Adaptation network system for controlling an antenna adaptation network with status tables

Abstract

System (100) for controlling an antenna matching network (106, 506), comprising: an RF path (102) for generating an RF signal (114, 514); a lookup table (112, 512) with a state table that correlates antenna states with impedance values, wherein the state table contains entries, each entry comprising an antenna state and a corresponding range of impedance values; and a state table analysis component (110, 508) for generating a matching network control signal (122, 536) from the RF signal using the lookup table, wherein the state table analysis component (110, 508) is configured to use a measured impedance and a reference state to identify the corresponding antenna state in the state table and to use the antenna state from the state table to generate the matching network control signal (122, 536).

Description

BACKGROUND

[0001] Modern communication devices / telephones contain integrated antennas for transmitting and receiving high-frequency (HF) signals. Designers strive to make these integrated antennas ever smaller while simultaneously ensuring they cover as many frequency bands as possible. Their small size allows them to be used in various types of end-user devices, while the wide operating frequency enables a given end-user device to be used with different communication standards.

[0002] These integrated antennas are, however, sensitive to extraneous factors or usage. This sensitivity, combined with the fact that a given antenna can be used across multiple frequency bands, makes it difficult to precisely match the antenna's impedance to the impedance of the RF circuitry in the transmitter. Some examples of extraneous factors that can affect the impedance of an integrated antenna include whether a hand is placed on the phone (and the specific position of such a hand, if present), whether the phone is close to a user's head, and / or whether any metal objects are near the antenna, among others. These fluctuations in impedance caused by extraneous factors result in an impedance mismatch between the antenna and the RF circuitry in the transmitter.Such an impedance mismatch can degrade the power radiated by the phone and increase its susceptibility to noise. From a user's perspective, an impedance mismatch can ultimately lead to reduced talk time and / or dropped calls.

[0003] One method for facilitating impedance matching between RF circuits in the transmitter and the antenna involves the use of antenna matching networks. In one example, sensors are placed inside a telephone casing to detect the presence or absence of extraneous variables. The detected environment is then compared to known usage scenarios (e.g., "free space," "hand on phone," "close to head," "metal plate," etc.), and a corresponding predefined matching network setting is selected based on the detected scenario.

[0004] Unfortunately, this conventional approach requires a large number of sensors in the mobile phone, increasing its size and cost (especially if there are many potential use cases to detect). For example, regarding a use case of "hand on phone," sensors may be needed to distinguish between "man's hand...", "woman's hand...", "child's hand...", and to further differentiate each of these hand types as having "dry skin...", "normal skin", "sweating skin", etc. Sensors might also be needed to detect the phone's casing and even its color, some of which can be modified via aftermarket accessories and may affect the antenna's impedance matching.Since the matching network settings for each use case still depend on frequency bands (and also frequency subbands), the conventional approach requires a detailed, dynamic evaluation of use cases for each new handset design. The need to evaluate and store all these use cases necessitates a large number of sensors, a significant amount of ROM, and considerable processing power. Conventional antenna matching methods are therefore inadequate, and more effective methods are needed.

[0005] US 8 072 285 B2 relates to an impedance matching circuit. The circuit comprises an RF amplifier, an RF antenna, and an impedance matching network that dynamically adjusts its internal impedance to minimize reflected power and thus achieve a near-optimal impedance match with the load. This internal impedance is adjusted based on the amplifier's forward power and the antenna's reflected power. Based on the forward and reflected power values, the microprocessor, using a lookup table, determines the bias voltage to be applied to the tunable ICs. SUMMARY OF THE INVENTION

[0006] The invention itself is the subject of the independent patent claims. The dependent patent claims relate to advantageous embodiments of the invention. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a block diagram of a system for controlling an antenna matching network with state tables. Fig. Figure 2 is a circuit diagram of an exemplary antenna matching network circuit. Fig. Figure 3 is a flowchart of a procedure for identifying a communication device / equipment and generating a state table. Fig. Figure 4 is an example of a Smith chart arrangement that can be used to correlate domain impedances with antenna / reference states. Fig. Figure 5 is a block diagram of an antenna matching network adjustment system. Fig. Figure 6 is a flowchart of a procedure for generating a control signal for an antenna matching network. DETAILED DESCRIPTION

[0007] The present invention will now be described with reference to the accompanying drawing figures, wherein the same reference numerals are used to refer to the same elements and wherein the structures and devices shown are not necessarily drawn to scale.

[0008] Systems and methods are disclosed that provide self-adjusting systems for controlling an antenna matching network based on state tables.

[0009] Fig. Figure 1 is a block diagram of a System 100 for controlling an antenna matching network with state tables. The System 100 uses impedance values ​​for different states in a lookup table to provide antenna impedance control.

[0010] The System 100 can be used in a mobile communication device such as a cellular phone. Such devices are subject to various usage conditions, such as a "hand on the phone," "man's hand," "woman's hand," "child's hand," "dry skin," "normal skin," "sweating skin," and the like. These usage conditions can alter the impedance values ​​of an integrated antenna. The System 100 can be used to match the antenna impedance to the transmission path or RF path, a process known as impedance matching.

[0011] The system 100 includes an RF path 102, a directional coupler 104, an antenna matching network 106, a state table analysis component 110, and a lookup table 112. The RF path 102 generates an RF signal 114 to be transmitted via an RF antenna 108, while the transmitter is subject to one or more states or one or more operating conditions.

[0012] The directional coupler 104 is connected between the RF path 102 and the antenna matching network 106. The directional coupler 104 receives a small portion of the RF signal 114 and / or a reflected signal from an antenna path and provides this small portion as a coupled signal 116. The remaining signal 124 is provided to the antenna matching network 106.

[0013] The antenna matching network 106 receives the residual signal 124 and can make the signal 124 available for transmission to an antenna 108. The antenna matching network 106 is configured to set or change the antenna impedance according to a received control signal 122. The control signal 122 indicates a desired impedance setting, which facilitates impedance matching. In one example, the control signal 122 is a matching impedance value. In another example, the control signal 122 contains capacitance settings for adjustable capacitors in the antenna matching network 106.

[0014] The lookup table 112 contains a series of entries. Each entry contains a range or converted impedance (typically a range of impedances) and an antenna state. Entries are referenced by a measured and converted impedance value (Zin) 118. The lookup table 112 provides the matching antenna state 120 corresponding to the impedance value 118. The lookup table 112 can be implemented in SRAM, such as the SRAM of a transmitter / receiver or some other suitable storage mechanism. Entries can be created using a labeling procedure as described below.

[0015] Lookup table 112 can include one or more tables based on frequency. Each table can be referred to as a state table and contains impedance ranges paired with antenna states for a specific frequency or frequency range. For example, a table of entries might be correlated with a mid-band frequency. The multiple tables are based on the frequency response.

[0016] In one example, the lookup table contains 112 values, which are rotated according to selected frequencies. This eliminates the need to generate multiple tables.

[0017] The state table analysis component 110 receives the coupled signal 116 from the directional coupler 104. The state table analysis component 110 measures an impedance using the coupled signal 116. The measured impedance is converted to a reference state that was used to generate the state table.

[0018] The implemented impedance value 118 is provided to the lookup table 112 as described above. In response, the current antenna state 120 is received. The state table analysis component 110 estimates a suitable impedance from the antenna state 120 and the measured impedance. The estimated suitable impedance is used to generate the control signal 122. In one example, the estimated suitable impedance is used to generate capacitance values ​​for the antenna matching network 106.

[0019] An external component, a state table labeling component 126, generates the lookup table 112 using a labeling procedure. This labeling procedure uses a reference state to generate table 112. Table 112 can be generated in a laboratory or other environment before normal use of the mobile communication device. In this example, the labeling component 126 is located outside of system 100.

[0020] It should be noted that impedance adjustments are performed in a relatively simple manner compared to conventional impedance matching methods. The state table analysis component 110 only accesses the lookup table 112 to obtain the required state information. As a result, testing on the radio path is not necessary, feedback receiver accuracy is less critical, and additional or improved antenna states can be identified.

[0021] Fig. Figure 2 is a circuit diagram of an exemplary antenna matching network circuit 200. It is understood that the antenna matching network circuit 200 is provided only as an example for the purpose of understanding and in no way limits the scope of the present invention. The antenna matching network 200 comprises first and second inductors arranged in series, each inductor having first and second terminals. Adjustable capacitors can also be coupled as shown. A control signal, such as the control signal 122 of the Fig. 1. The capacity values ​​for “tuning” the antenna matching network 200 can be changed to match the input impedance of the RF antenna 108 to the output impedance of the RF path 102.

[0022] Fig. Figure 3 is a flowchart of a procedure 300 for identifying a communication device / communication system and generating a state table. The identification can be implemented in hardware and / or software.

[0023] Procedure 300 begins in block 302, where a reference state is selected. The reference state can be selected to produce specific markings. For example, the reference state can be selected to mitigate insertion loss for predefined states such as an insertion loss of 50 ohms, for predefined load conditions, frequency, and / or the like. It is understood that there can be more than one reference state, and the device can also be marked for these additional reference states.

[0024] A variety of loads can be applied to the communication device for the reference state in block 304. One example of applying loads is performing load tuning, where possible impedances in a Smith chart are sampled at an output of an antenna matching network of the communication device. An exemplary load tuning method is sampling seven voltage standing wave ratio (VSWR) circuits or quantities with a phase grain size of 10 degrees.

[0025] Block 304 is described for a single reference state, but it is understood that the block can be repeated for other reference states.

[0026] Input impedances are measured and stored for the multitude of loads in Block 306. The impedances are measured using a suitable method, such as a vector network analyzer (VNA). Typically, the impedances are measured for one or more load impedances. As a result, one or more impedance measurements are stored for the reference condition. The impedances are stored using a suitable mechanism, such as a memory device, SRAM, software package, or similar. The measured impedances are defined for a converted area, which is S11 of the antenna matching network plus the load condition for the reference condition.

[0027] The reference state(s) are paired with measured impedances in block 308. Multiple states can be assigned to individual load detuning states.

[0028] A single antenna state is selected for each load or load detuning state according to selection criteria in Block 310. These selection criteria include, for example, relative transducer gain (RTG), insertion loss, and the like. In one example, the state that yields the highest RTG is selected. In another example, the state that yields the lowest insertion loss (lowest S11) is selected.

[0029] To select states for each load, also known as range impedance, a Smith chart or similar mechanism can be used. Further details on using a Smith chart for state selection are provided below.

[0030] Block 312 creates a state table or lookup table. The state table can be stored in a memory device such as SRAM. The state table contains a multitude of entries. Each entry includes a converted or range impedance and a corresponding state, also known as an antenna state. The converted impedance is based on the reference state used to identify the device. The converted range impedance is a measured impedance before an antenna matching network with a feedback receiver while the device is in the reference state. The converted range impedance passes through a reference state to decode, or obtain, the unconverted or actual impedance.

[0031] Variations of Method 300 are being considered. For example, Method 300 can be repeated for different frequency points, such as the edges and center of a frequency band.

[0032] Fig. Figure 4 is an example of a Smith chart arrangement 400, which can be used to correlate the implemented range impedances with antenna / reference states. The arrangement is provided as an example for illustrative purposes.

[0033] The arrangement is shown with five sectors, which can also represent antenna impedances. The sectors are shown with "pie" shapes, but it is understood that the impedance can appear in other shapes for the sectors. The sectors can be predefined or refined for a specific architecture. Additionally, the number of sectors can also be predefined.

[0034] Here, the arrangement 400 has a first sector 401, a second sector 402, a third sector 403, a fourth sector 404, and a fifth sector 405. The area occupied by each sector can be variable. Some sectors can be combined with other sectors. For example, the second sector 402 is relatively small and can be combined with the first sector 401 and / or the third sector 403 to simplify the number of states or sectors.

[0035] Fig. Figure 5 is a block diagram of an antenna matching network adjustment system 500. The system 500 uses information stored in a state table to effectively implement impedance matching.

[0036] The system 500 comprises a transmitter / receiver 540 and an antenna matching network 506. The transmitter / receiver 540 receives an RF signal 514 and provides a residual signal 524. The transmitter / receiver 540 can connect an analysis component, such as the analysis component 110 of the Fig. 1 comprise or be part of the same. The antenna matching network 506 receives the residual signal 524 and provides an output signal 538 suitable for transmission. The antenna matching network 506 also receives a control signal 536, which is used to adjust impedance and facilitate impedance matching.

[0037] The transmitter / receiver section 540 comprises a directional coupler 504, a feedback receiver 518, an antenna impedance estimator 508, a lookup table 512, and a noise signal component 510. The directional coupler 504 receives a small portion of the RF signal 514. The coupler 504 can also receive a feedback or reflected signal from the antenna matching network 506. The coupled or received signals are provided by the coupler 504 as a coupled signal 526.

[0038] Lookup table 512 contains a state table that correlates converted impedance values ​​with antenna states. The converted impedance values ​​are based on a reference state used in generating the state table. The state table contains entries with a range of impedance values ​​and a corresponding antenna state. An example of generating a state table is provided above.

[0039] The 518 feedback receiver measures the impedance (Zin) of the coupled signal. A suitable method is used to measure the impedance. The impedance (Zin) changes according to the usage conditions. For example, the current state impedance will have different values ​​depending on whether a mobile device is in a user's hand or being held by their head, and so on. The current state or usage typically changes over time, and thus the current state can differ from a previous state.

[0040] The antenna impedance estimator 508 receives the measured impedance and generates an impedance offset setting 534. The impedance estimator 508 uses the reference state to convert the measured impedance 528 into a converted impedance 530. The antenna impedance estimator 508 uses the converted impedance 530 to reference the lookup table 512. As shown above, the lookup table 512 contains the state table. The lookup table 512 identifies a matching state for the converted impedance 530 and returns a matching antenna state 532.

[0041] The impedance estimator 508 uses the matching state 532 and the measured impedance 528 to generate the impedance offset setting 534. This value represents a change in impedance for the antenna matching network 506, which facilitates impedance matching between the antenna matching network and the transmitter / receiver and transmission path.

[0042] The control signal component 510 receives the impedance offset setting 534 and generates the control signal 536. The control signal 536 configures the antenna matching network 506 for the matching state 532. The control signal 536 transmits information needed to improve or facilitate impedance matching. The component 510 can generate the control signal 536 using one or more suitable methods. In one example, the control signal 536 is generated to provide capacitance values ​​to the antenna matching network 506. The provided capacitance values ​​determine the impedance offset setting.

[0043] The control signal 536 can be provided to the antenna matching network 506 using a suitable interface. In one example, a radio frequency front end (RFFE) control interface is used.

[0044] System 500 facilitates communication by improving and simplifying impedance matching. It is understood that variations within System 500 are taken into account.

[0045] Fig. Figure 6 is a flowchart of a method 600 for generating a control signal for an antenna matching network. The control signal can be used by the antenna matching network to tune an antenna and facilitate impedance matching to a transmitter / receiver transmission path. For clarification, reference may be made to the systems and variations thereof described above.

[0046] Method 600 begins in Block 602, in which a state table is generated by identifying a device with a reference state. The device may include mobile devices, communication devices, and the like. The table is generated offline by subjecting the device to varying usage conditions or by simulating these conditions. Impedances are measured, and a number or plurality of antenna states are developed. The impedances are correlated or paired with the antenna states to form the state table. Method 300, described above, is a suitable method for generating the state table.

[0047] It should be noted that once the state table has been generated, it does not need to be regenerated during the use of the device.

[0048] Block 604 receives an RF signal. The RF signal is generated by an RF transmission path, such as the one described above. The RF signal typically contains information to be transmitted.

[0049] Block 606 provides an impedance measurement of the RF signal. This impedance measurement typically represents the current state of the RF transmission path. The measurement can be obtained by extracting a coupled signal from the RF signal and using a feedback receiver to measure the impedance. The coupled signal can also include a reflected transmitted signal.

[0050] The measured impedance is converted to a converted impedance in block 608 using the reference state. The reference state is the state used in block 602 for marking the device.

[0051] The converted impedance is used to obtain a current or appropriate state of the RF transmission path in block 610. The state table is referenced with the converted impedance to obtain the appropriate antenna state. The generation of the state table is described above.

[0052] In one variation, the measured impedance is compared with a previously measured impedance. If the difference is relatively small, a neighboring state can be applied to the antenna matching network.

[0053] The matching antenna state is used to set up an antenna matching network in Block 612. The antenna matching network is set up using a suitable mechanism. In one example, the antenna matching network is set up by using the matching state to develop an impedance offset amount. Capacitance values ​​or changes are calculated from the impedance offset amount. The capacitance values ​​are then provided as a configuration or control signal for the antenna matching network.

[0054] While the procedures presented and described herein are depicted and described as a series of actions or events, this disclosure is not limited to the sequence of such actions or events shown. For example, some actions may occur in different sequences and / or simultaneously with other actions or events besides those depicted and / or described herein. Additionally, not all of the actions depicted are required, and the waveforms are only examples; other waveforms may differ significantly from those depicted. Furthermore, one or more of the actions depicted herein may be carried out in one or more separate actions or phases.

[0055] It should be noted that the claimed subject matter can be implemented as a method, device, or article of manufacture using standard programming and / or operational procedures for producing software, firmware, hardware, or any combination thereof for controlling a computer to implement the disclosed subject matter (e.g., the systems shown above are non-limiting examples of circuits that can be used to implement disclosed methods and / or variations thereof). The term "article of manufacture" as used here is intended to encompass a computer program accessible from any computer-readable device, carrier, or medium. The person skilled in the art will recognize that many modifications can be made to this configuration.

[0056] An antenna matching network control system includes an RF path, a lookup table, and a state table analysis component. The RF path is configured to generate an RF signal. The lookup table contains a state table that correlates antenna states with impedance values. The state table analysis component is configured to generate a matching network control signal from the RF signal using the lookup table.

[0057] An antenna matching network system includes a directional coupler, a feedback receiver, a lookup table, and an antenna impedance estimator. The directional coupler is configured to receive an RF signal and generate a coupled signal. A residual signal from the RF signal is passed on from the directional coupler. The feedback receiver is configured to measure the impedance of or from the coupled signal. The lookup table is configured to provide a suitable antenna state in response to an input impedance. The antenna impedance estimator is configured to generate an impedance offset from the measured impedance and the suitable antenna state. The control signal component is configured to generate a control signal in response to the impedance offset. The control signal can be provided to facilitate impedance matching for an antenna matching network.

[0058] A method for generating a control signal for an antenna matching network is disclosed. The impedance of an RF signal is measured. A suitable antenna matching network state is obtained by referencing a state table with the measured impedance. An antenna matching network is then set up using the suitable antenna matching network state.

[0059] Although the invention has been presented and described with respect to one or more embodiments, modifications and / or alterations may be made to the examples shown. For example, although a transmission circuit / system described here may be presented as a transmitter circuit, a person skilled in the art will recognize that the invention presented here can also be applied to transmitter / receiver circuits. Furthermore, particularly with regard to the various functions performed by the components or structures (assemblies, devices, circuits, systems, etc.) described above, the terms used to describe such components (including references to a "means") shall, unless otherwise indicated, correspond to any component or structure that performs the specified function of the described component (e.g.,(which is functionally equivalent), although it is not structurally equivalent to the disclosed structure that performs the function in the exemplary embodiments of the invention presented herein. Furthermore, while a particular feature of the invention may be disclosed with respect to only one of several embodiments, such a feature may be combined with one or more other features of the other embodiments, as might be desirable and advantageous for any given or particular application. Moreover, to the extent that the terms "including," "comprising," "having," "incorporating," "with," or variants thereof are used in the detailed description and the claims, these terms shall be understood to mean inclusive in a manner similar to the term "comprising."

Claims

[1] System (100) for controlling an antenna matching network (106, 506), comprising: an RF path (102) for generating an RF signal (114, 514); a lookup table (112, 512) with a state table that correlates antenna states with impedance values, wherein the state table contains entries, each entry comprising an antenna state and a corresponding range of impedance values; and a state table analysis component (110, 508) for generating a matching network control signal (122, 536) from the RF signal using the lookup table, wherein the state table analysis component (110, 508) is configured to use a measured impedance and a reference state to identify the corresponding antenna state in the state table and to use the antenna state from the state table to generate the matching network control signal (122, 536). [2] System (100) according to claim 1, further comprising an antenna path with an impedance that changes according to usage conditions. [3] System (100) according to claim 2, wherein the conditions of use include the proximity of a hand to a mobile device. [4] System (100) according to one of claims 1 to 3, wherein the matching network control signal (122, 536) contains capacitance values. [5] System (100) according to any one of claims 1 to 4, wherein the matching network control signal (122, 536) corresponds to an impedance offset amount. [6] System (100) according to any one of claims 1 to 5, further comprising the antenna matching network (106, 506) for receiving the matching network control signal (122, 536). [7] System (100) according to claim 6, wherein the antenna matching network (106, 506) sets an antenna impedance according to the matching network control signal (122, 536). [8] System (100) according to any one of claims 1 to 7, wherein the state table corresponds to a first frequency. [9] System (100) according to claim 8, wherein the lookup table (112, 512) contains a second state table corresponding to a second frequency, wherein the second frequency is modified from the first frequency. [10] System (100) according to any one of claims 1 to 9, wherein the state table analysis component (508) includes a feedback receiver (518) and a directional coupler (504), wherein the directional coupler (504) receives a coupled signal from the RF signal (514) and the feedback receiver is configured to measure an impedance from the coupled signal. [11] System (100) according to claim 10, wherein the coupled signal includes a reflected signal from an antenna path. [12] System (100) according to any one of claims 1 to 11, wherein the impedance values ​​are converted impedance values ​​and the state table analysis component (110, 508) uses a reference state to convert the impedance values ​​into actual impedance values. [13] Antenna matching network system (100), comprising: a directional coupler (504) for generating a coupled signal (526); a feedback receiver (518) for measuring an impedance from the coupled signal (526); a lookup table (512) to provide an instantaneous antenna state (120) in response to the measured impedance; an antenna impedance estimator (508) for obtaining the instantaneous antenna state (120) from the lookup table (512) using the measured impedance and a reference state, and for generating an impedance offset amount from the instantaneous antenna state (120) and the measured impedance; and a control signal component (510) for generating a control signal (536) in response to the impedance offset amount. [14] System (100) according to claim 13, wherein the directional coupler (504) is further configured to use a reflected signal and an RF signal to generate the coupled signal. [15] System (100) according to claim 13 or 14, further comprising an antenna matching network (506) for receiving a residual signal from the directional coupler (504) and the control signal (536) and the antenna matching network (506) for generating an output signal (538) according to the antenna state. [16] Method for generating a control signal (122, 538) for an antenna matching network (106, 506), the method comprising: Measuring (306) the impedance of a signal; Converting (308) the measured impedance using a reference state; Referencing (310) a state table (112, 512) with the implemented impedance to obtain a suitable antenna state; and Setting up the antenna matching network (106, 506) using the matched impedance. [17] Method according to claim 16, wherein the method further comprises generating (312) the state table by labelling a device. [18] Method according to claim 17, wherein characterizing the device comprises the following: Applying (304) a plurality of load-pulls to a reference state; Measuring (306) impedance values ​​for the multitude of load imbalances; pairs (308) of antenna states with the measured impedance values; and Create (312) the state table using the pairings.

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