Patent Publication Number: US-9425753-B2

Title: Low-noise amplifier matching

Description:
BACKGROUND 
     1. Field 
     The present invention relates generally to low-noise amplifier matching devices. 
     2. Background 
     Multi-mode, multi-standard wireless communication devices usually require one or more high performance radio receivers, which should provide adequate signal-to-noise (SNR) performance for weak signals to achieve maximum sensitivity performance. Additionally, a multi-mode receiver should linearly handle signal and interference levels over a wide dynamic range with minimal distortion. That is, high linearity performance is needed. Distortion within a receiver may be caused by, for example, intermodulation and gain compression. Higher linearity results in reduced intermodulation levels and gain compression. Consequently, low noise, high gain performance is also needed. Typically, receiver design techniques, which simultaneously provide both high linearity and low noise, are difficult to achieve and are subject to design compromises. 
     One important constituent of a high performance receiver is a low-noise amplifier (LNA). An LNA may be a major determinant of the overall noise performance of the receiver. In other words, the characteristics of the LNA, such as high linearity and low noise, may dominate the overall receiver performance. Generally, an LNA is placed at the front-end of a receiver, near a receive antenna interface, to minimize radio frequency (RF) losses between an antenna and the LNA. The LNA is designed to provide high gain while contributing a minimal amount of excess noise beyond the noise appearing at an LNA input. This property is known as a low noise figure. To achieve a high linearity characteristic, the LNA should also have a high third-order input intercept point (IIP3), which is an input level where the third-order intermodulation product level equals the extrapolated linear desired output level. In general, a high value of IIP3 indicates high linearity performance. 
     Transceiver devices are shrinking in size while adding more LNAs to cover more frequency bands and more modes. Conventional RF transceiver application specific integrated circuits (ASICs) may include at least 20 LNAs to cover low bands (600 MHz to 960 MHz), middle bands (1400 to 2100 MHz) and high bands (2200 MHz to 2700 MHz). Device packages including at least 20 LNAs may be around 3.8 millimeters by 3.8 millimeters, yet the passive matching components for each LNA occupy area three times the size of a transceiver device. Moreover, each LNA must be manually impedance matched for best noise figure and gain, thus, consuming additional time. Accordingly, receiver LNA matching takes up a large amount of area, and requires significant effort to change each part. A typical LNA may have two passive matching components and, assuming 20 primary receiver LNAs and 20 diversity receiver LNAs, a receiver can include around 80 passive matching components. 
     A need exists for an enhanced wireless communication device. More specifically, a need exists for embodiments related to a wireless communication device including a programmable LNA matching device. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a device including a transceiver application specific integrated circuit, in accordance with an exemplary embodiment of the present invention. 
         FIG. 2  depicts a wireless communication device. 
         FIGS. 2A-2C  illustrate individual portions of the wireless communication device of  FIG. 2 . 
         FIG. 3  is a block diagram of an electronic device, according to an exemplary embodiment of the present invention. 
         FIG. 4  illustrates a device including a transceiver module coupled to a plurality of matching devices, in accordance with an exemplary embodiment of the present invention. 
         FIG. 5  illustrates another device including a transceiver module coupled to a plurality of matching devices, according to an exemplary embodiment of the present invention. 
         FIG. 6  illustrates a matching device, according to an exemplary embodiment of the present invention. 
         FIG. 7  illustrates another matching device, in accordance with an exemplary embodiment of the present invention. 
         FIG. 8  illustrates yet another matching device, according to an exemplary embodiment of the present invention. 
         FIG. 9  is a Smith Chart illustrating an example selection of an inductor value. 
         FIG. 10  depicts a device including a plurality of matching devices coupled to a transceiver module, according to an exemplary embodiment of the present invention. 
         FIG. 11  depicts a system including a matching device and a low-noise amplifier, in accordance with an exemplary embodiment of the present invention. 
         FIG. 12  is a plot illustrating an output of a noise figure measurement unit. 
         FIG. 13  is a flowchart depicting a method, in accordance with an exemplary embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     The detailed description set forth below in connection with the appended drawings is intended as a description of exemplary embodiments of the present invention and is not intended to represent the only embodiments in which the present invention can be practiced. The term “exemplary” used throughout this description means “serving as an example, instance, or illustration,” and should not necessarily be construed as preferred or advantageous over other exemplary embodiments. The detailed description includes specific details for the purpose of providing a thorough understanding of the exemplary embodiments of the invention. It will be apparent to those skilled in the art that the exemplary embodiments of the invention may be practiced without these specific details. In some instances, well-known structures and devices are shown in block diagram form in order to avoid obscuring the novelty of the exemplary embodiments presented herein. 
     Conventional transceivers of wireless communication devices are designed for global band and mode coverage, and may exceed 20 frequency bands in a single mobile handset. Further, as illustrated below in  FIGS. 1 and 2 , conventional transceivers may require a multitude of LNAs with band select filters for each receive signal path. A transceiver may include a switch that selects each receive signal path with the appropriate filters, LNA match, and accompanying LNA for the selected receiver paths. Further, transceivers may use an antenna switch module (ASM) followed by one or more filters, and, in many cases another switch depending on the number of LNAs or carrier aggregation. Each LNA within the transceiver may include two or three passive matching components, and passive matching component area may exceed transceiver ASIC area by several orders of magnitude. Despite receiver and LNA simulation that predicts starting LNA match values, manual empirical matching is still needed due to printed circuit board (PCB) parasitic and non-ideal passive components. Further, more LNA passive components equate to significantly more time devoted to matching. 
       FIG. 1  illustrates a device  100  including a transceiver ASIC  102  including LNAs  103 . Device  100  further includes primary receiver LNA matching circuitry  104  and diversity receiver LNA matching circuitry  106 . As illustrated in  FIG. 1 , each LNA  103  is coupled to dedicated matching components, which results in increased matching component area. 
       FIG. 2  illustrates a wireless communication device  200  including a portion  202  illustrated in detail in  FIG. 2A , a portion  204  illustrated in detail in  FIG. 2B , and a portion  206  illustrated in detail in  FIG. 2C . With reference to  FIG. 2A , communication device  200  includes a primary antenna  208  coupled to a first antenna module  210  and a diversity antenna  212  coupled to a second antenna module  214 . First antenna module  210  includes a switch  216  coupled to duplexers  220 A- 220 C. Further, second antenna module  214  includes a switch  222  coupled to a plurality of LNA paths including LNA matching circuits  224 A- 224 D associated with second antenna module  214  and diversity antenna  212 . It is noted that device  200  may include additional LNA receive paths (e.g., 20-30 LNA receive paths) associated with second antenna module  214  and diversity antenna  212 . 
     With reference to portion  204  illustrated in  FIG. 2B , device  200  further includes additional LNA matching circuits  224 E- 224 G within LNA receive paths associated with first antenna module  210  and primary antenna  208 . It is noted that device  200  may include additional LNA receive paths (e.g., 20 LNA receive paths) associated with first antenna module  210  and primary antenna  208 . With continued reference to portion  204 , device  200  also includes a transceiver integrated circuit (IC)  226  including a plurality of LNAs, wherein each LNA is associated with a dedicated LNA path. With reference to portion  206  illustrated in  FIG. 2C , device  200  may also include a mobile station modem ID  230  coupled to transceiver IC  226  (see  FIG. 2B ). As will be appreciated by a person having ordinary skill in the art, device  200 , which comprises a conventional transceiver, requires a multitude of LNAs with band select filters for each receive signal path. 
     Exemplary embodiments, as described herein, are directed to devices and methods related to programmable LNA matching. In accordance with various exemplary embodiments of the present invention, a programmable matching device, which allows for automated receiver noise matching for minimum receiver noise figure, may greatly reduce a significant number of LNA matching components within a wireless communication device. The programmable LNA matching device may include one or more built-in broad-band switches to multiplex LNA inputs from many band select filters including duplexers. Accordingly, one broad-band LNA, or a small number of LNAs, can service a large number of frequency bands such that a processor, using a settings lookup table, can set an optimum LNA match setting for each band. The programmable LNA may require one or more external inductors for various embodiments in order to realize higher Q. Other embodiments including glass or sapphire substrates could employ in package high Q inductors for a completely integrated solution. Further, embodiments may include integrated passive devices on glass along with a device die for a highly compact software controlled tunable device. Additionally, embodiments could integrate programmable LNA matching into a transceiver ASIC eliminating most LNA matching. 
     More specifically, according to one exemplary embodiment, a device may include at least one LNA and an LNA matching device coupled to the at least one LNA and configured to receive one or more control signals to provide an optimal LNA match setting for a selected band of a plurality of frequency bands. Another exemplary embodiment of the present invention includes methods for operating an LNA matching device. Various embodiments of such a method may include receiving a wireless signal at an LNA matching device and conveying the wireless signal from the LNA matching device to an LNA. The method may also include measuring a noise figure of the wireless signal and tuning the LNA matching device to minimize the noise figure for a selected band of a plurality of frequency bands. 
     Other aspects, as well as features and advantages of various aspects, of the present invention will become apparent to those of skill in the art through consideration of the ensuing description, the accompanying drawings and the appended claims. 
       FIG. 3  is a block diagram of an electronic device  300 , according to an exemplary embodiment of the present invention. According to one example, device  300  may comprise a portable electronic device, such as a mobile telephone. Device  300  may include various modules, such as a digital module  302 , an RF module  304 , and a power management module  306 . Digital module  302  may comprise memory and one or more processors. RF module  304 , which may comprise RF circuitry, may include a transceiver  305  including a transmitter  307  and a receiver  309  and may be configured for bi-directional wireless communication via an antenna  308 . In general, wireless communication device  300  may include any number of transmitters and any number of receivers for any number of communication systems, any number of frequency bands, and any number of antennas. According to an exemplary embodiment of the present invention, receiver  309  may include one or more of the exemplary embodiments described below. 
       FIG. 4  illustrates a device  350 , in accordance with an exemplary embodiment of the present invention. Device  350  includes a transceiver module  352  (e.g., a transceiver ASIC) having a plurality of LNA inputs  353 . Further, device  350  includes devices  360 A- 360 D, each of which may be referred to herein as a programmable LNA matching device. Each device  360 A- 360 D is configured to receive a plurality of inputs from, for example, a duplexer (not shown in  FIG. 4 ) and convey an output, which may be received by one of a plurality of LNAs of transceiver module  352 . As illustrated, each device  360 A- 360 D may have an external inductor Lx coupled thereto. By way of example, device  360 A may be configured to receive primary low band (LB) (e.g., 600 MHz to 960 MHz) and/or mid band (MB) (e.g., 1400 to 2100 MHz) inputs from one or more duplexer filter banks, and device  360 B may be configured to receive primary high-band (HB) (e.g., 2200 MHz to 2700 MHz) inputs from one or more duplexer filter banks. Further, device  360 C may be configured to receive diversity HB inputs from one or more duplexer filter banks, and device  360 D may be configured to receive diversity LB and/or MB inputs from one or more duplexer filter banks. As an example, each device  360 A- 360 D may include between four and ten inputs and four outputs. 
       FIG. 5  illustrates another device  380 , according to an exemplary embodiment of the present invention. Device  380  includes a transceiver module  382  (e.g., transceiver ASIC) having a plurality of LNA inputs  353 . Further, device  380  includes devices  380 A- 380 D, each of which may also be referred to herein as a programmable LNA matching device. Each device  380 A- 380 D is configured to receive a plurality of inputs from, for example, a duplexer (not shown in  FIG. 5 ) and convey an output, which may be received by an LNA of transceiver module  382 . As illustrated, each device  380 A- 380 D may have an external inductor Lx coupled thereto. By way of example, device  380 A may be configured to receive primary LB and/or mid band MB inputs from one or more duplexer filter banks, and device  380 B may be configured to receive primary HB inputs from one or more duplexer filter banks. Further, device  380 C may be configured to receive diversity HB inputs from one or more duplexer filter banks, and device  380 D may be configured to receive diversity LB and/or MB inputs from one or more duplexer filter banks. 
     As an example, each device  380 A- 380 D may include between two and ten inputs depending on number of bands or target area savings affected by package size. Further, each device  380 A- 380 D may include, for example, one output. As will be described in more detail below, an LNA matching device may function according to an automated matching algorithm for providing optimal matching for a selected LNA. It is noted that an input multiplexer switch, device die, and passive devices including external inductor Lx may be integrated on a glass or sapphire substrate for a highly integrated compact device solution. 
     Further, according to other embodiments, one or more LNAs may be integrated into device  380  with only one output. 
       FIG. 6  illustrates a device  400 , according to an exemplary embodiment of the present invention. Device  400  includes an LNA matching device  402 , which includes an input unit  403  including a switch S 1  for selectively coupling to one of a plurality of receive paths RX 1 -RX 10 . Although switch S 1  is illustrated as being configured for selectively coupling to one of ten possible receive paths, the present invention is not so limited. Rather, switch Si may be configured for selectively coupling to one of any number of receive paths. LNA matching device  402  further includes switches S 2 -S 4  and variable capacitors C 1  and C 2 . By way of example, variable capacitors C 1  and C 2  may comprise digitally stepped capacitors banks, analog tuned capacitors, or a combination thereof 
     As illustrated, switch S 2  is coupled between a node A and a node B. Node B may be further coupled to a shunt capacitor or a shunt inductor, if needed. A determination as to whether a shunt capacitor or shunt inductor should be coupled to node B may be based on the LNA optimum source impedance for best noise figure. Further, switch S 3  is coupled between node A and a node C, which is also coupled to a node D. Variable capacitor C 2  is coupled between node C and a node E, which may be further coupled to a ground voltage. Variable capacitor C 1  is coupled between node E and a node G, which may be further coupled to a shunt capacitor, if needed. Further, switch S 4  is coupled between node G and a node F. Node F is further coupled to an output unit  410 , which includes a switch S 5  for selectively coupling to one of a plurality of LNA inputs (i.e., LNA inputs LNA 1 -LNA 4 ). 
     Device  400  further includes an inductor L 1 , which is external to LNA matching device  402  and is coupled between nodes F and D. In addition, LNA matching device  402  may include a controller  404 , which may be configured for interfacing with another, external controller and for controlling operation of switches S 1 -S 5  and variable capacitors C 1  and C 2 . 
     According to one exemplary embodiment, controller  404  may select configurations of switches S 5  and S 1  depending on a band of operation. Further, controller  404  may configure switches S 3 , S 4 , and S 2  as needed to allow the selection of values for capacitors C 1  and C 2  combined with inductor L 1  and the optional Shunt C or L, if needed. If an LNA is designed for optimum noise figure near the characteristic impedance of a receiver (usually 50 ohms in most radio systems), then the topology of the exemplary embodiment shown in  FIG. 6  is sufficient. Depending on the location of the LNA minimum noise figure (e.g., on a Smith Chart), the source impedance is transformed such that an optimization algorithm may select values closest to the best noise figure location. It is noted that parasitics introduced by switch S 5  may be compensated by the design of device  400  with the proper selection of a value of inductor L 1 , and capacitor ranges for capacitors C 1  and C 2 . 
       FIG. 7  illustrates a device  450 , according to another exemplary embodiment of the present invention. Device  450  includes an LNA matching device  452  including an input  453  coupled to a receive path. LNA matching device  452  further includes switches S 2 -S 4  and variable capacitors C 1  and C 2 . Similar to LNA matching device  402  (see  FIG. 6 ), switch S 2  is coupled between node A and node B. Node B may be further coupled to a shunt capacitor or a shunt inductor, if needed. Further, switch S 3  is coupled between node A and node C, which is also coupled to node D. Variable capacitor C 2  is coupled between node C and node E, which may be further coupled to a ground voltage. Variable capacitor C 1  is coupled between node E and node G, which may be further coupled to a shunt capacitor, if needed. Further, switch S 4  is coupled between node G and a node H. Node H is further coupled to an output  460 , which may be coupled to an input of an LNA. 
     Device  450  further includes inductor L 1 , which is external to LNA matching device  452  and coupled between nodes H and D. In addition, LNA matching device  452  may include controller  404 , which may be configured for interfacing with another, external controller and for controlling operation of switches S 2 -S 4  and variable capacitors C 1  and C 2 . Unlike device  400  of  FIG. 6 , device  450  does not include multiplex switches and, therefore, does not include the associated insertion losses plus parasitic. The operation of device  450  may be the same as device  400  wherein node B could have an optional shunt C or shunt L depending on where the LNA optimum impedance is needed for best gain and noise figure. 
       FIG. 8  illustrates a device  500 , according to an exemplary embodiment of the present invention. Device  500  includes an LNA matching device  502 , which includes an input unit  503  including switch Si for selectively coupling to one of a plurality of low frequency inputs from, for example, a front end duplexer bank. Although switch S 1  is illustrated as being configured for selectively coupling to one of ten receive paths, the present invention is not so limited. Rather, switch Si may be configured for selectively coupling to one of any number of receive paths. LNA matching device  502  further includes switches S 2 -S 4  and variable capacitors C 1  and C 2 . Similar to LNA matching device  402  (see  FIG. 6 ), switch S 2  is coupled between node A and node B, which may be further coupled to a shunt capacitor or a shunt inductor, if needed. Further, switch S 3  is coupled between node A and node C, which is also coupled to node D. Variable capacitor C 2  is coupled between node C and node E, which may be further coupled to a ground voltage. Variable capacitor C 1  is coupled between node E and node G, which may be further coupled to a shunt capacitor, if needed. Further, switch S 4  is coupled between node G and node H. Node H is further coupled to an output  461 , which may be coupled to an input of an LNA. 
     As will be appreciated by a person having ordinary skill in the art, radio frequencies below 800 MHz may require physically larger, higher value matching inductors that have a high Q. Further, to save board area, two series connected small high Q inductors may be used instead of a physically large high Q inductor. Accordingly, as illustrated in  FIG. 8 , device  500  further includes inductor L 1 , which is external to LNA matching device  502  and coupled between nodes H and D. An additional inductor L 2 , which is also external to LNA matching device  502 , is coupled between node D and a node J. 
     LNA matching device  502  may further include controller  404 , which may be configured for interfacing with another, external controller and for controlling operation of switches S 1 -S 4  and variable capacitors C 1  and C 2 . The operation of device  500  may be the same as device  400  except device  500  does not include switch S 5 , and switch S 3  is open, causing the signal to pass through inductor L 2 . Device  500  may use a shunt capacitor C 3  with inductor L 2 , capacitor C 2 , inductor L 1  and perhaps capacitor C 1  to match a low frequency LNA. 
     Various receiver components, such as transceiver module  382  and LNA inputs  353  (see  FIG. 5 ), can employ a wide-band LNA using exemplary embodiments of the invention as a programmable LNA match that can be re-adjusted depending on the frequency band selected via switch S 1  in device  500 . Further, device  500  can be used for any band segmentation where low bands may need two series inductors, while the middle bands (typically 1400 MHz to 2100 MHz) may need only one inductor, and high bands (typically 2200 MHz to 2700 MHz or higher) may need only one inductor of a different value. The plurality of LNA inputs and associated matching components of a device (e.g., device  380  illustrated in  FIG. 5 ) may be reduced to, for example, four packaged parts and four inductors by implementing device  500 , thus resulting in area savings, decreased time for manual passive component matching, and software reconfigurable matching. Further , device  500  may enable easy modification of a front-end design for new or different frequency bands without manually re-matching the LNA. Moreover, a software lookup table, for example, can re-select values for capacitors C 1 , C 2 , and C 3  for a new band, saving time and money, and supporting multiple products for multiple market areas. 
     As will be appreciated by a person skilled in the art, a transceiver front-end, which may include a transmit-receive antenna radio-frequency switch and duplexer filters for the bands of interest, may be designed for carrying out various embodiments of the present invention. By printed circuit board design, component selection, and simulation, a person skilled in the art may determine the source impedance (Zs) across the band of interest, for example, as seen from input  453  of device  450  illustrated in  FIG. 7 . Additionally, the impedance required by the LNA for best noise figure and gain at a specific frequency within each frequency band of interest may be predicted via simulation or other test. Further, knowledge of the LNA noise figure and gain circles may be helpful but are not always necessary. Note that it may be difficult to have best noise figure and best gain at the same time across the frequency band. In addition to the source impedance, a locus of points where the best noise figure is predicted and an operating range may be determined Therefore, a value of inductor L 1  may be selected such that the capacitor values of C 1  and C 2  may cover the locus of points for best noise figure and cover a range of gain (gain circles), such that the source impedance enables the LNA to operate at the best combination of noise figure and gain for the best system output SNR. 
       FIG. 9  depicts a Smith Chart illustrating an example for selecting an inductor value for an LNA matching device. In this example, an inductor value for inductor L 1  of device  450  (see  FIG. 7 ) is selected wherein switch S 2  is open, switch S 3  is closed, and node B is not coupled to a shunt capacitor or a shunt inductor. Further, a source impedance is equal to 40-j12 ohms at 890 Mhz within an 860 MHz to 960 MHz range (e.g., B 5  and B 8  down link). As will be understood by a person having ordinary skill in the art, the optimal LNA noise figure may be Zopt=63+j8 Ohms; however, the optimal gain may be slightly off from this and may change across the band. The value of inductor L 1  is selected such that the range of capacitors C 1  and C 2  produces a locus of points around Zopt as an optimization algorithm (e.g., optimization algorithm  630  of  FIG. 11 ) searches for the optimal values of C 1  and C 2  which gives the best combination of system gain and cascaded noise figure. It is noted that the optimization algorithm may not know anything about the impedance and it may select the values for capacitors C 1  and C 2  and optimize based on the measured noise figure or output SNR. By the Friis&#39; formula, the LNA noise factor and gain dominates the system cascaded noise factor. In the diagram below, L 1  is a fixed value while C 1  and C 2  are randomly varied in value. Note that this example assumes the device parasitic shunt capacitance is included in capacitors C 1  and C 2 . With specific reference to  FIG. 9 , reference numeral  532  represents a range of values of capacitor C 1  and C 2  steps with a selected value of inductor L 1  over the frequency band of interest. Further, reference numeral  534  represents a selection of a fixed value of inductor L 1  to allow the range of values for capacitor C 1  and C 2  to cover a locus of points  536  for an optimal impedance (e.g., the best system output SNR). 
     A person skilled in the art selects a fixed inductor L 1  for the frequency band of interest such that the device along with the matching optimization algorithm can select the optimum values of C 1  and C 2  such that the system output SNR is maximum when measured with a continuous wave reference tone. This reference tone can be an external signal generator set for a known input SNR for a more precise measurement of system noise figure (NF) (with an optimum NF target or output SNR target the optimization algorithm will converge on settings for C 1  and C 2  quickly), or it can be an internal reference tone level set with some uncertainty so the system optimizes for best case output SNR. Proper selection of L 1  with any of the exemplary embodiments match optimization over a wide operating bandwidth which might not be possible without manually changing passive components or using external RF switches with passive components. Finally, some designs may not need a series inductance. A short transmission line connection in place of L 1  may be all that is needed. 
       FIG. 10  depicts a device  550 , according to another exemplary embodiment of the present invention. Device  550  includes a primary transceiver  552  and a diversity transceiver  554 . Device  550  further includes devices  556  and  558  coupled to primary transceiver  552 , and devices  560  and  562  coupled to diversity transceiver  554 . Each of devices  556 ,  558 ,  560 , and  562  may comprise device  400  (see  FIG. 6 ), device  450  (see  FIG. 7 ), device  500  (see  FIG. 8 ), or any combination thereof As illustrated in  FIG. 10 , each device  556 ,  558 ,  560 , and  562  is configured for selectively coupling to one of a plurality of LNAs. According to one exemplary embodiment, devices  556  and  558  may replace LNA matching devices  224 E,  224 F,  224 G, and so on (see  FIG. 2B ), resulting in fewer parts. Similarly, devices  560  and  562  may replace LNA matching devices  224 A,  224 B,  224 C,  224 D, and so on (see  FIG. 2A ), resulting in fewer parts. 
       FIG. 11  is a diagram of a system  600 , in accordance with yet another exemplary embodiment of the present invention. As will be appreciated by a person having ordinary skill in the art, system  600  may be configured to select values for capacitors C 1  and C 2  for an optimal output SNR of an LNA given a known input SNR of the LNA. System  600  includes a signal generator  602  coupled to an input of a programmable LNA matching device  610 . It is noted that programmable LNA matching device  610  may comprise one of the LNA matching devices described herein (i.e., LNA matching device  402 , LNA matching device  452 , or LNA matching device  502 ). Further, system  600  includes an inductor L, which is external to and coupled to LNA matching device  610 . An output of LNA matching device  610  may connect to an LNA port, or LNA ports, of a transceiver module  609 , depending on a particular embodiment. As an example, transceiver module  609  may comprise a transceiver ASIC. Transceiver module  609  includes an LNA  622  and a down-converter and low-pass filter (LPF)  624 . Within transceiver module  609 , an LNA RF output signal is down-converted via down-converter and LPF  624  and conveyed to a modem processor  611 . Modem processor  611  includes an analog-to-digital converter (ADC)  640  and a sample server  642 . ADC  640 , which may be configured with a known sampling rate, may receive an output of down-converter and LPF  624  and may couple to a memory or sample server  642  that stores N samples to be read out for processing by an optimization algorithm. Sample server  642  may output data via a USB to an external PC or some other bus to an applications processor. 
     Module  620 , which may comprise a software or algorithm module, includes a noise figure calculation unit  624 , a convergence unit  626 , an optimization algorithm  630 , and memory  634 . Noise figure calculation unit  624  may be configured to calculate a noise figure from the output SNR and output the result to convergence unit  626 . It is noted that system  600  may use the output SNR in lieu of calculated noise figure. Convergence unit  626  may receive, or may be programmed with, a target noise figure or a target output SNR. Further, convergence unit  626  may keep track of previous measured noise figures, or output SNRs, and compare one or more measurements to the current measurement. When no further improvement is found in the current measurement, system  600  may store an optimal impedance Zopt in memory  634  to build a table of settings for each frequency band of operation supported by device  610 . Module  620  can be part of (e.g., run on) an external PC, a digital signal processor of modem processor  611 , an application processor, or any suitable combination thereof 
     It is noted that system  600  may be configured to determine the maximum output SNR (i.e., which infers minimum or best noise figure). Knowing the input SNR allows module  620  to compute a cascaded noise figure (i.e., noise figure (dB)=SNRin(dB)−SNRout(dB)). In a properly designed receiver system, an LNA gain and noise figure may dominate the system cascaded noise figure. Those skilled in the art will understand that insufficient LNA gain allows for the subsequent parts of a receiver with high noise figure to contribute more to the system noise creating a rapid rise in cascaded noise. Maximizing system output SNR is indicative of optimal LNA signal gain and lowest system noise floor. A target noise figure or output SNR (i.e., continuous wave (CW) SNR and not the minimum detected modulated signal SNR), which may be previously determined, may be used (i.e., by convergence unit  626 ) for comparison to a measured noise figure (or output SNR). 
     An output of convergence unit  626  either triggers a new set of values for capacitors C 1  and C 2  if the target is not met, or outputs to memory  634  to preserve the optimal values for capacitors C 1  &amp; C 2 . Further, optimization algorithm unit  630  may be configured to receive stored optimization data from memory  634  and may continue to search for an optimal setting to produce an optimal result (i.e., compared to the setting stored in memory  634 ). The number of iterations could be determined by a step size or by a quantization of capacitor C 1  and C 2  step. 
     During a contemplated operation of system  600 , LNA matching device  610  may receive a CW reference tone from signal generator  602  of known amplitude and convey an output to LNA  622 . Further, noise figure measurement unit  624  may measure a noise figure of an output of LNA  622 . Further, an output of convergence unit  626  is received by optimization algorithm unit  630 , which may be configured to determine optimal configuration and/or settings of LNA matching device  610  based on one or more parameters of the output of LNA  622 . More specifically, optimization algorithm unit  630  may be configured to determine, based on a signal received from convergence unit  626 , an optimal configuration of one or more switches of LNA matching device  610  and an optimal setting for one or more variable capacitors of LNA matching device  610  to minimize the noise figure of LNA  622 . It is noted that optimization algorithm unit  630  and memory  634  may be part of a digital module, such as digital module  302  illustrated in  FIG. 3 . Further, functionality of optimization algorithm unit  630  may be carried out by one or more processors (e.g., within a digital module). 
     System  600  may function as a feedback loop that terminates when convergence is met. Optimal values of variables within device  610  (e.g., values of capacitors C 1  and C 2 ) may be determined by optimization algorithm unit  630  and set by controller  404 . These variables perform the role of matching an LNA to gamma opt for maximum output SNR (or minimum noise figure). After the variables are set by controller  404  via optimization algorithm unit  630 , an operation of system  600  may begin and a reference tone is sent to device  610  by signal generator  602 . 
     According to an exemplary embodiment, a CW reference tone may be internally generated and optimization algorithm  630  may select values of capacitors C 1  and C 2  for best possible CW SNR. Furthermore, an external reference may be used for comparison in order to determine an error in the self generated tone and, subsequently, the noise figure could be measured and optimized. This exemplary embodiment may require the optimization algorithm to run on a modem processor or application processor. As will be understood, this exemplary embodiment allows a system to self match, self test, and even adapt to new frequencies and new bands with a change in transceiver front end duplexer. Further, it may enable an original equipment manufacturer (OEM) to simply change the duplexer, run a self-match, or a self-tune optimization algorithm. 
       FIG. 12  is a plot  680  illustrating an output of noise figure calculation  624  (see  FIG. 11 ) computed from a known input CW SNR and output SNR. With reference again to  FIG. 11 , if a target match (i.e., convergence) is not met when compared to a desired output SNR (or noise figure), then a new set of inputs values (i.e., values for capacitors C 1  and C 2 ) may be determined again by optimization algorithm unit  630  and set by controller  404 . This process may continue until convergence is met. Optimization algorithm unit  630  may include a mathematically defined optimization algorithm (e.g., Nelder-Mead), which may find the optimal settings of capacitors C 1  and C 2 . 
       FIG. 13  is a flowchart illustrating a method  700 , in accordance with one or more exemplary embodiments. Method  700  may include receiving a wireless signal at a low-noise amplifier (LNA) matching device (depicted by numeral  702 ). In addition, method  700  may also include conveying the wireless signal from the LNA matching device to an LNA (depicted by numeral  704 ). Method  700  may also include measuring a noise figure of the wireless signal (depicted by numeral  706 ). Furthermore, method  700  may include tuning the LNA matching device to minimize the noise figure for a selected band of a plurality of frequency bands (depicted by numeral  708 ). 
     As described herein, the present invention provides for automated LNA tuning (e.g., via on chip software) to enable an LNA to support multiple (e.g., up to ten) receive paths, thus, reducing components within a wireless communication device and associated costs. Further, various embodiments may include adaptive LNA matching or closed loop LNA matching if an internal radio-frequency (RF) reference source is available. Therefore, a system could tune or match for maximum output SNR without knowing a noise figure or knowing little about an input SNR. In addition, various embodiments could include electronically tunable filters to provide a range of frequencies for electronically tunable preselect receiver filters. 
     Those of skill in the art would understand that information and signals may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof 
     Those of skill would further appreciate that the various illustrative logical blocks, modules, circuits, and algorithm steps described in connection with the exemplary embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the exemplary embodiments of the invention. 
     The various illustrative logical blocks, modules, and circuits described in connection with the exemplary embodiments disclosed herein may be implemented or performed with a general purpose processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. 
     In one or more exemplary embodiments, the functions described may be implemented in hardware, software, firmware, or any combination thereof If implemented in software, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Computer-readable media includes both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A storage media may be any available media that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer. Also, any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. Disk and disc, as used herein, includes compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk and blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media. 
     The previous description of the disclosed exemplary embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these exemplary embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the exemplary embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.