Patent Publication Number: US-2023163470-A1

Title: Communication device

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims priority of Taiwan Patent Application No. 110143114 filed on Nov. 19, 2021, the entirety of which is incorporated by reference herein. 
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The disclosure generally relates to a communication device, and more particularly, to a communication device with high isolation. 
     Description of the Related Art 
     With the advancements being made in mobile communication technology, mobile devices such as portable computers, mobile phones, multimedia players, and other hybrid functional portable electronic devices have become more common. To satisfy consumer demand, mobile devices can usually perform wireless communication functions. Some devices cover a large wireless communication area; these include mobile phones using 2G, 3G, and LTE (Long Term Evolution) systems and using frequency bands of 700 MHz, 850 MHz, 900 MHz, 1800 MHz, 1900 MHz, 2100 MHz, 2300 MHz, and 2500 MHz. Some devices cover a small wireless communication area; these include mobile phones using Wi-Fi systems and using frequency bands of 2.4 GHz, 5.2 GHz, and 5.8 GHz. 
     Antennas are indispensable elements of a mobile device supporting wireless communication. However, because of the small amount of internal space in the mobile device, the configuration of the antennas and their transmission lines are often very close, and they are likely to interfere with each other. Accordingly, it is necessary to propose a novel solution for solving the problem of low isolation in the conventional design. 
     BRIEF SUMMARY OF THE INVENTION 
     In an exemplary embodiment, the invention is directed to a communication device that includes a first ground element, a second ground element, a third ground element, a first signaling conductor, a second signaling conductor, a resonant circuit, and a dielectric substrate. The first signaling conductor is disposed between the first ground element and the second ground element. The second signaling conductor is disposed between the second ground element and the third ground element. The first signaling conductor is coupled through the resonant circuit to the first ground element. The dielectric substrate has a first surface and a second surface which are opposite to each other. The first ground element, the second ground element, the third ground element, the first signaling conductor, and the second signaling conductor are all disposed on the first surface of the dielectric substrate. The resonant circuit is configured to increase the isolation between the first signaling conductor and the second signaling conductor in a target frequency band. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein: 
         FIG.  1 A  is a top view of a communication device according to an embodiment of the invention; 
         FIG.  1 B  is a sectional view of a communication device according to an embodiment of the invention; 
         FIG.  2 A  is a top view of a communication device according to an embodiment of the invention; 
         FIG.  2 B  is a sectional view of a communication device according to an embodiment of the invention; 
         FIG.  3    is a diagram of the S-parameter of a communication device according to an embodiment of the invention; 
         FIG.  4 A  is a top view of an inductive element according to an embodiment of the invention; 
         FIG.  4 B  is a perspective view of an inductive element according to an embodiment of the invention; 
         FIG.  5 A  is a top view of a capacitive element according to an embodiment of the invention; 
         FIG.  5 B  is a top view of a capacitive element according to an embodiment of the invention; 
         FIG.  6 A  is a top view of a communication device according to an embodiment of the invention; 
         FIG.  6 B  is a diagram of the S-parameter of a communication device according to an embodiment of the invention; 
         FIG.  7 A  is a top view of a communication device according to an embodiment of the invention; 
         FIG.  7 B  is a diagram of the S-parameter of a communication device according to an embodiment of the invention; 
         FIG.  8 A  is a top view of a communication device according to an embodiment of the invention; and 
         FIG.  8 B  is a diagram of the S-parameter of a communication device according to an embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In order to illustrate the purposes, features and advantages of the invention, the embodiments and figures of the invention are shown in detail as follows. 
     Certain terms are used throughout the description and following claims to refer to particular components. As one skilled in the art will appreciate, manufacturers may refer to a component by different names. This document does not intend to distinguish between components that differ in name but not function. In the following description and in the claims, the terms “include” and “comprise” are used in an open-ended fashion, and thus should be interpreted to mean “include, but not limited to . . . ”. The term “substantially” means the value is within an acceptable error range. One skilled in the art can solve the technical problem within a predetermined error range and achieve the proposed technical performance. Also, the term “couple” is intended to mean either an indirect or direct electrical connection. Accordingly, if one device is coupled to another device, that connection may be through a direct electrical connection, or through an indirect electrical connection via other devices and connections. 
     The following disclosure provides many different embodiments, or examples, for implementing different features of the provided subject matter. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. For example, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features, such that the first and second features may not be in direct contact. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. 
     Furthermore, spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper” and the like, may be used herein for ease of description to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The apparatus may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly. 
       FIG.  1 A  is a top view of a communication device  100  according to an embodiment of the invention.  FIG.  1 B  is a sectional view of the communication device  100  according to an embodiment of the invention (along a sectional line LC 1  of  FIG.  1 A ). Please refer to  FIG.  1 A  and  FIG.  1 B  together. The communication device  100  may be applied to a mobile device, such as a smart phone, a tablet computer, or a notebook computer. In the embodiment of  FIG.  1   , the communication device  100  includes a first ground element  110 , a second ground element  120 , a third ground element  130 , a first signaling conductor  140 , a second signaling conductor  150 , a resonant circuit  160 , and a dielectric substrate  170 . The first ground element  110 , the second ground element  120 , the third ground element  130 , the first signaling conductor  140 , and the second signaling conductor  150  may all be made of metal materials, such as copper, silver, aluminum, iron, or their alloys. It should be understood that the communication device  100  may further include other components, such as a processor, a touch control panel, a speaker, a power supply module, and/or a housing, although they are not displayed in  FIG.  1 A  and  FIG.  1 B . 
     The first ground element  110 , the second ground element  120 , and the third ground element  130  can provide a ground voltage VSS. The first signaling conductor  140  may substantially have a straight-line shape. The first signaling conductor  140  is disposed between the first ground element  110  and the second ground element  120 . The second signaling conductor  150  may substantially have another straight-line shape, which may be substantially parallel to the first signal conductor  140 . The second signaling conductor  150  is disposed between the second ground element  120  and the third ground element  130 . In some embodiments, the first signaling conductor  140  and the second signaling conductor  150  are completely separate from the first ground element  110 , the second ground element  120 , and the third ground element  130 . 
     The first signaling conductor  140  is coupled through the resonant circuit  160  to the first ground element  110 . In some embodiments, the first signaling conductor  140  and the resonant circuit  160  are coupled in parallel with the first ground element  110 , but they are not limited thereto. It should be noted that the resonant circuit  160  is configured to increase the isolation between the first signaling conductor  140  and the second signaling conductor  150  in a target frequency band. That is, within the aforementioned target frequency band, the first signaling conductor  140  and the second signaling conductor  150  do not tend to interfere with each other. 
     The dielectric substrate  170  may be an FR4 (Flame Retardant 4) substrate, a PCB (Printed Circuit Board), or an FPC (Flexible Printed Circuit). The dielectric substrate  170  has a first surface E 1  and a second surface E 2  with are opposite to each other. The first ground element  110 , the second ground element  120 , the third ground element  130 , the first signaling conductor  140 , and the second signaling conductor  150  may all be disposed on the first surface E 1  of the dielectric substrate  170 . 
     The following embodiments will introduce different configurations and detailed structural features of the communication device. It should be understood that these figures and descriptions are merely exemplary, rather than limitations of the invention. 
       FIG.  2 A  is a top view of a communication device  200  according to an embodiment of the invention.  FIG.  2 B  is a sectional view of the communication device  200  according to an embodiment of the invention (along a sectional line LC 2  of  FIG.  2 A ).  FIG.  2 A  and  FIG.  2 B  are similar to  FIG.  1 A  and  FIG.  1 B . In the embodiment of  FIG.  2 A  and  FIG.  2 B , the communication device  200  further includes a system ground plane  280 , a first conductive via element  291 , a second conductive via element  292 , and a third conductive via element  293 . The system ground plane  280  is disposed on the second surface E 2  of the dielectric substrate  170 . The first conductive via element  291  penetrates the dielectric substrate  170 . The first ground element  110  is coupled through the first conductive via element  291  to the system ground plane  280 . The second conductive via element  292  penetrates the dielectric substrate  170 . The second ground element  120  is coupled through the second conductive via element  292  to the system ground plane  280 . The third conductive via element  293  penetrates the dielectric substrate  170 . The third ground element  130  is coupled through the third conductive via element  293  to the system ground plane  280 . The incorporation of the system ground plane  280 , the first conductive via element  291 , the second conductive via element  292 , and the third conductive via element  293  can help to reduce the transmission loss of the communication device  200 . 
     The first signaling conductor  140  has a first end  141  and a second end  142 . A first feeding point FP 1  is positioned at the first end  141  of the first signaling conductor  140 . The first feeding point FP 1  may be further coupled to a first antenna  281 . The second signaling conductor  150  has a first end  151  and a second end  152 . A second feeding point FP 2  is positioned at the first end  151  of the second signaling conductor  150 . The second feeding point FP 2  may be further coupled to a second antenna  282 . Furthermore, the second end  142  of the first signaling conductor  140  may be further coupled to a first RF (Radio Frequency) module  283 , and the second end  152  of the second signaling conductor  150  may be further coupled to a second RF module  284 . For example, the first antenna  281  may be excited by the first RF module  283  through the first signaling conductor  140 , and the second antenna  282  may be excited by the second RF module  284  through the second signaling conductor  150 . 
     In the embodiment of  FIG.  2 A  and  FIG.  2 B , a resonant circuit  260  of the communication device  200  includes an inductive element  262  and a capacitive element  264 . Specifically, the resonant circuit  260  has a first connection point NC 1  coupled to the first signaling conductor  140 , and a second connection point NC 2  coupled to the first ground element  110 . The inductive element  262  and the capacitive element  264  are coupled in series between the first connection point NC 1  and the second connection point NC 2 . The connection order of the inductive element  262  and the capacitive element  264  is not limited in the invention. In alternative embodiments, the positions of the inductive element  262  and the capacitive element  264  are exchangeable with each other. It should be noted the first connection point NC 1  is adjacent to the first feeding point FP 1 . The term “adjacent” or “close” over the disclosure means that the distance (spacing) between two corresponding elements is smaller than a predetermined distance (e.g., 10 mm or the shorter), or means that the two corresponding elements directly touch each other (i.e., the aforementioned distance/spacing between them is reduced to 0). 
       FIG.  3    is a diagram of the S-parameter of the communication device  200  according to an embodiment of the invention. The horizontal axis represents the operational frequency (MHz), and the vertical axis represents the S-parameter (dB). If the first feeding point FP 1  is set as a first port (Port 1) and the second feeding point FP 2  is set as a second port (Port 2), the S 21  parameter therebetween will be shown in  FIG.  3   . According to the measurement of  FIG.  3   , by using the resonant circuit  260 , the isolation between the first signaling conductor  140  and the second signaling conductor  150  in a target frequency band FB 1  can be improved by about 36 dB. For example, the target frequency band FB 1  may be from 5150 MHz to 5850 MHz, but it is not limited thereto. In some embodiments, the central frequency FC of the target frequency band FB 1  is described as the following equation (1): 
     
       
         
           
             
               
                 
                   FC 
                   = 
                   
                     
                       1 
                       
                         2 
                         ⁢ 
                         π 
                       
                     
                     · 
                     
                       1 
                       
                         
                           L 
                           · 
                           C 
                         
                       
                     
                   
                 
               
               
                 
                   ( 
                   1 
                   ) 
                 
               
             
           
         
       
     
     where “FC” represents the central frequency FC, “L” represents the inductance of the inductive element  262 , and “C” represents the capacitance of the capacitive element  264 . 
     Generally, the first signaling conductor  140  is mainly configured to transmit signals within a first frequency band, and the second signaling conductor  150  is mainly configured to transmit signals within a second frequency band. For example, the first frequency band may be from 2400 MHz to 2500 MHz, and the second frequency band may be from 5150 MHz to 5850 MHz. The second frequency band may overlap the target frequency band FB 1 . Since the resonant circuit  260  can absorb the current distributions within the target frequency band FB 1 , the communication device  200  of the invention can effectively avoid the interference between the first signaling conductor  140  and the second signaling conductor  150  (especially for the target frequency band FB 1 ). In addition, according to practical measurements, if the distance D 1  between the first connection point NC 1  and the first feeding point FP 1  is from 0 mil to 100 mil, the isolating function of the resonant circuit  260  can be further enhanced. Other features of the communication device  200  of  FIG.  2 A  and  FIG.  2 B  are similar to those of the communication device  100  of  FIG.  1 A  and  FIG.  1 B . Accordingly, the two embodiments can achieve similar levels of performance. Next, the following embodiments will introduce a variety of possible detailed structures of the inductive element  262  and the capacitive element  264 . 
       FIG.  4 A  is a top view of an inductive element  410  according to an embodiment of the invention. In the embodiment of  FIG.  4 A , the inductive element  410  includes a meandering conductor  420 , which is disposed on the first surface E 1  of the dielectric substrate  170 . For example, the meandering conductor  420  may include a plurality of U-shaped portions coupled with each other. The inductive element  410  has a first terminal point  411  and a second terminal point  412 , which may be positioned at two ends of the meandering conductor  420 , respectively. With respect to element sizes, the width W 1  of the meandering conductor  420  may be from 2 mil to 10 mil, and the width of the gap G 1  of the meandering conductor  420  may be from 2 mil to 10 mil. 
       FIG.  4 B  is a perspective view of an inductive element  450  according to an embodiment of the invention. In the embodiment of  FIG.  4 B , the inductive element  450  includes a first conductive pad  461 , a second conductive pad  462 , a third conductive pad  463 , a fourth conductive pad  464 , a first connection via element  481 , and a second connection via element  482 . The inductive element  450  has a first terminal point  451  and a second terminal point  452 . The first terminal point  451  is positioned at the first conductive pad  461 . The second terminal point  452  is positioned at the second conductive pad  462 . For example, each of the first conductive pad  461 , the second conductive pad  462 , the third conductive pad  463 , and the fourth conductive pad  464  may substantially have a circular shape with a radius R 1 . The first conductive pad  461  and the second conductive pad  462  are both disposed on the first surface E 1  of the dielectric substrate  170 . The third conductive pad  463  and the fourth conductive pad  464  are both disposed on the second surface E 2  of the dielectric substrate  170 . The fourth conductive pad  464  is further coupled to the third conductive pad  463 . For example, each of the first connection via element  481  and the second connection via element  482  may substantially have a cylindrical shape with a radius R 2 . The first connection via element  481  penetrates the dielectric substrate  170 . The first connection via element  481  is coupled between the first conductive pad  461  and the third conductive pad  463 . The second connection via element  482  penetrates the dielectric substrate  170 . The second connection via element  482  is coupled between the second conductive pad  462  and the fourth conductive pad  464 . With respect to element sizes, the radius R 1  of the aforementioned circular shape may be from 4 mil to 12 mil, the radius R 1  of the aforementioned circular shape may be substantially twice the radius R 2  of the aforementioned cylindrical shape (i.e., R 1 =2·R 2 ), and the distance D 2  between the first conductive pad  461  and the second conductive pad  462  may be longer than or equal to 2 mil. 
       FIG.  5 A  is a top view of a capacitive element  510  according to an embodiment of the invention. In the embodiment of  FIG.  5 A , the capacitive element  510  includes a first conductor  520  and a second conductor  530 , which may be disposed on the first surface E 1  of the dielectric substrate  170 . The capacitive element  510  has a first terminal point  511  and a second terminal point  512 . The first terminal point  511  is positioned at an end of the first conductor  520 . The second terminal point  512  is positioned at an end of the second conductor  530 . The second conductor  530  is adjacent to the first conductor  520 , but the second conductor  530  is completely separate from the first conductor  520 . A coupling gap GC 1  is formed between the second conductor  530  and the first conductor  520 . For example, each of the first conductor  520  and the second conductor  530  may include a plurality of E-shaped portions coupled with each other. Generally, the first conductor  520  and the second conductor  530  are substantially interleaved with each other. With respect to element sizes, the width W 2  of the first conductor  520  may be from 2 mil to 10 mil, the width W 3  of the second conductor  530  may be from 2 mil to 10 mil, and the width of the coupling gap GC 1  may be from 2 mil to 10 mil. 
       FIG.  5 B  is a top view of a capacitive element  550  according to an embodiment of the invention. In the embodiment of  FIG.  5 B , the capacitive element  550  includes a first conductor  560  and a second conductor  570 , which may be disposed on the first surface E 1  of the dielectric substrate  170 . The capacitive element  550  has a first terminal point  551  and a second terminal point  552 . The first terminal point  551  is positioned at an end of the first conductor  560 . The second terminal point  552  is positioned at an end of the second conductor  570 . The second conductor  570  is adjacent to the first conductor  560 , but the second conductor  570  is completely separate from the first conductor  560 . A coupling gap GC 2  is formed between the second conductor  570  and the first conductor  560 . For example, each of the first conductor  560  and the second conductor  570  may include a plurality of U-shaped portions coupled with each other. Generally, the first conductor  560  and the second conductor  570  are substantially parallel to each other. With respect to element sizes, the width W 4  of the first conductor  560  may be from 2 mil to 10 mil, the width W 5  of the second conductor  570  may be from 2 mil to 10 mil, and the width of the coupling gap GC 2  may be from 2 mil to 10 mil. 
       FIG.  6 A  is a top view of a communication device  600  according to an embodiment of the invention. In the embodiment of  FIG.  6 A , a resonant circuit  660  of the communication device  600  includes the inductive element  410  and the capacitive element  510  coupled in series. Furthermore, the first ground element  110  may further have a hollow region  115  for accommodating the resonant circuit  660 .  FIG.  6 B  is a diagram of the S-parameter of the communication device  600  according to an embodiment of the invention. According to the measurement of  FIG.  6 B , by using the resonant circuit  660 , the isolation between the first signaling conductor  140  and the second signaling conductor  150  in a target frequency band FB 2  may be improved by about 9.4 dB. For example, the target frequency band FB 2  may be from 5150 MHz to 5850 MHz, but it is not limited thereto. Other features of the communication device  600  of  FIG.  6 A  and  FIG.  6 B  are similar to those of the communication device  200  of  FIG.  2 A  and  FIG.  2 B . Accordingly, the two embodiments can achieve similar levels of performance. 
       FIG.  7 A  is a top view of a communication device  700  according to an embodiment of the invention. In the embodiment of  FIG.  7 A , a resonant circuit  760  of the communication device  700  includes the inductive element  450  and the capacitive element  510  coupled in series.  FIG.  7 B  is a diagram of the S-parameter of the communication device  700  according to an embodiment of the invention. According to the measurement of  FIG.  7 B , by using the resonant circuit  760 , the isolation between the first signaling conductor  140  and the second signaling conductor  150  in a target frequency band FB 3  may be improved by about 10.2 dB. For example, the target frequency band FB 3  may be from 5150 MHz to 5850 MHz, but it is not limited thereto. Other features of the communication device  700  of  FIG.  7 A  and  FIG.  7 B  are similar to those of the communication device  200  of  FIG.  2 A  and  FIG.  2 B . Accordingly, the two embodiments can achieve similar levels of performance. 
       FIG.  8 A  is a top view of a communication device  800  according to an embodiment of the invention. In the embodiment of  FIG.  8 A , a resonant circuit  860  of the communication device  800  includes the inductive element  450  and the capacitive element  550  coupled in series.  FIG.  8 B  is a diagram of the S-parameter of the communication device  800  according to an embodiment of the invention. According to the measurement of  FIG.  8 B , by using the resonant circuit  860 , the isolation between the first signaling conductor  140  and the second signaling conductor  150  in a target frequency band FB 4  may be improved by about 10.4 dB. For example, the target frequency band FB 4  may be from 5150 MHz to 5850 MHz, but it is not limited thereto. Other features of the communication device  800  of  FIG.  8 A  and  FIG.  8 B  are similar to those of the communication device  200  of  FIG.  2 A  and  FIG.  2 B . Accordingly, the two embodiments can achieve similar levels of performance. 
     The invention proposes a novel communication device, which includes a resonant circuit integrated with a dielectric substrate. In comparison to the conventional design, the invention has at least the advantages of high isolation and low manufacturing cost. Therefore, the invention is suitable for application in a variety of mobile communication devices. 
     Note that the above element sizes, element shapes, and frequency ranges are not limitations of the invention. A designer can fine-tune these settings or values according to different requirements. It should be understood that the communication device of the invention is not limited to the configurations of  FIGS.  1 - 8   . The invention may merely include any one or more features of any one or more embodiments of  FIGS.  1 - 8   . In other words, not all of the features displayed in the figures should be implemented in the communication device of the invention. 
     Use of ordinal terms such as “first”, “second”, “third”, etc., in the claims to modify a claim element does not by itself connote any priority, precedence, or order of one claim element over another or the temporal order in which acts of a method are performed, but are used merely as labels to distinguish one claim element having a certain name from another element having the same name (but for use of the ordinal term) to distinguish the claim elements. 
     While the invention has been described by way of example and in terms of the preferred embodiments, it should be understood that the invention is not limited to the disclosed embodiments. On the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.