Abstract:
The present disclosure relates to a sensor network, Machine Type Communication (MTC), Machine-to-Machine (M2M) communication, and technology for Internet of Things (IoT). The present disclosure may be applied to intelligent services based on the above technologies, such as smart home, smart building, smart city, smart car, connected car, health care, digital education, smart retail, security and safety services. A method and apparatus for processing a signal in a mobile device are provided. The method includes classifying signals transmitted and received between devices according to at least two predetermined rates, and transmitting and receiving the classified signals in connection lines supporting the at least two rates, respectively.

Description:
RELATED APPLICATION(S) 
       [0001]    This application claims the benefit under 35 U.S.C. §119(a) of a Korean patent application filed in the Korean Intellectual Property Office on Dec. 31, 2014 and assigned Serial No. 10-2014-0194748, the entire disclosure of which is incorporated herein by reference. 
       BACKGROUND 
       [0002]    The present disclosure relates to a mobile device, and more particularly, to a method and apparatus for processing signals in a mobile device. 
         [0003]    The Internet, which is a human centered connectivity network where humans generate and consume information, is now evolving to the Internet of Things (IoT) where distributed entities, such as things, exchange and process information without human intervention. The Internet of Everything (IoE), which is a combination of the IoT technology and the Big Data processing technology through connection with a cloud server, has emerged. As technology elements, such as “sensing technology”, “wired/wireless communication and network infrastructure”, “service interface technology”, and “Security technology” have been demanded for IoT implementation, a sensor network, a Machine-to-Machine (M2M) communication, Machine Type Communication (MTC), and so forth have been recently researched. 
         [0004]    Such an IoT environment may provide intelligent Internet technology services that create a new value to human life by collecting and analyzing data generated among connected things. IoT may be applied to a variety of fields including smart home, smart building, smart city, smart car or connected cars, smart grid, health care, smart appliances and advanced medical services through convergence and combination between existing Information Technology (IT) and various industrial applications. 
         [0005]    Since many components are combined to support various functions and performances in mobile devices for IoT implementation, the demand for high-rate data transmission between chips or devices in a mobile device has been increasing. For example, the resolution of some display devices in mobile devices have increased from full high definition (FHD) to quad HD (QHD), and an image sensor can also support a resolution of 1.3 million pixels with 10 million pixels or more not being uncommon. In addition, mobile devices can now use accessories requiring signal transmission in a high frequency band to use a camera or a display. To transmit such a signal in a high frequency band between chips or devices, the mobile industry processor interface (MIPI) standard that defines interfaces between components of a mobile device is widely used. 
         [0006]      FIG. 1  illustrates exemplary interfaces defined for respective usages in a general mobile device conforming to the MIPI standard. 
         [0007]    For convenience of description, a simplified configuration of a mobile device  100  is shown in  FIG. 1 . Referring to  FIG. 1 , the mobile device  100  may include an application processor (AP)  102  for controlling overall signal processing, a modern  104 , and a radio frequency integrated circuit (RFIC)  106 , and may be connected to additional devices supporting various performances and functions. For example, the MIPI standard defines a display serial interface (DSI) as an interface for a display unit  108  and a camera serial interface (CSI) as an interface for a camera  110 . Links may also be established for a microphone  112  and a speaker  114  through the modem  104  and serial low-power inter-chip media bus (SLIMbus). Further, sensors  120  or a battery  122  may be mounted in the mobile device. Each device may transmit and receive signals to and from the AP  102  via an interface defined for the device. 
         [0008]    MIPI standard mainly uses serialization for an interface between internal devices in a mobile device. Hardware configurations are simplified by serialization, and differential pairing can be used to enable robust implementation for a high data rate interface. MIPI has defined D-PHY and M-PHY as physical layers for data communication within a mobile device, and they are implemented as differential serial interfaces. Because of limitations in transmitting a high-bandwidth signal with the physical layer (PHY) specification, high-bandwidth signals are handled by increasing the number of physical lanes. 
         [0009]    The trend for mobile devices is that additional devices or sensors, such as a heartbeat sensor or a humidity sensor, are used in addition to devices commonly included such as a global positioning system (GPS) sensor or an accelerometer. Control signals for these additional devices have a narrower bandwidth than video or image signals. However, each additional device has a separate lane for control signals to allow for better control of each additional device. Accordingly, the number of lanes for control signals may be awkward to manage as the number of internal devices increase. 
         [0010]    The number of physical lanes for interfaces between chips or devices in a mobile device has been increasing for the above-described reasons, and interference between physical lanes leads to many problems in terms of signal integrity, electro-magnetic interference (EMI), and chip layout for physical connections. 
         [0011]    The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure. 
       SUMMARY 
       [0012]    An aspect of the present disclosure is to address at least the above-mentioned problems and/or disadvantages and to provide at least the advantages described below. Accordingly, an aspect of the present disclosure is to describe a configuration and operation of a device for efficiently reducing the number of physical connection lines for signal processing in a mobile device. 
         [0013]    In accordance with an aspect of the present disclosure, there is provided a method for classifying a type of signal as a classified signal, where the classification is to one of at least two predetermined rates for communicating the classified signal between devices in the mobile device. The classified signal may be communicated via a connection line supporting one of the two or more rates. 
         [0014]    The two rates may include a first rate satisfying a predetermined condition and a second rate higher than the first rate, where the connection line supporting the first rate supports bidirectional communication. The classified signal may be communicated in the connection line supporting the first rate. 
         [0015]    A first device may transmit a switching signal, indicating change in communication direction in the connection line supporting the first rate, to a second device prior to the first device transmitting the classified signal on the connection line. The switching signal may be transmitted by use of a separate channel or by a signal having a predetermined pattern. 
         [0016]    The connection line may support differential signaling and/or common transmission mode signaling, and at least one device may receive DC power via the connection line to which common transmission mode signaling is applied. 
         [0017]    One of a plurality of clock signals may be selected as a communication clock for use in communicating the classified signal, and the communication clock may be the slowest of the plurality of the clock signals that can be used communicating the classified signal. Selecting the communication clock may happen periodically or upon a change in a communication state, where the change in the communication state comprises determining whether another of the predetermined rates not being presently used needs to be used. 
         [0018]    The classified signal may be a signal that used a legacy protocol. 
         [0019]    In accordance with another aspect of the present disclosure, there is provided a mobile device for processing a signal. The mobile device includes a controller configured to classify a type of signal as a classified signal. The type of signal may be classified to one of at least two predetermined mates for communicating the classified signal between devices in the mobile device. A transceiver may be configured to communicate the classified signal in a connection line supporting one of the two or more rates. 
         [0020]    The one or more rates may comprise two a first rate satisfying a predetermined condition and a second rate higher than the first rate, and where a connection line supporting the first rate supports bidirectional communication. 
         [0021]    The mobile device may include a converter configured to convert the classified signal, which comprises parallel signals, to a serial signal prior to transmitting on the connection line, and convert a serial signal received on the connection line to parallel signals. 
         [0022]    A first of the devices may transmit a switching signal indicating change in communication direction in the connection line supporting the first rate to a second of the devices prior to the first device transmitting data on the connection line, wherein the switching signal is transmitted by use of at least one of a separate channel and a signal having a predetermined pattern. 
         [0023]    The transmission line may support differential signaling and/or common transmission mode signaling, and at least one of the devices may receive DC power via the connection line. 
         [0024]    One of a plurality of clock signals may be selected as a communication on clock for use in communicating the classified signals, and the communication clock may be selected periodically and/or upon a change in a communication state, where the change in the communication state may include determining whether to use another of the two or more predetermined rates not being presently used. The communication clock, of the plurality of the clock signals, may be the slowest that can be used in communicating the classified signals. 
         [0025]    The classified signals may comprise a legacy protocol signal to one of the two or more rates. 
         [0026]    Other aspects, advantages, and salient features of the disclosure rill become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses exemplary embodiments of the disclosure. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0027]    The above and other aspects, features and advantages of certain exemplary embodiments of the present disclosure will be more apparent from the following description taken in conjunction with the accompanying drawings, in which: 
           [0028]      FIG. 1  illustrates exemplary interfaces defined for respective usages in a general mobile device conforming to the mobile industry processor interface (MIPI) standard; 
           [0029]      FIG. 2A  is a block diagram illustrating an exemplary configuration of a general mobile device; 
           [0030]      FIG. 2B  is a block diagram illustrating a configuration for the mobile device of  FIG. 2A  according to an embodiment of the present disclosure; 
           [0031]      FIG. 2C  is a block diagram illustrating an exemplary configuration of a multiplexer and a demuliplexer in a mobile device according to an embodiment of the present disclosure; 
           [0032]      FIG. 3A  is a detailed block diagram illustrating an exemplary configuration of a multiplexer in a mobile device according to an embodiment of the present disclosure; 
           [0033]      FIG. 3B  is a detailed block diagram illustrating an exemplary configuration of a demultiplexer in a mobile device according to an embodiment of the present disclosure; 
           [0034]      FIGS. 4A and 4B  illustrate exemplary configurations of signals transmitted respectively in a data path and a control path, along a time axis according to an embodiment of the present disclosure; 
           [0035]      FIG. 5  is a block diagram illustrating an exemplary configuration of a mobile device for minimizing latency during switching between transmission and reception in a control path according to an embodiment of the present disclosure; 
           [0036]      FIG. 6A  is a block diagram illustrating an exemplary configuration of a mobile device for processing an inter-integrated circuit (I2C) signal according to an embodiment of the present disclosure; 
           [0037]      FIG. 6B  is a timing diagram illustrating exemplary signal states in the SLIMbus interface; 
           [0038]      FIG. 7A  is a block diagram illustrating an exemplary configuration of a mobile device for processing a serial low-power inter-chip media bus (SLIMbus) signal according to an embodiment of the present disclosure; 
           [0039]      FIG. 7B  is a block diagram of a data generator included in a virtual slave or a virtual master according to an embodiment of the present disclosure; 
           [0040]      FIG. 7C  illustrates exemplary waveforms of signals processed in a data generator according to an embodiment of the present disclosure. 
           [0041]      FIG. 8A  illustrates exemplary signals to which differential signaling and common transmission mode signaling are applied, respectively according to an embodiment of the present disclosure; 
           [0042]      FIG. 8B  illustrates an exemplary configuration of a mobile device to which differential signaling and common transmission mode signaling are applied, respectively according to an embodiment of the present disclosure; 
           [0043]      FIG. 8C  illustrates an example in which common transmission mode signaling is applied to direct current (DC) power transmission according to an embodiment of the present disclosure; and 
           [0044]      FIG. 9  is a flowchart illustrating an operation for performing communication switching by transmitting a switching signal on a separate channel during time division duplex (TDD) bidirectional communication of a common mode component signal according to another embodiment of the present disclosure. 
           [0045]      FIG. 10  is a flowchart illustrating an exemplary operation for processing a signal in a mobile device according to an embodiment of the present disclosure. 
       
    
    
       [0046]    Throughout the drawings, like reference numerals will be understood to refer to like parts, components, and structures. 
       DETAILED DESCRIPTION 
       [0047]    Preferred embodiments of the present disclosure will be described below in detail with reference to the attached drawings. A detailed description of a known function or structure will not be provided herein lest it obscures the subject matter of the present disclosure. The terms used in the following description are defined in consideration of their functions in the present disclosure and may vary according to the intent of a user or an operator. Therefore, the present disclosure should be defined by the appended claims and their equivalents. 
         [0048]    Embodiments of the present disclosure provide a method and apparatus for minimizing the number of connection lines for signals transmitted and received within a mobile device in order to perform functions and services for the mobile device. Accordingly, various embodiments of the disclosure may classify signals in a mobile device to one of a plurality of transmission rates, and these signals may use different transmission (or connection) lines depending on their assigned transmission rates. Generally, the term “transmission” line may refer to a plurality of transmission lines. For example, when a differential signal is sent via a transmission line, it should be understood that there are 2 transmission lines. Various embodiments of the present disclosure may be applicable to a mobile device such as, for example, a smart phone, a tablet personal computer (PC), or the like. 
         [0049]      FIG. 2A  is a block diagram illustrating an exemplary configuration of a general mobile device. 
         [0050]    Referring to  FIG. 2A , there is shown an exemplary configuration of an interface between a liquid crystal display (LCD) panel  204  and an application processor (AP)  202 , which are examples of additional devices mountable in a mobile device  200 . The AP  202  executes an operating system (OS) and applications for the mobile device  200 , and controls interfaces with a plurality of additional devices. In other words, the AP  202  may be responsible for overall processing of signals transmitted and received within the mobile device  200 . The AP  202  may be installed as a system on chip (SOC) within the mobile device  200 . As illustrated in  FIG. 2A , for example, a cable  206  comprising a total of 40 wires may be installed for communication between the AP  202  and the LCD panel  204 . While the cable  206  is described as comprising “wires,” it should be understood that a “wire” refers to a conductor. Accordingly, a wire may be an actual wire or a trace on a printed circuit board, etc. Similarly, the term “cable” refers to one or more wires. 
         [0051]      FIG. 2B  is a block diagram illustrating a configuration for the mobile device of  FIG. 2A  according to an embodiment of the present disclosure. 
         [0052]    Referring to  FIG. 2B , the mobile device  200  includes a multiplexer  208  connected to at least some of the connection lines of the AP  202  and a demultiplexer  210  connected to connection lines of the LCD panel  204 . The connection lines are the input/output (I/O) lines to/from a device. The multiplexer  208  may allow the AP  202  to communicate to various internal devices, such as the LCD panel  204 , as well as external devices such as the external accessory  220  connected to the mobile device  200 . 
         [0053]    Each of the multiplexer  208  and the demultiplexer  210  classifies signals in the connection lines to a transmission rate based on a predetermined criterion and connects the signals to various devices using, for example, six wires in the cable  212 . These 6 wires are far fewer than the 40 wires that may be typically used in the interface illustrated in  FIG. 2A . However, it should be noted that the number of connection lines between the AP and another device is purely exemplary in  FIGS. 2A and 2B . Thus, embodiments of the present disclosure may support various numbers of connection lines. 
         [0054]      FIG. 2C  is a block diagram illustrating an exemplary configuration of a multiplexer and a demultiplexer in a mobile device according to an embodiment of the present disclosure. For convenience of description, it is assumed that the multiplexer  208  and the demultiplexer  210  of  FIG. 2C  correspond to the multiplexer  208  and the demultiplexer  210 , respectively, of  FIG. 2B . 
         [0055]    Referring to  FIG. 2C , a D-PHY intermediate frequency (IF) unit  222  is connected to clock signal I/O connection lines and data signal I/O connection lines among the connection lines of the AP  202  in the multiplexer  208 . A CTRL IF unit  224  is connected to control signal I/O lines among the connection lines of the AP  202  in the multiplexer  208 . Likewise, a D-PHY IF unit  232  is connected to clock signal I/O connection lines and data signal I/O connection lines among the connection lines of the LCD panel  204  in the demultiplexer  210 . A CTRL IF unit  234  is connected to control signal I/O lines among the connection lines of the LCD panel  204  in the demultiplexer  210 . 
         [0056]    According to an embodiment of the present disclosure, the multiplexer  208  and the demultiplexer  210  include serializers/deserializers (SerDes)  246  and  236 . Each SerDes  236  or  246  may convert input parallel signals to an output serial signal, and an input serial signal to output parallel signal. Each of the SerDes  246  included in the multiplexer  208  and the SerDes  236  included in the demultiplexer  210  is connected to cables having different transmission rates according to an embodiment of the present disclosure. Specifically, it is assumed in an embodiment of the present disclosure that the cables connected to the SerDes  236  and  246  include cable  248  supporting unidirectional data to the demultiplexer  210  at 7.5 Gbps, which is a relatively high transmission rate, and cable  249  supporting bidirectional control signals at 3.75 Gbps, which is a relatively low transmission rate. Gbps is giga-bits per second. 
         [0057]    In the illustrated case of  FIG. 2C , there are shown two cables, each with its own different transmission rate. However, the disclosure is not limited to these examples. Rather, various embodiments of the present disclosure can have different transmission rates than those listed and different number of cables. In an embodiment of the present disclosure, if video data is transmitted to the LCD panel, the multiplexer  208  may receive signals from the AP  202  via 10 connection lines, and the demultiplexer  210  may communicate to the LCD panel  204  via 10 connection lines. However, the communication between the SerDes  236  and the SerDes  246  may be via only 4 connection lines, with the cable  248  supporting 7.5 Gbps for video data and the cable  249  supporting 3.75 Gbps for control signals. 
         [0058]    An embodiment of the present disclosure provides a method for maintaining functions, while minimizing latency, by integrating interfaces for signals conforming to different protocols using a multiplexer/demultiplexer in a mobile device. For this purpose, the mobile device should be able to tunnel I/O signals of the multiplexer/demultiplexer without breaching a legacy protocol. To support the tunneling, L1 tunneling may be used in an embodiment of the present disclosure, where signals conforming to different protocols are multiplexed only at Layer 1, the physical (PRY) layer. Accordingly, various embodiments of the present disclosure may use L1 tunneling to optimize power consumption and area while minimizing breach of other protocols. 
         [0059]    In an embodiment of the present disclosure, signals transmitted and received between an AP and another device in a mobile device may be classified to data signals and control signals, and lanes may be dedicated for these two types of signals with each lane having a different transmission rate. The data signal may correspond to an image signal, a video signal, or the like, and the control signal may correspond to a signal that may be input/output through, for example, a general purpose input/output (GPIO) pins. The GPIO pins may be used to control various devices as appropriate for their functions. 
         [0060]      FIGS. 3A and 3B  are detailed block diagrams of a multiplexer and a demultiplexer, respectively, according to an embodiment of the present disclosure. Dotted lines indicate data paths for transmitting data signals that may be, for example, video signals. 
         [0061]    Referring to  FIG. 3A , the multiplexer  300  includes high speed (HS) buffers  302  for mapping data signals received from an AP to four D-PHYs supported by display serial interface (DSI), and a SerDes  310  for serial to parallel conversion and parallel to serial conversion of I/O signals. According to an embodiment of the present disclosure, the SerDes  310  includes serializer  1   312 , serializer  2   314 , and deserializer  316 . Serializer  1   312  serializes data signals received through the four D-PHYs to one serial signal that is transmitted differentially. In an embodiment of the present disclosure, the serializer  1   312  may be configured to support a minimum transmission rate of 7.5 Gbps for a video signal. The 7.5 Gbps transmission rate may then be able to support 1.875 Gbps transmission rate for video data in each of the four D-PHY for a 1080p resolution display. 
         [0062]    Solid lines indicate control paths for control signals in  FIGS. 3A and 3B . The multiplexer  300  includes low power (LP) buffers  304  for classifying bidirectional control signals and storing the classified control signals. Serializer  2   314  serializes GPIO signals to a serial signal, which is then transmitted as a differential serial signal. Serializer  2   314  is configured to support, for example, a transmission rate of 3.75 Gbps. The SerDes  310  includes the deserializer  316  that receives a serial control signal to output four sets of control signals where some sets of the control signals may comprise parallel signals. The SerDes  310  may also be configured to support a transmission rate of 3.75 Gbps. 
         [0063]    Referring to  FIG. 3B , the demultiplexer  320  includes receiving-side devices being the counterparts of transmitting-side devices of the multiplexer  300 . The demultiplexer  320  includes a deserializer  332  for separating a serial signal received as one differential pair from the serializer  1   312  of the multiplexer  300  into four data signals and outputting the data signals by mapping the data signals to their respective D-PHYs. The deserializer  332  is configured to support, for example, a transmission rate of 7.5 Gbps. The demultiplexer  320  includes LP buffers  324 , serializer  1   334 , and a serializer  2   336  respectively corresponding to the LP buffers  304 , serializer  2   314 , and the deserializer  316  in the multiplexer  300 . 
         [0064]    The transmission rates of the serializers or the deserializer, 7.5 Gbps and 3.75 Gbps, are purely exemplary. Thus, a SerDes according to an embodiment of the present disclosure may be configured to support various transmission rates. For example, if a transmission rate per lane corresponding to a D-PHY is N, a transmission rate required for the serializer  1   312  may be 4*N. 
         [0065]    While the multiplexer  300  and the demultiplexer  320  have been names as such for explanation purposes with respect to data being sent from the multiplexer  300  to the demultiplexer  320 , either of the devices may perform both multiplexing and demultiplexing functions. Transmission from the multiplexer  300  to the demultiplexer  320  may be referred to as transmitting downstream, and transmitting from the demultiplexer  320  to the multiplexer  300  may be referred to as transmitting upstream. 
         [0066]      FIGS. 4A and 4B  illustrate the configurations of signals transmitted in a data path and a control path, respectively, along the time axis according to an embodiment of the present disclosure. For convenience of description, it is assumed that the signals are transmitted in the data paths and the control paths in each of the multiplexer and the demultiplexer illustrated in  FIGS. 3A and 3B . 
         [0067]    Referring to  FIG. 4A , a data path may support a higher transmission rate, for example, 7.5 Gbps, than a control path, and may support unidirectional communication. The data signals H 0  to H 7 , which may be input in parallel through the various D-PHYs, may be converted to a serial data signal  400 . To distinguish the serial data signal  400  from subsequent serial data signals, a packet identification signal  402 , that is, P 1  and P 2 , are inserted in the serial data signal. 
         [0068]    Referring to  FIG. 4B , the control path may support a lower transmission rate (e.g 3.75 Gbps) relative to the data path (e.g. 7.5 Gbps), and may support bidirectional communication. The bidirectional communication may be time division duplexed to alternate transmission in equal time periods in the downstream direction and the upstream direction. 
         [0069]    Accordingly, control signals received in parallel, for example, the control signals G 0 -G 7   410 , Z 0 -G 7   414 , may be converted to a serial format and transmitted downstream by the multiplexer  300  as part of a serial control signal interval  420 . Similarly, the control signals received in parallel, for example, the control signals G 0 -G 7   410 , Z 0 -G 7   414 , may be converted to a serial format and transmitted upstream by the demultiplexer  320  as part of a subsequent serial control signal interval  420 . 
         [0070]    Packet identification signals  412  may be inserted after bits corresponding to the control signals G 0 -G 7   410 . Accordingly, there may be packet identification signals  412  after the control signals G 0 -G 7   410 , and packet identification signals  416  after the control signals Z 0 -G 7   414 . Various embodiments of the invention may use different guard intervals as appropriate. 
         [0071]    As described above, because control signals transmitted and received in a control path are bidirectional signals in a mobile device, a structure for minimizing latency during switching between transmission and reception in the control path is required. 
         [0072]      FIG. 5  is a block diagram illustrating an exemplary configuration of a mobile device for minimizing latency during switching between transmission and reception in a control path according to an embodiment of the present disclosure. 
         [0073]    Referring to  FIG. 5 , a mobile device according to an embodiment of the present disclosure is provided with a detector  509  at a front end of a lane supporting bidirectional communication (hereinafter, referred to as a “bidirectional lane”), for pre-sensing whether bidirectional communication has started in the bidirectional lane. The detector  509  may control the power state of the mobile device in four cases for the detection result. A master and a slave may correspond, for example, to the afore-described multiplexer  300  and demultiplexer  320 , respectively. The master  500  includes a D-PHY receiver  508  for receiving the high-speed clock signal, MIPI clock, that may be used by the SerDes  502 . The MIPI clock may be from an AP of a mobile device that includes the master  500 . The MIPI clock and a slow clock may be provided to the detector  509 , and the detector  509  may select one of the MIPI clock and the slow clock as a source clock to a phase-locked loop (PLL)  506  by the detector  509 . The output of the PLL  506  may be referred to as the main clock that may be input to the SerDes  502 . According to an embodiment of the present disclosure, the detector  509  may operate the mobile device in a total of four power states by controlling the main clock, the source clock, and controlling on/off states of the PLL  506 . The detector  509  may select one of the inputs MIPI clock and slow clock as the source clock for the PLL  506 . 
         [0000]    
       
         
               
               
               
               
             
               
               
               
               
               
             
           
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 PLL 
                 source clock 
                 main clock 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 standby 
                 off 
                 slow clock 
                 slow clock 
               
               
                   
                 sub-tunneling 
                 on 
                 slow clock 
                 PLL-out 
               
               
                   
                 normal 
                 on 
                 MIPI clock 
                 PLL-out 
               
               
                   
                 ULP 
                 off 
                 slow clock 
                 slow clock 
               
               
                   
                   
               
             
          
         
       
     
         [0074]    Referring to [Table 1], the power state of the mobile device according to an embodiment of the present disclosure may be one of a standby state, a sub-tunneling state, a normal state, and an ultra-low power (ULP) state according to a detection result of the detector  509 . The normal state refers to a state here the mobile device has maximum power consumption. In the normal state, the PLL  506  is turned on, and the MIPI clock is input as the source clock for the PLL  506  and the output of the PLL  506  may be the main clock to the SerDes  502 . The PLL  506  may generate an output that is five tunes faster than the source clock, where the factor five may depend on various design and implementation parameters. 
         [0075]    The sub-tunneling state refers to a state in which only the sub-SerDes  504   b  having a relatively low rate is operated. In the sub-tunneling state, the PLL  506  is turned on, a slow clock is input as the source clock to the PLL  506 , and the output from the PLL  506  is connected as the main clock to the SerDes  502 . In the ULP state and the standby state, the PLL  506  is turned off and a slow clock is input as the source clock. Accordingly, the output of the PLL  506  may be the source clock. Therefore, in the ULP and standby states minimum power is consumed by the SerDes  502 . Here, the ULP state of the mobile device represents off state of remaining operations except for a basic operation, and the standby state represents a low power state of the mobile device. 
         [0076]    According to an embodiment of the present disclosure, the detector  509  may adjust the power state of the mobile device periodically or according to a real-time detection result of a bidirectional lane. For example, if all lanes operate at the maximum rate, the mobile device is operating in a normal state. If only a CTRL IF unit  224  or  234  ( FIG. 2C ) operates without transmission of a high-rate video signal in the mobile device, the power consumption of the mobile device may be minimized by operating the mobile device in the ULP state. The power state control of the mobile device may be performed dynamically according to use or non-use of each IF unit and each lane. 
         [0077]    Another embodiment of the present disclosure may be used for devices that use inter-integrated circuit (I2C) protocol in a structure for minimizing the number of connection lines in a mobile device, and a configuration of the mobile device using the same. 
         [0078]    The I2C protocol is used mainly for a system setting supporting a low transmission rate such as, for example, a data rate of about 100 Kbps, 400 Kbps, 1 Mbps, or 3.4 Mbps, where Kbps is kilo-bits per second and Mbps is mega-bits per second. I2C devices may be concatenated serially and two wires may be shared for data transmission and reception between a device operating as a master and a device operating as a slave. Since the I2C protocol supports a bidirectional bus, an I2C signal may be distorted due to a response delay from a slave or a change in electrical characteristics during communication between a plurality of masters and a plurality of slaves. Further, if a transceiver or bridge functioning as a relay is inserted in an I2C signal path, a response delay from a slave is further prolonged in view of a round trip latency caused by the relay. In  FIG. 6A , a virtual master and virtual slave for minimizing delay illustrated. 
         [0079]    As illustrated in  FIG. 6A , therefore, a virtual master  600   b  and a virtual slave  610   b  are inserted symmetrically to parts  600   a  and  610   a  for analog processing of IC2 signals from a master and a slave in an embodiment of the present disclosure. The virtual master  600   b  and the virtual slave  610   b  may have an open drain structure or an open collector structure. A signal input to a master is provided to a SerDes  602   a  through the virtual master  600   b  and serialized together with signals of other protocols. Similarly, a signal input to a slave is provided to a SerDes  604   b  through the virtual slave  610   b  and serialized together with signals of other protocols. As an input signal of each of the master and the slave is serialized together with signals of other protocols as described above, latency may be minimized compared to a case in which all signals are identified and then output. 
         [0080]    Another embodiment of the present disclosure provides a method for processing a SLIMbus signal in a structure for minimizing the number of connection lines in a mobile device, and a configuration of the mobile device for performing the method. 
         [0081]    A SLIMbus interface was proposed to overcome shortcomings of legacy inter-chip interfaces, serial peripheral interface (SPI), synchronous serial interface (SSI), I2C, and integrated inter-chip sound (I2S). The legacy inter-chip interfaces have more wires for more slaves and support peer-to-peer (P2P) communication. In contrast, the SLiMbus interface may support multiple slaves and multiple masters using two wires. This SLIMbus interface has a total of four layers—Device layer, Protocol layer, Frame layer, and Physical layer. 
         [0082]    In an embodiment of the present disclosure, the SLIMbus interface enables SLIMbus tunneling, maintaining the functionality of the physical layer. The physical layer of the SLIMbus interface is divided into a physical medium independent (PMI) part and a physical medium dependent (PMD) part. The SLIMbus interface includes two wires for transmitting and receiving a CLK signal and a DATA signal, respectively, and conforms to an asynchronous, multi-drop bus standard. Each wire may operate in a single-ended mode supporting unidirectional communication, a ground referenced mode, and a voltage mode. Herein, ground referenced means that a signal changes based on a voltage ground, that is, ‘0V’, and the voltage mode means that a signal is transmitted by a voltage difference. A DATA signal is output or driven at a rising edge corresponding to the wire of a CLK signal and captured at a falling edge, as illustrated in  FIG. 6B . 
         [0083]      FIG. 6B  illustrates exemplary signal states in the SLIMbus interface. 
         [0084]    Referring to  FIG. 6B , the first waveform is the waveform of the CLK signal and the last waveform is the waveform of the DATA signal. The second waveform is the waveform of a signal ‘0b100’ transmitted through driver  1 , and the third waveform is the waveform of a signal ‘0b101’ transmitted through driver  2 . 
         [0085]    The DATA signal may be placed in one of three states, high, low, and hold, in the SLIMbus interface. The CLK signal may be generated in a device operating as a framer and the other devices are used for input of the DATA signal. The CLK signal is unencoded and the DATA signal is non-return-to-zero-inverted (NRZI)-encoded. If a previous data signal is different (hereinafter, referred to as “transitioned”) from a current data signal, a High state is placed in NRZI, and if the previous data signal is identical to the current data signal, a Low state is placed in NRZI. The DATA signal uses logic-OR signaling. Herein, each component drives the DATA signal to the High and Low states during a High interval of the CLK signal. If the DATA signal is in the Low state, the DATA signal is held even though the CLK signal is in a High period according to NRZI. During a Low period of the CLK signal, the previous state of the DATA signal is held. 
         [0086]    According to this characteristic, a logical-OR operation is performed when multiple components are multi-driven. The afore-described NRZI and logic-OR signaling prevent multi-driving. NRZI is characterized by inversion of a previous value when a DATA signal is in the High state. In view of this NRZI characteristic, when different components drive the DATA signal to the High state, the DATA signal is driven to the same state (High or Low) and thus collision does not occur. In addition, when the DATA signal is driven to the Low state, the driving is not needed due to logic-OR signaling, thus preventing collision between components. Now, an embodiment of the present disclosure provides a tunneling method for enabling signal transmission, while maintaining the functionality of a physical layer in SLIMbus. 
         [0087]      FIG. 7A  is a block diagram illustrating an exemplary configuration of a mobile device for processing a SLIMbus signal according to an embodiment of the present disclosure. 
         [0088]    Referring to  FIG. 7A , for SLIMbus tunneling, a multiplexer  702  and a demultiplexer  710  are configured to include a virtual slave  704  and a virtual master  714 , respectively, in a mobile device according to an embodiment of the present disclosure. The multiplexer  702  and the demultiplexer  710  include SerDes  706  and  712 , respectively, for conversion of data input/output from/to the virtual slave  704  and the virtual master  714 . In an embodiment, each of the SerDes  706  and  712  may convert  32  parallel signals to a single serial signal and may convert a single serial signal to 32 parallel signals. However, various embodiments of the present disclosure may have different number of parallel data conversion by a SerDes in order to process a SLIMbus signal or other types of signals in a mobile device. 
         [0089]    With respect to  FIG. 7A , signals to a SerDes, whether to SerDes  706  or to SerDes  712 , will be said to go upstream. Similarly, signals from a SerDes, whether from SerDes  706  or from SerDes  712 , will be said to go downstream. 
         [0090]    The virtual slave  704  corresponds to a virtual device component for the SLIMbus interface. The virtual slave  704  may receive a CLK signal and a DATA signal from an AP  700  through two wires, and a wire for a bidirectional DATA signal from/to the AP  700 . The virtual master  714  corresponds to a virtual framer/manager for the SLIMbus interface. The virtual master  714  also has a wire for outputting a CLK signal to the slave device  718  and a wire for a bidirectional DATA signal from/to the slave device  718 . 
         [0091]    According to an embodiment of the present disclosure, the virtual slave  704  includes a complementary metal-oxide semiconductor (CMOS) input/output (IO) device  720 , up-streamers  722   a  and  722   b , and a data generator  722   c , for SLIMbus tunneling. The CMOS IO device  720  includes an input unit for the CLK signal and an input/output unit for the DATA signal for interfacing with the AP  700 . The CMOS IO device  720  outputs the CLK signal to the up-streamer  1   722   a , outputs data signal to up-streamer  2   722   h , and receives data signal from the data generator  722   c . The CMOS IO device  720  controls pull-up/pull-down resistors to clarify the Low and High states of an input signal. The up-streamer  1   722   a  sends a clock signal to the SerDes  706 . The up-streamer  2   722   b  samples the DATA signal at a high frequency using the CLK signal and provides the sampled DATA signal to the SerDes  706 . The data generator  722   c  received data from the SerDes  706 . 
         [0092]    Upon receipt of an input signal from the SerDes  706 , the data generator  722   c  monitors transition of the input DATA signal according to the characteristics of the physical layer in the SLIMbus interface. Upon detection of transition, the data generator  722   c  outputs an appropriate value in a High period of the CLK signal. This is explained in more detail with respect to  FIGS. 7B and 7C . 
         [0093]    Similarly, the virtual master  714  includes a CMOS IO device  730 , a down-streamer  732   a , a data generator  732   b , and an up-streamer  732   c , in correspondence with the virtual slave  704 . Since the virtual master  714  acts as a framer, the CMOS IO device  730  adjusts a slew rate generated for a signal output from the SerDes  712 . The down-streamer  732   a  acquires a clock signal from the SerDes  712  and outputs the clock signal to the CMOS IO device  730 . The data generator  732   b  acquires a data signal from the SerDes  712 . Upon detection of transition of the data signal, the data generator  732   b  outputs the data signal during a High period of the clock signal to the CMOS IO device  730 . The data generator  732   b  uses the clock signal received from the SerDes  712  as a SLIMbus CLK signal. The up-streamer  732   c  samples the data signal received from the CMOS IO device  730  at a high frequency and provides the sampled data signal to the SerDes  712 . 
         [0094]    The CMOS IO device  730  receives the clock signal from the down-streamer  732   a  and outputs it to the slave device  718  via the CLK wire. The CMOS IO device  730  also receives the data signal from the data generator  732   b  and outputs it to the slave device  718  via the bidirectional DATA wire. The CMOS IO device  730  receives data from the slave device  718  via the bidirectional DATA wire and outputs it to the up-streamer  732   c.    
         [0095]      FIG. 7B  is a block diagram illustrating an exemplary data generator included in a virtual slave or a virtual master according to an embodiment of the present disclosure. For the convenience of description, it is assumed that the data generator is the data generator  722   c  or  732   b  illustrated in  FIG. 7A . 
         [0096]    Referring to  FIG. 7B , the data generator according to an embodiment of the present disclosure monitors transition of an input data signal. Upon detection of transition of the data signal, the data generator drives the data signal in a High period of a CLK signal. 
         [0097]    Specifically, the data generator  722   c  or  732   b  largely includes a data configurer  740   a  and a transition detector  740   b . The transition detector  740   b  generates an output enable signal, and the data configurer  740   a  outputs an inverted signal of a previous SLIMbus DATA signal. 
         [0098]      FIG. 7C  illustrates exemplary waveforms of signals processed in a data generator according to an embodiment of the present disclosure. 
         [0099]    Referring to  FIG. 7C , the transition detector  740  detects transition of a data signal received from a SerDes. Then, the data configurer  740   a  maintains the SLiMbus data signal in a High state during a High period of a SLIMbus CLK signal at time t 1 . If the transition detector  740  has not detected transition of the data signal received from the SerDes, the data configurer  740   a  floats the SLIMbus DATA signal where the pull-up/pull-down resistors may bias it to a HIGH level at time t 2 . Described below are other embodiments of the present disclosure for minimizing the number of signal transmission lines used in a mobile device by using differential signaling and common transmission mode signaling. 
         [0100]    Differential signaling may be used for high-rate signal transmission at or above, for example, hundreds of Mbps in a mobile device according to an embodiment of the present disclosure. Although differential signaling is performed using two lines, interference may be minimized during signal transmission due to use of for example, current sensors with low signal amplitude. 
         [0101]      FIG. 8A  illustrates exemplary signals to which differential signaling and common transmission mode signaling are applied, respectively, according to an embodiment of the present disclosure. 
         [0102]    Referring to  FIG. 8A , for differential signaling, the difference between the amplitudes of two signals having a phase difference of 180 degrees may be calculated and a differential signal having an amplitude twice as large as the amplitudes of each of the signals may be generated. Specifically, a differential signal  800   c  having an amplitude of 2 may be output by subtracting the amplitude of a dotted-line signal  800   b  having an amplitude of −1 and a phase difference of 180 degrees with respect to a solid-line signal  800   a  having an amplitude of 1 from the amplitude of the solid-line signal  800   a . For a general differential signal, common mode components  802   a  and  802   b  corresponding to the reference of a waveform are fixed to a direct current (DC) level. On the other hand, a common mode component signal of the differential signal may be able to be used for transmission of a bidirectional signal and, an average signal of common mode components  804   a  and  804   b  is represented as  804   c.    
         [0103]      FIG. 8B  is a block diagram illustrating an exemplary configuration of a mobile device to which differential signaling and common transmission mode signaling are applied. If legacy differential signaling is used, the configuration of  FIG. 8B  may increase a data rate without increasing the number of transmission lines required for the mobile device. 
         [0104]    Because a common mode component signal supports unidirectional communication, if some data is loaded in the common mode component signal, the common mode component signal has a lower transmission rate than a differential signal. Therefore, a transceiver may be configured to transmit a control signal by a common mode component signal and a data signal by a differential signal as illustrated in  FIG. 8B  according to an embodiment of the present disclosure. The transceiver may substitute for a multiplexer and a demultiplexer in a mobile device according to an embodiment of the present disclosure. 
         [0105]    Since the differential signal and the common mode component signal are electrically separate, they may be used in different directions. That is, if a data signal transmitted in the form of a differential signal is set to a transmission direction, the transmission direction of a control signal transmitted in a common mode component signal may be set to a reverse direction of the data signal. Accordingly, a transmission line for a differential signal may be configured to support unidirectional communication and, at the same time, a transmission line for a common mode component signal may be configured to support bidirectional communication in an embodiment of the present disclosure, as illustrated in  FIG. 8B . 
         [0106]    In this case, while not shown, an input signal decider may be further included in order to determine the rate of an input signal and to assign the input signal for a differential signal or for a common mode component signal according to the determined rate. Specifically, if the input signal is a data signal, the input signal decider may assign the data signal to the transmission line for a different signal because the data signal is a high-rate signal. If the input signal is a control signal, the input signal decider may assign the control signal to the transmission line for a common mode component signal because the control signal is a low-rate signal. The same differential transmission lines are being used for the differential signals and common mode signals. 
         [0107]    In general, a mobile device uses a separate power line to transmit DC power. As more devices are mounted in the mobile device, the resulting addition of power lines also increases overhead. 
         [0108]    In another embodiment of the present disclosure, common transmission mode signaling is applicable to DC power transmission.  FIG. 8C  illustrates an example in which common transmission mode signaling is applied to DC power transmission according to an embodiment of the present disclosure. 
         [0109]    Referring to  FIG. 8C , bias-T blocks  820   a  and  820   b  are added for transmission of a common mode component signal. Therefore, DC power as well as a high-rate data signal may be transmitted in a differential signal transmission line  822 . The bias-T blocks  820   a  and  820   b  are circuits that pass only DC components without passing Alternating Current (AC). DC power and a control signal in the form of an AC signal may be separated from each other in the frequency domain based on the property of the circuits. Meanwhile, a method for using a common mode component signal for TDD bidirectional communication is considered in another embodiment of the present disclosure. In TDD bidirectional communication, turn-around handshaking is needed to avoid simultaneous channel driving between a transmitting end and a receiving end. With the turn-around handshaking, it is possible to perform communication switching by transmitting switching signal indicating switching from transmission to reception or from reception to transmission on a separate channel, or using a specific protocol. Another embodiment of the present disclosure provides two methods for TDD bidirectional communication using a common mode component signal. 
         [0110]      FIG. 9  is a flowchart illustrating an exemplary case in which communication switching is performed by transmitting a switching signal on a separate channel in TDD bidirectional communication using a common mode component signal according to another embodiment of the present disclosure. 
         [0111]    Referring to  FIG. 9 , for convenience of description, devices located at both ends of a transmission line for a differential signal and a transmission line for a common mode component signal are referred to as a first device  900  and a second device  902 . Communication is not being conducted yet between the first device  900  and the second device  902 . If the first device  900  determines to perform forward communication for a common mode component signal, the first device  900  sets a transmission mode for the common mode component signal. Then, the first device  900  transmits a switching signal indicating the transmission mode for the common mode component signal to the second device  902  in operation  904 . The switching signal may be transmitted on a channel established for transmission of a separate switching signal between the first device  900  and the second device  902 . It is assumed herein that information indicating whether the switching signal indicates the transmission mode or reception mode for the common mode component signal is preset between the first device  900  and the second device  902 . 
         [0112]    Upon receipt of the switching signal, the second device  902  is set to the reception mode for the common mode component signal. In operation  906 , the first device  900  transmits a differential signal to the second device  902  in the differential signal transmission line. It is assumed that the first device  900  determines to perform reverse communication for the common mode component signal by starting turn-around handshaking in operation  908 . Then, the first device  900  transmits a switching signal indicating the reception mode for the common mode component signal to the second device  902 . Thus, the first device  900  ends transmission of the common mode component signal and sets the reception mode for the common mode component signal in operation  910   a.    
         [0113]    Similarly, the second device  902  may set the transmission mode for the common mode component signal and then waits for data transmission in operation  910   b . Meanwhile, switching may be performed between transmission and reception of a common mode component signal using a specific protocol in the second method according to an embodiment of the present disclosure. For example, 8b/10b encoding widely used for a video signal may have specific bit patterns that are unused. Such a specific bit pattern may be used as a switching signal between transmission and reception of a common mode component signal. In this case, switching between transmission and reception of the common mode component signal may be indicated by transmitting the specific bit pattern instead of a switching signal in operations  904  to  908  of  FIG. 9 . It is assumed that the specific bit pattern is preset between the first device  900  and the second device  902 . 
         [0114]      FIG. 10  is a flowchart illustrating an exemplary operation for processing a signal in a mobile device according to an embodiment of the present disclosure. 
         [0115]    Referring to  FIG. 10 , the mobile device classifies signals generated from an AP and additional devices according to at least two predetermined rates in operation  1000 . The additional devices may include an LCD panel, a camera, a speaker, and the like that provide functions and services executable in the mobile device, as described before. Two rates may be the transmission rates of data signals and control signals, that is, 7.5 Gbps and 3.75 Gbps, respectively, by way of example. However, signals may be classified according to more rates in various embodiments of the present disclosure. 
         [0116]    In operation  1005 , the mobile device transmits and receives the classified signals in transmission lines supporting the at least two rates, respectively. In the case of an I2C signal and a SLIMbus signal, the operation for transmitting classified signals is performed based on the configuration of a mobile device supporting I2C and SLIMbus according to each embodiment of the present disclosure. According to an embodiment of the present disclosure, differential signaling and common transmission mode component signaling may be applied to the at least two rates. For a transmission line for transmitting and receiving a control signal among the transmission lines, a switching signal indicating switching between transmission and reception may be transmitted to a device at an end of the transmission line on a separate channel or in predetermined pattern. In the mobile device, it is also possible to supply DC power to a device that is connected via a transmission line that has common mode component signaling. Details of these embodiments have been described before and thus will not be described to avoid redundancy. 
         [0117]    A signal can be processed efficiently without the need for adding connection lines in a mobile device configured according to various embodiments of the present disclosure. 
         [0118]    As is apparent from the foregoing description, a mobile device according to an embodiment of the present disclosure classifies signals transmitted and received between a main processor and additional devices that support additional functions using at least two predetermined rates, and transmits and receives the classified signals in transmission lines supporting those rates. Therefore, the number of connection lines and power consumption can be reduced during signal processing, and signals supporting other protocols and interfaces can be transmitted and received without the need for using additional connection lines in the mobile device. 
         [0119]    While the disclosure has been shown and described with reference to certain exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the disclosure as defined by the appended claims and their equivalents.