Abstract:
Provided is a transceiver. The transceiver includes: a transmission unit modulating at least one of a plurality of baseband transmit signals to an RF band and amplifying the modulated at least one; a duplexer transmitting transmit signals outputted from the transmission unit to an antenna by selecting a signal in a downlink frequency band or an uplink frequency band or filtering a receive signal received from the antenna by the downlink frequency band or the uplink frequency band; a reception unit demodulating the receive signals in the downlink frequency band or the uplink frequency band from the duplexer into at least one baseband signal; a first switch delivering a transmit signal provided from the transmission unit to a first RF band filter of the duplexer in a first communication mode and a second communication mode; and a second switch delivering a first receive signal delivered from a second RF band filter of the duplexer to the reception unit in the first communication mode and a third communication mode, wherein each of the transmission unit and the reception unit includes one power amplifier and one low noise amplifier.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This U.S. non-provisional patent application claims priority under 35 U.S.C. §119 of Korean Patent Application No. 10-2014-0016225, filed on Feb. 12, 2014, the entire contents of which are hereby incorporated by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    The present invention disclosed herein relates to a wireless transceiver supporting a frequency division multiplexing mode and a time division multiplexing mode. 
         [0003]    A Long-Term Evolution (LTE) system combines Orthogonal Frequency Divisional Multiplexing (OFDM) and Multi-Input Multi-Output (MIMO) techniques in order to implement wireless communication for high speed and large amount of data transmission. An early LTE system is commercialized based on frequency divisional duplex (FDD). Such a system is referred to as an LTE-FDD system. The LTE-FDD system allocates different frequency bands to a downlink (DL) and an uplink (UL), respectively, so that data of a base station and a terminal is transmitted/received. The DL is a channel where data is transmitted from a base station to a terminal and the UL is a channel where data is transmitted from a terminal to a base station. However, in relation to FDD, when the amount of data transmitted to one of the UL and the DL is relatively less, this directly relates to frequency resource waste. 
         [0004]    In order to compensate this, an LTE-TDD system combined with TDD is introduced. The LTD-TDD system divides a time in one frequency band and perform data transmission between a base station and a terminal. The LTE-TDD system may manage data transmission efficiently by dividing the UL and the DL into a plurality of time slots and varying a distribution ratio of the time slots. 
         [0005]    As a result, in the LTE-FDD system, the DL and the UL may be allocated with different frequency bands and thus continuous data transmission may be possible between a base station and a terminal. However, in the LTE-FDD system, both DL and UL frequency bands are used at a specific time slot and UL transmission and DL transmission operations are performed through LTE-FDD. The number of time slots allocated at this point may vary depending on the amount of data and efficient frequency usage may be possible. 
         [0006]    Accordingly, provides are increasingly adopting the LTE TDD system. However, in the case of a terminal equipped with a transceiver for typical LTE-FDD system, it is difficult for the terminal to be compatible with the LTE-TDD system. Accordingly, reasonably priced transceivers for easy mode switching between LTE-TDD and LTE-FDD are on demands. 
       SUMMARY OF THE INVENTION 
       [0007]    The present invention provides a transceiver supporting both LTE-FDD and LTE-TDD. 
         [0008]    Embodiments of the present invention provide transceivers including: a transmission unit modulating at least one of a plurality of baseband transmit signals to an RF band and amplifying the modulated at least one; a duplexer transmitting transmit signals outputted from the transmission unit to an antenna by selecting a signal in a downlink frequency band or an uplink frequency band or filtering a receive signal received from the antenna by the downlink frequency band or the uplink frequency band; a reception unit demodulating the receive signals in the downlink frequency band or the uplink frequency band from the duplexer into at least one baseband signal; a first switch delivering a transmit signal provided from the transmission unit to a first RF band filter of the duplexer in a first communication mode and a second communication mode; and a second switch delivering a first receive signal delivered from a second RF band filter of the duplexer to the reception unit in the first communication mode and a third communication mode, wherein each of the transmission unit and the reception unit includes one power amplifier and one low noise amplifier. 
         [0009]    In some embodiments, in the second communication mode, the second switch may deliver a transmit signal from the transmission unit to the second RF band filter of the duplexer. 
         [0010]    In other embodiments, in the third communication mode, the first switch may deliver a second receive signal provided from the first RF band filter of the duplexer to the reception unit. 
         [0011]    In still other embodiments, the transmission unit may include a transmission switch terminal selecting at least one of a plurality of RF band transmit signals according to a communication mode and providing the selected at least one to the power amplifier. 
         [0012]    In even other embodiments, the transmission switch terminal may include: a mixing switch mixing the plurality of RF band transmit signals according to the communication mode; and a selection switch selecting one of the plurality of RF band transmit signals or the mixed transmit signal according to the communication mode. 
         [0013]    In yet other embodiments, each of the plurality of RF band transmit signals may include signals modulated to the uplink or downlink frequency band. 
         [0014]    In further embodiments, the reception unit may include: the low noise amplifier amplifying RF band receive signals provided from the first switch or the second switch; a reception switch terminal selecting at least one of the RF band receive signals according to a communication mode; and a plurality of baseband filters demodulating the receive signals into a baseband. 
         [0015]    In still further embodiments, the reception switch terminal may include: a selection switch delivering the RF band receive signals to one of the plurality of baseband filters or delivering the RF receive signals to the plurality of baseband filters simultaneously, according to the communication mode; and a distribution switch distributing receive signals in an RF band provided from the selection switch into the plurality of baseband filters simultaneously according to the communication mode. 
         [0016]    In even further embodiments, the reception unit may include mixers demodulating the RF band receive signals into a baseband. 
         [0017]    In yet further embodiments, the first communication mode may correspond to a frequency division duplex (FDD) mode; the second communication mode may correspond to a time division duplex (TDD) transmission mode; and the third communication mode may correspond to a TDD reception mode. 
         [0018]    In other embodiments of the present invention, transceivers include: a transmission switch terminal selecting one or all of a first transmit signal of a downlink frequency and a second transmit signal of an uplink frequency; a power amplifier amplifying a transmit signal delivered from the transmission switch terminal; a duplexer separating the amplified transmit signal into a downlink or uplink frequency band and transmitting the separated signal to an antenna or filtering a receive signal received from the antenna by the downlink or uplink frequency band; a low noise amplifier amplifying receive signals in the downlink or uplink frequency band from the duplexer; a reception switch terminal distributing a receive signal outputted from the low noise amplifier into first and second demodulation units demodulating signals into the downlink or uplink frequency band; a first switch delivering a transmit signal of the power amplifier to a first RF band filter of the duplexer in a frequency division mode and a time division transmission mode; and a second switch delivering a first receive signal delivered from a second RF band filter of the duplexer to the low noise amplifier in the frequency division mode and a time division reception mode. 
         [0019]    In some embodiments, the second switch may deliver a transmit signal from the power amplifier to a second RF band filter of the duplexer in the time division transmission mode. 
         [0020]    In other embodiments, the first switch may deliver a second receive signal provided from the first RF band filter of the duplexer to the low noise amplifier in the time division reception mode. 
         [0021]    In still other embodiments, the transmission switch terminal may include: a selection switch delivering the first transmit signal to the power amplifier in the frequency division mode; and a mixing switch mixing the first transmit signal and the second transmit signal and delivering the mixed signal to the selection switch in the time division transmission mode, wherein the selection switch may deliver a signal delivered from the mixing switch to the power amplifier in the time division transmission mode. 
         [0022]    In even other embodiments, the reception switch terminal may include: a selection switch delivering an output of a low noise amplifier to the first demodulation unit demodulating signals into the uplink frequency band in the frequency division mode; and a distribution switch distributing the output of the low noise amplifier into the first demodulation unit and the second demodulation unit demodulating signals by the uplink and downlink frequency bands, respectively in the time division reception mode. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0023]    The accompanying drawings are included to provide a further understanding of the present invention, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the present invention and, together with the description, serve to explain principles of the present invention. In the drawings: 
           [0024]      FIGS. 1A and 1B  are block diagrams illustrating FDD and TDD transceivers, respectively; 
           [0025]      FIG. 2  is a block diagram illustrating a transceiver according to an embodiment of the present invention; 
           [0026]      FIG. 3  is a table illustrating states of switches for each mode in the transceiver of  FIG. 2 ; 
           [0027]      FIG. 4  is a block diagram illustrating a data path of the transceiver  100  according to an embodiment of the present invention; 
           [0028]      FIG. 5  is a block diagram illustrating a data path of the transceiver  100  in a TDD transmission mode according to an embodiment of the present invention; and 
           [0029]      FIG. 6  is a block diagram illustrating a data path of the transceiver in a TDD reception mode according to an embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0030]    Preferred embodiments of the present invention will be described below in more detail with reference to the accompanying drawings. The present invention may, however, be embodied in different forms and should not be constructed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present invention to those skilled in the art. 
         [0031]    Terms used herein are merely provided for illustration of specific embodiments, and not limited to the present invention. A singular form, otherwise indicated, include a plural form. Herein, the term “comprise” or “have” intends to mean that there may be specified features, numerals, steps, operations, elements, parts, or combinations thereof, not excluding the possibility of the presence or addition of the specified features, numerals, steps, operations, elements, parts, or combinations thereof. 
         [0032]    Otherwise indicated herein, all the terms used herein, which include technical or scientific terms, may have the same meaning that is generally understood by a person skilled in the art. In general, the terms defined in the dictionary should be considered to have the same meaning as the contextual meaning of the related art, and, unless clearly defined herein, should not be understood abnormally or excessively formal meaning. 
         [0033]    The term ‘terminal device’ or ‘terminal’ used in this specification may be referred to as a user equipment (UE), a mobile station (MS), a user terminal (UT), a wireless terminal, an access terminal (AT), a terminal, a subscriber unit, a subscriber station (SS), a wireless device, a wireless communication device, a wireless transmit/receive unit (WTRU), a mobile node, a mobile, or another term. Various embodiments of a terminal may include a cellular phone, a smartphone with wireless communication function, a personal digital assistant with wireless communication function, a wireless modem, a portable computer with wireless communication function, a capturing device such as a digital camera with wireless communication function, a gaming device with wireless communication function, a music storing and playing home appliance with wireless communication function, an internet home appliance capable of wireless internet access and browsing, and portable units or terminal integrating combinations of such functions, but the present invention is not limited thereto. 
         [0034]    The term ‘cell’ or ‘base station’ used in this specification may generally refer to a fixed or mobile point communicating a terminal and may be a collective term for a base station, a Node-B, an eNode-B, a base transceiver system (BTS), an access point, a transmit point, a receive point, a remote radio head (RRH), remote radio unit (RRU), a relay, and a Femto-Cell. Furthermore, a transceiver described in the present invention may be a device applied to both a terminal and a base station. For convenience of description, advantages of the present invention are described by using a transceiver in a base station as an example. 
         [0035]    The meaning of “include,” “comprise,” “including,” or “comprising,” specifies a property, a region, a fixed number, a step, a process, an element and/or a component but does not exclude other properties, regions, fixed numbers, steps, processes, elements and/or components. An embodiment described and exemplified herein includes a complementary embodiment thereof. 
         [0036]    Hereinafter, it will be described about an exemplary embodiment of the present invention in conjunction with the accompanying drawings. 
         [0037]      FIGS. 1A and 1B  are block diagrams illustrating FDD and TDD transceivers, respectively. Referring to  FIG. 1A , the FDD transceiver  10  includes mixers  11  and  16 , a power amplifier  12 , and a duplex  13 , an antenna  14 , and a low noise amplifier  15 . Here, the FDD transceiver  10  is a transmission block of a base station and an uplink frequency and a downlink frequency are expressed conversely in a terminal. 
         [0038]    During a downlink transmission operation, the mixer  11  modulates a baseband transmit signal FDD_TX provided from a baseband modem and a DAC (not shown) into a signal of a carrier frequency F DL  band in a downlink channel. Then, the power amplifier  12  amplifies the poser of the signal provided from the mixer  11 . The power amplifier  12  amplifies the signal modulated by the mixer  11  into a wireless emission available level. The duplex  13  separates the amplified signal into a downlink channel and an uplink channel. That is, only a signal of a carrier frequency f DL  band in the downlink channel may be transmitted by an RF band filter  13   a  in the duplex  13 . 
         [0039]    During an uplink reception operation, by an RF band filter  13   b  in the duplex  13 , a carrier frequency f UL  band signal in the downlink channel is selected from a wireless signal received from the antenna  14 . Then, the selected signal is amplified by the low noise amplifier  15  and then is converted into a baseband receive signal FDD_RX by the mixer  16 . Then, the baseband receive signal FDD_RX is delivered to an ADC and a baseband modem (not shown) and processed. 
         [0040]    In the FDD transceiver, a transmit signal and a receive signal are separated based on a difference between a carrier frequency f UL  in an uplink channel and a carrier frequency f DL  in a downlink channel. 
         [0041]    Referring to  FIG. 1B  illustrating the TDD transceiver  20 , during a downlink transmission operation, a baseband transmit signal TDD_TX is filtered by the baseband filter  21 . Then, the filtered baseband transmit signal TDD_TX is modulated into a carrier frequency F C  by the mixer  22 . Then, the power amplifier  23  amplifies a transmit signal of the carrier frequency f C  band. The transmit signal amplified by the power amplifier  23  may be transmitted to the antenna  25  when a node A is selected by a switch  24 . 
         [0042]    During an uplink reception operation, a wireless signal received by the TDD transceiver  20  enters the switch  24  through the antenna  25 . The wireless signal is delivered to the low noise amplifier  26  in a time slot where a node B is selected by the switch  24 . The received signal is amplified by the low noise amplifier  26  and is converted into a baseband signal by the mixer  27 . The baseband signal is filtered by the baseband filter  28  again and is outputted as a baseband receive signal TDD_RX in an uplink channel. Then, the baseband receive signal TDD_RX may be delivered to an ADC and a baseband modem (not shown) and processed. 
         [0043]    In the TDD transceiver, according to time slots allocated to an uplink or a downlink respectively, the switch  24  selects a channel. Accordingly, when the node of the switch  24  is positioned to A, a downlink channel is activated. On the other hand, when the node of the switch  24  is positioned to B, an uplink channel is activated. 
         [0044]    Referring to  FIGS. 1A and 1B , in order to configure a transceiver supporting both TDD and FDD, the size and cost of a transceiver are drastically increased. 
         [0045]      FIG. 2  is a block diagram illustrating a transceiver according to an embodiment of the present invention. Referring to  FIG. 2 , the transceiver  100  may support both an FDD mode and a TDD mode with one power amplifier  130  and one low noise amplifier  160 . The transceiver  100  includes a transmit (TX) unit and a receive (RX) unit using both a downlink frequency band and an uplink frequency band in a TDD mode. 
         [0046]    The Tx unit includes mixers  110  and  115  respectively modulating transmit signals of a downlink frequency f DL  and an uplink frequency  UL , a mixing switches SW T1    120 , a select switch SW T2    125 , and a power amplifier  130 . The RX unit includes a low noise amplifier  160 , a select switch SW R2    170 , a distribution switch SW R1    175 , mixers  180  and  185 , and baseband filters  190  and  195 . Furthermore, the transceiver  100  includes a first switch SW T3    140 , a second switch SW R3    145 , a duplexer  150 , and an antenna  155 . 
         [0047]    The TX unit may modulate baseband transmit signals TX_ 1  and TX_ 2  into a downlink frequency f DL  and an uplink frequency f UL , respectively, through the mixers  110  and  115 . 
         [0048]    The mixing switch  120  may be deactivated in an FDD mode. That is, in the FDD mode, the mixing switch  120  is open. Accordingly, in the FDD mode, the mixer  115  modulating the second transmit signal TX_ 2  into a signal of the uplink frequency f UL  becomes deactivated. However, in the transmit time slot of the TDD mode, the mixing switch  120  mixes the baseband transmit signals TX_ 1  and TX_ 2  modulated into the downlink frequency f DL  and uplink frequency f UL  and delivers them into the select switch  125 . Then, the select switch  125  delivers the transmit signal modulated into the two frequencies f DL  and f UL  to the power amplifier  130 . 
         [0049]    In the FDD mode, the first switch  140  and the second switch  145  may connect the TX unit, the RX unit, and the duplexer  150 . The first switch  140  may deliver the first transmit signal TX_ 1  modulated to the downlink frequency f DL  to the RF band filter  152  of the duplexer  150 . The RF band filter  152  passes the first transmit signal TX_ 1  through the downlink frequency f DL  band and then delivers it to the antenna  155 . Then, the second switch  145  delivers a band signal of the uplink link frequency f UL  received from the RF band filter  154  of the duplexer  150  to the RX unit. 
         [0050]    Moreover, the TDD mode may be divided into a TDD transmission mode and a TDD reception mode. According to the TDD transmission mode and the TDD reception mode, the switches  120 ,  125 ,  140 ,  145 ,  170 , and  175  may perform different selection operations. In the TDD transmission mode, the transmit signals TX_ 1  and TX_ 2  are respectively modulated into the downlink frequency f DL  and uplink frequency f UL  and are mixed by the mixing switch  120 . Transmit signals mixed with two bands are amplified by the power amplifier  130  and separated in the duplexer  150  through the first and second switches  140  and  145 . 
         [0051]    In the TDD reception mode, receive signals received through the antenna  155  are separated by each band through the duplexer  150 . Then, the receive signals separated by each band are provided to the low noise amplifier  160  through the first and second switches  140  and  145 . The receive signals amplified by the low noise amplifier  160  are separated into the mixers  180  and  185  through the selection switch  170  and the distribution switch  185 . The receive signals converted into a baseband by each of the mixers  180  and  185  are filtered through the baseband filters  190  and  195  and then outputted as baseband receive signals RX_ 1  and RX_ 2  in two bands. 
         [0052]    Operations of each component in the transceiver  100  depending on each mode are described briefly above. According to a communication mode, a signal path may be changed by the mixing switch  120 , the selection switch  125 , the selection switch  180 , the distribution switch  175 , the first switch  140 , and the second switch  145 . By a selection operation of switches according to such a communication mode, a transceiver device supporting a multi mode may be implemented through one power amplifier  130  and one low noise amplifier  160 . Detailed operations for each mode are described with reference to the tables and drawings 
         [0053]      FIG. 3  is a table illustrating states of switches for each mode in the transceiver of  FIG. 2 . Referring to  FIG. 3 , the transceiver  100  has different switch states according to an FDD mode and a TDD mode. Furthermore, the TDD mode is divided into a downlink mode TDD_DL and an uplink mode TDD_UL according to a time slot. The TDD downlink mode is referred to as a TDD transmission mode and the TDD uplink mode is referred to as a TDD reception mode. It is apparent that such definition is the definition of a base station and is conversely defined in a terminal. 
         [0054]    First, in the FDD mode, the mixing switch  120  and the distribution switch  175  are maintained in an open state. Then, the selection switches  125  and  180  and the first and second switches  140  and  145  are controlled to select the node A. In such a state, the first transmit signal TX_ 1  in a baseband is converted into a signal of the downlink frequency f DL  and is delivered to the antenna  155  through the duplex  150 . Then, the second receive signal RX_ 2  of the uplink frequency f UL  received from the antenna  155  is amplified by the low noise amplifier  160  and converted into a baseband signal by the mixer  185  and the baseband filter  195 . In the FDD mode, the mixers  115  and  180 , the switches  120  and  175 , and the baseband filter  190  may be deactivated. 
         [0055]    In the TDD transmission mode, the mixing switch  120  becomes shunt. That is, the mixing switch  120  mixes the first transmit signal TX_ 1  modulated to the downlink frequency f DL  and the second transmit signal TX_ 2  modulated to the uplink frequency f UL  and delivers the mixed signal to the node B of the selection switch  125 . At this point, the selection switch  125  selects the node B so as to deliver the transmit signals TX_ 1  and TX_ 2  mixed by the mixing switch  120  to the power amplifier  130 . 
         [0056]    The first switch  140  selects the node A so as to deliver the transmit signals TX_ 1  and TX_ 2  provided from the power amplifier  130  to the RF band filter  152  of the duplexer  150 . At this point, the first transmit signal TX — 1 among the mixed transmit signals TX_ 1  and TX_ 2  modulated to an RF band by the RF band filter  152  is delivered to the antenna  155 . Additionally, the second switch  145  selects the node B so as to deliver the transmit signals TX_ 1  and TX_ 2  provided from the power amplifier  130  to the RF band filter  154 . At this point, the second transmit signal TX — 2 among the mixed transmit signals TX_ 1  and TX_ 2  modulated to an RF band by the RF band filter  152  is delivered to the antenna  155 . 
         [0057]    Furthermore, in the TDD transmission mode, the distribution switch  175  in the RX unit may maintain an open state. Then, the selection switch  170  may cut off the delivery of a receive signal by selecting the node B. 
         [0058]    In the TDD reception mode, the TX unit is deactivated and only the RX unit is activated. That is, the mixing switch  120  in the TX unit is controlled to be in an open state and the selection switch  125  is controlled to select the node B. However, the distribution switch  175  in the RX unit becomes shunt and the selection switch  170  is controlled to select the node B. Furthermore, the first switch  140  may be set to select the node B in order to form a reception path. Then, the second switch  145  is set to select the node A in order to form a reception path. 
         [0059]    According to the each mode setting of a switch, a transceiver supporting an FDD mode, a TDD transmission mode, and a TDD reception mode by using one power amplifier  130  and one low noise amplifier  160  may be configured. Especially, in the TDD transmission mode and the RDD reception mode, the two bands of the uplink frequency f UL  and the downlink frequency f DL  are used so that frequency resources may be used efficiently. 
         [0060]      FIGS. 4 to 6  are block diagrams illustrating a transmission or reception path for each mode according to a switch state of  FIG. 3 . 
         [0061]      FIG. 4  is a block diagram illustrating a data path of the transceiver  100  according to an embodiment of the present invention. Referring to  FIG. 4 , an operation of the transceiver  100  in an FDD mode may be described briefly. In the FDD mode, the mixing switch  120  and the distribution switch  175  maintain an open state. Then, each of the selection switches  125  and  170  and the first and second switches  140  and  145  may be controlled to select the node A. 
         [0062]    In such a state, a transmission operation is as follows. The first transmit signal TX_ 1  is modulated to the downlink frequency f DL  and is delivered to the selection switch  125 . Then, the first transmit signal TX_ 1  modulated to the downlink frequency f DL  is amplified by the power amplifier  130  and is delivered to the duplex  150  through the first switch  140 . The first transmit signal TX_ 1  modulated to the downlink frequency f DL  is filtered to pass a wireless band by the RF band filter  152  of the duplex  150 . The RF band filter  152  has a filter characteristic passing through a wireless band of the downlink frequency f DL . The first transmit signal TX_ 1  modulated to the downlink frequency f DL  processed by the duplex  150  is delivered as a transmit signal T(t) to the antenna  155 . 
         [0063]    A reception operation in the FDD mode is as follows. An uplink receive signal R(t) received through the antenna  155  is filtered by the RF band filter  154  of the duplexer  150 . Then, the filtered receive signal R(t) is delivered to the low noise amplifier  160  by the second switch  145 . The receive signal R(t) amplified by the low noise amplifier  160  is delivered to the mixer  185  by the selection switch  170 . The mixer  185  demodulates the receive signal R(t) by using the uplink frequency f UL . Then, the receive signal R(t) is demodulated to a baseband signal and delivered to the baseband filter  195 . The receive signal in a baseband is outputted as the second receive signal RX_ 2  by the baseband filter  195 . Then, although not shown in the drawings, the second receive signal RX_ 2  is processed by an ADC and delivered to a baseband modem. 
         [0064]    According to the above-mentioned transceiver  100 , the selection switch  125  and the first switch  140  in the FDD mode are configured to modulate the first transmit signal TX_ 1  into the downlink frequency f DL  and to be selected by the duplexer  150  in order for the transmission of the first transmit signal TX_ 1  in a baseband. Then, the selection switch  170  and the second switch  145  are configured to select the uplink frequency f UL  of the duplexer  150  and demodulate it into a baseband in order to receive the second receive signal RX_ 2 . 
         [0065]      FIG. 5  is a block diagram illustrating a data path of the transceiver  100  in a TDD transmission mode according to an embodiment of the present invention. Referring to  FIG. 5 , a signal delivery path of the transceiver  100  in the TDD transmission mode is shown. In the TD transmission mode, the TX unit of the transceiver  100  is activated and the RX unit is deactivated. The TDD transmission mode may be activated in a downlink time slot interval. Then, in the TDD transmission mode, data may be transmitted by both the downlink frequency f DL  and the uplink frequency f UL . 
         [0066]    First, the transmit signals TX_ 1  and TX_ 2  in a baseband are provided to the mixers  110  and  115 . The transmit signals TX_ 1  and TX_ 2  in a baseband are modulated into signals of an RF band, respectively, by the mixers  110  and  115 . Then, the mixing switch  120  becomes shunt. The mixing switch  120  mixes the first transmit signal TX_ 1  modulated to the downlink frequency f DL  and the second transmit signal TX_ 2  modulated to the uplink frequency f UL  and then delivers it to the node B of the selection switch  125 . At this point, the selection switch  125  delivers the transmit signals TX_ 1  and TX_ 2  in an RF band mixed by the mixing switch  120  to the power amplifier  130 . 
         [0067]    The transmit signals TX_ 1  and TX_ 2  in an RF band, which are amplified by the power amplifier  130 , are transmitted to the antenna  155  through two transmission paths. That is, one transmission path is configured by the first switch  140  and the RF band filter  152 . The amplified transmit signals TX_ 1  and TX_ 2  in an RF band, which are outputted from the power amplifier  130 , are provided to the RF band filter  152  of the duplexer  150  through the first switch  140 . The first transmit signal TX_ 1  modulated to the downlink frequency f DL  by the RF band filter  152  is delivered as a transmit signal T 1 ( t ) to the antenna  155 . Another transmission path is configured by the second switch  145  and the RF band filter  154 . The amplified transmit signals TX_ 1  and TX_ 2  in an RF band, which are outputted from the power amplifier  130 , are provided to the RF band filter  154  of the duplexer  150  through the second switch  145 . The second transmit signal TX_ 2  modulated to the uplink frequency f UL  by the RF band filter  154  is delivered as a transmit signal T 2 ( t ) to the antenna  155 . 
         [0068]    According to the above TDD transmission mode, the transceiver  100  may use both the downlink frequency f DL  and the uplink frequency f UL  during transmission. Accordingly, the utilization of a frequency resource may be maximized in a time slot for TDD transmission. 
         [0069]      FIG. 6  is a block diagram illustrating a data path of the transceiver  100  in a TDD reception mode according to an embodiment of the present invention. Referring to  FIG. 6 , a signal delivery path of the transceiver  100  in the TDD reception mode is shown by a dotted line. In the TDD transmission mode, the TX unit of the transceiver  100  is deactivated and the RX unit is activated. The TDD transmission mode is activated in an uplink time slot interval of the TDD mode. Then, in the TDD transmission mode, data may be received by both the downlink frequency f DL  and the uplink frequency f UL . 
         [0070]    First, the first receive signal R 1 ( t ) and the second receive signal R 2 ( t ) in an RF band may be provided from the antenna  155  to the duplexer  150 . The RF band filter  152  of the duplexer  150  selects a receive signal in the downlink frequency f DL  band and delivers the selected receive signal to the first switch  140 . The RF band filter  154  of the duplexer  150  selects a receive signal in the uplink frequency f UL  band and deliver the selected receive signal to the second switch  145 . By the first and second switches  140  and  145 , the receive signals separated by the duplexer  150  are delivered to the power amplifier  130  of the RX unit again. 
         [0071]    The receive signals R 1 ( t ) and R 2 ( t ) in an RF band, which are amplified by the low noise amplifier  160 , are distributed into the mixers  180  and  185  through the selection switch  170  and the distribution switch  175 . Through the node B of the selection switch  170 , the receive signals R 1 ( t ) and R 2 ( t ) are delivered to the distribution switch  175 . Then, the receive signals R 1 ( t ) and R 2 ( t ) are delivered to the mixers  180  and  185  by the distribution switch  175 . 
         [0072]    The mixer  180  demodulates the receive signals R 1 ( t ) and R 2 ( t ) into a baseband by using the downlink frequency f DL . Then, the center frequency of the receive signals R 1 ( t ) and R 2 ( t ) is converted into a baseband signal located in the baseband. Only the receive signal R 1 ( t ) received at the downlink frequency fix, by the baseband filter  190  is selected from the receive signals R 1 ( t ) and R 2 ( t ) in the baseband. The receive signal RX_ 1  in the baseband, which is selected by the baseband filter  190 , may be outputted. 
         [0073]    The mixer  185  demodulates the receive signals R 1 ( t ) and R 2 ( t ) into a baseband by using the uplink frequency f UL . Then, the center frequency of the receive signals R 1 ( t ) and R 2 ( t ) is converted into a baseband signal located in the baseband. Only the receive signal R 2 ( t ) received at the uplink frequency f UL  by the baseband filter  195  is selected from the receive signals R 1 ( t ) and R 2 ( t ) in the baseband. The receive signal RX_ 2  in the baseband, which is selected by the baseband filter  190 , may be outputted. 
         [0074]    According to the above TDD reception mode, the transceiver  100  may use both the downlink frequency f DL  and the uplink frequency f UL  during reception. Accordingly, the utilization of a frequency resource may be maximized in a time slot for TDD reception. 
         [0075]    The above-mentioned transceivers of  FIGS. 2 to 6  are described by using transceivers in a base station as examples. However, it is apparent that the transceiver of the present invention is identically applied to a terminal. 
         [0076]    According to an embodiment of the present invention, in a device configured with inexpensive components, a transceiver supporting both an LTE-FDD mode and an LTE-TDD mode may be implemented. 
         [0077]    While this invention has been particularly shown and described with reference to preferred 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 invention as defined by the appended claims. The preferred embodiments should be considered in descriptive sense only and not for purposes of limitation. Therefore, the scope of the invention is defined not by the detailed description of the invention but by the appended claims, and all differences within the scope will be construed as being included in the present invention. 
         [0078]    The above-disclosed subject matter is to be considered illustrative, and not restrictive, and the appended claims are intended to cover all such modifications, enhancements, and other embodiments, which fall within the true spirit and scope of the present invention. Thus, to the maximum extent allowed by law, the scope of the present invention is to be determined by the broadest permissible interpretation of the following claims and their equivalents, and shall not be restricted or limited by the foregoing detailed description.