Patent Publication Number: US-10333758-B2

Title: Method and apparatus for converting analog radio frequency (RF) signals to the digital domain in a multiband and multicarrier wireless communication system

Description:
CLAIM OF PRIORITY 
     This patent application a continuation of U.S. patent application Ser. No. 15/254,812, filed on Sep. 1, 2016, which a continuation of U.S. patent application Ser. No. 14/570,640, filed on Dec. 15, 2014, which in turn makes reference to, claims priority to and claims benefit from United States Provisional Patent Application Ser. No. 61/940,127 filed on Feb. 14, 2014. Each of the above identified applications is hereby incorporated herein by reference in its entirety. 
    
    
     FIELD 
     The present disclosure generally relates to wireless communications systems. In particular, the present disclosure relates to a method and system for converting wideband analog radio frequency (RF) signals to the digital domain in a multiband and multicarrier wireless communications system. 
     BACKGROUND 
     Today&#39;s wireless communication systems generally use a single radio frequency (RF) band, having a bandwidth anywhere from less than 5 MHz to over 200 MHz, to transmit and receive data. These wireless communication systems are generally capable of transmitting multiple RF carriers in one RF band. 
     The Federal Communications Commission (FCC) in the United States, and their equivalent organizations in other countries, continue to free up new RF bands, which is creating new requirements for both industry standards organizations, such as the 3rd Generation Partnership Project (3GPP) and cellular operators, for advanced wireless communication systems that can efficiently use these new RF bands. 
     Today&#39;s wireless communications standards generally utilize two multiplexing techniques. For example, the GSM and CDMA standards utilize Frequency Domain Duplex (FDD) multiplexing techniques. The WiFi and WiMAX standards utilize Time Domain Duplex (TDD) multiplexing techniques and use a single RF carrier in one RF band. New developments in wireless communications standards that use TDD multiplexing, such as WiFi (802.11ac) and Long-Term Evolution (LTE), specify the transmission and reception of data over multiple RF bands where each RF band has one or more RF carriers. The multiple RF carriers may be contiguous in one RF band (i.e., intra band contiguous), non-contiguous in one RF band (i.e., intra band non-contiguous), or non-contiguous in two RF bands (i.e., inter band non-continuous).  FIG. 1A  shows three contiguous RF carriers in a single RF band, or intra-band;  FIG. 1B  shows two contiguous RF carriers and one non-contiguous RF carrier in a single RF band, or intra-band; and  FIG. 1C  shows two contiguous RF carriers in a first RF band and one RF carrier in a second non-contiguous RF band, or inter-band. 
     A “brute force” method that is typically used to adapt conventional wireless communication systems to accommodate the requirements of new multi-band wireless communications standards involves implementing separate transceivers for each RF band and transmitting and receiving data in each RF band using a single radio. The “brute force” method, however, limits the ability of an operator of the wireless communications systems to manage power consumption of the radio. 
     Examples of known multiband and multicarrier wireless communication systems that are capable of transmitting and receiving data in two RF bands using one or more RF carriers are shown in  FIG. 2A  and  FIG. 2B .  FIG. 2A  and  FIG. 2B  each show a conventional multiband and multicarrier wireless communication system  200  that includes a baseband unit  202  connected to two separate RF transceivers  204 ,  206  by optical cables  208 ,  210 . The two RF transceivers  204 ,  206  are in turn connected to a single multi-band antenna  212  by two RF coax cables  214 ,  216 , respectively. The difference between conventional multiband and multicarrier wireless communication system shown in  FIG. 2A  and the one shown in  FIG. 2B  is that the two RF transceivers  204 ,  206  are packaged into a single box  218  in the conventional multiband and multicarrier wireless communication system shown in  FIG. 2 . 
     Each RF transceiver in a conventional multiband and multicarrier wireless communication system, such as those shown in  FIG. 2A  and  FIG. 2B , includes analog-to-digital converters (ADCs) for converting RF signals between the analog and digital domains, and digital-to-analog-converters (DACs) for converting RF signals between the digital and analog domains. When converting an analog signal to the digital domain, to accurately represent that signal it must be sampled at a frequency between 2 to 5 times the bandwidth of the RF signal. Nyquist theory states that sampling at 2 times the bandwidth of the RF signal is required; however often up to 5 times the bandwidth of the analog RF signal is used in order to cancel out harmonics. Changes in wireless standards have resulted in wireless signals increasing in bandwidth that non-contiguously span intra-band and inter-band frequency ranges, requiring ADCs and DACs with increasing sampling rates. These ADCs and DACs are expensive and inefficient in the use of electrical power. Furthermore, the sampling rates of ADCs and DACs are unlikely to keep pace with the demands placed upon them by the evolving wireless standards. 
     Improvements in the conversion of wideband analog RF signals to the digital domain in multiband and multicarrier wireless systems are therefore desirable. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a graph illustrating power spectral density versus frequency of three transmitted RF signals modulated on three contiguous carriers in a single RF band for a known multicarrier and multiband wireless communication system. 
         FIG. 1B  is a graph illustrating power spectral density versus frequency of a three transmitted RF signals modulated on two contiguous carriers and one disjoint carrier in a single RF band for a known multicarrier and multiband wireless communication system. 
         FIG. 1C  is a graph illustrating power spectral density versus frequency of a two transmitted RF signals modulated on two contiguous carriers in one RF band and one transmitted RF signal modulated a carrier in another RF band known multicarrier and multiband wireless communication system. 
         FIGS. 2A and 2B  are block diagrams of known multiband and multicarrier wireless communication systems. 
         FIG. 3  is a graph illustrating power spectral density versus frequency of a wideband analog RF signal. 
         FIG. 4  is a flowchart illustrating a method of converting wideband analog RF signals to the digital domain in accordance with an embodiment of the present disclosure. 
         FIG. 5  is a block diagram of an analog-to-digital conversion system for converting analog radio frequency (RF) signals to the digital domain in a multiband and multicarrier wireless communications system in accordance with an embodiment of the present disclosure. 
         FIG. 6  is a circuit diagram of an analog-to-digital conversion system for converting analog radio frequency (RF) signals to the digital domain in a multiband and multicarrier wireless communications system in accordance with an embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     For simplicity and clarity of illustration, reference numerals may be repeated among the figures to indicate corresponding or analogous elements. Numerous details are set forth to provide an understanding of the embodiments described herein. The embodiments may be practiced without these details. In other instances, well-known methods, procedures, and components have not been described in detail to avoid obscuring the embodiments described. The description is not to be considered as limited to the scope of the embodiments described herein. Reference to specific elements of various embodiments of the present disclosure will now be made. 
     The present disclosure generally relates to a method and system for converting wideband analog radio frequency (RF) signals between the analog and digital domains. 
     The method of the present disclosure takes advantage of the difference between the sum of the bandwidths of narrowband analog RF signals that make up a wideband analog RF signal and the total bandwidth of the wideband analog RF signal, as shown in  FIG. 3 .  FIG. 3  shows a graph of the power spectral density versus frequency of an example wideband analog RF signal. The wideband analog RF signal  302  is made up of or includes three narrowband analog RF signals  304 ,  306 ,  308 . The narrowband analog RF signal  304  has a spectral range or bandwidth BWA, the narrowband analog RF signal  306  has a spectral range or bandwidth BWB, and the narrowband analog RF signal  308  has a spectral range or bandwidth BWC. The total occupied bandwidth of the three narrowband analog signals  304 ,  306 ,  308  is equal to the sum of BWA, BWB and BWC, and is always less that the total bandwidth of the wideband analog RF signal  302 . 
     The present disclosure provides a method and system that tracks the occupied bandwidth of the narrowband analog RF signals that make up a wideband analog RF signal rather than a total bandwidth of the wideband analog RF signal. 
     A flowchart illustrating a method of converting wideband analog RF signals to the digital domain according to an embodiment of the present disclosure is shown in  FIG. 4 . The method is performed by an analog-to-digital conversion system that is implemented in a RF transceiver of a multiband and multicarrier wireless communication system. 
     The method begins at  400  and proceeds to step  405 . At step  405 , a wideband analog RF signal is received. The wideband analog RF signal that is received includes one or more narrowband analog RF signals. Each narrowband analog RF signal occupies a distinct non-overlapping spectral band within a spectrum of the wideband analog RF signal. After receiving wideband analog RF signal, the method proceeds to step  410 . At step  410 , the method analog-to-digital converts only the narrowband analog RF signals occupying the distinct non-overlapping spectral bands, and the methods ends at step  415 . 
     In an embodiment, the step  410  of analog-to-digital converting only the narrowband RF analog signals occupying the distinct non-overlapping spectral bands includes separating the one or more narrowband analog RF signals from the wideband analog RF signal. 
     In another embodiment, separating the one or more narrowband analog RF signals from the wideband analog RF signal, which is part of step  410 , includes down converting the first wideband analog RF signal to pairs of orthogonal baseband analog signals using a set of down conversion frequencies, where each down conversion frequency is tuned to a center of one of the distinct non-overlapping spectral bands, and filtering the pairs of orthogonal baseband analog signals to generate a set of filtered orthogonal analog baseband signals, each pair of filtered orthogonal analog baseband signals corresponding to one of the distinct narrowband analog RF signals. In another embodiment, the step  410  of analog-to-digital converting includes converting each pair of filtered orthogonal analog baseband signals to a pair of digital signals. 
     In another embodiment, the step  410  of analog-to-digital converting includes converting each of the first pairs of filtered orthogonal baseband analog signals to pairs of digital signals. In another embodiment, down converting includes amplifying each of the first pairs of orthogonal baseband analog signals. In still another embodiment, filtering includes filtering the first pairs of amplified orthogonal baseband analog signals to generate the first pairs of filtered orthogonal baseband analog signals. 
     In another embodiment, the first pairs of orthogonal baseband signals each include a first in-phage baseband signal and a first quadrature baseband signal 
     In another embodiment, the method includes, similar to step  405 , receiving a second wideband analog RF signal comprising one or more second narrowband RF analog signals, each of the second narrowband analog RF signals occupying a distinct non-overlapping spectral band within a spectrum of the second wideband analog RF signal, wherein the first and second wideband analog RF signals are spectrally non-overlapping. The method further includes, similar to step  410 , analog-to-digital converting only the second narrowband RF analog signals occupying the distinct non-overlapping spectral bands within a spectrum of the second wideband analog RF signal. 
     In another embodiment, analog-to-digital converting only the second narrowband analog RF signals occupying the distinct non-overlapping spectral bands includes separating the one or more second narrowband analog RF signals from the second wideband analog RF signal. 
     In another embodiment, wherein separating the one or more second narrowband analog RF signals from the second wideband analog RF signal includes down converting the second wideband analog RF signal to second pairs of orthogonal baseband analog signals using a set of down conversion frequencies, where each down conversion frequency is tuned to a center of one of the distinct non-overlapping spectral bands, and filtering the pairs of orthogonal baseband analog signals to generate pairs of filtered orthogonal baseband analog signals, each pair of filtered orthogonal baseband analog signals corresponding to one of the distinct narrowband analog RF signals. 
     Referring now to  FIG. 5 , a block diagram of an analog-to-digital conversion system  500  for converting wideband analog radio frequency (RF) signals to a digital domain according to an embodiment of the present disclosure. The analog-to-digital converter system  500  is implemented in an RF transceiver of a multiband and multicarrier wireless and is configurable so that the system  500  can convert up to N wideband analog RF signals to the digital domain. Each of the N wideband analog RF signals can include one or more narrowband analog RE signals. Each of the narrowband analog RF signals occupies a distinct non-overlapping spectral band within a spectral range of its corresponding wideband analog RE signal. 
     The analog-to-digital conversion system  500  includes a first cross-connect switch  502 , N down converter modules  504 , a second cross-connect switch  506 , and N analog-to-digital converters (ADCs)  508 , where N is a positive integer. In an embodiment, the N ADCs are time-interleaved ADCs. 
     The first cross-connect switch  502  includes N inputs for receiving wideband analog RE signals and N outputs. Each of the N outputs is electrically connected to one of the N down converter modules  504 . The first cross-connect switch  502  is configurable to electrically connect any of the N inputs to one or more of the N down converter modules  504 . Similarly, the second cross-connect  506  is configurable to electrically connect any one of the down converter modules  504  to one or more of the N ADCs  508 . In an implementation, the cross connect switch  502  or  506  can distribute a single input to multiple outputs. 
     In an embodiment, in operation, the first cross-connect  504  receives a wideband analog RE signal that includes M narrowband analog RE signals, where M is a positive integer. Each of the M narrowband analog RE signals occupies a distinct non-overlapping spectral band within a spectrum of the wideband analog RE signal. The first cross-connect  504  is configured such that the wideband analog RF signal is output to M down converter modules  506 . Each of the M down converter modules  504  is tuned a center frequency of one of the distinct non-overlapping bands. The M down converter modules  504  divide or separate only the M analog narrowband RE signals from the wideband analog RE signal and output the M analog narrowband RE signals to a second cross-connect switch  506 . The second cross-connect switch  506  is configured to output each of the M analog RF signals to an appropriate ADC module  508 . Each appropriate ADC module  508  samples the narrowband analog RE signal it receives and outputs a digital representation of the narrowband analog RE signal for post-processing into a single digital signal that represent the original wideband analog RE signal. 
     In an embodiment, ADC modules  508  may be enabled and disabled so that only those ADC modules  508  necessary for converting a wideband analog RF signal are enabled. 
       FIG. 6  shows a circuit diagram of an analog-to-digital converter system  600  for converting wideband analog signals to the digital domain according to an embodiment of the present disclosure. The analog-to-digital converter system  600  is implemented in an RF transceiver of a multiband and multicarrier wireless communication system and is configurable so that the system  600  can convert up to two wideband analog RF signals to the digital domain. Each of the two wideband analog RF signals can include either one narrowband analog RF signal or two narrowband analog RF signals, where each of the narrowband analog RF signals occupies a distinct non-overlapping spectral band within a spectral range of the wideband analog RF signal. 
     The system  600  includes a first amplifier  602  and a second amplifier  604 . The first amplifier  602  has a pair of inputs  606   a ,  606   b  for receiving a first wideband analog RF signal and an output that is electrically connected by  608  to a first input of a first cross-connect  610 . The second amplifier  604  also has a pair of inputs  612   a ,  612   b  for receiving a second wideband analog RF signal and an output that is electrically connected by  614  to a second input of the first cross-connect  610 . In the example embodiment shown in  FIG. 6 , the first and second wideband analog RF signals are differential analog RF signals. 
     The first cross-connect  610  also has a first output that is electrically connected by  516  to a first input of a first down converter module  618  and a second output that is electrically connected by  620  to a first input of a second down converter module  622 . The first cross-connect  610  is configurable to electrically connect the output of the first amplifier  602  to: (1) the first input of the first down converter module  618 ; (2) the first input of the second down converter module  622 ; or (3) the first input of both the first and second down converter modules  618 ,  622 . Similarly, the first cross-connect  610  is configurable to electrically connect the output of the second amplifier  64  to: (1) the input of the first down converter module  618 ; (2) the first input second down converter module  622 ; or (3) the first inputs of both the first and second down converter modules  620 ,  624 . Thus, the first down converter module  618  is capable of receiving the wideband analog RF signal from the output of the first amplifier  602  or the second wideband analog RF signal from the output of the second amplifier  604 , depending on the configuration of the first cross-connect  610 . Also, the second down converter module  618  is capable of receiving the wideband analog RF signal from the output of the first amplifier  602  or the second wideband analog RF signal from the output of the second amplifier  606 , again depending on the configuration of the first cross-connect  610 . 
     Referring again to  FIG. 6 , the system  600  also includes a first local oscillator  624  for generating a first local oscillator signal and a second local oscillator  626  for generating a second oscillator signal. The first and second local oscillators  624 ,  626  are electrically connected by  628 ,  630 , respectively, to a local oscillator selector  632 . The local oscillator selector  632  is configurable to electrically connect, by  634 , one of the first oscillator signal generated by the first local oscillator  626  and the second oscillator signal generated by the second local oscillator  628  to a second input of the first down converter module  618 . The local oscillator selector  632  is also configurable to electrically connect, by  636 , one of the first oscillator signal generated the first local oscillator  626  and the second oscillator signal generated by the second local oscillator  628  to a second input of the second down converter module  622 . 
     The first down converter module  618  includes a first pair of mixers  638   a ,  638   b , a first pair of amplifiers  640   a ,  640   b , a first pair of filters  642   a ,  642   b , and a first phase shifter  644 . The first phase shift generator  644  receives, by  634 , one of the first and second local oscillator signals from the local oscillator selector  632 , generates a first in-phase signal and a first quadrature signal from the one of the first and second local oscillator signals, and provides the in-phase and quadrature signals to the mixers  638   a ,  638   b , respectively. 
     Similarly, the second down converter module  622  includes a second pair of mixers  646   a ,  646   b , a second pair of amplifiers  648   a ,  648   b , a second pair of filters  650   a ,  650   b  and a second phase shifter  652 . The second phase shift generator  652  receives by  636 , one of the first and second local oscillator signals from the local oscillator selector  632 , generates a second in-phase signal and a second quadrature signal from the one of the first and second local oscillator signals, and provides the in-phase and quadrature signals to the mixers  648   a ,  648   b , respectively. 
     The first pair of filters  642   a ,  642   b  is electrical connected to a first pair of inputs of a second cross-connect  654 . Similarly, a pair of outputs of the second pair of filters  650   a ,  650   b  is electrically connected to a first pair of inputs of the second cross-connect  654 . 
     The second cross-connect  654  has a first pair of outputs electrically connected to a first pair of analog-to-digital converters  656   a ,  656   b  and a second pair of outputs electrically connected to a second pair of analog-to-digital converters  658   a ,  658   ab . The second cross-connect  654  is configurable to connect any of the first pair of filters  642   a ,  642   b  and the second pairs of filters  652   a ,  652   b  to any of the first pair of analog-to-digital converters  656   a ,  656   b  and the second pair of analog-to-digital converters  658   a ,  658   b , respectively. Each pair of analog-to-digital converters,  656   a ,  656   b  and  658   a ,  658   b , is electrically connected, by  660 , to a clock generator  662  for receiving a clock signal that has a frequency of two to five times the bandwidth of any of the narrowband analog RF signal occupying the distinct non-overlapping spectral bands. 
     An example of the operation of the analog-to-digital converter system  600  will now be described. In this example, the analog-to-digital conversion system  600  receives only one wideband analog RF signal that includes two narrowband analog RF signals. A first narrowband analog RF signal of the two narrowband analog RF signals occupies a first non-overlapping spectral band within a spectrum of the first wideband analog RF signal. A second narrowband analog RF signal of the two narrowband analog RE signals that occupies a second non-overlapping spectral band within a spectrum of the first wideband analog RE signal. 
     The first cross-connect  610  is configured to electrically connect the output of the first amplifier  602  to the first input of the first down converter module  616  and to the first input of the second down converter module  622 . The second cross-connect  654  is configured such that its first pair of outputs is electrically connected to the first pair of analog-to-digital converters  656   a ,  656   b  and its second pair of outputs is electrically connected to the second pair of analog-to-digital converters  658   a ,  658   b.    
     The local oscillator selector  632  is configured to electrically connect, by  634 , the first clock signal generated by the first local oscillator  624  to the input of the first phase shifter  644  of the first down converter module  616  and to electrically connect, by  536 , the second clock signal generated by the second local oscillator  628  to the input of the second phase shifter  652  of the second down converter module  622 . The first local oscillator  624  is tuned to a center frequency of the first non-overlapping spectral band and the second local oscillator  626  is tuned to a center frequency of the second non-overlapping spectral band. 
     In operation, the first amplifier  602  receives the first wideband analog RF signal and amplifies the first wideband analog RE signal. The amplified first wideband analog RE signal is then provided by the first cross-connect  610  to both the first and second down converter modules  618 ,  622  to separate the first and second narrowband analog RE signals from the first wideband analog RE signal. The first and second narrowband analog RE signals are separated from the wideband analog RF signal as follows. The first down converter module  618  receives the first wideband analog RE from the first amplifier  602  via  608 ,  616 . A first mixer  638   a  of the first pair of mixers  638   a ,  638   b  multiplies the first wideband analog RE signal with the first in-phase signal received from the first phase shifter  644  to generate a first in-phase baseband signal. A second mixer  638   b  of the first pair of mixers  638   a ,  638   b  also multiplies the first wideband analog RE signal with the first quadrature signal received from the first phase shifter  644  to generate a first quadrature baseband signal. The first in-phase baseband signal and first quadrature baseband signal together form a first pair of orthogonal baseband signals. 
     The second down converter module  622  receives the first wideband analog RF from the second amplifier  604  via  614 ,  620 , A first mixer  646   a  of the second pair of mixers  646   a ,  646   b  multiplies the first wideband analog RF signal with the second in-phase signal received from the second phase shifter  652  to generate a second in-phase baseband signal. A second mixer  646   b  of the second pair of mixers  646   a ,  646   b  also multiplies the first wideband analog RF signal with the second quadrature signal received from the second phase shifter  652  to generate a second quadrature baseband signal. The second in-phase and second quadrature baseband signals together form a second pair of orthogonal baseband signals. 
     The first pair of orthogonal baseband signals is provided by the first pair of mixers  638   a ,  638   b  to the first pair of amplifiers  640   a ,  640   b . The first pair of amplifiers  640   a ,  640   b  amplify the first pair of orthogonal baseband signals and provide the first pair of amplified orthogonal baseband signals to the first pair of filters  642   a ,  642   b , which filter or separate the first pair of amplified orthogonal baseband signals corresponding to the first narrowband analog RF signal occupying the first non-overlapping spectral band. The first pair of filtered orthogonal baseband signals includes a first filtered in-phase baseband analog signal and a first filtered quadrature baseband analog signal. The first pair of filtered orthogonal baseband signals is provided by the first pair of filters  642   a ,  642   b  to the first pair of inputs of the second cross-connect  654 . 
     Similarly, the second pair of orthogonal baseband signals is provided by the second pair of mixers  646   a ,  646   b  to the first pair of amplifiers  648 ,  648   b . The second pair of amplifiers  648   a ,  648   b  amplify the second pair of orthogonal baseband signals and provide the second pair of amplified orthogonal baseband signals to the second pair of filters  650   a ,  650   b , which filter out or separate the second pair of amplified orthogonal baseband signals corresponding to the second narrowband analog RF signal occupying the second non-overlapping spectral band within the spectrum of the first wideband analog RF signal. The second pair of filtered orthogonal baseband signals include a second filtered in-phase baseband analog signal and a second filtered quadrature baseband analog signal. The second pair of filtered orthogonal baseband signals are provided by the first pair of filters  644   a ,  654   b  to the first pair of inputs of the second cross-connect  654 . 
     The first pair of inputs of the second cross-connect  654  are electrically connected to the first pair of ADCs  656   a ,  656   b  and the second pair of inputs of the second cross-connect  654  are connected to the second pair of ADCs  658   a ,  658   b . The first pair of ADCs  656   a ,  656   b  receives the first pair of filtered baseband orthogonal signals and converts the first pair of filtered baseband orthogonal signals to a first pair of digital signals using the clock signal provided on  660  by the clock generator  662 . Similarly, the second pair of ADCs  658   a ,  658   b  receives the second pair of filtered orthogonal baseband signals and converts the second pair of filtered orthogonal baseband signals to a second pair of digital signals using the clock signal provided on  660  by the clock generator  662 . Both the first and second pair of digital signals are provided by the analog-to-digital conversion system  600  for further processing as is known in the art. The clock signal provided by on  660  the clock generator  662  samples the first and second pairs of filtered baseband orthogonal signals at two to five times the bandwidth of the first and second non-overlapping spectral bands, respectively. 
     Another example of the operation of the analog-to-digital converter system  600  will now be described. In this example, the analog-to-digital conversion system  600  receives two wideband analog RF signals, where each wideband analog RF signal includes one narrowband analog RF signal. A first narrowband analog RF signal occupies a first non-overlapping spectral band within a spectrum of the first wideband analog RF signal and a second narrowband analog RF signal occupies a second non-overlapping spectral band within a spectrum of the second wideband analog RF signal. 
     The first cross-connect  610  is configured to electrically connect the output of the first amplifier  602  to the first input of the first down converter module  616  and to electrically connect the output of the second amplifier  604  to the first input of the second down converter module  622 . The second cross-connect  654  is configured such that its first pair of outputs are electrically connected to the first pair of analog-to-digital converters  656   a ,  656   b  and its second pair of outputs is electrically connected to the second pair of analog-to-digital converters  658   a ,  658   b.    
     The local oscillator selector  632  is configured to electrically connect, by  634 , the first clock signal generated by the first local oscillator  624  to the input of the first phase shifter  644  of the first down converter module  616  and to electrically connect, by  636 , the second clock signal generated by the second local oscillator  628  to the input of the second phase shifter  652  of the second down converter module  622 . The first local oscillator  624  is tuned to a center frequency of the first non-overlapping spectral band and the second local oscillator  626  is tuned to a center frequency of the second non-overlapping spectral band. 
     In operation, the first amplifier  602  receives the first wideband analog RF signal and amplifies the first wideband analog RF signal. The first amplified wideband analog RF signal is then provided by the first cross-connect  610  to the first converter module  618  to separate the first narrowband analog RF signal from the first wideband analog RF signal. The second amplifier  604  receives the second wideband analog RF signal. The second amplified wideband analog RF signal amplifies is the provided by the first cross-connect  610  to the second converter module  622  to separate the second narrowband analog RF signal from the second wideband analog RF signal. 
     The first and second narrowband analog RF signals are separated from the first and second wideband analog RF signals, respectively, as follows. The first down converter module  618  receives the first amplified wideband analog RF from the first amplifier  602  via  608 ,  616 . A first mixer  638   a  of the first pair of mixers  638   a ,  638   b  multiplies the first wideband analog RF signal with the first in-phase signal received from the first phase shifter  644  to generate a first in-phase baseband signal. A second mixer  638   b  of the first pair of mixers  638   a ,  638   b  also multiplies the first amplified wideband analog RF signal with the first quadrature signal received from the first phase shifter  644  to generate a first quadrature baseband signal. The first in-phase and first quadrature baseband signals together form a first pair of orthogonal baseband signals. 
     The second down converter module  622  receives the second amplified wideband analog RF from the second amplifier  604  via  614 ,  620 . A first mixer  646   a  of the second pair of mixers  646   a ,  646   b  multiplies the second amplified wideband analog RF signal with the second in-phase signal received from the second phase shifter  652  to generate a second in-phase baseband signal. A second mixer  646   b  of the second pair of mixers  646   a ,  646   b  also multiplies the second amplified wideband analog RF signal with the second quadrature signal received from the second phase shifter  652  to generate a second quadrature baseband signal. The second in-phase and second quadrature baseband signals together form a second pair of orthogonal baseband signals. 
     The first pair of orthogonal baseband signals is provided by the first pair of mixers  538   a ,  538   b  to the first pair of amplifiers  640   a ,  640   b . The first pair of amplifiers  640   a ,  540   b  amply the first pair of orthogonal baseband signals and provide the first pair of amplified orthogonal baseband signals to the first pair of filters  642   a ,  642   b , which filter or separate the first pair of amplified orthogonal baseband signals corresponding to the first narrowband analog RE signal occupying the first non-overlapping spectral band within the spectrum of the first wideband analog RE signal. The first pair of filtered orthogonal baseband signals includes a first filtered in-phase baseband analog signal and a first filtered quadrature baseband analog signal. The first pair of filtered orthogonal baseband signals is provided by the first pair of filters  642   a ,  642   b  to the first pair of inputs of the second cross-connect  654 . 
     Similarly, the second pair of orthogonal baseband signals is provided by the second pair of mixers  646   a ,  546   b  to the first pair of amplifiers  648 ,  648   b . The second pair of amplifiers  648   a ,  648   b  amply the second pair of orthogonal baseband signals and provide the second pair of amplified orthogonal baseband signals to the second pair of filters  650   a ,  650   b , which filter out or separate the second pair of amplified orthogonal baseband signals corresponding to the second narrowband analog RF signal occupying the second non-overlapping spectral band within the spectrum of the second wideband analog RF signal. The second pair of filtered orthogonal baseband signals include a second filtered in-phase baseband analog signal and a second filtered quadrature baseband analog signal. The second pair of filtered orthogonal baseband signals are provide by the first pair of filters  644   a ,  654   b  to the first pair of inputs of the second cross-connect  654 . 
     The first pair of inputs of the second cross-connect  654  are electrically connected to the first pair of ADCs  656   a ,  656   b  and the second pair of inputs of the second cross-connect  654  are connected to the second pair of ADCs  658   a ,  658   b . The first pair of ADCs  656   a ,  656   b  receives the first pair of filtered baseband orthogonal signals and coverts the first pair of filtered baseband orthogonal signals to a first pair of digital signals using the clock signal provided on  660  by the clock generator  662 . Similarly, the second pair of ADCs  658   a ,  658   b  receives the second pair of filtered orthogonal baseband signals and converts the second pair of filtered orthogonal baseband signals to a second pair of digital signals using the clock signal provided on  660  by the clock generator  662 . Both the first and second pair of digital signals are provided by the analog-to-digital conversion system  600  for further processing as is known in the art. The clock signal provided by the clock generator  662  samples the first and second pairs of filtered baseband orthogonal signals at two to five times the bandwidth of the first and second non-overlapping spectral bands, respectively. 
     Advantageously, the method and system of the present disclosure enable a single RF transceiver to efficiently convert wideband analog RF signals between the analog and digital domains. In an embodiment, the analog-to-digital converters of the single RF transceiver track the occupied bandwidth of a plurality of narrowband analog RF signals rather than a total bandwidth of the wideband analog RF signal. This enables the system of the present disclosure to have a smaller form factor, to consume less power, and to be cheaper to manufacture than the known systems used in multiband and multicarrier receivers. 
     Embodiments of the disclosure may be represented as a computer program product stored in a machine-readable medium (also referred to as a computer-readable medium, a processor-readable medium, or a computer usable medium having a computer-readable program code embodied therein). The machine-readable medium can be any suitable tangible, non-transitory medium, including magnetic, optical, or electrical storage medium including a diskette, compact disk read only memory (CD-ROM), memory device (volatile or non-volatile), or similar storage mechanism. The machine-readable medium can contain various sets of instructions, code sequences, configuration information, or other data, which, when executed, cause a processor to perform steps in a method according to an embodiment of the disclosure. Those of ordinary skill in the art will appreciate that other instructions and operations necessary to implement the described implementations may also be stored on the machine-readable medium. The instructions stored on the machine-readable medium may be executed by a processor or other suitable processing device, and may interface with circuitry to perform the described tasks. 
     The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the claims should not be limited by the preferred embodiments set forth in the examples, but should be given the broadest interpretation consistent with the description as a whole. All changes that come with meaning and range of equivalency of the claims are to be embraced within their scope.