Electronic device

Abstract

The invention relates to electronic equipment. The electronic equipment comprises a first antenna, a second antenna and a third antenna, the first antenna comprises a first antenna body and a first capacitor, the first capacitor and the first antenna body are connected at a first connection point, and the first capacitor is used for grounding the first antenna body; the second antenna comprises a second antenna body and a second capacitor, the second capacitor and the second antenna body are connected at a second connection point, and the second capacitor is used for grounding the second antenna body; and the third antenna comprises a third antenna body, the third antenna body comprises the first antenna body and a frame between the first connection point and the second connection point, and the third antenna feeds through the first connection point and is grounded through the second capacitor. According to the embodiment, the third antenna can be obtained by multiplexing the first antenna, the fusion degree of the first antenna and the second antenna can be improved, and the size of the electronic equipment can be reduced.

Description

Technical Field

[0001] The present disclosure relates to the field of antenna technology, and in particular to an electronic device. Background Art

[0002] As electronic devices become more and more versatile, they require more and more antennas. Considering that the antenna space in electronic devices is getting smaller and smaller, it is necessary to improve the integration of antennas. Summary of the invention

[0003] The present disclosure provides an electronic device to solve the deficiencies of the related art.

[0004] According to a first aspect of an embodiment of the present disclosure, an electronic device is provided, comprising a first antenna, a second antenna and a third antenna; the first antenna comprises a first antenna body and a first capacitor, the first capacitor and the first antenna body are connected at a first connection point, and the first antenna body is grounded; the second antenna comprises a second antenna body and a second capacitor, the second capacitor and the second antenna body are connected at a second connection point, and the second antenna body is grounded;

[0005] The third antenna includes a third antenna body, wherein the third antenna body includes the first antenna body and a frame between the first connection point and the second connection point. The third antenna is fed through the first connection point and is grounded through the second capacitor.

[0006] Optionally, the first antenna includes a first antenna matching circuit and a first signal source; the first antenna matching circuit includes a series capacitor, and the series capacitor is connected in series between the first antenna body and the first signal source.

[0007] Optionally, the capacitance of the series capacitor is less than or equal to 4 pF.

[0008] Optionally, the capacitance of the series capacitor is less than or equal to 1 pF.

[0009] Optionally, when the first antenna operates in a first frequency band and the third antenna operates in a third frequency band, a capacitance value of the first capacitor is greater than or equal to 5 pF;

[0010] Alternatively, when the first antenna operates in the fifth frequency band and the third antenna operates in the third frequency band, the capacitance value of the first capacitor is greater than or equal to 20 pF;

[0011] The center frequency of the fifth frequency band is smaller than the center frequency of the first frequency band.

[0012] Optionally, the third antenna includes a third antenna matching circuit and a third signal source; the third antenna matching circuit is electrically connected to the third signal source; and the capacitance value of the equivalent capacitance to ground of the third antenna matching circuit is greater than or equal to 4pF.

[0013] Optionally, the third antenna includes a third antenna matching circuit and a third signal source; the third antenna matching circuit is electrically connected to the third signal source; the third antenna matching circuit includes a third capacitor, a grounding inductor and a residual matching sub-circuit; the first end of the third capacitor is electrically connected to the antenna body of the third antenna, the second end of the third capacitor is respectively electrically connected to the first end of the grounding inductor and the first end of the residual matching sub-circuit, and the second end of the residual matching sub-circuit is electrically connected to the third signal source; the second end of the grounding inductor is grounded.

[0014] Optionally, when the third antenna operates in a third frequency band, the capacitance value of the third capacitor is greater than or equal to 4 pF, and the inductance value of the ground inductor is less than or equal to 3 nF.

[0015] Optionally, a fourth antenna is also included; the fourth antenna includes a fourth antenna body and a frame between the first connection point and the second connection point; the fourth antenna is fed through the second connection point, and the fourth antenna is grounded through the first capacitor.

[0016] Optionally, when the second antenna operates in the second frequency band and the fourth antenna operates in the fourth frequency band, the capacitance value of the second capacitor is greater than or equal to 5 pF;

[0017] Alternatively, when the second antenna operates in the sixth frequency band and the fourth antenna operates in the fourth frequency band, the capacitance value of the second capacitor is greater than or equal to 20 pF;

[0018] The center frequency of the sixth frequency band is smaller than the center frequency of the second frequency band.

[0019] The technical solution provided by the embodiments of the present disclosure may have the following beneficial effects:

[0020] The electronic device provided in the embodiment of the present disclosure includes a first antenna, a second antenna and a third antenna; the first antenna includes a first antenna body and a first capacitor, the first capacitor is connected to the first antenna body at a first connection point, and is used to ground the first antenna body; the second antenna includes a second antenna body and a second capacitor, the second capacitor is connected to the second antenna body at a second connection point, and is used to ground the second antenna body; the third antenna includes a third antenna body, the third antenna body includes the first antenna body and a frame between the first connection point and the second connection point, and the third antenna is fed through the first connection point and is grounded through the second capacitor. In this way, in this embodiment, the first antenna can be reused to obtain the third antenna, which is beneficial to improving the integration of the first antenna and the second antenna, and is beneficial to reducing the volume of the electronic device.

[0021] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present disclosure and, together with the description, serve to explain the principles of the present disclosure.

[0023] Figure 1 It is a block diagram of an electronic device according to an exemplary embodiment.

[0024] Figure 2 The figure is a schematic diagram showing a first antenna ground return according to an exemplary embodiment.

[0025] Figure 3 The figure is a schematic diagram showing the ground return of the second antenna according to an exemplary embodiment.

[0026] Figure 4 is a schematic diagram showing impedance matching of a first antenna according to an exemplary embodiment.

[0027] Figure 5 is a schematic diagram showing impedance matching of a second antenna according to an exemplary embodiment.

[0028] Figure 6 is a schematic diagram showing impedance matching of a third antenna according to an exemplary embodiment.

[0029] Figure 7 is a schematic diagram showing impedance matching of a third antenna according to an exemplary embodiment.

[0030] Figure 8 is a block diagram of another electronic device according to an exemplary embodiment.

[0031] Fig. 9is a schematic diagram showing S parameters of a first antenna according to an exemplary embodiment.

[0032] Fig.10 is a schematic diagram of S parameters of a second antenna according to an exemplary embodiment.

[0033] Fig.11 is a schematic diagram showing S parameters of a third antenna according to an exemplary embodiment.

[0034] Fig.12 It is a block diagram of an electronic device according to an exemplary embodiment. DETAILED DESCRIPTION

[0035] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described exemplarily below do not represent all embodiments consistent with the present disclosure. Instead, they are merely examples of devices consistent with some aspects of the present disclosure as detailed in the attached claims. It should be noted that the features in the following embodiments and implementations may be combined with each other without conflict.

[0036] The present disclosure provides an electronic device. Figure 1 , the electronic device 100 includes a first antenna A1, a second antenna A2 and a third antenna A3. Figure 2 The first antenna A1 includes a first antenna body 11 and a first capacitor C1. The first capacitor C1 and the first antenna body 11 are connected to a first connection point B1 for grounding the first antenna body 11 to GND. Figure 3 The second antenna A2 includes a second antenna body 21 and a second capacitor C2. The second capacitor C2 and the second antenna body 21 are connected to a second connection point B2 for connecting the second antenna body 21 to a ground GND.

[0037] The third antenna A3 includes a third antenna body, which includes the first antenna body 11 and a frame between the first connection point B1 and the second connection point B2. The third antenna A3 is fed through the first connection point B1 and is grounded GND through the second capacitor C2.

[0038] In this embodiment, the first antenna body 11 and the second antenna body 21 can be implemented based on the frame 10 of the electronic device 100. Taking the first antenna body 11 of the first antenna A1 as an example, the first antenna body 11 is the frame portion between the partition strip 12 and the first connection point B1. Taking the antenna body of the third antenna A1, in addition to the first antenna body 11, it also includes the frame portion between the first connection point B1 and the second connection point B2. The second antenna body 21 of the second antenna A2 refers to the frame portion between the partition strip 22 and the second connection point B2. It should be noted that the antenna body of each antenna can be set according to the specific scenario, and the setting method of each antenna body mentioned above is only for example description and is not limited here.

[0039] In this way, in this embodiment, the first antenna can be reused to obtain the third antenna, which is beneficial to improving the integration of the first antenna and the second antenna and is beneficial to reducing the volume of the electronic device.

[0040] In this embodiment, the operating frequency bands of the first antenna A1, the second antenna A2 and the third antenna A3 are set as follows:

[0041] The operating frequency band of the first antenna A1 is staggered from the operating frequency band of the third antenna A3, that is, the operating frequency bands of the first antenna A1 and the third antenna A3 are different.

[0042] The operating frequency band of the second antenna A2 is staggered from the operating frequency band of the third antenna A3, that is, the operating frequency bands of the second antenna A2 and the third antenna A3 are different.

[0043] In one example, the first antenna A1 operates in the first frequency band, which includes the N77 / 78 / 79 frequency band to cover the 3.3GHz to 5GHz frequency band; the second antenna A2 operates in the second frequency band, which includes 1.7GHz to 2.7GHz; the third antenna A3 operates in the third frequency band, which covers 1176.45±1.023MHz, and the third antenna A3 is used as a GPS L5 antenna. Of course, the first antenna A1, the second antenna A2 and the third antenna A3 can also operate in other frequency bands, for example, the first antenna A1 operates in the fifth frequency band, which refers to a frequency band less than or equal to 1GHz. The appropriate frequency band can be selected for each antenna according to the specific scenario. When the frequency bands of the two antennas do not conflict, each solution falls within the protection scope of the present disclosure.

[0044] In one embodiment, see Figure 4 The first antenna A1 includes a first antenna matching circuit 13 and a first signal source S1; the first antenna matching circuit 13 includes a series capacitor C11, and the series capacitor C11 is connected in series between the first antenna body 11 and the first signal source S1, and is used to perform impedance matching on the first antenna A1 to increase the isolation between the first antenna A1 and the third antenna A3.

[0045] It should be noted that in the first antenna A1, a series capacitor C11 is provided between the first antenna body 11 and the first signal source S1 to avoid small inductance grounding, thereby meeting the requirements of the SAR sensor and the third antenna A3. In one example, the capacitance value of the series capacitor C11 needs to be less than or equal to 4pF, that is, not greater than 4pF. In another example, the capacitance value of the series capacitor C11 needs to be less than or equal to 1pF. In this way, in this example, by setting the capacitance of the series capacitor C11, the performance of the third antenna A3 can be guaranteed while ensuring the normal operation of the first antenna A1.

[0046] Continue to see Figure 2 , the first antenna A1 is grounded to GND at the first connection point B1 through the first capacitor C1. At this time, the capacitance value of the first capacitor C1 needs to be implemented with a large capacitor to achieve the effect of zero ohm (0ohm) grounding to ensure the suspension requirement of the first antenna A1. In one example, when the first antenna A1 operates in the first frequency band and the third antenna operates in the third frequency band, the capacitance value of the first capacitor C1 is greater than or equal to 5pF, which can ensure that the first antenna A1 and the third antenna A3 operate in their respective operating frequency bands. In another example, when the first antenna A1 operates in the fifth frequency band (the center frequency is less than the center frequency of the first frequency band, such as less than or equal to 1GHz) and the third antenna A3 operates in the third frequency band, the capacitance value of the first capacitor C1 is greater than or equal to 20pF, which can ensure the requirements of the first antenna A1 and the third antenna A3.

[0047] In one embodiment, see Figure 5 The second antenna A2 includes a second antenna matching circuit 23 and a second signal source S2; the second antenna matching circuit 23 includes a series capacitor C21, which is connected in series between the second antenna body 21 and the second signal source S2, and is used to perform impedance matching on the second antenna A2 to increase the isolation between the second antenna A2 and the third antenna A3.

[0048] It should be noted that in the second antenna A2, a series capacitor C21 is provided between the second antenna body 21 and the second signal source S2 to avoid small inductance grounding, thereby meeting the needs of the SAR sensor and the needs of the third antenna A3. In one example, the capacitance value of the series capacitor C21 needs to be less than or equal to 4pF, that is, not greater than 4pF. In another example, the capacitance value of the series capacitor C21 needs to be less than or equal to 1pF. In this way, in this example, by setting the capacitance of the series capacitor C21, the performance of the third antenna A3 can be guaranteed while ensuring the normal operation of the second antenna A2.

[0049] Continue to see Figure 3, the second antenna A2 is grounded to GND at the second connection point B2 through the second capacitor C2. At this time, the capacitance value of the second capacitor C2 needs to be implemented with a large capacitor to achieve the effect of zero ohm (0ohm) grounding to ensure the suspension requirement of the second antenna A2. In one example, when the second antenna A2 operates in the second frequency band and the third antenna operates in the third frequency band, the capacitance value of the second capacitor C2 is greater than or equal to 5pF, which can ensure the requirements of the second antenna A2 and the third antenna A3. In another example, when the second antenna A2 operates in the fifth frequency band (the center frequency is less than the center frequency of the first frequency band, such as less than or equal to 1GHz) and the third antenna A3 operates in the third frequency band, the capacitance value of the second capacitor C2 is greater than or equal to 20pF, which can ensure the requirements of the second antenna A2 and the third antenna A3.

[0050] In one embodiment, see Figure 6 The third antenna A3 includes a third antenna matching circuit 31 and a third signal source S3. The third antenna matching circuit 31 is connected in series between the antenna body of the third antenna A3 and the third signal source S3; the capacitance value of the ground equivalent capacitance C32 of the third antenna matching circuit 31 is greater than or equal to 4pF, thereby meeting the requirement that the third antenna 3 cannot be short-connected to the ground when used as a floating antenna.

[0051] In another example, see Figure 7 , the third antenna A3 includes a third antenna matching circuit 31 and a third signal source S3; the third antenna matching circuit 31 is connected in series between the antenna body of the third antenna A3 and the third signal source S3; the third antenna matching circuit 31 includes a third capacitor C33, a grounding inductor L and a residual matching subcircuit 321; the first end of the third capacitor C33 is electrically connected to the antenna body of the third antenna A3, the second end of the third capacitor C33 is electrically connected to the first end of the grounding inductor L and the first end of the residual matching subcircuit 321 respectively, and the second end of the residual matching subcircuit 321 is electrically connected to the third signal source S3; the second end of the grounding inductor L is grounded GND. In this embodiment, when the third antenna A3 can operate in the third frequency band, the capacitance of the third capacitor C33 is greater than or equal to 4pF, and the grounding inductor L is less than or equal to 3nF, thereby satisfying the requirement that the third antenna 3 cannot be short-connected to the ground when used as a floating antenna.

[0052] In one embodiment, see Figure 8 The electronic device further includes a fourth antenna A4, which includes a second antenna A2 and a first capacitor C1. The fourth antenna A4 is fed via the second connection point B2, and the fourth antenna A4 is grounded GND via the first capacitor C1.

[0053] In this embodiment, when the second antenna A2 operates in the second frequency band and the fourth antenna A4 operates in the fourth frequency band (for example, 1176.45±1.023MHz), the capacitance value of the second capacitor C2 is greater than or equal to 5pF; or, when the second antenna A2 operates in the sixth frequency band (for example, less than or equal to 1GHz) and the fourth antenna A4 operates in the fourth frequency band, the capacitance value of the second capacitor is greater than or equal to 20pF; the center frequency of the sixth frequency band is less than the center frequency of the second frequency band.

[0054] Based on the above, the S parameters of each antenna of the electronic device are as follows: Fig. 9 , Fig.10 and Fig.11 shown.

[0055] See also Fig. 9 The amplitude of the S parameter of the first antenna A1 in the working frequency bands of 3.6 GHz and 4.6 GHz is approximately -15 dB.

[0056] See also Fig.10 , the S parameter of the second antenna A2 has an amplitude of about -12dB at 1.8GHz and an amplitude of about -9dB at 2.5GHz.

[0057] See also Fig.11 , the amplitude of the S parameter of the third antenna A3 at 1.19 GHz is approximately -19 dB.

[0058] Fig.12 1 is a block diagram of an electronic device according to an exemplary embodiment. For example, the electronic device 1200 may be a smart phone, a computer, a digital broadcast terminal, a tablet device, a medical device, a fitness device, a personal digital assistant, etc.

[0059] Reference Fig.12 The electronic device 1200 may include one or more of the following components: a processing component 1202 , a memory 1204 , a power component 1206 , a multimedia component 1208 , an audio component 1210 , an input / output (I / O) interface 1212 , a sensor component 1214 , a communication component 1216 , and an image acquisition component 1218 .

[0060] The processing component 1202 generally controls the overall operation of the electronic device 1200, such as operations associated with display, phone calls, data communications, camera operations, and recording operations. The processing component 1202 may include one or more processors 1220 to execute computer programs. In addition, the processing component 1202 may include one or more modules to facilitate interaction between the processing component 1202 and other components. For example, the processing component 1202 may include a multimedia module to facilitate interaction between the multimedia component 1208 and the processing component 1202.

[0061] The memory 1204 is configured to store various types of data to support operations on the electronic device 1200. Examples of such data include computer programs for any application or method operating on the electronic device 1200, contact data, phone book data, messages, pictures, videos, etc. The memory 1204 can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic memory, flash memory, magnetic disk or optical disk.

[0062] The power supply component 1206 provides power to various components of the electronic device 1200. The power supply component 1206 may include a power management system, one or more power supplies, and other components associated with generating, managing, and distributing power for the electronic device 1200. The power supply component 1206 may include a power supply chip, and the controller may communicate with the power supply chip to control the power supply chip to turn on or off the first switching device, so that the battery supplies power to the mainboard circuit or does not supply power.

[0063] The multimedia component 1208 includes a screen that provides an output interface between the electronic device 1200 and the target object. In some embodiments, the screen may include a liquid crystal display (LCD) and a touch panel (TP). If the screen includes a touch panel, the screen may be implemented as a touch screen to receive input information from the target object. The touch panel includes one or more touch sensors to sense touch, slide, and gestures on the touch panel. The touch sensor may not only sense the boundaries of a touch or slide action, but also detect the duration and pressure associated with the touch or slide operation.

[0064] The audio component 1210 is configured to output and / or input audio file information. For example, the audio component 1210 includes a microphone (MIC), and when the electronic device 1200 is in an operation mode, such as a call mode, a recording mode, and a speech recognition mode, the microphone is configured to receive external audio file information. The received audio file information can be further stored in the memory 1204 or sent via the communication component 1216. In some embodiments, the audio component 1210 also includes a speaker for outputting audio file information.

[0065] The I / O interface 1212 provides an interface between the processing component 1202 and a peripheral interface module, which may be a keyboard, a click wheel, a button, etc.

[0066] The sensor component 1214 includes one or more sensors for providing various aspects of status assessment for the electronic device 1200. For example, the sensor component 1214 can detect the open / closed state of the electronic device 1200, the relative positioning of components, such as the display screen and keypad of the electronic device 1200, and the sensor component 1214 can also detect the position change of the electronic device 1200 or a component, the presence or absence of contact between the target object and the electronic device 1200, the orientation or acceleration / deceleration of the electronic device 1200, and the temperature change of the electronic device 1200. In this example, the sensor component 1214 can include a magnetic sensor, a gyroscope, and a magnetic field sensor, and can also include an inertial sensor, an image sensor, etc., wherein the magnetic field sensor includes at least one of the following: a Hall sensor, a thin film magnetoresistive sensor, and a magnetic liquid acceleration sensor.

[0067] The communication component 1216 is configured to facilitate wired or wireless communication between the electronic device 1200 and other devices. The electronic device 1200 can access a wireless network based on a communication standard, such as WiFi, 2G, 3G, 4G, 5G, or a combination thereof. In an exemplary embodiment, the communication component 1216 receives broadcast information or broadcast-related information from an external broadcast management system via a broadcast channel. In an exemplary embodiment, the communication component 1216 also includes a near field communication (NFC) module to facilitate short-range communication. For example, the NFC module can be implemented based on radio frequency identification (RFID) technology, infrared data association (IrDA) technology, ultra-wideband (UWB) technology, Bluetooth (BT) technology and other technologies. In one example, the communication component 1216 includes the first antenna and the second antenna mentioned above, and / or also includes a third antenna.

[0068] In an exemplary embodiment, the electronic device 1200 may be implemented by one or more application-specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), controllers, microcontrollers, microprocessors, or other electronic components.

[0069] Those skilled in the art will readily appreciate other embodiments of the present disclosure after considering the specification and practicing the disclosure disclosed herein. The present disclosure is intended to cover any variations, uses, or adaptations that follow the general principles of the present disclosure and include common knowledge or customary techniques in the art that are not disclosed in the present disclosure. The description and examples are to be considered exemplary only, and the true scope and spirit of the present disclosure are indicated by the following claims.

[0070] It should be understood that the present disclosure is not limited to the exact structures that have been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present disclosure is limited only by the appended claims.

Claims

1. An electronic device, characterized in that: The invention comprises a first antenna, a second antenna and a third antenna; the first antenna comprises a first antenna body and a first capacitor, the first capacitor and the first antenna body are connected at a first connection point, and the first antenna body is grounded; the second antenna comprises a second antenna body and a second capacitor, the second capacitor and the second antenna body are connected at a second connection point, and the second antenna body is grounded; The third antenna includes a third antenna body, wherein the third antenna body includes the first antenna body and a frame between the first connection point and the second connection point. The third antenna is fed through the first connection point and is grounded through the second capacitor.

2. The electronic device according to claim 1, characterized in that: The first antenna includes a first antenna matching circuit and a first signal source; the first antenna matching circuit includes a series capacitor, and the series capacitor is connected in series between the first antenna body and the first signal source.

3. The electronic device according to claim 2, characterized in that: The capacitance value of the series capacitor is less than or equal to 4 pF.

4. The electronic device according to claim 2, characterized in that: The capacitance value of the series capacitor is less than or equal to 1 pF.

5. The electronic device according to claim 1, characterized in that: When the first antenna operates in the first frequency band and the third antenna operates in the third frequency band, the capacitance value of the first capacitor is greater than or equal to 5 pF; Alternatively, when the first antenna operates in the fifth frequency band and the third antenna operates in the third frequency band, the capacitance value of the first capacitor is greater than or equal to 20 pF; The center frequency of the fifth frequency band is smaller than the center frequency of the first frequency band.

6. The electronic device according to claim 1, characterized in that: The third antenna includes a third antenna matching circuit and a third signal source; the third antenna matching circuit is electrically connected to the third signal source; and the capacitance value of the equivalent capacitance to ground of the third antenna matching circuit is greater than or equal to 4pF.

7. The electronic device according to claim 1, characterized in that: The third antenna includes a third antenna matching circuit and a third signal source; the third antenna matching circuit is electrically connected to the third signal source; the third antenna matching circuit includes a third capacitor, a grounding inductor and a residual matching subcircuit; the first end of the third capacitor is electrically connected to the antenna body of the third antenna, the second end of the third capacitor is electrically connected to the first end of the grounding inductor and the first end of the residual matching subcircuit respectively, and the second end of the residual matching subcircuit is electrically connected to the third signal source; the second end of the grounding inductor is grounded.

8. The electronic device according to claim 7, characterized in that: When the third antenna operates in the third frequency band, the capacitance value of the third capacitor is greater than or equal to 4 pF, and the inductance value of the ground inductor is less than or equal to 3 nF.

9. The electronic device according to claim 1, characterized in that: It also includes a fourth antenna; the fourth antenna includes a fourth antenna body and a frame between the first connection point and the second connection point; the fourth antenna is fed through the second connection point, and the fourth antenna is grounded through the first capacitor.

10. The electronic device according to claim 9, characterized in that: When the second antenna operates in the second frequency band and the fourth antenna operates in the fourth frequency band, the capacitance value of the second capacitor is greater than or equal to 5 pF; Alternatively, when the second antenna operates in the sixth frequency band and the fourth antenna operates in the fourth frequency band, the capacitance value of the second capacitor is greater than or equal to 20 pF; The center frequency of the sixth frequency band is smaller than the center frequency of the second frequency band.

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