Antenna Tuning

Abstract

Disclosed are various embodiments for tuning an antenna. Multiple phase sets for a tuning circuit impedance are generated. Each phase set includes multiple phase values. A reflected voltage corresponding to each of the phase values is determined. For each phase set, one of the phase values is selected based on the corresponding reflected voltage. The phase values for each phase set that is subsequent to an initial phase set are generated. The phase values are based on the selected phase value for the previous the phase set.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to copending U.S. provisional application entitled “CELLULAR BASEBAND PROCESSING” assigned Ser. No. 61/618,049, filed Mar. 30, 2012, the entirety of which is hereby incorporated by reference herein.

BACKGROUND

In a wireless communication device, maximum power transfer between a transceiver and an antenna may occur when the impedance of the transceiver and the impedance of the antenna match. However, various factors may cause the impedance of the antenna to vary. For example, environmental conditions, the way a user holds the communication device, and other factors, may cause the impedance of the antenna to drift.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the present disclosure can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the disclosure. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.

FIG. 1 is a drawing of a communication device according to various embodiments of the present disclosure.

FIG. 2 is a drawing of an equivalent circuit of tuning circuitry of the communication device in FIG. 1 according to various embodiments of the present disclosure.

FIGS. 3A-3C are drawings of Smith charts illustrating examples of functionality implemented in the communication device of FIG. 1 according to various embodiments of the present disclosure.

FIG. 4 is a flowchart illustrating an example of functionality executed in the communication device of FIG. 1 according to various embodiments of the present disclosure.

DETAILED DESCRIPTION

The present disclosure is directed towards systems, apparatus, and methods for tuning an antenna in a communication device. A non-limiting example is as follows. Tuning circuitry for an antenna is configured to have a tuning impedance with a reflection coefficient having a magnitude that is based on a predetermined impedance for a transceiver. A pair of phase values for a first phase set for the impedance of the tuning circuitry is generated. A reflected voltage is obtained with the tuning circuitry using the first phase value of the phase set. A reflected voltage is then obtained with the tuning circuitry using the second phase value of the phase set. The reflected voltages are compared, and the phase value corresponding to the smallest reflected voltage is selected. A pair of phase values for a second phase set is then generated based on the selected phase value of the first phase set.

The process of generating pairs of phase values for phase sets based on the selected phase value of the previous phase set may be repeated for a predetermined number of iterations. Using the selected tuning impedance and the final selected phase value determined from the iterations, the tuning circuitry is then configured to cause the impedance of an output path to closely match the impedance of the transceiver. In the following discussion, a general description of the system and its components is provided, followed by a discussion of the operation of the same.

With reference to FIG. 1, shown is a drawing of a communication device 103 according to various embodiments of the present disclosure. The communication device 103 may be configured to transmit data to and receive data from a base station or another communication device 103. To this end, the communication device 103 may comprise, for example, a processor-based system such as a mobile computing device or other type of device. Such a mobile computing device may be embodied in the form of a cellular telephone, a web pad, a tablet computer system, a laptop computer, a netbook, an electronic book reader, a music player, a portable gaming device, two-way radio, or any other device with like capability.

The communication device 103 may include transceiver circuitry 106, baseband circuitry 108, tuning circuitry 109, detector circuitry 113, an antenna 116, and other components not discussed in detail herein for simplicity. The communication device 103 shown in FIG. 1 is merely one example among others in accordance with the present disclosure.

The transceiver circuitry 106 may be configured to output or receive a data signal 119, such as voice data, messaging data, control data, or any other type of data, that is to be transmitted or received using the antenna 116. To this end, the transceiver circuitry 106 may include a transmitter, a receiver, processing circuitry, control circuitry, and/or other components. In order to transmit and/or receive the data signal 119, the transceiver circuitry 106 may include mixers, modulators, demodulators, preamps, power amps, control circuitry, and/or other components not shown for simplicity.

The baseband circuitry 108 may control various aspects of the transceiver circuitry 106, tuning circuitry 109, and possibly other components of the communication device 103. To this end, the baseband circuitry 108 may provide a tuning control signal 123 and receive a detection signal 115, which will be discussed later. The tuning control signal 123 may be provided to the tuning circuitry 109 and control various values and configurations of the tuning circuitry 109, which will also be discussed later.

Also, there may be a source impedance 129 associated with the transceiver circuitry 106. The source impedance 129 may be complex (i.e., includes a real and imaginary component) and thereby have a magnitude and phase value. The value of the source impedance 129 may be predetermined. For example, the value of the source impedance 129 may be set during design of the communication device 103.

The antenna 116 may receive the data signal 119 and transmit the data to a receiving device as a wireless signal. Alternatively, the antenna 116 may receive a wireless signal from a transmitting device and provide the data signal 119 to the transceiver circuitry 106. Additionally, an antenna impedance 133 may be associated with the antenna 116. The antenna impedance 133 may be complex (i.e., have a real component and imaginary component), and thus have a magnitude and phase value.

The tuning circuitry 109 may be configured to improve the power transfer between the transceiver circuitry 106 and the antenna 116. To this end, an adjustable tuning impedance 136 may be associated with the tuning circuitry 109. The tuning impedance 136 may be adjusted, for example, by altering the values of capacitors, inductors, or other types of components of the tuning circuitry 109 using the tuning control signal 123.

By altering the tuning impedance 136, a load impedance 139 (as experienced by the transceiver circuitry 106) may be adjusted. Maximum power transfer between the transceiver circuitry 106 and the antenna 116 may occur when the load impedance 139 matches the source impedance 129. As such, the tuning circuitry 109 may be configured to adjust its tuning impedance 136 so that the load impedance 139 substantially matches the source impedance 129. As a result, an improved power transfer and voltage standing wave ratio (VSWR) may be obtained.

The detector circuitry 113 may be configured to detect a forward voltage (i.e., the voltage of an incident wave from the transceiver circuitry 106) and a reflected voltage (i.e., the voltage reflected due to an impedance mismatch). To this end, the detector circuitry 113 may include one or more directional couplers, bidirectional couplers, envelope detectors, etc. The result of the detected forward voltage and or reflected voltage may be provided to the transceiver circuitry 106 using the detector signal 115.

Next, a general description of the operation of the various components of the communication device 103 is provided. To begin, it is assumed that the communication device 103 is powered up and prepared to initiate the procedure of matching the load impedance 139 to the source impedance 129.

The communication device 103 may first determine a ratio of the reflected voltage to the forward voltage for the antenna 116. To this end, the detector circuitry 113 may obtain and measure the reflected voltage and the forward voltage. With the reflected voltage and the forward voltage obtained, the communication device 103 may determine the ratio thereof.

The communication device 103 may then select a magnitude for a reflection coefficient of the tuning impedance 136. The selected magnitude for the reflection coefficient of the tuning impedance 136 may be based on a predetermined impedance of the transceiver circuitry 106. For example, the selected magnitude for the reflection coefficient of the tuning impedance 136 may be slightly greater than the magnitude of the transceiver circuitry 106.

Additionally, the magnitude for the reflection coefficient of the tuning impedance 136 may be based on the ratio of the reflected voltage to the forward voltage for the antenna 116. For example, the selected magnitude may be proportional to the ratio of the reflected voltage to the forward voltage. Thus, if the ratio of the reflected voltage to the forward voltage were relatively high, the selected magnitude for the reflection coefficient of the tuning impedance 136 may be relatively high as compared to when the ratio is relatively low.

With the magnitude for the reflection coefficient of the tuning impedance 136 being selected, the communication device 103 may begin the process of determining the phase value of the tuning circuitry 109 so that the load impedance 139 may closely match the source impedance 129. The communication device 103 may generate a first phase set, wherein the first phase set includes multiple phase values. For example, the communication device 103 may generate a first phase set that has a pair of phase values. The phase values of the first phase set may be predefined in various embodiments. Thus, as a non-limiting example, the first phase set may include a first phase value of π radians and a second phase value of 0 radians.

The tuning circuitry 109 may then be configured to have the previously selected magnitude for the reflection coefficient of the tuning impedance 136. Additionally, the phase of the tuning impedance 136 may be selected to be the first phase value of the first phase set. Using this configuration, the communication device 103 may transmit or receive a data signal 119 and determine the reflected voltage using the detector circuitry 113.

The tuning circuitry 109 may then be configured so that the tuning impedance 136 has a phase that is the second phase value of the first phase set. Again, the communication device 103 may transmit or receive a data signal 119 and determine the reflected voltage using the detector circuitry 113.

The two reflected voltages may be compared, and the phase value of the first phase set that corresponds to the smaller reflected voltage may be selected. Using the selected phase value from the first phase set, the communication device 103 may then generate the phase values for the second phase set. As a non-limiting example, the first phase value of the second phase set may be the selected phase value from the first phase set plus π/4 radians. Also as a non-limiting example, the second phase value of the second phase set may be the selected phase value from the first phase set minus π/4 radians.

Using the first phase value of the second phase set, the communication device 103 may determine the corresponding reflected voltage. Then, the communication device 103 may determine the reflected voltage that corresponds to the second phase value of the second phase set. These reflected voltages may be compared, and the phase value that corresponds to the smallest reflected voltage may be used to determine the phase values of the third phase set.

The process of generating phase values for subsequent phase sets may be repeated over multiple iterations. As a non-limiting example, the following equation may be used to determine the first phase value for each phase set that is subsequent to the first phase set:

$\begin{array}{cc}{\theta }_{1k}={\theta }_{k-1}+\frac{\pi }{2^k},& \left(\mathrm{eq}.1\right)\end{array}$

wherein k is the iteration number, θ_1k is the first phase value for the k^th phase set, and θ_k−1 is the selected phase value from the immediately previous phase set (i.e., the phase value from the immediately previous phase set that corresponds to the smaller reflected voltage).

Additionally, the following, equation may be used to determine the second phase value for each phase set that is subsequent to the first phase set:

$\begin{array}{cc}{\theta }_{1k}={\theta }_{k-1}-\frac{\pi }{2^k},& \left(\mathrm{eq}.2\right)\end{array}$

wherein k is the iteration number, θ_2k is the second phase value for the k^th phase set, and θ_k−1 is the selected phase value from the immediately previous phase set (i.e., the phase value from the immediately previous phase set that has corresponds to the smaller reflected voltage).

From eqs. 1-2, it may be appreciated that the difference between the first phase value and second phase value decreases for each subsequent phase set. As such, the process described above may be stopped after the completion of a predetermined number of iterations. Thus, with reference to eqs. 1-2, the process may be stopped upon k reaching a predetermined value. As an alternative, the process may be stopped upon the reflected voltage being within a predetermined threshold.

Upon the iterations being stopped, the phase value of the final phase set that corresponds to the smallest reflected voltage may be selected and stored. The stored phase value may be used to configure the tuning circuitry 109 so that the load impedance 139 closely matches the source impedance 129, as will now be described.

With reference now to FIG. 2, shown is an equivalent circuit of the tuning circuitry 109 of FIG. 1 according to various embodiments. As shown, the equivalent circuit of the tuning circuitry 109 includes a first admittance 203, a second admittance 206, and a third admittance 209. Additionally, a load reflection coefficient 213 is represented. The load reflection coefficient may be a ratio of the forward voltage to the reflected voltage.

The tuning circuitry 109 may be modeled as both a lossless and a reciprocal two-port network. A lossless network has the following characteristics:

$\begin{array}{cc}\sum _{k=1}^nS_{\mathrm{ki}}S_{\mathrm{kj}}^{*}=\begin{array}{cc}1& \mathrm{for}i=j\\ 0& \mathrm{for}i\ne j\end{array}\},& \left(\mathrm{eq}.3\right)\end{array}$

wherein S_ij represents the scattering parameter (i.e., S-parameter) of the i^th row and j^th column of a scattering matrix (i.e., S-matrix) for the network. A reciprocal network has the following characteristics:

S_ij=S_ji   (eq. 4).

Thus, from eqs. 3-4, the following relationships may be obtained for a two-port network:

|S₁₁|=|S₂₂|  (eq. 5), and

θ₂₂=π+2θ₂₁−θ₁₁   (eq. 6),

wherein θ_ij is a respective phase value for the network. Therefore, the scattering matrix for a lossless and reciprocal two-port network may be expressed as:

$\begin{array}{cc}S=\left[\begin{array}{cc}{s}_{11}& \sqrt{1-{s_{11}}^2}{}^{{\mathrm{j\theta }}_{21}}\\ \sqrt{1-{s_{11}}^2}{}^{{\mathrm{j\theta }}_{21}}& -s_{11}^{*}{}^{{\mathrm{j2\theta }}_{21}}\end{array}\right]=\hspace{1em}\left[\begin{array}{cc}-s_{22}^{*}{}^{{\mathrm{j2\theta }}_{21}}& \sqrt{1-{s_{22}}^2}{}^{{\mathrm{j\theta }}_{21}}\\ \sqrt{1-{s_{22}}^2}{}^{{\mathrm{j\theta }}_{21}}& s_{22}\end{array}\right].& \left(\mathrm{eq}.7\right)\end{array}$

Also, in a two-port network, the following relationship is present:

S*₂₂=Γ_L   (eq. 8),

wherein Γ_L represents the load reflection coefficient 213 for the network. Thus, using eq. 7, the following relationship may be obtained:

$\begin{array}{cc}S=\left[\begin{array}{cc}-{\Gamma }_L{}^{{\mathrm{j2\theta }}_{21}}& \sqrt{1-{{\Gamma }_L}^2}{}^{{\mathrm{j\theta }}_{21}}\\ \sqrt{1-{{\Gamma }_L}^2}{}^{{\mathrm{j\theta }}_{21}}& {\Gamma }_L^{*}\end{array}\right],& \left(\mathrm{eq}.9\right)\end{array}$

wherein Γ_L is the load reflection coefficient 213, and θ₂₁ is the phase shift of the network.

Thus, upon the values of Γ_L and θ₂₁ being determined, the tuning circuitry 109 may be configured so that the load impedance 139 (FIG. 1) substantially matches the source impedance 129 (FIG. 1). Γ_L, the load reflection coefficient 213 for the network, is the ratio of the reflected voltage to the forward voltage, which may be determined as previously discussed. θ₂₁ may be closely approximated by using the phase value of the final phase set that has the smallest reflected voltage, as previously discussed.

Eq. 9 may also be expressed in terms of transmission parameters (i.e., ABCD-parameters) as follows:

$\begin{array}{cc}A=\frac{\left(1+S_{11}\right)*\left(1-S_{22}\right)+S_{12}*S_{21}}{2*S_{21}},& \left(\mathrm{eq}.10\right)\\ B=\frac{\left(1+S_{11}\right)*\left(1+S_{22}\right)-S_{12}*S_{21}}{2*S_{21}},\mathrm{and}& \left(\mathrm{eq}.11\right)\\ D=\frac{\left(1-S_{11}\right)*\left(1+S_{22}\right)+S_{12}*S_{21}}{2*S_{21}}& \left(\mathrm{eq}.12\right)\end{array}$

Using eqs. 10-12, eq. 9 may also be expressed in terms of admittance parameters (i.e., Y-parameters) as follows:

$\begin{array}{cc}{Y}_1=\frac{D-1}{B},& \left(\mathrm{eq}.13\right)\\ Y_2=\frac{1}{B},\mathrm{and}& \left(\mathrm{eq}.14\right)\\ Y_3=\frac{A-1}{B},& \left(\mathrm{eq}.14\right)\end{array}$

wherein Y₁ is the first admittance 203, Y₂ is the second admittance 206, and Y₃ is the third admittance 209. Accordingly, the values for the first admittance 203, the second admittance 206, and the third admittance 209 of the equivalent circuit of the tuning circuitry 109 may be determined, and the tuning circuitry 109 may be configured so that the load impedance 139 closely matches the source impedance 129. As such, power transfer between the transceiver circuitry 106 and the antenna 116 may be improved.

Referring next to FIGS. 3A-3C, shown is a sequence of Smith charts 300 illustrating examples of functionality implemented in the communication device 103 (FIG. 1) according to various embodiments of the present disclosure. The Smith charts of FIGS. 3A-3C are merely examples of the various functionality that may be performed in the communication device 103.

Beginning with FIG. 3A, the Smith chart 300 shown represents an example of the relationships between the source impedance 129 (FIG. 1), load impedance 139 (FIG. 1), tuning impedance 136 (FIG. 1), and antenna impedance 133 (FIG. 1) upon the first phase set being generated in accordance with the present disclosure. Point 303 represents the source impedance 129, which may be known or predetermined. In the example shown, the transceiver impedance may be 50Ω, for example. Point 306 represents the antenna impedance 133.

The points 309a and 309a′ represent the tuning impedances 136 of the first phase set. The points 309a and 309a′ correspond to tuning impedances 136 using the first phase value and the second phase value, respectively, of the first phase set. The magnitude for the reflection coefficient of the tuning impedances 136 are based on the source impedance 129, which is represented by point 303. In the example shown, the magnitudes for the reflection coefficient of the tuning impedances 136 are slightly greater than the transceiver impedance. Thus, visually, the points 309a and 309a′ (representing the tuning impedances 136) extend outwardly with respect to the point 303 (representing the source impedance 129).

In the example shown, the first phase value of the first phase set (represented by point 309a) has a phase value of π radians, while the second phase value of the first phase set (represented by point 309a′) has a phase value of 0 radians. The points 313a and 313a′ represent the load impedances 139 that correspond to the first phase value and second phase value, respectively, of the first phase set.

The communication device 103 has determined that the reflected voltage that corresponds to the first phase value of the first phase set (represented by point 309a) is smaller than the reflected voltage that corresponds to the second phase value of the first phase set (represented by point 309a′). Thus, point 309a (shown as darkened in the Smith chart 300) is selected by the communication device.

Turning now to FIG. 3B, shown is a Smith chart 300 representing an example of the relationships between the source impedance 129 (FIG. 1), load impedance 139 (FIG. 1), tuning impedance 136 (FIG. 1), and antenna impedance 133 (FIG. 1) upon the second phase set being generated in accordance with the present disclosure. Point 303 represents the source impedance 129, and point 306 represents the antenna impedance 133. The points 309a and 309a′, discussed previously with respect to FIG. 3A, represent the tuning impedances 136 using the phase values for the first phase set. Further, the points 313a and 313b′, discussed previously with respect to FIG. 3A, represent the load impedances 139 that correspond to the tuning impedances 136 using the phase values of the first phase set.

The points 309b and 309b′ represent the tuning impedances 136 of the second phase set. The points 309b and 309b′ correspond to the tuning impedances using the first phase value and the second phase value, respectively of the second phase set. The phase values of the second phase set are based on the phase value of the first phase set that resulted in the smaller reflected voltage.

In the present example, eqs. 1-2 are being used to determine the phase values. Thus, in the present example, the first phase value of the second phase set is 5π/4 radians, and the second phase value of the second phase set is 3π/4 radians. The points 313b and 313b′ represent the load impedances 139 that correspond to the first phase value and second phase value, respectively, of the second phase set.

In the present example, the communication device 103 has determined that the reflected voltage that corresponds to the first phase value of the second phase set (represented by point 309b) is smaller than the reflected voltage that corresponds to the second phase value of the second phase set (represented by point 309b′). Thus, point 309b (shown as darkened in the Smith chart 300) is selected by the communication device 103.

With reference now to FIG. 3C, shown is a Smith chart 300 representing an example of the relationships between the source impedance 129 (FIG. 1), load impedance 139 (FIG. 1), tuning impedance 136 (FIG. 1), and antenna impedance 133 (FIG. 1) upon the third phase set being generated in accordance with the present disclosure. As compared to the Smith chart 300 in FIG. 3B, the Smith chart 300 in FIG. 3A now includes points 309c and 309c′, which correspond to the tuning impedances 136 using the first phase value and second phase value, respectively, of the third phase set. Using eqs. 1-2, in the present example, the phase value corresponding to point 309c is 11π/8 radians, and the phase value corresponding to point 309c′ is 9π/8 radians. The points 313c and 313c′ represent the load impedances 139 that correspond to the first phase value and second phase value, respectively, of the third phase set. Because the magnitude for the reflection coefficient of the tuning impedances 136 has been selected to be slightly greater than the source impedance 129 (represented by the point 303), the tuning impedance 136 may trace an outline of at least a portion of a circle that surrounds the point 303.

In the present example, the communication device 103 has determined that the reflected voltage that corresponds to the second phase value of the third phase set (represented by point 309c′) is smaller than the reflected voltage that corresponds to the first phase value of the second phase set (represented by point 309c). Thus, point 309c′ (shown as darkened in the Smith chart 300) is selected by the communication device 103.

Referring next to FIG. 4, shown is a flowchart that provides one example of the operation of the communication device 103 according to various embodiments. The flowchart of FIG. 4 provides merely an example of the many different types of functional arrangements that may be employed to implement the operation of the communication device 103 as described herein. The flowchart of FIG. 4 may be viewed as depicting an example of steps of a method implemented in the communication device 103 according to one or more embodiments.

Beginning with block 400, the communication device 103 begins transmitting or receiving the data signal 119 (FIG. 1). In various embodiments, the signal 119 may be transmitted or received throughout the process described herein. In block 403, the communication device 103 obtains the reflected voltage and forward voltage from the antenna 116 (FIG. 1), for example, by using the detector circuitry 113 (FIG. 1). Next, as shown in block 406, the communication device 103 determines the ratio of the reflected voltage to the forward voltage, which is represented as Γ_L in eq. 9. In block 409, the magnitude of the reflection coefficient for the tuning impedance 136 (FIG. 1) of the tuning circuitry 109 (FIG. 1) is selected. The magnitude may be selected, for example, based on the predetermined source impedance 129 (FIG. 1) (e.g., the transmitter and/or receiver). Additionally, the magnitude may be proportional to the ratio of the reflected voltage to the forward voltage (determined in block 403).

Moving to block 413, the phase values for the first phase set for the tuning impedance 136 of the tuning circuitry 109 are determined. The phase values of the first phase set may be predetermined in various embodiments. Next, as shown in block 416, the tuning impedance 136 of the tuning circuitry 109 is configured to be the selected magnitude (selected in block 409) and the first phase value of the phase set. Thereafter, the reflected voltage is detected and stored, as depicted in block 419.

The communication device 103 then moves to block 423 and configures the tuning impedance 136 of the tuning circuitry 109 to be the selected magnitude (selected in block 406) and the second phase value of the phase set. As shown in block 426, the reflected voltage is detected and stored. Thus, the communication device 103 determines a reflected voltage in response to using each of the phase values of the phase set for the tuning impedance 136 of the tuning circuitry 109.

The communication device 103 then selects the phase value of the current phase set that corresponds to the smaller reflected voltage (detected in blocks 419 and 426), as shown in block 429. In block 436, the communication device determines whether it is done generating phase sets. The process of generating phase sets may be done, for example, upon a completion of a predetermined number of iterations of generating the phase values. In various embodiments, the process of generating phase sets may be done, for example, upon a reflected voltage being within a predetermined threshold.

If the process of generating phase sets is not done, the phase values for the next phase set is generated, as shown in block 439. Thus, a plurality of phase sets for the tuning impedance 136 of the tuning circuitry 109 are generated. The phase values for the subsequent phase set may be based on the selected phase value of the previous phase set. Thereafter, the communication device 103 returns to block 416, and the process is repeated as shown. Upon the process of generating the phase sets being done, the communication device 103 moves to block 443 and configures the tuning circuitry 109 so that the load impedance 139 substantially matches the source impedance 129.

The flowchart of FIG. 4 shows the functionality and operation of portions of the communication device 103. If portions are embodied in software, each block may represent a module, segment, or portion of code that comprises program instructions to implement the specified logical function(s). The program instructions may be embodied in the form of source code that comprises human-readable statements written in a programming language or machine code that comprises numerical instructions recognizable by a suitable execution system such as a processor in the communication device 103. The machine code may be converted from the source code, etc. If embodied in hardware, each block may represent a circuit or a number of interconnected circuits to implement the specified logical function(s).

Although the flowchart of FIG. 4 shows a specific order of execution, it is understood that the order of execution may differ from that which is depicted. For example, the order of execution of two or more blocks may be varied relative to the order shown. Also, two or more blocks shown in succession in FIG. 4 may be executed concurrently or with partial concurrence. Further, in some embodiments, one or more of the blocks shown in FIG. 4 may be skipped or omitted. In addition, any number of counters, state variables, warning semaphores, or messages might be added to the logical flow described herein, for purposes of enhanced utility, accounting, performance measurement, or providing troubleshooting aids, etc. It is understood that all such variations are within the scope of the present disclosure.

Various systems described herein may be embodied in general-purpose hardware, dedicated hardware, software, or a combination thereof. If embodied in hardware, each block in FIG. 4 can be implemented as a circuit or state machine that employs any one of or a combination of a number of technologies. These technologies may include, but are not limited to, discrete logic circuits having logic gates for implementing various logic functions upon an application of one or more data signals, application specific integrated circuits (ASICs) having appropriate logic gates, one or more programmable logic devices (e.g., a field programmable gate array (FPGA), a complex programmable logic device (CPLD), etc.), or other components, etc. Such technologies are generally well known by those skilled in the art and, consequently, are not described in detail herein.

It is emphasized that the above-described embodiments of the present disclosure are merely possible examples of implementations set forth for a clear understanding of the principles of the disclosure. Many variations and modifications may be made to the above-described embodiment(s) without departing substantially from the spirit and principles of the disclosure. All such modifications and variations are intended to be included herein within the scope of this disclosure and protected by the following claims.

Claims

1. A system, comprising:

a transmitter;

an antenna in communication with the transmitter; and

tuning circuitry for the antenna, the tuning circuitry being configured to: generate a plurality of phase sets for an impedance of the tuning circuitry, each of the phase sets comprising a plurality of phase values; select one of the phase values for each of the phase sets, the selected one of the phase values being based on a reflected voltage corresponding to each of the phase values; and generate the phase values for each of the phase sets subsequent to an initial one of the phase sets, the phase values being based on the selected one of the phase values of a previous one of the phase sets.

2. The system of claim 1, wherein the tuning circuitry is further configured to select a magnitude of a reflection coefficient for the impedance of the tuning circuitry based on a predetermined source impedance of the transmitter.

3. The system of claim 2, wherein the magnitude of the reflection coefficient for the impedance is further selected based on a ratio of the reflected voltage to a forward voltage for the antenna.

4. The system of claim 1, wherein the previous one of the phase sets is an immediately previous one of the phase sets.

5. The system of claim 1, wherein a difference between the phase values for each of the phase sets decreases for each subsequent one of the phase sets.

6. The system of claim 1, wherein the tuning circuitry is further configured to configure a load impedance for the transmitter to substantially match a source impedance upon the reflected voltage being within a predetermined threshold, the load impedance comprising the impedance of the tuning circuitry and an antenna impedance, the load impedance being based on a final one of the selected one of the phase values.

7. The system of claim 1, wherein the tuning circuitry is further configured to configure a load impedance for the transmitter to substantially match a source impedance upon a predetermined number of the phase sets being generated, the load impedance comprising the impedance of the tuning circuitry and an antenna impedance, the load impedance being based on a final one of the selected one of the phase values.

8. An apparatus, comprising:

circuitry configured to select a magnitude of a reflection coefficient for an impedance of a tuning circuit for an antenna;

circuitry configured to generate a plurality of phase sets for the impedance of the tuning circuit, each of the phase sets comprising a plurality of phase values;

circuitry configured to determine a reflected voltage in response to using the magnitude of the reflection coefficient and the phase values of each of the phase sets for the impedance of the tuning circuit;

circuitry configured to select, for each of the phase sets, one of the phase values based on the corresponding reflected voltage; and

circuitry configured to generate the phase values for each of the phase sets subsequent to an initial one of the phase sets, the phase values being based on the selected one of the phase values of a previous one of the phase sets.

9. The apparatus of claim 8, wherein the previous one of the phase sets is an immediately previous one of the phase sets.

10. The apparatus of claim 8, wherein a difference between the phase values for each of the phase sets decreases for each subsequent one of the phase sets.

11. The apparatus of claim 8, further comprising circuitry configured to configure a load impedance to substantially match a source impedance upon the reflected voltage being within a predetermined threshold, the load impedance comprising the impedance of the tuning circuit and an antenna impedance, the load impedance being based on a final one of the selected one of the phase values.

12. The apparatus of claim 8, further comprising circuitry configured to configure a load impedance to substantially match a source impedance upon a predetermined number of the phase sets being generated, the load impedance comprising the impedance of the tuning circuit and an antenna impedance, the load impedance being based on a final one of the selected one of the phase values.

13. The apparatus of claim 8, wherein the magnitude of the reflection coefficient for the impedance of the tuning circuit is based on a predetermined source impedance.

14. The apparatus of claim 13, wherein the magnitude of the reflection coefficient for the impedance of the tuning circuit is further based on a ratio of the reflected voltage to a forward voltage for the antenna.

15. A method, comprising:

generating, in a circuit, a plurality of phase sets for an impedance of a tuning circuit for an antenna, each phase set comprising a plurality of phase values;

determining, in the circuit, a reflected voltage in response to using each of the phase values of each of the phase sets for the impedance of the tuning circuit;

selecting, in the circuit, for each of the phase sets, one of the phase values based on the corresponding reflected voltage; and

generating, in the circuit, the phase values for each of the phase sets subsequent to an initial one of the phase sets, the phase values being based on the selected one of the phase values of a previous one of the phase sets.

16. The method of claim 15, wherein a difference between the phase values for each of the phase sets decreases for each subsequent one of the phase sets.

17. The method of claim 15, wherein generating the phase values for each of the phase sets is stopped in response to the reflected voltage being within a predetermined threshold.

18. The method of claim 15, wherein generating the phase values is stopped upon a completion of a predetermined number of a plurality of iterations of generating the phase values

19. The method of claim 15, further comprising selecting, in the circuit, a magnitude of a reflection coefficient for the impedance of the tuning circuit based on a predetermined source impedance.

20. The method of claim 19, wherein the magnitude of the reflection coefficient for the impedance is further based on a ratio of the reflected voltage to a forward voltage for the antenna.