Abstract:
A method for processing signals includes generating a frequency response adjusted signal of an antenna, and adjusting a gain of the antenna by varying a gain of a programmable amplifier that amplifies the frequency response adjusted signal. The generating of the frequency response adjusted signal may take place prior to the gain adjusting. A frequency response of the antenna may be dynamically adjusted during the generating. A programmable filter used for the generating may be autonomously adjusted. The gain of the antenna may be dynamically adjusted. The gain of the programmable amplifier may be autonomously varied. The programmable filter and the programmable amplifier may be adjusted sequentially.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS/INCORPORATION BY REFERENCE 
       [0001]    This application makes reference to, claims priority to, and claims the benefit of U.S. Provisional Application Ser. No. 60/895,698, filed on Mar. 19, 2007. 
         [0002]    The above referenced application is hereby incorporated herein by reference in its entirety. 
     
    
     FIELD OF THE INVENTION 
       [0003]    Certain embodiments of the invention relate to signal processing for communication systems. More specifically, certain embodiments of the invention relate to a method and system for equalizing antenna circuit matching variations. 
       BACKGROUND OF THE INVENTION 
       [0004]    Communication receiver systems that rely on receiving radio frequency signals are dependent on certain characteristics of the antenna used, in order to ensure correct operation. One such parameter, for example, may be the antenna impedance. If the impedance between the receiver and the antenna is not matched, the feed line may generate reflections at such unmatched impedance interfaces, reflecting the received signal back towards the source. This may generate so-called standing waves and reduces the effective power transfer from the antenna to the receiving device. 
         [0005]    Another factor that may impact the operation of a receiver may be variations due to manufacturing. In particular for small antennas and/or antennas that may be operated in physically constrained spaces, small changes in the operating environment may impact the antenna characteristics. For example, small antennas on Printed Circuit Boards (PCBs) may exhibit relatively large sample variation. In addition, due to the close proximity of a PCB antenna with other circuitry, there may be some electromagnetic coupling that may affect the antenna performance. Furthermore, antennas from different manufacturers may also differ in their characteristics. 
         [0006]    Antennas generally respond differently at different frequencies. For example, the antenna gain may be frequency dependent. Also, changes in the operating environment, for example temperature, may affect the circuit-antenna matching. 
         [0007]    Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with some aspects of the present invention as set forth in the remainder of the present application with reference to the drawings. 
       BRIEF SUMMARY OF THE INVENTION 
       [0008]    A method and/or system for equalizing antenna circuit matching variations, substantially as shown in and/or described in connection with at least one of the figures, as set forth more completely in the claims. 
         [0009]    These and other advantages, aspects and novel features of the present invention, as well as details of an illustrated embodiment thereof, will be more fully understood from the following description and drawings. 
     
    
     
       BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS 
         [0010]      FIG. 1  is a block diagram illustrating an exemplary FM receiver system, in accordance with an embodiment of the invention. 
           [0011]      FIG. 2  is a block diagram illustrating an exemplary embodiment of an antenna matching system, in accordance with an embodiment of the invention. 
           [0012]      FIG. 3A  is a circuit diagram illustrating an exemplary embodiment of an antenna matching system, in accordance with an embodiment of the invention. 
           [0013]      FIG. 3B  is a circuit diagram illustrating an exemplary programmable capacitance, in accordance with an embodiment of the invention. 
           [0014]      FIG. 4  is a flow chart illustrating an exemplary sequential antenna matching algorithm, in accordance with an embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0015]    Certain embodiments of the invention may be found in a method and system for equalizing antenna circuit matching variations. Aspects of the method and system for equalizing antenna circuit matching variations may comprise adjusting a frequency response of an antenna via a programmable filter and a gain of the antenna by varying a programmable amplifier. The antenna frequency response and the antenna gain may be adjusted dynamically and/or autonomously. The programmable amplifier and the programmable filter may be adjusted sequentially or simultaneously. The programmable filter may be an LC-type circuit and the programmable amplifier may be a low-noise amplifier. In an exemplary embodiment of the invention, the programmable filter may comprise a programmable capacitance in a matrix arrangement and/or a programmable inductance in a matrix arrangement. 
         [0016]      FIG. 1  is a block diagram illustrating an exemplary FM receiver system, in accordance with an embodiment of the invention. Referring to  FIG. 1 , there is shown an FM receiver system  100  comprising an antenna  102 , an antenna matching block  104 , and a FM receiver  106 . The antenna matching block  104  may comprise suitable logic, circuitry and/or code to enable matching the antenna  102  to an FM receiver  106 . The FM receiver  106  may comprise suitable logic, circuitry and/or code to enable processing of the radio frequency signals received via the antenna  102 . 
         [0017]    In an exemplary FM receiver system as illustrated in  FIG. 1 , it may be desirable that the input signal to the FM receiver  106  may comprise certain well-defined characteristics. Due to a large number of factors, the antenna  102  characteristics may be variable. For example, the operating environment and manufacturing tolerances may affect the antenna characteristics. In these instances, it may be desirable to adjust the antenna  102  characteristics in the antenna matching block  104  that may achieve well-defined input signals for the FM receiver  106 . 
         [0018]      FIG. 2  is a block diagram illustrating an exemplary embodiment of an antenna matching system, in accordance with an embodiment of the invention. Referring to  FIG. 2 , there is shown an antenna matching system  200 , comprising an antenna  202 , an antenna matching block  204  and a load circuit  206 . The antenna matching block  204  may comprise an antenna tuning block  208 , an amplifier  210  and a control block  212 . 
         [0019]    The antenna tuning block  208  may comprise suitable logic, circuitry and/or code to enable tuning of the antenna  202 . The amplifier  210  may comprise suitable logic, circuitry and/or code to enable amplification of the signal fed to amplifier  210  from the antenna tuning block  208 . The gain of amplifier  210  may be controlled by the control block  212 , which may comprise suitable logic, circuitry and/or code to enable control of the antenna tuning block  208  and/or the amplifier  210 . 
         [0020]    The antenna  202  may be subject to considerable sample variation. Differences between antennas may be due to differences between manufacturers and/or tolerances in the manufacturing process. Particularly very small antennas, for example on printed circuit boards (PCBs), may exhibit large variations between different samples. Furthermore, antenna installation and/or arrangement on a printed circuit board may affect the antenna characteristics, as may environmental factors. Moreover, the antenna gain may typically be frequency dependent. For at least the reasons given above, it may be desirable to tune the antenna characteristics. 
         [0021]    The antenna tuning block  208  may be, for example, a programmable filter. This may permit adjustment of, for example, a frequency response of the antenna and its resonant frequency. Primarily, the antenna tuning block  208  may be enabled to adjust the frequency response of the antenna  202 . The amplifier  210  may be used to compensate for variability in antenna gain. The load circuit  206  may be a system requiring an antenna input signal. 
         [0022]    The antenna matching  204  may be controlled by one or more of a plurality of performance metrics. For example, if the load circuit  206  may be a communications receiver, the control block  212  may adjust the gain of amplifier  210  and the antenna tuning block  208  as a function of the sensitivity. Other exemplary metrics that may be used may comprise Signal-to-Interference-and-Noise ratio (SINR), Bit Error Rate (BER) and/or Packet Error Rate (PER). In some instances, it may also be desirable to increase blocking of certain frequencies, for example, due to interference. The control block  212  may also be controlled manually. In some embodiments of the invention, the control block  212  may autonomously and dynamically adjust the antenna  202  characteristics. In other embodiments of the invention, the antenna tuning block  208  and the amplifier  210  may be calibrated and not be adjusted dynamically. 
         [0023]      FIG. 3A  is a circuit diagram illustrating an exemplary embodiment of an antenna matching system, in accordance with an embodiment of the invention. Referring to  FIG. 3A , there is shown an antenna matching system  300  comprising an antenna equivalent circuit  302 , an antenna tuning block  308 , an amplifier  310  and a load  306 . The antenna equivalent circuit  302  may be a Thevenin equivalent circuit of an antenna and may be used to approximately model the behavior of a receive antenna substantially similar to antenna  202 . The antenna equivalent circuit  302  may comprise a voltage source  314  and an antenna impedance  304 . The antenna impedance may comprise a resistor  316 , an inductor L  318  and a capacitor C  320 . The antenna tuning block  308  may comprise a variable inductor dL  322  and a variable capacitor dC  324 . The amplifier  310  may be substantially similar to amplifier  210 . 
         [0024]    The antenna equivalent circuit  302  may comprise voltage source  314  that may represent the received signal at antenna  202 , and the antenna impedance  304 . The frequency characteristics of the antenna equivalent circuit  302  may be determined primarily by the capacitance C  320  and the inductor L  318 . The resonant frequency of the antenna may be defined approximately by (antenna under purely resistive load) the following relationship: 
         [0000]    
       
         
           
             
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         [0025]    The antenna tuning block  308  may adjust the frequency response and the resonant frequency of the antenna by adjusting the total inductance and capacitance through inductor dL  322  and capacitor dC  324 . The resonant frequency may be approximately given by the following relationship: 
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         [0026]    The capacitor dC  324  and the inductor dL  322  may be programmable and may be controlled by a control block substantially similar to the control block  212 . Similarly, the amplifier  310  may be controlled by a control block. The amplifier  310  may adjust the gain available to the load  306 . 
         [0027]      FIG. 3B  is a circuit diagram illustrating an exemplary programmable capacitance, in accordance with an embodiment of the invention. Referring to  FIG. 3B , there is shown a programmable capacitance  325  comprising switches  330   a - g ,  334   a - e ,  336   a - g ,  340   a - e ,  342   a - e ,  344   a - g  and  348   a - e , and capacitors  332   a - f ,  338   a - f ,  346   a - f.    
         [0028]    In one embodiment of the invention, a programmable capacitor may be implemented in a switchable matrix, as illustrated in  FIG. 3B . The matrix may be of size M×N capacitors, where M and N may be positive integers. Depending on how the switches  330   a - g ,  334   a - e ,  336   a - g ,  340   a - e ,  342   a - e ,  344   a - g  and  348   a - e  may be set, a large number of values for the programmable capacitance  325  may be set by switching capacitances in series and in parallel, as desired. 
         [0029]    A programmable inductance may be implemented in a matrix fashion in a substantially similar manner to the programmable capacitance illustrated in  FIG. 3B . 
         [0030]      FIG. 4  is a flow chart illustrating an exemplary sequential antenna matching algorithm, in accordance with an embodiment of the invention. The sequential antenna matching algorithm may be initialized in step  402 . In step  404 , the performance function may be sensed. As described for  FIG. 2 , the performance function may be SNR, BER and/or any other function that may permit the parameters of, for example, the antenna tuning block  208  and/or the control block  212  to be adjusted suitably. According to the exemplary embodiment of the invention depicted in  FIG. 4 , the gain in amplifier  210  and the antenna tuning in antenna tuning block  208  may be performed in a sequential manner. Accordingly, in step  406 , the antenna tuning block  208  may be adjusted, for example via the control block  212 . In step  408 , the performance function may be sensed, in response to changes to the antenna tuning block  208 . The gain of the amplifier  210  may be adjusted in step  410  for example via the control block  212 . The algorithm may recommence in step  404 . In another embodiment of the invention, adjusting the antenna tuning block  208  and the amplifier  210  may be performed in parallel, instead of sequentially. 
         [0031]    In accordance with an embodiment of the invention, a method and system for equalizing antenna circuit matching variations may comprise adjusting a frequency response of an antenna  202  via a programmable filter, for example antenna tuning block  208 , and adjusting a gain of the antenna  202  by varying, for example, a gain of a programmable amplifier  210 . The antenna frequency response and the antenna gain may be adjusted dynamically and/or autonomously, as described for  FIG. 2 . The programmable amplifier  210  and the programmable filter  208  may be adjusted sequentially or simultaneously. The programmable filter  208  may be an LC-type circuit and the programmable amplifier  210  may be a low-noise amplifier. In an exemplary embodiment of the invention, the programmable filter  208  may comprise a programmable capacitance in a matrix arrangement and/or a programmable inductance in a matrix arrangement, as illustrated in  FIG. 3B . 
         [0032]    Another embodiment of the invention may provide a machine-readable storage, having stored thereon, a computer program having at least one code section executable by a machine, thereby causing the machine to perform the steps as described above for equalizing antenna circuit matching variations. 
         [0033]    Accordingly, the present invention may be realized in hardware, software, or a combination of hardware and software. The present invention may be realized in a centralized fashion in at least one computer system, or in a distributed fashion where different elements are spread across several interconnected computer systems. Any kind of computer system or other apparatus adapted for carrying out the methods described herein is suited. A typical combination of hardware and software may be a general-purpose computer system with a computer program that, when being loaded and executed, controls the computer system such that it carries out the methods described herein. 
         [0034]    The present invention may also be embedded in a computer program product, which comprises all the features enabling the implementation of the methods described herein, and which when loaded in a computer system is able to carry out these methods. Computer program in the present context means any expression, in any language, code or notation, of a set of instructions intended to cause a system having an information processing capability to perform a particular function either directly or after either or both of the following: a) conversion to another language, code or notation; b) reproduction in a different material form. 
         [0035]    While the present invention has been described with reference to certain embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the scope of the present invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present invention without departing from its scope. Therefore, it is intended that the present invention not be limited to the particular embodiment disclosed, but that the present invention will include all embodiments falling within the scope of the appended claims.