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    • 专利摘要:
    A method for automatic impedance matching of a radio frequency chain comprising: an impedance matching network (RAC) having an input and an output, a first radio frequency device (DFR1) connected to said input and a second device with radio frequency (DRF2) connected to said output, said impedance matching network having a reconfigurable topology and comprising a plurality of reactive elements (CA, LA, CB, LB, CB, LB) of which at least one has a reactance variable, the method comprising choosing the configuration of the impedance matching network to achieve impedance matching while minimizing losses. Automatic impedance adaptation module for implementing such a method. Radiofrequency transmit and receive channels comprising such a module.
    公开号:FR3028691A1
    申请号:FR1460964
    申请日:2014-11-13
    公开日:2016-05-20
    发明作者:Foucauld Emeric De
    申请人:Commissariat a lEnergie Atomique CEA；Commissariat a lEnergie Atomique et aux Energies Alternatives CEA；
    IPC主号:
    专利说明:

    [0001] TECHNICAL FIELD AND METHOD FOR AUTOMATIC IMPEDANCE ADAPTATION, ESPECIALLY FOR A RADIOFREQUENCY TRANSMITTING OR RECEPTION CHAIN The invention relates to a method for automatic impedance matching of a radio frequency chain, such as a radio frequency chain. radiofrequency transmission or reception, and more specifically on an automatic antenna adaptation method. The invention also relates to an automatic impedance matching module enabling the implementation of such a method, as well as to radiofrequency transmission and reception strings comprising such an automatic adaptation module. impedance. In certain radiofrequency information transmission applications, it has been found that the transmitting or receiving antenna can have an impedance strongly dependent on conditions external to the antenna, and particularly depending on the medium in which the antenna is placed. For example, in medical telemetry, it may be necessary to introduce the antenna into a probe placed in the human body, and the impedance then strongly depends on the biological medium in which the antenna 20 is located. It depends on the electrical properties (conductivity, dielectric constant) of surrounding tissues (muscles, fat) or liquid medium (blood, other liquids) in which the antenna can be immersed. Even in more conventional radio frequency transmission applications (mobile telephony, etc.) the antenna impedance may vary. In general, the variations of antenna impedance are particularly sensitive for very small antennas having a high quality coefficient, used in applications with high miniaturization constraints. These impedance variations can lead to losses called mismatch losses: these losses result from the fact that the transmission channel which feeds the antenna, or the reception chain which receives a signal from the antenna 302 86 91 2 , is generally designed to have optimum performance when it is loaded (at the output for the transmission chain or at the input for the reception chain) by a well-defined nominal impedance; it has degraded performance when it is loaded by an impedance different from its nominal value. Mismatch losses can be up to 40 dB. This is why it is known to interpose, between the output of a power amplifier and the antenna of a transmission channel, an impedance matching network, in English "matching network", which makes that the transmission chain sees an impedance different from that of the antenna and preferably equal to the nominal value for which it was designed, for example 100 ohms or 500 ohms. The adaptation network is tunable, that is to say that its elements, capacitive and / or inductive, have adjustable values to take into account the environmental conditions of the antenna so that the adaptation is the best possible under any circumstances. Similarly, it is known to interpose such an impedance matching network between the antenna of a reception chain and the input of a low noise amplifier. Several techniques have been proposed for automatically tuning such an adaptation network, so as to follow, for example, variations in the antenna impedance induced by external conditions. US 4,375,051 teaches the use, in a transmission chain, of a bidirectional coupler for detecting mismatch by measuring the fraction of power provided by an amplifier that is reflected by the antenna. This measurement serves to enslave the impedance network to modify its configuration in a direction tending to reduce the reflected power. This method suffers from two drawbacks: on the one hand, the reflected power may be low and subject to parasitic interference, since any interference picked up by the antenna distorts the measurement because it adds to the reflected power. On the other hand, there is no one-to-one relationship between the amount of reflected power, which serves as an input to the servo-control, and the complex value of impedance that would have to be given to the lattice. adaptation to really adapt the amplifier to the antenna. This method therefore leads to a new impedance that is not necessarily optimal, because at a given power corresponds to several pairs of complex impedances. Document US 2009/0130991 discloses a method for adjusting the values of the reactances of an impedance matching circuit arranged between a reception antenna and a low noise amplifier in which the reactances of the elements of said adaptation circuit are Iteratively adjusted so as to maximize the intensity of the output signal of said low-noise amplifier. The convergence of the iterative optimization algorithm can be very slow. Documents EP 2,037,576, WO 2011/026858, EP 2,509,222 and EP 2,509,227 describe various variants of a method for automatically adapting the impedance of a radio frequency transmission or reception system, in which Measurements of current and voltage at the input (for a transmission channel) or at the output (for a reception channel) of the matching network make it possible to determine the antenna impedance. The knowledge thus obtained from the antenna impedance makes it possible to use conventional techniques, for example based on a Smith chart, to adjust the impedance values of the elements of the adaptation network so as to arrive at a suitable adaptation. 'impedance. A disadvantage of such a method - as well as the method disclosed by US 4 375 051 cited above - is not to take into account the losses introduced by the impedance matching network. These losses have their origin in the non-ideal behavior of the reactive elements (capacitors and chokes), the impedance of which has a non-zero resistive component, and in some cases may be greater than the efficiency gain afforded by the adaptation of impedance.
    [0002] The invention aims to remedy the aforementioned drawbacks of the prior art. More particularly, it aims to provide an automatic impedance matching method for taking into account losses 3028691 4 introduced by the impedance matching network, while being simple to implement and converging quickly. It also aims to provide an impedance matching module for implementing such a method.
    [0003] According to the invention, this object is achieved by: an adaptation network having, in addition to variable reactance elements, a reconfigurable topology; and a processor configured or programmed to configure said matching network by adjusting the reactance values of said elements and determining its topology in order to achieve impedance matching while minimizing losses. An object of the invention is therefore an automatic impedance matching method of a radio frequency chain comprising: an impedance matching network having an input and an output, a first radio frequency device connected to said input and a second radio frequency device connected to said output, said impedance matching network having a reconfigurable topology and comprising a plurality of reactive elements of which at least one has a variable reactance, the method comprising: at least one current and a voltage at the input or output of said impedance matching network; determining, by a data processor receiving as input the results of said measurements, a topology of said matching network and a reactance value of said or each said reactive element so as to jointly optimize the adaptation of impedance between said first and said second radio frequency device and the power efficiency of said matching network; and configuring said impedance matching network such that it takes said topology and said or each said reactive element having a variable reactance takes said reactance value.
    [0004] According to various embodiments: the method may comprise the following steps: a) measuring at least one current and a voltage at the input or output of said impedance matching network; B) calculating a complex impedance Zm, defined by the ratio of the voltage and the current measured taking into account their phase shift and representing a load impedance of said first radio frequency device or an input impedance of said second radio frequency device, according to that the measurements of step a) have been performed at the input or output of said impedance matching network; c) from said complex impedance Zm, the topology and the current known values of the reactive elements of said impedance matching network, calculating the value of a complex impedance Zd representative of an output impedance of said first device to A radio frequency or an input impedance of said second radio frequency device, depending on whether the measurements of step a) were performed at the input or output of said impedance matching network; d) for a plurality of possible topologies of said impedance matching network, computing new reactance values of said one or each said reactive element having a variable reactance, such that said load impedance of said first radio frequency device or said input impedance of said second radio frequency device takes a value as close as possible to a predefined nominal value; E) selecting, from among said topologies of said impedance matching network, that which minimizes losses when the reactance of said or each said reactive element having a variable reactance takes the value calculated in step d); and f) configuring the impedance matching network so that it takes the topology determined in step e) and the reactance of said or each said reactive element having a variable reactance takes the calculated value of step d). More particularly, the measurements of step a) can be performed at the output of said impedance matching network, the method also comprising the following step, implemented after said step f): g) calculating the electrical power output of said impedance matching network from the measured voltage and current, and iteratively adjusting the reactance of said or each said reactive element having a variable reactance so as to maximize said electrical power. Said first radiofrequency device may be or comprise a power amplifier and said second radio frequency device may be or comprise an antenna. Said first radiofrequency device may be or comprise an antenna and said second radio frequency device may be or comprise a low noise amplifier. Said first radiofrequency device may be or comprise an antenna and said second radiofrequency device may be or comprise a low noise amplifier, the method also comprising the following step, implemented after said step f): g) measuring the electrical power output of said low-noise amplifier, and iteratively adjusting the reactance of said or each said reactive element having a variable reactance so as to maximize said electrical power. Another object of the invention is an automatic impedance matching module to be arranged between a first radio frequency device and a second radio frequency device, said module comprising: an impedance matching network having an input intended to be connected to said first radiofrequency device and an output intended to be connected to said second radio frequency device, said impedance matching network comprising a plurality of reactive elements of which at least one has a variable reactance; a current and voltage measuring device arranged to measure a current and a voltage at the input or output of said impedance matching network; at least one first configuration device of said impedance matching network, adapted to modify the reactance of said or each said reactive element having a variable reactance; and a data processor configured to receive input current and voltage measurements from said measurement device and output control signals from said one or more first configuration devices; characterized in that: said impedance matching network has a reconfigurable topology; the module also comprises at least a second configuration device of said impedance matching network, able to modify its topology; said data processor is configured to determine a topology of said matching network and a reactance value of said or each said reactive element so as to jointly optimize the impedance matching between said first and said second radio frequency device 15 and the power efficiency of said matching network, and for generating control signals from said first and second configuration devices adapted for said devices to configure the impedance matching network so that it takes said topology and that said each said reactive element having a variable reactance takes said value. According to various embodiments: said data processor may be configured to: calculate a complex impedance Zm, defined by the ratio between the voltage and the current measured by said measuring device taking into account their phase shift and representing an impedance of charging said first radio frequency device or an input impedance of said second radio frequency device, according to whether said measuring device is arranged to make measurements at the input or output of said impedance matching network; from said complex impedance Zm, topology and current known values of the reactive elements of said impedance matching network, calculating the value of a complex impedance Zd representative of an output impedance of said first radio frequency device or an input impedance of said second radio frequency device, depending on whether said measuring device is arranged to make measurements at the input or output of said impedance matching network; for a plurality of possible topologies of said impedance matching network, computing new reactance values of said or each said reactive element having a variable reactance, such that said load impedance of said first radio frequency device or said impedance the input of said second radio frequency device takes a value as close as possible to a predefined nominal value; selecting, from among said topologies of said impedance matching network, that which minimizes losses when the reactance of said or each said reactive element having a variable reactance takes the calculated value; generating control signals from said first and second configuration devices adapted for said devices to configure the impedance matching network so that it takes the selected topology and said or each said reactive element having a variable reactance take the calculated value. Said data processor may also be configured to receive as input an electrical power measurement, or data for computing electrical power, and to generate control signals from said one or more first configuration devices adapted for said devices to adjust. iteratively the reactance of said or each said reactive element having a variable reactance so as to maximize said electric power. In addition, said data processor may be configured to calculate said electrical power from the current and voltage measurements from said measurement device. Alternatively, said impedance matching module may also include a power meter arranged to measure an output electrical power of said second radio frequency device and to provide a measurement result to said data processor.
    [0005] Yet another object of the invention is a radiofrequency transmission system comprising a power amplifier, an antenna and such an automatic impedance matching module connected between an output of said power amplifier and an input port. of said antenna.
    [0006] Yet another object of the invention is a radio frequency reception chain comprising an antenna, a low noise amplifier and such an automatic impedance matching module connected between an output port of said antenna and an input of said amplifier. low noise.
    [0007] Radio frequency means any frequency between 3 kHz and 300 GHz. The term "power amplifier" means an amplifier whose output is connected to or intended to be connected, directly or indirectly, to an emitter antenna.
    [0008] The term "low-noise amplifier" means an amplifier having an input connected to or intended to be connected, directly or indirectly, to a receiving antenna. The term "reactive element" means an electrical component whose impedance has, at at least one frequency in the radiofrequency domain, a reactive component (capacitive or inductive) greater than or equal to-and preferably greater by a factor of 10 or more - its resistive component. The "topology" of an electrical network is defined by the set of elements that make it up (capacitors, chokes, resistors, etc.) and their interconnection, ignoring the value of their resistance, inductance or capacitance. It is understood that several elements of the same type connected in series or in parallel are considered as constituting a single element. Thus, no topology is changed by replacing, for example, a single capacitor with two capacitors connected in parallel. It will be considered in the following that the signals in the matching network have a unique frequency f = 2nw, which makes it possible to characterize a capacitive or inductive element (reactive element) by a reactance value. This approximation is generally satisfactory in the field of radio frequencies. Other characteristics, details and advantages of the invention will become apparent on reading the description given with reference to the appended drawings given by way of example and which represent, respectively: FIG. 1A, the block diagram of a module automatic impedance matching according to an embodiment of the invention; FIG. 1B, the electrical diagram of the impedance matching network of the module of FIG. 1A; FIG. 2 is a flow diagram of an automatic impedance matching method according to one embodiment of the invention; FIGS. 3 and 4, respectively, the functional diagrams of a radiofrequency transmission system and a radio frequency reception system according to respective embodiments of the invention; and FIG. 5, the equivalent electrical diagram of an impedance matching network in Pi used to calculate its power efficiency. FIG. 1A shows the functional block diagram of an automatic impedance matching module according to an embodiment of the invention, inserted into a radio frequency chain. The module comprises a configurable impedance matching network RAC having two gates, two DME, DMS measuring devices arranged at said gates (but in fact only one may suffice), a PD data processor receiving data input measuring devices generated by said measuring devices and generating control signals for two control devices DC1, DC2 which configure the RAC network. The two gates of the RAC impedance match network are connected to a first radio frequency device DRF1 and a second radio frequency device DRF2, respectively. In the following, unless otherwise indicated, it will be considered that the first radio frequency device DRF1 is a power amplifier AP and that the second radio frequency device DRF2 is an antenna ANT operating in transmission (see FIG. radio frequency chain is a transmission chain; filters may also be provided between the amplifier and the impedance matching network and / or between the latter and the antenna. Other cases are also possible, in particular the first radiofrequency device DRF1 may be an ANT antenna operating in reception and the second radiofrequency device DRF2 may be an ABB low noise amplifier, whereby the radio frequency chain is a chain reception. In the following, it will always be considered that the electric power propagates from DRF1 to DRF, so that the measuring device DME is arranged at the input of the impedance matching network and the measuring device DMS is arranged. at the exit 15 of the latter. DME, DMS measuring devices are used to measure the input and output voltage and current of the matching network, respectively. These devices may in particular be of the type described in the aforementioned document EP 2,037,576, and comprise: an impedance ZMCE, ZMCS connected in series; a VM device for measuring the voltage upstream and downstream of this impedance. Preferably, the measurement impedances ZMCE, ZMCS are reactive, and more preferably, capacitive. In the example of FIG. 1A, the measurements are made in differential mode, so that each measuring device comprises two identical measurement capacities, but this is not essential. Each VM device essentially consists of a conventional frequency change circuit and an analog to digital converter. Indeed, the voltages at the terminals of the measurement impedances are electrical signals at the carrier frequency f. To reduce the power consumption, and improve the calculation accuracy, it may be interesting to perform the low frequency impedance calculation. It is then expected a conversion to a lower frequency to be able to make the calculations that follow. It should be noted that in certain cases, circuit elements present in the radiofrequency reception circuits of the system may be used to constitute this measuring circuit. Indeed, if the system operates in transmission and reception, the receiving part has frequency change circuits and these circuits can very well be used to perform the voltage measurements. The voltage drop measurement Vis-V2s (V2E-V1E) across the ZMCS impedance (ZMCE) is used to determine the output (input) current of the matching network. The output (input) voltage of the adaptation network is measured directly by the device VM. By calculating the ratio and phase shift between the current and the output voltage of the matching network as measured by the ZMCS device, it is therefore possible to determine a complex impedance Z, which represents the output impedance of the matching network. Similarly, by calculating the ratio and phase shift between the current and the input voltage of the matching network as measured by the ZMCS device, a complex impedance can be determined which represents the input impedance of the network 20. adaptation, and therefore the load impedance of radio frequency device DRF1 (the amplifier, in a transmission chain). Figure 1B shows the schematic of a possible embodiment of the RAC impedance matching network. This network is reconfigurable for two reasons: on the one hand, a set of controlled switches INTA, INTB, INTc makes it possible to modify the topology; on the other hand, it comprises a set of reactive elements CA, CB, Cc, LA, LB, Lc at least some of which (at least one, preferably several) have a variable reactance. In the example of Figure 1 B, given in a non-limiting manner, the network has a generally "Pi" configuration with a central branch and two lateral branches or legs. Depending on the configuration of the switches, each of these branches can be capacitive, inductive or constitute a parallel LC circuit; in addition, the legs can be disconnected. Thus, for example, it is possible to act on the switches to configure the impedance matching network to take a topology selected from the following: Pi topology with capacitive legs and inductive central branch; Pi topology with 5 inductive legs and capacitive central branch; simple parallel RC circuit connected in series between the first and the second radiofrequency device. In the example of Figure 1 B, all the reactive elements of the impedance matching network have a reactance (and therefore a inductance or capacity) variable, but this is not essential.
    [0009] A first configuration device DC1 controls the switches INTA, INTB, INTc, thus determining the topology of the impedance matching network RAC. A second configuration device DC2 acts - electrically and / or mechanically - on the reactive elements CA, CB, Cc, LA, LB, Lc to modify their reactance. These configuration devices 15 are in turn driven by the data processor PD, or they are integrated in the latter. For example, the first configuration device may comprise control electronic circuits of the INTA, INTB, INTc switches and the second device for configuring the voltage generators for varying the capacity of variable capacity diodes and current generators enabling varying the inductance of inductors having a saturable core; there are also voltage-controlled inductors, as well as microelectromechanical type (MEMS) tunable inductors, see for example: - Casha, O.; Grech, I.; Micallef, J.; Gatt, E.; Morche, D.; Viala, B .; Michel, J.P .; Vincent, P.; de Foucauld, E.: "Utilization of MEMS Tunable Inductors in the Design of RF Voltage-Controlled Oscillators," 15th IEEE International Conference on Electronics, Circuits and Systems, 2008. ICECS 2008; L. Collot, J. Lintignat, B. Viala, D. Morche, J-P. Michel, B.
    [0010] The PD data processor is typically a microprocessor programmed in a timely manner, but the data processor PD is typically a microprocessor that is timed appropriately. it can also be a hardware configured digital circuit, or a combination of both. This processor performs the following operations: 5 - From the voltage and current measurements made by the measuring device DME and / or DMS, it determines the input and / or output impedance of the adaptation network of impedance. Starting from the input and / or output impedance of the adaptation network, from the latter (topology and value of the reactances), it determines the value of the impedance of the device DRF1 or of the device DRF2. Typically, in the case of a radiofrequency transmission or reception string, it will be necessary to determine the impedance of the antenna corresponding to DRF2 in a transmission chain and to DRF1 in a reception chain. It determines the value that the reactances of the variable elements of the impedance matching network must take to achieve an impedance matching of the radio frequency chain. Typically, in a transmission chain it will be necessary to ensure that the load impedance of the power amplifier (DRF1) is equal to, or as close as possible to, a predefined optimal impedance (generally, the output impedance of said amplifier). Similarly, in the case of a reception chain it will be necessary to ensure that the impedance at the input of the low noise amplifier (DRF2) is equal to, or as close as possible to, a predefined optimal impedance (generally, the input impedance of said amplifier).
    [0011] This calculation is repeated for each possible topology (or at least for a predefined set of possible topologies) of the RAC network. This results in a plurality of admissible configurations of the RAC network, having different topologies and all making it possible to perform impedance matching. Among these acceptable configurations, it selects the one that has the best power output, and therefore the lowest losses. For this, it must have a characterization of the different reactive elements of the adaptation network. Then, it controls the configuration devices DC1, DC2 of the adaptation network accordingly. These various operations correspond to the steps "b", "c", "d" and "e" of the flowchart of FIG. 2. Step "a" corresponds to the measurement operations performed by the device DME and / or DMS, while step "f" corresponds to the configuration of the RAC network by the devices DC1 and DC2. Step "g" is optional. It consists in iteratively adjusting the impedance values - using the configuration device DC2 driven by the processor PD - so as to optimize the electrical power at the output of the adaptation network, or even the electrical power measured in FIG. another point in the radio frequency chain. The idea underlying this step is that sometimes it may be advantageous to accept a slight impedance mismatch if it is accompanied by a significant reduction in losses introduced by the adaptation network. In the case of a transmission channel, it is relevant to maximize the output power of the adaptation network, which is supplied to the antenna ANT; this power can be calculated from the current and the output voltage of the RAC network, measured by the DMS device. The use of an input measuring device, DME, is not necessary (Figure 3). In the case of a reception channel, on the other hand, it is preferable to maximize the power W at the output of the low noise amplifier ABB, which requires a dedicated measuring device DMP, which may have a structure similar to that of DMS and DME. This arrangement is illustrated in FIG. 4. In the example illustrated by this figure, furthermore, the DME measuring device is present, but DMS is absent; the reverse would also have been possible. The use of a device for measuring the power distinct from the measurement device (s) used to achieve the impedance matching is also possible in the case of a transmission system. This is particularly advantageous if it is desired to perform the current and voltage measurements used for automatic impedance matching at the input of the matching network, and not at its output. It should be noted that step "g" can also be implemented when the impedance matching network has a fixed topology (in which case step "d" is executed once and step " e "is not right). Compared with the method described in US 2009/0130991, the convergence is faster because the iterative optimization starts from an impedance matching situation, which is already close to optimality.
    [0012] In the following, the implementation of steps "b" to "e" and "g" will be described in more detail with reference to the specific case illustrated in FIG. 3, namely a transmission chain with current measurement. and the output voltage of the impedance matching circuit. The generation in other cases, such as that of a reception chain does not pose any particular difficulty. Step "b": calculation of the current load impedance. The measuring circuit DMS receives the voltage signals V1s and V2s previously defined. These voltages are at the carrier frequency f; they are preferably switched to an intermediate frequency or baseband by conventional frequency changing circuits using a local oscillator and mixers. Then the voltage levels Vis and V2S; brought back to this intermediate frequency or in baseband, are used to calculate the vector current i which crosses the measurement impedance ZMCS and therefore the complex impedance Vis / i seen by the amplifier. The phase shifts are retained in the frequency change. The i module is the ratio of the V1s module and the ZDMS impedance module; the phase shift of i with respect to the voltage V1s is an angle θ which represents the argument of the impedance Zn ,. This angle can be determined from the phase difference between Vis and V2s subtracted from rc / 2 knowing that the phase shift between i and (Vis-V2s) is rc / 2 since, in the embodiment of Figure 1, ZMCS is a capacitive impedance: Zmcs = 1 / (jc0Cmcs), where "j" is the imaginary unit, w is the frequency of the radiofrequency signal and CMCS is the capacitance of the capacitor that constitutes the measurement impedance. The phase difference between Vis and V25 can be calculated for example by multiplying the analog signals Vis and V2s, brought back to baseband, and observing the periodic variation of the product of the two signals. This product oscillates between a positive maximum value and a negative minimum value. The algebraic sum of these two values is proportional to the cosine of the phase shift and the coefficient of proportionality is the algebraic difference of these two values. Consequently, by relating the sum of the two values to the difference of the two values, we find the cosine of the phase shift from which we draw the phase shift between Vis and V2s, from which we deduce the phase difference between V1s and i. Other methods of calculating the phase shift can be used, for example by digitizing the two signals Vis and V2s on a bit, equal to 1 when the signal is positive and 0 when it is negative. The time shift of the bit pulse trains 1 resulting from the digitization of Vis, with respect to the same pulse trains corresponding to the digitization of V2s, represents the phase difference between Vis and V2s. The sign of the phase shift is identified by observing the rising edges of the signals thus digitized on one bit; this can be done by a flip-flop D which receives on one signal input one of the voltages V1s or V2s and on a clock input the other of these voltages, and which carries back to its output the state of the input signal at the time of a rising edge on the clock input.
    [0013] Once we have the 0 argument of the impedance Zm, we can easily calculate its real part and its imaginary part. Step "c": calculation of the current impedance of the antenna. From this measurement of Zm, knowing the configuration of the adaptation network (topology and current numerical values of the capacitors and inductances), and also the numerical value of the measurement capacitance ZDMS, it is possible to calculate the impedance of the 'antenna.
    [0014] 3028691 18 This calculation is immediate because we simply have: Zant = ZDMS-ZMCS Step "d": calculation of modified values for the reactances of the adaptation network.
    [0015] 5 Knowing both the current impedance of the Zant antenna and the equivalent impedance of the Zeq adaptation network, function of (CA, Cc, LB), as well as the measurement impedance ZMCS, it is a question of calculate the values AC, Cc LB that must be given to the variable elements so that the impedance of the set ZDME, as it will be seen at the terminals of the amplifier (and therefore at the input of the network of adaptation) is equal to the nominal value Zoo (usually the output impedance of the amplifier): ZDKAE = Zopt. To do this we can use techniques well known to those skilled in the art, based for example on the use of a Smith chart. The aforementioned EP 2,037,576 provides an example of application of such a method. In contrast to the case studied in this document, however, in the context of the present invention the dimensioning of the adaptation network RAC is repeated a plurality of times by considering different possible topologies. For example, in the case of the configurable network of FIG. 1B, two distinct topologies can be taken into account: a "Pi" topology with inductive central branch and capacitive legs (this is the topology used for measuring of Zm), and a topology also in "Pi" but with capacitive central branch and inductive legs.
    [0016] Step "e": calculation of the power efficiency (or, equivalently, losses). FIG. 5 shows an equivalent diagram of the impedance matching circuit of FIG. 1B in its "Pi" configuration with inductive central branch and capacitive legs, placed in the radio frequency chain of FIG. 3. The equivalent resistance R1 represents the combined effect of the output impedance of the power amplifier PA, assumed to be known and purely resistive, and the parasitic resistance of the AC capacitor; C1 is, in this particular case, equal to CA. The equivalent resistance R2 represents the combined effect of the input impedance of the Zant antenna, measured during step "c" and considered purely resistive, and the parasitic resistance of capacitors CB and ZDMS; C2 is an equivalent capability accounting for capacitive effects due to CB and ZDMS. The inductive element LB is split into two parts L1 and L2 for convenience of calculation, with L1 + L2 = LB. The same goes for its parasitic resistance rL = ri + r2. At this point we can define the quality factors QC1, Qc2, Or, QL2 of the equivalent elements C1, C2, L1 and L2: Qci = GORiCi Qc2 = wR2C2 GOLi QL1 = r1 coL2 = r2 The power output TI is then given by 1 1 + [QC1 + QC21 QL1 QL2 We can check that the value of TI does not depend on how we break down LB = 1_1 + 1-2.
    [0017] Note that the efficiency TI depends on the value of C1, C2, L1 and L2 and therefore of CA, LB and Cc; thus, it varies as one adjusts the reactance value of the RAC adapter network elements to achieve impedance matching. Moreover, the value of the parasitic resistors can also vary during this adjustment.
    [0018] A general method of yield calculation, which can be applied to arbitrary topology, is detailed in the article by Yehui Han and David J. Perreault, "Analysis and Design of High Efficiency Matching Networks," IEEE Transactions on Power Electronics, Vol. . 21, No. 5, September 2006, pages 1484 - 1491. QL2 11 = 302 86 91 20 It is therefore possible to calculate the value of the efficiency TI for all the configurations of the network RAC determined during the step "d", then choose the one with the highest yield value.
    [0019] Step "g": iterative optimization of the output power of the adaptation network. This last step, which is optional, consists in iteratively varying the reactances of the RAC network around the values determined during step "d", without modifying the topology of the chosen network following step "f", this for the purpose. to maximize the power transmitted to the antenna and measured using the DMS device. Unlike the previous steps, the optimization is done by acting on the actual circuit and measuring the power effectively transmitted, and not on the basis of calculations using a model of the circuit. This iterative optimization takes into account the fact that a slight impedance mismatch can be more than compensated by a reduction in the level of losses in the matching circuit. It also makes it possible to correct the inaccuracies inherent in the models used to determine the configuration carrying out the impedance matching. This step can be implemented as explained in US 2009/0130991 supra. However, as the iterative algorithm is initialized by an impedance matching configuration - so close to optimality - its convergence is fast. The invention has been described with reference to a particular embodiment, but it is not limited thereto. For example, the first and the second radio frequency device may not be an antenna and a power or low noise amplifier; it is not essential that the radio frequency chain is a transmission or reception chain. In addition, the impedance matching network may not have a "Pi" topology but, for example, a "Te" topology or a more complex type. Moreover, the optimization of the configuration of the adaptation network taking into account both the impedance matching and the losses can be done differently than according to the method of FIG. 2; an alternative may be to test a plurality of configurations - defined by a topology and a set of reactance values of the reactive elements of the network - sampling the configuration space, and then to choose the optimal configuration, i.e. say, maximizing at least one performance criterion such as the power transferred through the matching network.
    权利要求:
    Claims (13)
    [0001]
    REVENDICATIONS1. A method of automatic impedance matching of a radio frequency chain comprising: an impedance matching network (RAC) having an input and an output, a first radio frequency device (DRF1) connected to said input and a second radiofrequency device (DRF2) connected to said output, said impedance matching network having a reconfigurable topology and comprising a plurality of reactive elements (CA, LA, CB, LB, CB, LB) of which at least one has a Variable reactance, the method comprising: - measuring at least one current and a voltage at the input or output of said impedance matching network; determining, by a data processor receiving as input the results of said measurements, a topology of said matching network and a reactance value of said or each said reactive element so as to jointly optimize the adaptation of impedance between said first and said second radio frequency device and the power efficiency of said matching network; and - configuring said impedance matching network so that it takes said topology and said or each said reactive element having a variable reactance takes said reactance value.
    [0002]
    The method of claim 1 comprising the steps of: a) measuring at least one current and a voltage at the input or output of said impedance matching network; b) calculating a complex impedance Zm, defined by the ratio of the voltage and the current measured taking into account their phase shift and representing a load impedance of said first radio frequency device 30 or an input impedance of said second radio frequency device, according to the measurements of step a) have been performed at the input or output of said impedance matching network; C) from said complex impedance Zm, the topology and the current known values of the reactive elements of said impedance matching network, calculating the value of a complex impedance Zd representative of an output impedance of said first a radio frequency device or input impedance of said second radio frequency device, depending on whether the measurements of step a) have been performed at the input or output of said impedance matching network; d) for a plurality of possible topologies of said impedance matching network, computing new reactance values of said or each said reactive element having a variable reactance, such that said load impedance of said first radio frequency device or said the input impedance of said second radio frequency device takes a value as close as possible to a predefined nominal value; e) selecting, from among said topologies of said impedance matching network, that which minimizes losses when the reactance of said or each said reactive element having a variable reactance takes the value calculated in step d); and f) configuring the impedance matching network so that it takes the topology determined in step e) and the reactance of said or each said reactive element having a variable reactance takes the calculated value of step d).
    [0003]
    3. The method according to claim 2, wherein the measurements of step a) are performed at the output of said impedance matching network, the method also comprising the following step, implemented after said step f). g) calculating the electrical power (W) output from said impedance matching network from the measured voltage and current, and iteratively adjusting the reactance of said or each said reactive element having a variable reactance so as to maximize said electrical power. 3028691 24
    [0004]
    4. Method according to one of the preceding claims, wherein said first radiofrequency device is or comprises a power amplifier (AP) and said second radiofrequency device 5 is or comprises an antenna (ANT).
    [0005]
    The method according to one of the preceding claims, wherein said first radio frequency device is or comprises an antenna (ANT) and said second radio frequency device is or comprises a low noise amplifier (ABB).
    [0006]
    The method of one of claims 1 or 2 wherein said first radio frequency device is or comprises an antenna (ANT) and said second radio frequency device is or comprises a low noise amplifier (ABB), the method also comprising the following step, carried out after said step f): g ') measuring the electrical power (W) output of said low-noise amplifier, and iteratively adjusting the reactance of said or each said reactive element having a variable reactance; maximizing said electrical power.
    [0007]
    7. Automatic impedance matching module intended to be arranged between a first radio frequency device (DRF1) and a second radio frequency device (DRF2), said module comprising: an impedance matching network (RAC) having an input for connection to said first radio frequency device and an output for connection to said second radio frequency device, said impedance matching network comprising a plurality of reactive elements (CA, LA, CB, LB, CB , LB) of which at least one has a variable reactance; A current and voltage measuring device (DME, DMS), arranged to measure a current and a voltage at the input or output of said impedance matching network; At least one first configuration device (DC1) of said impedance matching network, adapted to modify the reactance of said or each said reactive element having a variable reactance; and - a data processor (PD) configured to receive input current and voltage measurements from said measurement device and to output control signals from said one or more first configuration devices; characterized in that: - said impedance matching network has a reconfigurable topology; the module also comprises at least a second configuration device (DC2) of said impedance matching network, able to modify its topology; said data processor is configured to determine a topology of said matching network and a reactance value of said or each said reactive element so as to jointly optimize the impedance matching between said first and said second radio frequency device and the power efficiency of said matching network, and for generating control signals from said first and second configuration devices adapted for said devices to configure the impedance matching network so that it takes said topology and that said or each said reactive element having a variable reactance takes said value.
    [0008]
    An impedance matching module according to claim 7 wherein said data processor is configured to: calculate a complex impedance Zm defined by the ratio of the voltage to the current measured by said measurement device taking into account their phase shifting and representing a load impedance of said first radio frequency device or an input impedance of said second radio frequency device, according to whether said measuring device is arranged to make measurements at the input or output of said adaptation network of impedance; Based on said complex impedance Zm, the topology and the current known values of the reactive elements of said impedance matching network, calculating the value of a complex impedance Zd representative of an output impedance of said first device to radio frequency or an input impedance of said second radio frequency device, according to whether said measuring device is arranged to make measurements at the input or output of said impedance matching network; for a plurality of possible topologies of said impedance matching network, computing new reactance values of said or each said reactive element having a variable reactance, such that said load impedance of said first radio frequency device or said impedance the input of said second radio frequency device takes a value as close as possible to a predefined nominal value; selecting, from among said topologies of said impedance matching network, that which minimizes losses when the reactance of said or each said reactive element having a variable reactance takes the calculated value; generating control signals from said first and second configuration devices adapted for said devices to configure the impedance matching network to take the selected topology and said or each said reactive element having a variable reactance take the calculated value.
    [0009]
    An impedance matching module according to claim 8, wherein said data processor is also configured to receive as input an electrical power measurement (W), or data for computing electrical power, and to generate control signals of said first configuration device or devices adapted so that said devices iteratively adjust the reactance of said or each said reactive element having a variable reactance so as to maximize said electrical power. 30
    [0010]
    An impedance matching module according to claim 9, wherein said data processor is configured to calculate said electrical power from the current and voltage measurements from said measurement device.
    [0011]
    An impedance matching module according to claim 9, further comprising a power meter arranged to measure an output electrical power of said second radio frequency device and to provide a measurement result to said data processor. 10
    [0012]
    A radio frequency transmission line comprising a power amplifier (AP), an antenna (ANT) and an automatic impedance matching module according to one of claims 7 to 10 connected between an output of said power amplifier and a power amplifier. input port of said antenna. 15
    [0013]
    13. Radio frequency reception chain comprising an antenna (ANT), a low noise amplifier (ABB) and an automatic impedance matching module according to one of claims 7 to 11 connected between an output port of said antenna and an input of said low noise amplifier.
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    同族专利:
    公开号 | 公开日
    FR3028691B1|2019-08-16|
    US10666219B2|2020-05-26|
    EP3021484B1|2021-01-27|
    EP3021484A1|2016-05-18|
    US20160142035A1|2016-05-19|
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    优先权:
    申请号 | 申请日 | 专利标题
    FR1460964A|FR3028691B1|2014-11-13|2014-11-13|METHOD AND MODULE FOR AUTOMATIC IMPEDANCE ADAPTATION, ESPECIALLY FOR A RADIO FREQUENCY TRANSMISSION OR RECEPTION CHAIN|
    FR1460964|2014-11-13|FR1460964A| FR3028691B1|2014-11-13|2014-11-13|METHOD AND MODULE FOR AUTOMATIC IMPEDANCE ADAPTATION, ESPECIALLY FOR A RADIO FREQUENCY TRANSMISSION OR RECEPTION CHAIN|
    EP15191601.2A| EP3021484B1|2014-11-13|2015-10-27|Method and device for automatically adapting impedance, in particular for a channel transmitting or receiving radio frequencies|
    US14/936,319| US10666219B2|2014-11-13|2015-11-09|Automatic impedance matching method and module, particularly for a radio-frequency transmission or reception chain|
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