Abstract:
A front end radio architecture (FERA) with power management is disclosed. The FERA includes a first power amplifier (PA) block having a first-first PA and a first-second PA, and a second PA block having a second-first PA and a second-second PA. First and second modulated switchers are adapted to selectively supply power to the first-first PA and the second-first PA, and to supply power to the first-second PA and the second-second PA, respectively. The first and second modulated switchers have a modulation bandwidth of at least 20 MHz and are both suitable for envelope tracking modulation. A control system is adapted to selectively enable and disable the first-first PA, first-second PA, the second-first PA, and the second-second PA. First and second switches are responsive to control signals to route carriers and received signals between first and second antennas depending upon a selectable mode of operation such as intra-band or inter-band operation.

Description:
RELATED APPLICATIONS 
     This application claims the benefit of U.S. provisional patent application No. 61/481,311, filed May 2, 2011, the disclosure of which is incorporated herein by reference in its entirety. This patent application is also related to provisional patent application Ser. No. 13/045,604 entitled LTE-ADVANCED (4G) FRONT END RADIO ARCHITECTURE, filed Mar. 11, 2011, now U.S. Pat. No. 8,537,723; patent application Ser. No. 13/045,621 entitled SPLIT-BAND POWER AMPLIFIERS AND DUPLEXERS FOR LTE-ADVANCED FRONT END FOR IMPROVED IMD, filed Mar. 11, 2011, now U.S. Pat. No. 8,644,198; and provisional patent application Ser. No. 61/313,392 entitled LTE-ADVANCED FRONT END ARCHITECTURE, filed Mar. 12, 2010; the disclosures of which are incorporated herein by reference in their entireties. 
    
    
     FIELD OF THE DISCLOSURE 
     The present disclosure relates to front end radio architectures (FERAS) directed towards long term evolution advanced (LTE-Advanced) user equipment (UE). 
     BACKGROUND 
     A long term evolution advanced (LTE-Advanced) network standard has been developed to provide wireless data rates of 1 Gbps downlink and 500 Mbps uplink. The LTE-Advanced network standard also offers multi-carrier transmission and reception within a single band as well as multi-carrier transmission and reception within two separate bands. Multi-carrier transmission within a single band is referred to as intra-band transmission and reception. In contrast, multi-carrier transmission and reception within two different bands is referred to as inter-band transmission and reception. LTE-Advanced technology is also known as fourth generation (4G) technology. 
     LTE-Advanced operation requires a simultaneous dual carrier transmission in the same band (i.e., intra-band) and into different bands (i.e., inter-band). A transmission of dual LTE-Advanced carriers in a single band in a non-contiguous manner will result in an increased peak-to average ratio (PAR) of around 1 dB. This increase is over an increase of about 1 dB of PAR due to a use of clustered single carrier frequency division multiple access (SC-FDMA). The combined increase in PAR results in a significant negative impact on efficiency of a transmitter chain made up of a transceiver and a power amplifier (PA). 
     In this regard, envelope following techniques for linear modulation are highly desirable for LTE-Advanced customers and others in the years to come because envelope following and pseudo-envelope following enables a very efficient use of energy. Envelope following techniques employ envelope following systems that are power management systems that control power amplifiers (PAs) in such a way that the PA collector/drain voltage (referred to herein as VCC) follows an RF input signal envelope. The RF input signal envelope is an instantaneous voltage of a PA input RF signal, (referred to herein as VIN). 
     Implementing pseudo-envelope following improves overall efficiency of PA systems because a power management function is realized using high efficiency switcher systems. However, using envelope following techniques is not practical for transmitter chains that involve dual intra-band carriers due to a large bandwidth requirement that would be placed on a typical switching power supply. The reason for the large bandwidth requirement is that bandwidth is a function of frequency separation between the dual intra-band carriers. For the purpose of this disclosure, envelope following systems include pseudo-envelope following systems, wherein pseudo-envelope following is envelope tracking that includes power amplifier (PA) collector/drain voltage pre-distortion to ameliorate power amplifier nonlinearity. It should be understood that envelope following is sometimes referred to as envelope tracking by some. 
     Lack of practical envelope following systems present a major challenge for realizing front end radio architectures (FERAs) that are necessary for providing multi-carrier operation using intra-band and inter-band transmission and reception. FERAs that do not employ envelope following systems cannot operate efficiently due to the extra 2 dB of PAR. 
       FIG. 1  is a schematic of a related art front end radio architecture (FERA)  10  that is not configured to accept power from power management architectures that employ envelope following. The FERA  10  includes a transmitter block  12  for transmitting LTE Advanced multi-carrier signals. The FERA  10  also includes a first power amplifier (PA)  14  powered by a first switcher  16  and a second PA  18  powered by a second switcher  20 . 
     A first duplexer  22  for an RF band A and a first receive (RX) diversity/multiple-input multiple-output (MIMO) filter  24  for an RF band B are coupled between the first PA  14  and a first band switch  26 . The first duplexer  22  and the first RX diversity/MIMO filter  24  are selectively coupled to a first antenna  28  through the first band switch  26 . The first duplexer  22  outputs signals RX_A captured by the first antenna  28 . The first RX diversity/MIMO filter  24  outputs signals RX_B_DIV also captured by the first antenna  28 . The band switch  26  is controlled by a control signal CTRL 1 . 
     A second duplexer  30  for the RF band B and a second RX diversity/MIMO filter  32  are coupled between the second PA  18  and a second band switch  34 . The second duplexer  30  is selectively coupled to a second antenna  36  through the second band switch  34 . The second duplexer  30  outputs signals RX_B captured by the second antenna  36 . The second RX diversity/MIMO filter  32  outputs signals RX_A_DIV also captured by the second antenna  36 . 
     The transmitter block  12  includes a first transmitter  38 , a first RF modulator  40 , a first radio frequency (RF) phase locked loop (PLL)  42 , a second transmitter  44 , a second RF modulator  46 , and a second RF PLL  48 . The transmitter block  12  further includes a multi-carrier combiner  50  for combining signals output from the first RF modulator  40  and the second RF modulator  46 . 
     The related art FERA  10  can operate in an intra-band multi-carrier mode. During operation of the related art FERA  10  in the intra-band multi-carrier mode, the first transmitter  38  outputs analog baseband (ABB) signals to the first RF modulator  40 . Similarly, the second transmitter  44  outputs ABB signals to the second RF modulator  46 . In response, the first RF modulator  40  in cooperation with the first RF PLL  42  outputs a first carrier within the RF band A while the second RF modulator  46  in cooperation with the second RF PLL  48  outputs a second carrier that is also within the band A. The first PA  14  provides power amplification of the first carrier and the second carrier which are output through the first duplexer  22  to the first antenna  28 . 
     The related art FERA  10  also includes an inter-band multicarrier mode. During operation of the related art FERA  10  using the inter-band multi-carrier mode, the first RF modulator  40  in cooperation with the first RF PLL  42  outputs a first carrier within the RF band A while the second RF modulator  46  in cooperation with the second RF PLL  48  outputs a second carrier within the RF band B. The first PA  14  provides power amplification of the first carrier which is output through the first duplexer  22  to the first antenna  28 . The second PA  18  provides power amplification of the second carrier which is output through the second duplexer  30  to the second antenna  36 . 
     While the related art FERA  10  offers a realizable architecture for LTE-Advanced operation, the related art FERA  10  is wasteful with regard to energy, in that the FERA  10  is not structured to take advantage of a high energy efficiency operation provided by envelope following systems. Energy efficiency in battery powered user equipment (UE) such as mobile terminals that implement LTE-Advanced operation is very important, since a relatively long operation time between battery charges is desirable. 
       FIG. 2  is a spectrum diagram that illustrates a common collector voltage (VCC) bandwidth (BW) switcher modulation requirement for intra-band dual carrier transmission. In particular, the modulation bandwidth of the switcher  16  ( FIG. 1 ) and the switcher  20  ( FIG. 1 ) is a function of an offset frequency Df between a carrier # 1  and a carrier # 2 . Therefore, the higher the offset frequency Df between the carrier # 1  and the carrier # 2 , the higher the modulation bandwidth must be. At some point, the offset frequency Df is large enough that related art approaches for modulating a VCC pseudo envelope following (PEF) signal via either the switcher  16  or the switcher  20  are no longer practical. For example, if the offset frequency is 40 MHz, then the supply modulation bandwidth needed for envelope tracking is about 1.5×(40 MHz+20 MHz) or about 90 MHz for LTE-Advanced carriers having around 20 MHz of bandwidth. A multiplier of 1.5 is a result of a square root operation of PEF calculation. Moreover, even if the offset frequency Df is equal to zero between two adjacent carriers having a 20 MHz bandwidth each, a resulting 50 MHz VCC BW is too large for efficient modulation of the VCC PEF via either the switcher  16  or the switcher  20 . Thus, there is a need to practically meet the VCC BW switcher modulation bandwidth requirement in order to implement LTE-Advanced operation in a more efficient manner than is possible with the related art FERA  10 . 
     SUMMARY 
     Embodiments of the present disclosure provide a front end radio architecture (FERA) and power management architecture for LTE-Advanced operation. The FERA includes a first power amplifier (PA) block having a first-first PA and a first-second PA, and a second PA block having a second-first PA and a second-second PA. First and second modulated switchers are adapted to selectively supply power to the first-first PA and the second-first PA, and to supply power to the first-second PA and the second-second PA, respectively. The first and second modulated switchers have a modulation bandwidth of at least 20 MHz and are both suitable for envelope tracking modulation. A control system is adapted to selectively enable and disable the first-first PA, first-second PA, the second-first PA, and the second-second PA. First and second switches are responsive to control signals to route carriers and received signals between first and second antennas depending upon a selectable mode of operation such as intra-band or inter-band operation. 
     The first modulated switcher is adapted to supply power to the first-first PA and the second-first PA, while the second modulated switcher is adapted to supply power to the first-second PA and the second-second PA. The first switch has a first control input, a first throw terminal, a second throw terminal, and a first pole terminal coupled to a first throw and a second throw, wherein the first switch is responsive to a first control signal to selectively close and open the first throw with the first throw terminal, and to selectively close and open the second throw with the second throw terminal. The second switch has a second control input, a third throw terminal, a fourth throw terminal, and a second pole terminal coupled to a third throw and a fourth throw, wherein the second switch is responsive to a second control signal to selectively close and open the third throw with the third throw terminal, and to selectively close and open the fourth throw with the fourth throw terminal. 
     The first duplexer is coupled between an output of the first-first PA and the first throw terminal, whereas the second duplexer is coupled between an output of the first-second PA and the second throw terminal. The third duplexer is coupled between an output of the second-first PA and the third throw terminal, whereas a fourth duplexer is coupled between an output of the second-second PA and the fourth throw terminal. The control system is adapted to selectively enable and disable the first-first PA, the first-second PA, the second-first PA, and the second-second PA, and to provide the first control signal and the second control signal. 
     Those skilled in the art will appreciate the scope of the disclosure and realize additional aspects thereof after reading the following detailed description in association with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings incorporated in and forming a part of this specification illustrate several aspects of the disclosure, and together with the description serve to explain the principles of the disclosure. 
         FIG. 1  is a schematic of a related art front end radio architecture (FERA) that is not configured to accept power from power management architectures that employ envelope following. 
         FIG. 2  is a spectrum diagram that illustrates a common collector voltage (VCC) bandwidth (BW) switcher modulation requirement for intra-band dual carrier transmission. 
         FIG. 3  is a schematic of a FERA that in accordance with the present disclosure is configured for operation with envelope following techniques. 
         FIG. 4  is a schematic of the FERA during intra-band operation for band A. 
         FIG. 5  is a schematic of the FERA during intra-band operation for band B. 
         FIG. 6  is a schematic of the FERA during intra-band operation between band A and band B. 
         FIG. 7  is a schematic of the FERA during intra-band operation between band A and band B with receive diversity using MIMO. 
         FIG. 8  is a schematic of the FERA during intra-band operation between band A and band B with receive diversity/MIMO and swapped carrier transmission. 
         FIG. 9  is a schematic of the FERA that is modified to reduce BOM costs by including split band duplexers for band A. 
         FIG. 10  is a schematic of the FERA that is modified to reduce BOM costs by including split band duplexers for band B. 
         FIG. 11  depicts a mobile terminal that incorporates the FERA of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     The embodiments set forth below represent the necessary information to enable those skilled in the art to practice the disclosure and illustrate the best mode of practicing the disclosure. Upon reading the following description in light of the accompanying drawings, those skilled in the art will understand the concepts of the disclosure and will recognize applications of these concepts not particularly addressed herein. It should be understood that these concepts and applications fall within the scope of the disclosure and the accompanying claims. 
     Embodiments of the present disclosure provide front end radio architecture (FERA) and power management architecture for LTE-Advanced operation. In particular, the FERA and power management of the present disclosure is configured to employ envelope following that is compatible with existing bandwidth limited to 20 MHz LTE-Advanced for dual carriers implemented in both intra-band and inter-band scenarios. 
       FIG. 3  is a schematic of a FERA  52  that in accordance with the present disclosure is configured for operation with envelope following techniques. The FERA  52  includes a transmitter block  54  for transmitting LTE Advanced multi-carrier signals. The FERA  52  also includes a first PA block  56  having a first-first PA  58  that is selectively powered by a first modulated switcher  60  and a first-second PA  62  that is selectively powered by a second modulated switcher  64 . The FERA  52  further includes a second PA block  66  having a second-first PA  68  that is selectively powered by the first modulated switcher  60  and a second-second PA  70  that is selectively powered by the second modulated switcher  64 . The first modulated switcher  60  has a first output filter comprising a first inductor L 1 , while the second modulated switcher  64  includes a second output filter comprising a second inductor L 2 . 
     A first duplexer  72  for a first band A carrier C 1 A and a band A receive signal RX_A is coupled between an output of the first-first PA  58  and a first terminal of a first single pole double throw (SP2T) switch  74 . A second duplexer  76  for a second band A carrier C 2 A and a band A diversity/MIMO receive signal RX_A_Div is coupled between an output of the first-second PA  62  and a first terminal of a second SP2T switch  78 . The first duplexer  72  is selectively coupled to a first antenna  80  through the first SP2T switch  74 . The first duplexer  72  outputs the receive signal RX_A captured by the first antenna  80 . The second duplexer  76  is selectively coupled to a second antenna  82  through the second SP2T switch  78 . The second duplexer  76  outputs the diversity/MIMO receive signal RX_A_DIV captured by the second antenna  82 . The first SP2T switch  74  is controllable by a first control signal CTRL 1 _ 1 , whereas the second SP2T switch  78  is controllable by a second control signal CTRL 2 _ 1 . 
     A third duplexer  84  for a first band B carrier C 1 B and a band B receive signal RX_B is coupled between an output of the second-first PA  68  and a second terminal of the first SP2T switch  74 . A fourth duplexer  86  for a second band B carrier C 2 B and a band B diversity/MIMO receive signal RX_B_Div is coupled between an output of the second-second PA  70  and a second terminal of a second SP2T switch  78 . The third duplexer  84  is selectively coupled to the first antenna  80  through the first SP2T switch  74 . The third duplexer  84  outputs the receive signal RX_B captured by the first antenna  80 . The fourth duplexer  86  is selectively coupled to the second antenna  82  through the second SP2T switch  78 . The fourth duplexer  86  outputs the diversity/MIMO receive signal RX_B_DIV captured by the second antenna  82 . 
     The transmitter block  54  includes a first transmitter  88 , a first RF modulator  90 , a first radio frequency (RF) phase locked loop (PLL)  92 , a second transmitter  94 , a second RF modulator  96 , and a second RF PLL  98 . The transmitter block  54  further includes a multi-carrier combiner  100  for combining signals output from the first RF modulator  90  and the second RF modulator  96 . 
     The FERA  52  can operate in an intra-band multi-carrier mode. During operation of the FERA  52  in the intra-band multi-carrier mode, the first transmitter  88  outputs analog baseband (ABB) signals to the first RF modulator  90 . Similarly, the second transmitter  94  outputs ABB signals to the second RF modulator  96 . In response, the first RF modulator  90  in cooperation with the first RF PLL  92  outputs a first carrier, C 1 A, within RF band A while the second RF modulator  96  in cooperation with the second RF PLL  98  outputs a second carrier, C 2 A, that is also within the band A. The first-first PA  58  provides power amplification of the first carrier, C 1 A, which is output through the first duplexer  72  to the first antenna  80 . The first-second PA  62  provides power amplification of the second carrier, C 2 A, which is output through the second duplexer  76  to the second antenna  82 . 
     The FERA  52  also includes an inter-band multicarrier mode. During operation of the FERA  52  using the inter-band multi-carrier mode, the first RF modulator  90  in cooperation with the first RF PLL  92  outputs a first carrier within the RF band A while the second RF modulator  96  in cooperation with the second RF PLL  98  outputs a second carrier within the RF band B. The first PA block  56  provides power amplification of the first carrier, which is output through the first duplexer  72  to the first antenna  80 . The second PA block  66  provides power amplification of the second carrier, which is output through the fourth duplexer  86  to the second antenna  82 . 
       FIG. 4  is a schematic of the FERA  52  during intra-band operation for band A. Dashed lines in  FIG. 4  represent deactivated or unused components. In the case of intra-band carrier aggregation into band A, the second PA block  66  is deactivated, while the third duplexer  84  and the fourth duplexer  86  are unused. However, the first PA block  56  remains completely energized with the first-first PA  58  being supplied with power from the first modulated switcher  60  and the first-second PA  62  being supplied with power from the second modulated switcher  64 . The CTRL 1 _ 1  signal closes the first throw of the first SP2T switch  74  so that the first carrier C 1 A is transmitted from the first antenna  80 , while the band A receive signal RX_A is captured by the first antenna  80  and output from the first duplexer  72 . Similarly, the CTRL 2 _ 1  signal closes a first throw of the second SP2T switch  78  so that the second carrier C 2 A is transmitted from the second antenna  82 , and so that the band A diversity/MIMO receive signal RX_A_DIV captured by the second antenna  82  is output from the second duplexer  76 . 
       FIG. 5  is a schematic of the FERA  52  during intra-band operation for band B. Dashed lines in  FIG. 5  represent deactivated or unused components. In the case of intra-band carrier aggregation into band B, the first PA block  56  is deactivated, while the first duplexer  72  and the second duplexer  76  are unused. However, the second PA block  66  remains completely energized with the second-first PA  68  being supplied with power from the first modulated switcher  60 , and the second-second PA  70  being supplied with power from the second modulated switcher  64 . The CTRL 1 _ 1  signal closes a second throw of the first SP2T switch  74  so that the first carrier C 1 B is transmitted from the first antenna  80 , and so that the band B receive signal RX_B captured by the first antenna  80  is output from the third duplexer  84 . Similarly, the CTRL 2 _ 1  signal closes a second throw of the second SP2T switch  78  so that the second carrier C 2 B is transmitted from the second antenna  82 , and so that the band B diversity/MIMO receive signal RX_B_DIV captured by the second antenna  82  is output from the fourth duplexer  86 . 
       FIG. 6  is a schematic of the FERA  52  during intra-band operation between band A and band B. Dashed lines represent deactivated or unused components. In the case of intra-band carrier aggregation between band A and band B, the first PA block  56  and the second PA block  66  are only partially energized. In particular, the first-first PA  58  is powered by the first modulated switcher  60  and the second-second PA  70  is powered by the second modulated switcher  64 , while the second-first PA  68  and the first-second PA  62  are deactivated. The second duplexer  76  and the third duplexer  84  are unused. The control signal CTRL 1 _ 1  closes the first throw of the first SP2T switch  74  so that the first carrier C 1 A is transmitted from the first antenna  80 , and so that the band A receive signal RX_A is output from the first duplexer  72 . Similarly, the control signal CTRL 2 _ 1  closes the second throw of the second SP2T switch  78  so that the second carrier C 2 B is transmitted from the second antenna  82 , and so that the diversity/MIMO receive signal RX_B_DIV is output from the fourth duplexer  86 . 
       FIG. 7  is a schematic of the FERA  52  during intra-band operation between band A and band B with receive diversity using MIMO. Dashed lines represent deactivated or unused components. In the case of intra-band carrier aggregation between band A and band B with receive diversity using MIMO, the first PA block  56  and the second PA block  66  are only partially energized as in  FIG. 6 . However, in order to realize diversity using MIMO for both band A and band B, the first and second throws of the first SP2T switch  74  and the second switch  78  are closed by the control signals CTRL 1 _ 1  and CTRL 2 _ 1 . In this manner, the first carrier C 1 A is transmitted from the first antenna  80 , while the band A receive signal RX_A captured by the first antenna  80  is output from the first duplexer  72 , and the diversity/MIMO receive signal RX_A_DIV captured by the second antenna  82  is output from the second duplexer  76 . Similarly, the second carrier C 2 B is transmitted from the second antenna  82 , while the band B receive signal RX_B captured by the first antenna  80  is output from the third duplexer  84 , and the diversity/MIMO receive signal RX_B_DIV captured by the second antenna  82  is output from the fourth duplexer  86 . 
       FIG. 8  is a schematic of the FERA  52  during intra-band operation between band A and band B with receive diversity using MIMO and swapped carrier transmission. Dashed lines represent deactivated or unused components. In the case of intra-band carrier aggregation between band A and band B with receive diversity using MIMO and swapped carrier transmission, the first PA block  56  and the second PA block  66  are only partially energized. However, in contrast to the operation depicted in  FIG. 7 , the first-first PA  58  and the second-second PA  70  are deactivated, while the second first PA  68  is energized by the first modulated switcher  60  and the first-second PA  62  is energized by the second modulated switcher  64 . Yet, the first and second throws of the first SP2T switch  74  and the second switch  78  remain closed by the control signals CTRL 1 _ 1  and CTRL 2 _ 1 . In this way, the band A receive signal RX_A captured by the first antenna  80  is output from the first duplexer  72 , and the band B receive signal RX_B also captured by first antenna  80  is output from the third duplexer  84 . Moreover, the band A diversity/MIMO receive signal RX_A_DIV captured by the second antenna  82  is output from the second duplexer  76 , while the band B diversity/MIMO receive signal is output from the fourth duplexer  86 . Further still, the carrier C 2 A is transmitted from the second antenna  82 , while the carrier C 1 B is transmitted from the first antenna  80 . 
     The FERA  52  allows envelope tracking for dual carriers in both intra-band and inter-band operation, which eliminates a need for an extra 1 dB of PAR. As a result, the FERA  52  offers improved efficiency for dual carrier operation. Moreover, intermodulation distortion is reduced due to separated transmitter chains comprised of the first PA block  56  and the second PA block  66 . Further still, the configuration of the first SP2T switch  74  and the second SP2T switch  78  combined with the first duplexer  72 , the second duplexer  76 , the third duplexer  84 , and the fourth duplexer  86  allows for carrier transmission diversity. However, these advantages offered by the FERA  52  come with an increased bill of materials (BOM) cost of an extra TX filter per band. Also, unless the extra complexity of a half-power split type amplifier is implemented an additional cost of an extra PA block is included in the FERA  52 . 
       FIG. 9  is a schematic of the FERA  52  that is modified to reduce BOM costs by replacing the first duplexer  72  with a first split band duplexer  102 , and by replacing the second duplexer  76  with a second split band duplexer  104 . The first split band duplexer  102  includes a first TX filter  106  for passing the carrier C 1 A located in the lower half TX band of band A. Similarly, the second split band duplexer  104  includes a second TX filter  108  for passing the carrier C 2 A located in the upper half TX band of band A. The combined bandwidth of the first TX filter  106  and the second TX filter  108  is adaptable to cover the upper and lower halves of a given TX band. 
       FIG. 10  is a schematic of the FERA  52  that is also modified to reduce BOM costs by replacing the third duplexer  84  with a third split band duplexer  103 , and by replacing the fourth duplexer  86  with a fourth split band duplexer  105 . A third TX filter  107  passes the carrier C 1 B located in the lower half TX band of band B. Similarly, a fourth TX filter  109  passes the carrier C 2 B located in the upper half TX band of band B. 
     One modification to the FERA  52  would allow a transmission of both halves of band A from the first antenna  80  and both halves of band B from the other antenna  82  by tuning the first PA block  56  for the carriers C 1 A and C 1 B, and the second PA block  66  for the carriers C 2 A and C 2 B. In this case, the first modulated switcher  60  would supply the second-second PA  70  and the second modulated switcher  64  would supply the second-first PA  68 . In this way, the first antenna  80  would only be associated with band A and the second antenna  82  would only be associated with band B. However, IMD could be an issue with this implementation since the two half band carriers may not have enough antenna isolation between them. In contrast, the RX_A_DIV output and the RX_B_DIV output could remain as is shown in  FIG. 3 . The resulting receiver and transmitter separation would be relatively large. Thus, reducing the design requirements for filtering. 
       FIG. 11  depicts user equipment (UE) in the form of a mobile terminal  110  that incorporates a preferred embodiment of the FERA  52  of the present disclosure. The mobile terminal  110  may be, but is not limited to, a mobile telephone, a personal digital assistant (PDA), or the like. The basic architecture of the mobile terminal  110  may also include a baseband processor  112 , a control system  114 , and an interface  116 . The first antenna  80  receives information-bearing RF signals from one or more remote transmitters provided by a base station (not shown). The first switch  74  under the control of the CTRL 1 _ 1  signal output from the control system  114  allows the information-bearing RF signals to feed through the first duplexer  72  and into a band A RX  118 . The band A RX  118  includes a low noise amplifier (LNA)  120  that amplifies the signal, and a first filter circuit  122  that minimizes broadband interference in the received signals. The band A RX  118  also includes downconversion and digitization circuitry  124 , which downconverts the filtered, received signals to intermediate or baseband frequency signals, which are then digitized into one or more digital streams. 
     Similarly, the second antenna  82  receives information-bearing RF signals from one or more remote transmitters provided by a base station (not shown). The second switch  78  under the control of the CTRL 2 _ 1  signal output from the control system  114  allows the information-bearing signals to feed through the fourth duplexer  86  and into a band B RX 126 . The band B RX 126  includes a second LNA  128  that amplifies the signals, and a second filter circuit  130  that minimizes broadband interference in the received signals. The band B RX 126  also includes downconversion and digitization circuitry  132 , which downconverts the filtered, received signals to intermediate or baseband frequency signals, which are then digitized into one or more digital streams. 
     The baseband processor  112  processes the digitized received signals to extract the information or data bits conveyed in the received signals. This processing typically comprises demodulation, decoding, and error correction operations. As such, the baseband processor  112  is generally implemented in one or more digital signal processors (DSPs). 
     On the transmit side, the baseband processor  112  receives digitized data, which may represent voice, data, or control information, which it encodes for transmission, from the control system  114 . The encoded data is output to the transmitter block  54 . The PA blocks  56  and  66  amplify the carriers C 1 A, C 2 A, C 1 B, and C 2 B to levels appropriate for transmission from the first antenna  80  and the second antenna  82 . Different combinations of the carriers C 1 A, C 2 A, C 1 B, and C 2 B may also be transmitted from the first antenna  80  and the second antenna  82  under control of the control signals CTRL 1 _ 1  and CTRL  2 _ 1 , as described previously. 
     A user may interact with the mobile terminal  110  via the interface  116 , which may include interface circuitry  134  associated with a microphone  136 , a speaker  138 , a keypad  140 , and a display  142 . The interface circuitry  134  typically includes analog-to-digital converters, digital-to-analog converters, amplifiers, and the like. Additionally, it may include a voice encoder/decoder, in which case it may communicate directly with the baseband processor  112 . 
     The microphone  136  will typically convert audio input, such as the user&#39;s voice, into an electrical signal, which is then digitized and passed directly or indirectly to the baseband processor  112 . Audio information encoded in the received signal is recovered by the baseband processor  112  and converted by the interface circuitry  134  into an analog signal suitable for driving the speaker  138 . The keypad  140  and the display  142  enable the user to interact with the mobile terminal  110 , inputting numbers to be dialed, address book information, or the like, as well as monitoring call progress information. 
     Those skilled in the art will recognize improvements and modifications to the embodiments of the present disclosure. All such improvements and modifications are considered within the scope of the concepts disclosed herein and the claims that follow.