuit. Therefore, the filter circuit having the bridge T-shaped network structure shown in FIG. FIG. 4 shows an axially symmetric circuit on the left side. Therefore, the open impedance Zf and short circuit impedance Zs of this axisymmetric circuit are (1)
It is expressed by the formula and the formula (2).

[0022] ^{Zf = j {1-ω 2} L3 (C2 + C3)} ÷ ωC2 (ω 2 L3 C3 -1) = jXf ... (1) Zs = jωL2 (1-ω 2 L1 C1) ÷ {(1-ω ² L1 C1) (1-ω ² L2 C2) −ω ² L1 C1} = jXs (2) In the lattice type circuit shown in FIG. 3 in which the value of each impedance is expressed by equation (1) or equation (2) Can be said as follows when the transmission characteristics are examined from the image parameter plane. The open impedance seen from one port is (Zf
+ Zs) / 2, the short circuit impedance is 2Zf Zs /
Since (Zf + Zs), the image impedance is (Z
^{f Zs) 1/2 = (- Xf} Xs) can be represented by ^1/2,
Also, the hyperbolic function value tanhθ of the transfer constant θ is {4Zf Zs
/ (Zf + Zs) ² } = {4Xf Xs / (Xf + Xs)
² }. Therefore, the following conclusions can be obtained by classifying the image impedance depending on whether or not the image impedance takes an imaginary number. Xs / Xf is negative (Xs is 0 and X
The band (frequency) in which f is infinity and Xs is infinity and Xf is 0 becomes the pass band, and X is
The band (frequency) where s / Xf is positive is the attenuation band.
The image attenuation amount α [dB] at this time can be expressed by the following equation (3).

Α = 8.686 · log | {1+ (Xs / Xf) ^1/2 } / {1- (Xs / Xf) ^1/2 } | (3) Above, the filter circuit of FIG. 1 has attenuation poles. The operation as a filter circuit having the above has been described by replacing it with a lattice type circuit, but in the following, the reason why the filter circuit is configured by a bridging T-type network will be qualitatively described.

Even if a strip line resonator is connected in series with LC circuit configurations such as capacitors and inductors to form attenuation poles, there is a limit such that the amount of attenuation cannot be increased and the inclination of the attenuation pole cannot be made steep. On the other hand, if the filter circuits are cascade-connected in multiple stages, these requirements can be met. However, connecting filter circuits in multiple stages to realize a filter circuit having desired characteristics leads to an increase in the size of a device using the filter circuit.

The following points can be said when the above points are viewed from the good side, not from the defect side. By combining filter characteristics having a plurality of attenuation poles, it is possible to obtain a large amount of attenuation and an arbitrary inclination of the attenuation poles. Therefore, it suffices that a plurality of transmission characteristics having attenuation poles can be combined with a single-stage filter circuit without applying multistage cascade connection. According to such an idea, in the first embodiment, a plurality of transmission characteristics having attenuation poles are formed by the bridge T-type network, and the transmission characteristics obtained by combining them are obtained. Of course, in the filter circuit shown in FIG. 1, the impedance elements influence each other to realize the desired characteristics, and it is meaningless to separate the impedance characteristics into a plurality of transmission characteristics, but it is qualitative. I referred to such a concept for the sake of detailed explanation.

All or part (C1 / 2 and 2L1) of the bridge impedance section 1 in FIG. 1 has an attenuation pole 1
It can be seen as one resonance configuration (series resonance configuration), and the other part can be seen as another resonance configuration centered on the stripline resonator. Adjust the attenuation pole frequency of these resonance configurations appropriately. By making them coincide with each other, a large amount of attenuation can be obtained and a steep inclination of the attenuation pole can be realized.

As described above, according to the first embodiment,
It is possible to obtain a desired attenuation pole characteristic (amount of attenuation, its inclination, bandwidth, etc.) by a single-stage filter circuit without vertically connecting a plurality of filter circuits.

For example, when the pass center frequency and the pass blocking center frequency required by the device to which the filter circuit is applied are close to each other, a filter capable of sufficiently discriminating between the cutoff and the pass. Although it has been difficult to construct a circuit in the past, this circuit can be easily handled in the first embodiment. Therefore, the filter circuit of the first embodiment is suitable as a filter circuit around the duplexer of the transmitting / receiving shared antenna in the mobile communication device.

Incidentally, in relation to the second embodiment described later, the filter circuit of the first embodiment is suitable as a receiving filter circuit around a duplexer of a transmission / reception shared antenna in a mobile communication device. is there. From the viewpoint of widely removing the noise component in the received signal, the bandwidth of the attenuation pole is required to be wider in the receiving filter circuit than in the transmitting filter circuit. On the other hand, the transmitting power is required in the transmitting filter circuit. In order to make effective use, it is required not to cause insertion loss at frequencies other than the reception frequency.

FIG. 5 is a characteristic curve diagram showing a frequency characteristic example (reflection coefficient S11 and transfer coefficient S21) of the filter circuit of the first embodiment, and FIG. 6 is a frequency characteristic example of a conventional filter circuit (reflection coefficient S11). It is a characteristic curve figure which shows coefficient S11 and transfer coefficient S21). The conventional circuit here is a stripline resonator with a capacitor connected in series. From these FIGS. 5 and 6 (particularly the transmission coefficient S21), it can be seen that a large amount of attenuation can be realized without increasing the width of the attenuation pole. 5 and 6, the value of one scale on the frequency axis (horizontal axis) is different.

(B) Second Embodiment Next, a second embodiment of the filter circuit according to the present invention will be described in detail with reference to the drawings. FIG. 7 is a circuit diagram showing an equivalent circuit of a filter circuit using the stripline resonator of the second embodiment, and FIG. 8 is an exploded perspective view of the filter circuit. In FIG. 7, parts that are the same as or correspond to those in FIG. 1 are designated by the same reference numerals (elements with the same reference numerals do not necessarily have the same value), and in FIG. The same or corresponding parts as in FIG. 2 are designated by the same reference numerals.

In FIG. 7, the difference between the filter circuit of the second embodiment and the filter circuit of the first embodiment is the configuration of the T-shaped vertical bar arm impedance section 4 in the bridge T-shaped network. The T-shaped vertical arm impedance part 4 of the second embodiment is
A capacitor 2C4 is connected in series to a stripline resonator which is equivalently represented by a parallel resonance circuit of a capacitor 2C3 and an inductor L3 / 2.

The capacitor 2C4 provided in this second embodiment functions so as to narrow the band of the attenuation pole more than in the first embodiment.

The filter circuit of the second embodiment is also characterized in that it has an equivalent circuit configuration shown in FIG. 7, and its mounting method is arbitrary, but for example, the mounting configuration shown in FIG. 8 should be applied. You can

In FIG. 8, the filter circuit has a three-layer structure, and the first layer, the second layer, and the third layer are mainly composed of the dielectric substrates 10, 30, and 20, respectively. In the mounted state, the dielectric substrates 10 and 20, 20 and 3 of each layer
0 is adhered via a dielectric adhesive.

First layer dielectric substrate 10 in the second embodiment
Corresponds to the first-layer dielectric substrate 10 of the first embodiment, and the difference is the shape of the plating region on the lower surface, which will be described later. The third-layer dielectric substrate 20 of the second embodiment corresponds to the second-layer dielectric substrate 20 of the first embodiment, except that the electrode region 22 of the capacitor is one electrode (pad) of the capacitor 2C4. Is the point. On the upper surface of the second-layer dielectric substrate 30 in the second embodiment, there is a region serving as the other common electrode (pad) of the two capacitors C2 and C2, and the other electrode (pad) of the capacitor 2C4. Area 31 is provided.

Second-layer dielectric substrate 30 in the second embodiment
In, the upper surface is plated except for the electrode area 31 and the peripheral area thereof, and the side surfaces are entirely plated. The plating area of the first-layer dielectric substrate 10 is made equal to the plating area of the upper surface of the second-layer dielectric substrate 30 that faces the second-layer dielectric substrate 30.

In this second embodiment, the capacitor 2
Although C4 is provided, it can be replaced with the lattice type circuit shown in FIG. 3 (the calculation formula of the open impedance Zf is different) by the same idea as described above, and it can be seen that it functions as a filter circuit.

Therefore, also in the second embodiment, desired characteristics of the attenuation pole (amount of attenuation, inclination thereof, etc.) can be obtained by a single-stage filter circuit without vertically connecting a plurality of filter circuits. be able to.

FIG. 9 is a characteristic curve diagram showing the frequency characteristics (reflection coefficient S11 and transfer coefficient S21) of the filter circuit of the second embodiment. From this FIG. 9 (particularly the transfer coefficient S21),
It can be seen that a large amount of attenuation can be realized with a width of the attenuation pole narrower than that in the first embodiment (in particular, there is no slope sag on the low frequency side).

Therefore, in the filter circuit of the second embodiment, in order to effectively use the transmission power, it is required that the bandwidth of the attenuation pole is narrow so that insertion loss does not occur at frequencies other than the reception frequency. It is suitable for a transmission filter circuit in a duplexer connected to an antenna for both transmission and reception of a mobile communication device.

(C) Third Embodiment Next, a third embodiment of the filter circuit according to the present invention will be described in detail with reference to the drawings. FIG. 10 is a circuit diagram showing an equivalent circuit of a filter circuit using the stripline resonator of the third embodiment, and the same or corresponding portions as those in FIG. Elements that are numbered are not necessarily the same).

In FIG. 10, the difference between the filter circuit of the third embodiment and the filter circuit of the second embodiment is the configuration of the T-shaped vertical bar arm impedance unit 4 in the bridge T-shaped network. T-shaped vertical arm impedance part 4 of the third embodiment
Is equivalently equivalent to the capacitor 2C3 and the inductor L3 / 2.
The inductor L4 / 2 is connected in series to the stripline resonator represented by the parallel circuit of FIG.

The inductor L4 / 2 provided in the third embodiment functions so as to form a band portion in which the amount of attenuation is larger than that in the first embodiment in the attenuation band.

The filter circuit of the third embodiment is also characterized in that it has the equivalent circuit configuration shown in FIG. 10. The mounting method is arbitrary, and the illustration and description of the mounting structure are omitted.

Therefore, also in the third embodiment, desired characteristics of the attenuation pole (amount of attenuation, inclination thereof, etc.) can be obtained by a single-stage filter circuit without vertically connecting a plurality of filter circuits. be able to.

FIG. 11 is a characteristic curve diagram showing the frequency characteristics (reflection coefficient S11 and transfer coefficient S21) of the filter circuit of the third embodiment. From this FIG. 11 (particularly the transfer coefficient S21), it can be seen that a band portion in which the attenuation amount is larger than that in the first embodiment is formed in the attenuation band. In addition, in FIG.
From the above-mentioned drawing showing the frequency characteristic, the transfer coefficient S21
Be careful because the value of 1 scale against is doubled.

Therefore, the filter circuit of the third embodiment surely removes the transmission frequency component at the attenuation pole, and
A receiving filter circuit in a duplexer connected to a transmitting / receiving shared antenna of a mobile communication device, which is required to be capable of widely removing noise components and has almost no insertion loss for receiving frequency components. It is suitable.

(D) Fourth Embodiment Next, a fourth embodiment of the filter circuit according to the present invention will be described in detail with reference to the drawings. FIG. 12 is a circuit diagram showing an equivalent circuit of a filter circuit using the stripline resonator of the fourth embodiment, and the same or corresponding parts as those in FIG. Elements that are numbered are not necessarily the same).

In FIG. 12, the difference between the filter circuit according to the fourth embodiment and the filter circuit according to the second embodiment is that the arm impedance parts 2 and 3 obtained by dividing the upper side of the T-shape in the bridging T-shaped network into two parts. The point is that they are each composed of a series circuit of a capacitor C2 and an inductor L5 having the same value.

However, as shown in FIG. 13, the frequency characteristic is rather close to that of the third embodiment, and the filter circuit of the fourth embodiment can obtain substantially the same effect as that of the third embodiment. .

(E) Other Embodiments In the above, four embodiments of the filter circuit according to the present invention have been described.
~ It demonstrates using FIG.

FIG. 14 shows a basic connection configuration of the bridge T-type network which is a feature of the present invention. As described in the section of the first embodiment, the bridge impedance units 1 and T are shown.
The upper side of the shape is divided into two arm impedance portions 2 and 3, and the T-shaped vertical arm impedance portion 4 is formed.

The filter circuit of the present invention includes a stripline resonator in which the T-shaped vertical bar arm impedance portion 4 is a λ / 2 long tip open stripline resonator or a λ / 4 long tip shorted stripline resonator. The impedance units 1, ..., 4 may have any configuration as long as they have this feature.

The bridge impedance unit 1 is shown in FIG.
What was illustrated in (a)-(c) can be applied. That is, a parallel circuit of a capacitor and an inductor, a parallel circuit of an inductor / capacitor series circuit and an inductor, a parallel circuit of an inductor / capacitor series circuit and a capacitor, and the like are applicable. The bridge impedance unit 1 may be configured using a strip line.

As one of the arm impedance portions 2 obtained by dividing the upper side of the T-shape into two parts, those illustrated in FIGS. 16 (a) to 16 (d) can be applied. That is, a single capacitor,
It is possible to apply a single inductor, a series circuit of an inductor and a capacitor, a parallel circuit of an inductor and a capacitor, and the like. As the other arm impedance part 3 obtained by dividing the upper side of the T-shape into two parts, the same kind as the impedance part 2 can be applied as illustrated in FIGS.

As described above, the T-shaped vertical arm impedance portion 4 includes a stripline resonator formed of a λ / 2 long tip open stripline resonator or a λ / 4 long tip shorted stripline resonator. As shown in FIGS. 18 (a) to 18 (d), a stripline resonator alone, a capacitor connected in series to the stripline resonator, or an inductor connected in series to the stripline resonator. Examples thereof include a connected type and a stripline resonator in which a capacitor and an inductor are connected in series (in FIG. 18, the stripline resonator is represented by a parallel resonant circuit of the capacitor and the inductor).

That is, each of the combinations of the configurations of the impedance units 1, ..., 4 shown in FIGS. 15 to 18 is an embodiment of the filter circuit of the present invention.

The filter circuit of the present invention can be applied to devices for various uses, and is not limited to the filter circuit in the duplexer connected to the transmitting / receiving shared antenna of the mobile communication device.

Therefore, depending on the device to be applied, the value of each impedance part may be selected so that it functions not as a band elimination filter as described above but as a filter having other functions such as a band pass filter.

[0061]

As described above, according to the present invention, in a filter circuit using a stripline resonator, a bridge T-shaped network in which a plurality of impedance portions are arranged in a bridge T-shape is entirely constructed. Since the impedance portion of the T-shaped vertical bar position includes the stripline resonator, it is possible to provide a filter circuit that easily realizes a desired frequency characteristic by selecting the value of each impedance portion.

Further, when such a filter circuit is applied to a filter circuit in a demultiplexer of a mobile communication device, the device can be downsized and the demultiplexing characteristic can be improved.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an equivalent circuit of a filter circuit according to a first embodiment.

FIG. 2 is an exploded perspective view showing a mounting configuration of the filter circuit according to the first embodiment.

FIG. 3 is an explanatory diagram showing a lattice type circuit that can replace the filter circuit of the first embodiment.

FIG. 4 is an illustration showing that the filter circuit of the first embodiment can be replaced with a lattice type circuit.

FIG. 5 is a characteristic curve diagram showing frequency characteristics of the filter circuit of the first embodiment.

FIG. 6 is a characteristic curve diagram showing frequency characteristics of a conventional filter circuit.

FIG. 7 is a circuit diagram showing an equivalent circuit of a filter circuit according to a second embodiment.

FIG. 8 is an exploded perspective view showing a mounting structure of a filter circuit according to a second embodiment.

FIG. 9 is a characteristic curve diagram showing frequency characteristics of the filter circuit of the second embodiment.

FIG. 10 is a circuit diagram showing an equivalent circuit of a filter circuit according to a third embodiment.

FIG. 11 is a characteristic curve diagram showing frequency characteristics of the filter circuit of the third embodiment.

FIG. 12 is a circuit diagram showing an equivalent circuit of a filter circuit according to a fourth embodiment.

FIG. 13 is a characteristic curve diagram showing frequency characteristics of the filter circuit of the fourth embodiment.

FIG. 14 is a block diagram showing a configuration of a bridge T-type network.

FIG. 15 is a diagram showing a configuration example of a bridging impedance unit of the filter circuit of the present invention.

FIG. 16 is a diagram showing a configuration example of one impedance portion obtained by dividing the upper side of the T shape of the filter circuit of the present invention into two.

FIG. 17 is a diagram showing a configuration example of the other impedance part obtained by dividing the upper side of the T shape of the filter circuit of the present invention into two.

FIG. 18 is a diagram showing a configuration example of an impedance part at a T-shaped vertical bar position of the filter circuit of the present invention.

[Explanation of symbols]

1 ... Bridge impedance part, 2 ... One impedance part that bisects the upper side of T-shape, 3 ... Another impedance part that bisects the upper side of T-shape, 4 ... Impedance part at the T-shaped vertical bar position, 2C3 ... A capacitance component (capacitor) when a stripline resonator is represented by a parallel resonance circuit, L
3/2: Inductance component (inductor) when a stripline resonator is represented by a parallel resonance circuit.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Katsuhiko Gunji 1-12 Toranomon, Minato-ku, Tokyo Oki Electric Industry Co., Ltd. (72) Inventor Toshikazu Yasuoka 1-7-12 Toranomon, Minato-ku, Tokyo Oki Electric Industry Co., Ltd. (72) Koichiro Shimizu 1-7-12 Toranomon, Minato-ku, Tokyo Oki Electric Industry Co., Ltd. (72) Kosuke Horii 1-7-12 Toranomon, Minato-ku, Tokyo Oki Electric Industrial Co., Ltd. (72) Inventor Masao Iwata 1-7-12 Toranomon, Minato-ku, Tokyo Oki Electric Industry Co., Ltd.

Claims (8)

[Claims] 1. In a filter circuit using a stripline resonator, a bridge T-shaped network in which a plurality of impedance units are arranged in a bridge T-shape is wholly constituted, and an impedance unit at a vertical bar position of the T-shape is provided. And a filter circuit including a stripline resonator. 2. The impedance portion of the T-shaped vertical bar is
Either a stripline resonator alone, a series circuit of a stripline resonator component and a capacitor, a series circuit of a stripline resonator component and an inductor, or a series circuit of a stripline resonator component, a capacitor and an inductor. The filter circuit according to claim 1, wherein 3. A bridging impedance section bridging between two pairs of terminals is a parallel circuit of a capacitor and an inductor, a series circuit of a capacitor and an inductor and a parallel circuit of an inductor, or a series circuit of a capacitor and an inductor. 3. The filter circuit according to claim 1, wherein the filter circuit is a parallel circuit of a capacitor and a capacitor. 4. The impedance part of each arm obtained by dividing the upper side of the T-shape into two parts is a capacitor alone, an inductor alone,
The filter circuit according to any one of claims 1 to 3, comprising either a series circuit of an inductor and a capacitor or a parallel circuit of an inductor and a capacitor. 5. A mobile communication device in which a transmission / reception shared antenna and a transmission circuit or a reception circuit are connected via a demultiplexer, wherein the transmission frequency component is passed and the reception frequency component is prevented from passing. A mobile communication device to which the filter circuit according to any one of claims 1 to 4 is applied as a transmission filter circuit provided in a wave filter. 6. In the transmission filter circuit, the impedance portion at the T-shaped vertical bar position is a series circuit of a stripline resonator constituent portion and a capacitor, and the bridging impedance portion is a series circuit of an inductor and a capacitor. 6. The mobile communication device according to claim 5, wherein the impedance part of each arm, which is a parallel circuit of an inductor and an inductor, and which divides the upper side of the T shape into two parts is a single capacitor. 7. A mobile communication device in which a transmission / reception shared antenna is connected to a transmission circuit or a reception circuit via a demultiplexer, wherein the reception frequency component is passed and the transmission frequency component is prevented from passing. A mobile communication device to which the filter circuit according to any one of claims 1 to 4 is applied as a receiving filter circuit provided in a wave filter. 8. The receiving filter circuit, wherein the impedance portion at the vertical bar position of the T-shape is a series circuit of a stripline resonator component and a capacitor, and the bridging impedance portion is a series circuit of an inductor and a capacitor. 8. The mobile communication device according to claim 7, wherein the impedance part of each arm, which is a parallel circuit of an inductor and a capacitor, is formed by halving the upper side of the T-shape. .