JP4523478B2 - Band-pass filter, high-frequency module, and wireless communication device using the same - Google Patents

Description

  The present invention relates to a bandpass filter having a broadband and steep attenuation characteristic, which is preferably used for an ultra-wideband UWB (Ultra WideBand) in the field of wireless communication, and a wireless communication device using the same. UWB is used as a data transmission medium for PC peripheral devices such as PC adapters, external storage devices, printers, scanners, and hubs, or as a data transmission medium for digital home appliances such as digital televisions, projectors, 5.1ch speaker systems, and video cameras. Is expected to be used.

In recent years, attention has been paid to an ultra wide band (UWB) as a new communication means.
UWB realizes large-capacity data transfer with a pass band of 3.1 GHz to 10.6 GHz.
When this UWB is compared with a wireless local area network (hereinafter referred to as W-LAN) used as one of data communication means, the communication distance and the data transfer rate are different. In the W-LAN, the communication distance is 30 to 100 m, the transmission power is 500 mW, and the communication speed is about 11 Mbps, whereas in the UWB, the communication distance is as short as 10 m, but the transmission power is 100 mW and the power consumption is low. Is capable of high-speed data communication of 100 Mbps at a communication distance of about 10 m and 480 Mbps at a communication distance of 2 m or less.

According to the US FCC regulations, there are some rules for the frequency band used for UWB, but a wide band from 3.1 GHz to 10.6 GHz is used.
Thus, one feature of UWB is the use of a wide band. The ratio band (bandwidth / center frequency) is required to be 40% or more, and in some cases 110%.
Further, the average transmission power density of UWB is defined as a low value of less than −41.25 dBm / MHz. Here, −41.25 dBm / MHz corresponds to radiated power that generates an electric field strength of 54 dBμV = 500 μV / m at a distance of 3 m from the wave source.

Thus, another feature of UWB is low transmission power.
An example of the spectrum mask under the outdoor environment defined by the FCC is that the transmission power in the passband from 3.16 GHz to 4.75 GHz is the reference (0 dB), −20 dB at 3.1 GHz, −1.6 dB at −1.61 GHz It is specified to be 30 dB. Moreover, under substantial use conditions, it is necessary to consider the influence with W-LAN (802.11.a), and attenuation of 5.15 GHz is required.

  Therefore, another feature of UWB is that the transmission power spectrum is required to be steeply attenuated in a short band adjacent to the pass band.

From the above, in a UWB wireless communication device, a filter inserted into a transmission / reception signal passage path is required to have a wide band, low loss, and high attenuation near the pass band.
In recent years, SAW filters and BAW filters based on quartz and piezoelectric ceramics that can obtain high Q values have been used as narrowband filters that require low loss and high attenuation in the communication field. Is 3 to 4% or less at a center frequency of 2 GHz, and the bandwidth is 0.06 to 0.08 GHz, which is two orders of magnitude narrower than the bandwidth of UWB. These bandwidths are determined by the electromechanical coupling coefficient of the crystal or the piezoelectric substrate, and it is difficult to increase the bandwidth from the viewpoint of materials.

  In general, as a technique for obtaining a band-pass filter having a steep attenuation characteristic in a frequency band of 2 to 5 GHz, a dielectric filter in which a plurality of dielectric resonators are combined is used. A dielectric resonator is excellent in Q value, and a steep attenuation characteristic can be obtained with a dielectric filter using the dielectric resonator. However, there is a problem that the size of the dielectric filter becomes large. For example, in a three-stage dielectric filter that combines three dielectric resonators having a pass frequency with a center frequency of 5.25 GHz and a specific band of about 4%, The size is about 6 × 3 × 2 mm. Furthermore, since it is necessary to increase the number of dielectric resonators in order to increase the bandwidth of a specific bandwidth of 40% or more, the dielectric filter has a problem that it is not possible to achieve both broadband and miniaturization.

  An object of the present invention is to provide a band-pass filter and a high-frequency module that have a wide pass bandwidth, a small size and low loss, and can obtain a high attenuation in a narrow band, and a radio communication device using the same. And

Bandpass filter of the present invention, inputs each one end is coupled to the ungrounded end of Ru is grounded, the first and the sixth resonator is approximately a quarter wavelength in length, wherein the first resonator And an output unit coupled to the non-grounded end of the sixth resonator, and the second to fifth resonators are electromagnetically coupled to each other, and the first resonator is ungrounded. And the non-grounded end of the second resonator are capacitively coupled by the first capacitor element, and the non-grounded end of the first resonator and the non-grounded end of the third resonator are the second It is capacitively coupled with the capacitor element, the fourth and the ungrounded end of the resonator and the ungrounded end of the sixth resonator is capacitively coupled with the third capacitor element, ungrounded end of the fifth resonator and the sixth and ungrounded end of resonator is capacitively coupled with a fourth capacitor element, the input and output unit 5及6 is a shall be coupled to each of the first and sixth resonator through a capacitor element or the first and second inductor elements.

  The bandpass filter having this configuration can realize electromagnetic coupling between the second to fifth resonators. This coupling may be edge coupling or surface coupling (broadside coupling). For this coupling, a wide band of the band-pass filter can be obtained by appropriately selecting the coupling amount of each resonator. Further, by preparing a plurality of resonators, it is possible to make the attenuation characteristic steep.

  In general, since there is a loss in the resonator, increasing the number of resonators increases the loss in the passband. For example, in the case of a band-pass filter using a Chebyshev function having a pass band of 3.16 GHz to 4.75 GHz, when the ripple is 0.2 dB and the resonator Q is 180, the loss is − Although it was about 1.0 dB, the attenuation was insufficient at −18 dB. In the seven-stage resonator configuration, the attenuation is about -32 dB, but the loss is as large as -1.9 dB. It has been theoretically confirmed that a bandpass filter having a 6-stage resonator configuration can obtain a result satisfying both a loss of −1.6 dB and an attenuation of −25 dB.

  Therefore, in the present invention, a 6-stage resonator is used, strong inductive coupling of the second to fifth resonators is realized, and the reactance component forming the input / output unit is appropriately selected to obtain a wide band, and the first With strong inductive coupling between the first to fourth capacitors and these resonators, an attenuation pole can be formed on the high frequency side where an attenuation characteristic of −20 dB or more is required at about 300 MHz. Thereby, a high attenuation characteristic can be obtained.

Further, the structure of the band-pass filter using the six-stage resonator of the present invention is preferably a symmetric system centering on the third resonator and the fourth resonator, and the band-pass filter using the five resonators. Compared to a bandpass filter using a filter and seven resonators, there is also an advantage that the circuit can be easily dropped into a pattern.
For the input unit and the output unit, fifth and sixth capacitor elements or inductor elements coupled to the first and sixth resonators are used. In this case, by setting the constant of the element to a predetermined value, strong coupling can be obtained at the time of input / output of the signal in the input unit and the output unit, so that the pass loss of the band pass filter can be reduced.

If the ungrounded end of any one of the second to fifth resonators is grounded via a capacitor element, the length of the resonator can be made less than ¼ wavelength. The dimension in the length direction can be reduced, and the band-pass filter can be mounted with higher density. In general, the energy distribution of the resonator whose one end is grounded has the highest electric field energy at the non-grounded end in the length direction of the line, and the electric field energy becomes weaker as it goes to the other end that is grounded. On the other hand, the magnetic field energy is highest at one end grounded, and the magnetic field energy becomes weaker as it goes to the non-grounded end. Electric field energy is defined by CV ^2/2 (C is the capacitance, V is voltage), the magnetic field energy is defined by the LI ^2/2 (L is inductance, I is current). In order to shorten the resonator length, it may be devised so that the same amount of energy can be obtained from other than the resonator. Accordingly, it is possible to increase the capacitance of the non-grounded end or increase the inductance of the grounded end. Also in the band pass filter of the present invention, the resonator length can be shortened by providing the capacitance of the non-grounded end of the resonator. Therefore, the band pass filter can be downsized.

The shape of the conductive plate constituting the resonator becomes rectangle (rectangular) shape.
The resonator can be formed of, for example, a strip line, a microstrip line, or a coplanar line.
The resonator can be formed inside a dielectric multilayer substrate in which a plurality of dielectric layers are stacked. By using a dielectric having a high dielectric constant, the band-pass filter can be reduced in size and height.

  It is preferable that the dielectric constant of the dielectric is set to 10 or less at UWB 3.1 GHz to 10.6 GHz. In general, a resonator near the resonance frequency can be equivalently expressed by a parallel connection circuit of an equivalent inductor Lp and an equivalent capacitor element Cp as shown in FIG. The Q of the resonator at this time is proportional to the frequency ω and the capacitance of the equivalent capacitor element Cp. When a dielectric having a high dielectric constant is used, the equivalent capacitor element Cp increases and the resonator Q increases. A high Q of the resonator means that the passband of the resonator is narrowed, and a passband of a bandpass filter using a resonator having a high Q is narrowed. If this is illustrated in FIG. 11, it can be seen that when the resonance frequency is constant, the pass band becomes wider as Cp becomes smaller. Therefore, the dielectric constant is desirably 10 or less.

Further, if a structure in which each ground electrode upper surface and a lower surface of the front Ki誘 collector multilayer substrate is disposed, Rukoto to ground the grounding terminal of the first to sixth resonator can be easily. Further, an electromagnetic shielding effect can be obtained by the ground electrodes sandwiching the upper and lower sides of the dielectric multilayer substrate .
Before distance D between Kigu land electrodes is desirably 1.0mm or less. Thereby, the thickness of the dielectric multilayer substrate can be reduced.

Capacitance of the fifth and sixth capacitor element is preferably less than or 0.5p F ~1.5pF. In the band-pass filter of the present invention, the circuit and the external load are coupled by reactance. In the conventional band pass filter, since the pass band is relatively narrow, it is desirable that the circuits Q and Qe indicating the steepness of the circuit have high values. When the input / output load and the filter circuit are coupled by a capacitor, since Qe is a function of the reciprocal of the capacitor, they are coupled by a small capacitor of 0.1 pF or less. On the other hand, since the band pass filter of the present invention requires a bandwidth of about 1.5 GHz or more, Qe is desirably small. Therefore, the fifth capacitor element and the sixth capacitor element, and requires a large capacity of more than 0.5 p F. On the other hand, when the capacities of the fifth capacitor element and the sixth capacitor element are excessively increased, the band becomes wider while the steep attenuation is lost. Since the band pass filter used in UWB requires a steep attenuation characteristic in a narrow band of 0.4 GHz to 0.6 GHz, even if the capacitances of the fifth capacitor element and the sixth capacitor element are too large, the attenuation characteristic is obtained. It becomes inappropriate from the point of view. Therefore, it is desirable that it is less than 1.5 pF.

  In addition, the present invention relates to a wireless communication device that is equipped with the band-pass filter and can be miniaturized. According to this wireless communication device, it is possible to improve reception sensitivity, wideband communication, low power consumption, and prevention of mutual interference with a wireless LAN.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a diagram showing a circuit configuration of a bandpass filter according to the present invention.
The bandpass filter includes six resonators 21 to 26 stacked one above the other. The resonators 21 to 26 are configured by strip lines, microstrip lines, or coplanar lines.

At least the four resonators 22 to 25 are rectangular conductor plates having the same dimensions, and may be arranged in parallel on the same dielectric surface, or may be arranged so as to overlap each other when viewed from the lamination direction. .
With this arrangement, the four resonators 25 to 25 are electromagnetically coupled to each other, and particularly have strong inductive coupling (indicated by M in FIG. 1).

The end portions on one side (the lower side in FIG. 1) of each of the six resonators 21 to 26 are both grounded (referred to as ground ends).
The ungrounded ends of the resonators 21 and 26 are capacitively coupled to the input electrode IN and the output electrode OUT via the capacitor elements C5 and C6, respectively. These capacitively coupled portions are referred to as “input unit” and “output unit”.

Capacitor elements C5 and C6 constituting the input unit and output unit may be lumped circuit constants or distributed constant lines.
The lengths of the six resonators 21 to 26 are all ¼ wavelength.
With this structure, strong inductive coupling can be obtained between the four resonators 22 to 25, and the passband can be widened. Further, by arranging the four resonators 22 to 25 so as to face each other, the band pass filter can be reduced in size.

In FIG. 2, the ungrounded ends of the resonators 22 to 25 are capacitively coupled to the input electrode IN and the output electrode OUT via the capacitor elements C1 to C4, respectively, and the ungrounded ends of the resonators 22 to 25 are connected to the capacitors. A structure grounded through elements C7 to C10 is shown. Capacitor elements C7 to C10 may be lumped constants or distributed constants.
When this configuration is compared with FIG. 1, the non-grounded ends of the resonators 22 to 25 are grounded via the capacitor elements C7 to C10. Thus, part of the effective length of the resonators 22 to 25 is replaced by the capacitor elements C7 to C10, and the length of the resonators 22 to 25 can be made less than ¼ wavelength.

Therefore, in this band pass filter, the lengths of the resonators 22 to 25 can be shortened, which is further advantageous for downsizing.
Next, a method for manufacturing the bandpass filter described in FIGS. 1 and 2 will be described.
The band pass filter has a structure in which the resonator is formed on each dielectric layer of a dielectric multilayer substrate in which a plurality of dielectric layers are laminated.

The dielectric multilayer substrate is configured by laminating a plurality of dielectric layers having the same size and shape, and a conductor layer having a predetermined conductor pattern is formed on each dielectric layer.
Each dielectric layer is formed of, for example, low temperature co-fired ceramics (LTCC), and the conductor layer formed on each dielectric layer is formed of a low resistance conductor such as copper or silver. The

Such a multilayer substrate is formed by a well-known multilayer ceramic technology. For example, a conductive paste is applied to the surface of a ceramic green sheet to form each conductor pattern constituting each resonator, and then laminated. It is formed by thermocompression bonding and firing under the required pressure and temperature.
Each dielectric layer is appropriately formed with via-hole conductors necessary for connecting the upper and lower conductor layers over a plurality of layers.

The dielectric constant of the LTCC is, for example, about 9.4, and the thickness of one dielectric layer (before firing) is, for example, 0.075 mm. The thickness of the dielectric multilayer substrate is 0.9 mm.
In the bandpass filters shown in FIGS. 1 and 2, the ends of the resonators 21 to 26 need to be grounded.
For this reason, as will be described below, a ground pattern for grounding the ends of the resonators 21 to 26 may be provided on the upper and lower dielectric layers of the conductor patterns constituting the resonators 21 to 26. The ground pattern may be formed on the upper surface or the lower surface, or on the same plane as the resonator.

3 and 4 show external views when the band-pass filter of the present invention is configured as a chip component. FIG. 3 is an external view from the front, and FIG. 4 is an external view from the back.
Reference numeral 17 denotes a dielectric multilayer substrate in which a wiring pattern which will be described later with reference to FIG. 5 is routed.
E1 and E2 are ground electrodes, IN is an input terminal electrode, and OUT is an output terminal electrode. Even when the input / output terminals are reversed, the bandpass filter of the present invention functions in the same manner.

The ground electrodes E1 and E2 are connected via a side electrode E3 provided on the side surface of the dielectric multilayer substrate 17. The side electrode E3 is also connected to a conductor pattern formed inside each dielectric layer.
FIG. 5 is an exploded view showing the front and back surfaces of the dielectric multilayer substrate 17 and the wiring pattern inside the dielectric. From the top, the surface layer, the second layer to the twelfth layer, and the pattern on the back surface are shown.

A ground electrode E1 is formed on the surface layer, and the ground electrode E1 is connected to a dielectric side electrode E3. The dielectric side electrode E3 is connected to the seventh-layer conductor pattern and the back ground electrode E2 via the dielectric side surface.
In the seventh layer, rectangular resonators 21 to 26 are arranged in parallel. Among these, the edges from the resonator 21 to the resonator 26 are arranged close to each other so as to obtain strong coupling. The resonators 21 to 26 have one end in the length direction connected to the ground electrode E3.

In the second layer, electrodes 34 and 35 (see also FIG. 2) are formed. These electrodes 34 and 35 form capacitances of the eighth capacitor element C8 and the ninth capacitor element C9 with the ground electrode E1 on the surface layer. The electrode 34 and the electrode 35 are connected to ungrounded ends of the resonator 23 and the resonator 24 in the seventh layer through vias.
In the sixth layer, an input electrode IN and an output electrode OUT are formed. The input electrode IN is extended to the back surface through the side surface of the dielectric, and the output electrode OUT is also extended to the back surface through the side surface of the dielectric.

One end of the input electrode IN is connected to the electrode 31b that forms the capacitor element C5. One end of the output electrode OUT is connected to the electrode 32b that forms the capacitor element C6.
In the sixth layer, an electrode 27 for forming the first capacitor element C1 is provided between the first resonator 21 and the second resonator 22 wired in the seventh layer. . Further, an electrode 29 for forming the fourth capacitor element C4 is also provided between the fifth resonator 25 and the sixth resonator 26 wired in the seventh layer.

In the seventh layer, an electrode 31a for forming the capacitor element C5 is formed between the sixth layer electrode 31b and the eighth layer electrode 31b, and the sixth layer electrode 32b and the eighth layer electrode 32b. An electrode 32a for forming the capacitor element C6 is formed therebetween.
In the eighth layer, the input electrode IN is connected to the input electrode IN on the back surface through the side surface of the dielectric, as in the sixth layer. Similarly, the output electrode OUT is connected to the output electrode OUT on the back surface through the side surface of the dielectric.

In the eighth layer, the input electrode IN is connected to the electrode 31b forming the capacitor element C5. The output electrode OUT is connected to the electrode 32b that forms the capacitor element C6.
The electrode 28 formed in the eighth layer forms the second capacitor element C2 between the first resonator 21 and the third resonator 23 in the seventh layer. The electrode 30 forms a third capacitor element C3 between the fourth resonator 24 and the sixth resonator 26 in the seventh layer.

The twelfth layer electrode 33 forms a capacitor element C7 with the ground electrode E2 on the back surface, and the electrode 36 forms a capacitor element C10 with the ground electrode 18 on the back surface.
The electrode 33 is connected to the second resonator 22 arranged in the seventh layer through a via. The electrode 36 is connected to the fifth resonator 25 arranged in the seventh layer through a via.

On the second to eleventh layers, land patterns that prevent non-conduction due to misalignment during stacking are arranged. A ground electrode E2, an input electrode IN, and an output electrode OUT are formed on the back surface.
With the above configuration, it is possible to obtain a small bandpass filter having high attenuation characteristics in a passband of 3.1 to 4.9 GHz, a specific band of about 40%, 5.15 GHz, and 2.48 GHz.

Next, FIG. 6 shows a configuration example of a wireless communication device equipped with the bandpass filter described above.
According to the figure, the wireless communication device includes a baseband IC 45 that processes a baseband signal, an RFIC 44 that processes a high-frequency signal, a high-frequency switch 41 that switches between transmission and reception, a balun 43 that converts a balanced signal and an unbalanced signal, and a bandpass filter 42. And an antenna.

The RFIC 44 performs frequency conversion and high frequency amplification of the transmission signal acquired from the baseband IC 45, and performs low noise amplification of the reception signal. The high frequency switch 41 is a switch that temporally switches the path between transmission and reception.
The band-pass filter 42 is a band-pass filter according to the present invention that passes the UWB transmission / reception signal band and sharply attenuates signals outside the band. With this function, mutual interference with other systems can be prevented without attenuating transmitted / received signals.

  Although the embodiments of the present invention have been described above, the embodiments of the present invention are not limited to the above-described embodiments, and various modifications can be made within the scope of the present invention.

The pass characteristics and reflection characteristics of the bandpass filter formed with the circuit configuration of FIG. 1 were measured using a vector network analyzer 8719ES manufactured by Agilent Technologies.
As a result, as shown in FIG. 7, a graph of transmission characteristics S21 and reflection characteristics S11 was obtained.
According to FIG. 7, the passing loss is less than 1.5 dB within a band of about 1.5 GHz from 3.16 GHz (indicated by m1) to 4.75 GHz (indicated by m2). W-LAN IEEE. An attenuation of 30 dB or more was obtained at 2.5 GHz (indicated by m3) where 802.11b exists. Therefore, an attenuation of 20 dB or more is obtained in a narrow frequency band of about 0.6 GHz. On the other hand, W-LAN IEEE. 802.11. A high attenuation of 38 dB is shown at 5.15 GHz (indicated by m4) where a is present, and an attenuation of 20 dB or more is obtained in a narrow frequency band of about 0.4 GHz. Furthermore, the attenuation amount of 20 dB or more was shown up to 10 GHz even at a frequency of 5.15 GHz or more.

The thickness of the band pass filter of the present invention is 0.9 mm, and a small filter with a low loss in a wide band of 1.5 GHz and a steep attenuation characteristic at 0.4 GHz before and after the pass band can be realized.
Next, the band-pass filter of the present invention was simulated under the condition of a ceramic substrate having a dielectric constant of 9.4 using a circuit simulator ADS manufactured by Agilent Technologies.

FIG. 8 is a graph showing the relationship between the thickness of the dielectric and the maximum value of the loss within the passband.
According to FIG. 8, in a dielectric having a dielectric constant of 9.4 and a dielectric thickness of 0.9 mm, the loss in the passband is 1.44 dB. Further, when the dielectric thickness is 0.86 mm, the insertion loss is 1.5 dB or more. When converted to a dielectric thickness of 0.9 mm, the insertion loss is 1.5 dB with a dielectric constant of 9.83. Therefore, it can be seen that the dielectric constant of the dielectric used in the bandpass filter of the present invention is desirably 10 or less.

  On the other hand, when the dielectric thickness is 1.0 mm, the loss in the pass band is 1.27 dB from FIG. 8, and the pass characteristics are good. This is the same as when the dielectric constant is lowered to 8.46 at a dielectric thickness of 0.9 mm. If the dielectric thickness is increased, the loss of the pass band of the filter is reduced. However, in recent years, the height of components is desired to be 1.0 mm or less in consideration of mounting on mobile phones. Therefore, it is not preferable to make the dielectric thickness larger than 1.0 mm.

As described above, in the band pass filter of the present invention, the distance between the upper and lower surface grounds is preferably 1.0 mm or less.
In this verification, a resonator with Q = 163 was used.
FIG. 9 is a diagram showing the relationship between the insertion loss of the passband filter of the present invention and the Q of the distributed constant line. It can be seen that increasing the Q value of the distributed constant line reduces the loss of the bandpass filter. The Q value of the distributed constant line is improved by increasing the conductivity at high frequency of the line.

  When the band pass filter of the present invention is configured on the ADS of the circuit simulator and the pass characteristics are examined, when the capacitance of the capacitor element C5 and the capacitor element C6 is 0.8 pF, the frequency is changed from 3.16 GHz to 4.16 GHz. Whereas the maximum loss is -1.32 dB at 75 GHz, when the capacitances of the capacitor element C5 and the capacitor element C6 are 0.4 pF, ripples are present in the passband, the band is narrowed, and the maximum loss is It was 1.68 dB. On the other hand, when the capacitances of the capacitor element C5 and the capacitor element C6 are 1.5 pF, the steepness of attenuation is lost and the attenuation amount is less than 3.1 GHz, and accordingly, the pass characteristic of 3.16 GHz is increased. Deteriorated to 1.66 dB.

From the above, it is desirable that the capacitor elements C5 and C6 have a capacitance of 0.5 pF or more and less than 1.5 pF in the bandpass filter of the present invention.
In this example, the MB-OFDM method, which is one of UWB, is taken as an example of the passband. However, from 3.1 GHz to 4. GHz, which is a passband on the low frequency side of another method, the DS-CDMA method. The same discussion can be made at 9 GHz. By adjusting the lengths of the first to sixth resonators and the capacities of the first to tenth capacitor elements of the band-pass filter of the present invention, it can be used in a DS-CDMA UWB. .

It is a figure which shows the circuit structural example of the bandpass filter of this invention. It is a figure which shows the other circuit structural example of the band pass filter of this invention. It is a figure which shows the external appearance of a band pass filter. It is a figure which shows the external appearance which looked at the bandpass filter from the other surface. It is the figure which showed each layer wiring pattern of the bandpass filter from the upper surface. It is a block diagram which shows the structural example of the radio | wireless communication apparatus carrying the band pass filter of this invention. It is a graph which shows the pass characteristic and reflection characteristic of the Example of a band pass filter. It is the graph which showed the relationship between the thickness of the dielectric material of a bandpass filter, and the maximum value of the loss in a passband. It is a graph which shows the relationship between the high frequency electrical conductivity (converted into Q) of the electrode which comprises a bandpass filter, and the loss in a passband. FIG. 6 is an equivalent circuit diagram in the vicinity of a resonance frequency of a resonator having one end grounded. It is a figure which shows the reactance in the resonance frequency vicinity of the resonator by which the end was earth | grounded.

Explanation of symbols

21: 1st resonator, 22: 2nd resonator, 23: 3rd resonator, 24: 4th resonator, 25: 5th resonator, 26: 6th resonator, C1: 1st capacitor element, C2: 2nd capacitor element, C3: 3rd capacitor element, C4: 4th capacitor element, C5: 5th capacitor element, C6: 6th capacitor element, C7: 7th Capacitor element, C8: eighth capacitor element, C9: ninth capacitor element, C10: tenth capacitor element, 17: dielectric, E1 to E3: ground electrode, IN: input electrode, OUT: output electrode, 27-36: Wiring pattern

Claims (11)

Each one end of Ru is grounded, the first length is approximately 1/4 wavelength and a sixth resonator, and an input unit coupled to the ungrounded end of the first resonator, the sixth resonance of An output coupled to the non-grounded end of the vessel,
The second to fifth resonators are electromagnetically coupled to each other;
The ungrounded end of the first resonator and the ungrounded end of the second resonator are capacitively coupled by a first capacitor element, and the ungrounded end of the first resonator and the third resonator are coupled. the ungrounded terminal is capacitively coupled with the second capacitor element, and the ungrounded end of the fourth resonator and the ungrounded end of the sixth resonator is capacitively coupled with the third capacitor element, wherein ungrounded end of the fifth and the sixth resonator ungrounded end of resonator is capacitively coupled with a fourth capacitor element,
The inputs and outputs are the fifth and sixth capacitor element or the first and second of said respective through inductor element first and sixth band pass filter to be coupled to the resonator of the. Wherein the second ungrounded end of the fifth one of resonators is grounded via the capacitor element, the band pass filter of claim 1, wherein the length of the resonator is less than one quarter wavelength. The bandpass filter according to claim 1 or 2, wherein a shape of a conductor plate constituting the resonator is a rectangular shape.   The bandpass filter according to claim 1 or 2, wherein the resonator is a strip line, a microstrip line, or a coplanar line. The bandpass filter according to claim 1, wherein the resonator is formed inside a dielectric multilayer substrate in which a plurality of dielectric layers are stacked. The dielectric constant of the dielectric layer, the band pass filter according to claim 5, wherein 10 or less at 3.1 GHz to 10.6 GHz. The band pass filter according to claim 5, wherein ground electrodes are respectively disposed on an upper surface and a lower surface of the dielectric multilayer substrate . Bandpass filter according to claim 7, wherein the distance D between the front Kigu land electrode is 1.0mm or less. The fifth and bandpass filter according to claim 1, wherein the capacitance of the sixth capacitor element is less than 0.5 p F or 1.5 pF. A high-frequency module having the band-pass filter according to any one of claims 1 to 9. Radio communication apparatus using the high-frequency module according to the bandpass filter, or claim 10 as claimed in any one of claims 9.

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