GB2529887A - Tuning reconfigurable multi-port antennas - Google Patents

Tuning reconfigurable multi-port antennas Download PDF

Info

Publication number
GB2529887A
GB2529887A GB1415784.6A GB201415784A GB2529887A GB 2529887 A GB2529887 A GB 2529887A GB 201415784 A GB201415784 A GB 201415784A GB 2529887 A GB2529887 A GB 2529887A
Authority
GB
United Kingdom
Prior art keywords
circuit
matching circuit
rssi
snr
digital controller
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB1415784.6A
Other versions
GB201415784D0 (en
GB2529887B (en
Inventor
Sampson Hu
Xiang Gao
Zhengpeng Wang
Surinder Thind
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Smart Antenna Technologies Ltd
Original Assignee
Smart Antenna Technologies Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Smart Antenna Technologies Ltd filed Critical Smart Antenna Technologies Ltd
Priority to GB1415784.6A priority Critical patent/GB2529887B/en
Publication of GB201415784D0 publication Critical patent/GB201415784D0/en
Publication of GB2529887A publication Critical patent/GB2529887A/en
Application granted granted Critical
Publication of GB2529887B publication Critical patent/GB2529887B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01QANTENNAS, i.e. RADIO AERIALS
    • H01Q1/00Details of, or arrangements associated with, antennas
    • H01Q1/12Supports; Mounting means
    • H01Q1/22Supports; Mounting means by structural association with other equipment or articles
    • H01Q1/24Supports; Mounting means by structural association with other equipment or articles with receiving set
    • H01Q1/241Supports; Mounting means by structural association with other equipment or articles with receiving set used in mobile communications, e.g. GSM
    • H01Q1/242Supports; Mounting means by structural association with other equipment or articles with receiving set used in mobile communications, e.g. GSM specially adapted for hand-held use
    • H01Q1/243Supports; Mounting means by structural association with other equipment or articles with receiving set used in mobile communications, e.g. GSM specially adapted for hand-held use with built-in antennas
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01QANTENNAS, i.e. RADIO AERIALS
    • H01Q1/00Details of, or arrangements associated with, antennas
    • H01Q1/12Supports; Mounting means
    • H01Q1/22Supports; Mounting means by structural association with other equipment or articles
    • H01Q1/24Supports; Mounting means by structural association with other equipment or articles with receiving set
    • HELECTRICITY
    • H03BASIC ELECTRONIC CIRCUITRY
    • H03HIMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H7/00Multiple-port networks comprising only passive electrical elements as network components
    • H03H7/38Impedance-matching networks
    • H03H7/40Automatic matching of load impedance to source impedance
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04BTRANSMISSION
    • H04B1/00Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/02Transmitters
    • H04B1/04Circuits
    • H04B1/0458Arrangements for matching and coupling between power amplifier and antenna or between amplifying stages
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04BTRANSMISSION
    • H04B1/00Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/06Receivers
    • H04B1/16Circuits
    • H04B1/18Input circuits, e.g. for coupling to an antenna or a transmission line
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04BTRANSMISSION
    • H04B1/00Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/38Transceivers, i.e. devices in which transmitter and receiver form a structural unit and in which at least one part is used for functions of transmitting and receiving
    • H04B1/3827Portable transceivers

Abstract

A tuning circuit, or a method of tuning an antenna device, comprises: a digital controller 5 connected to individually operable switches 4a-c which connect between multiple antenna ports 2a-c and respective matching circuits 3a-c to allow independent tuning of the matching circuits. A baseband processor 6 determines a received signal strength indication RSSI signal and a signal to noise ratio SNR signal for each signal port 2a-c and sends these signals to a digital controller 5 which adjusts the switches 4a-c to achieve a required RSSI and SNR values. RSSI values and related switch and/or matching circuit settings may be stored in a look-up table of a memory. An operational amplifier and analogue to digital converter may be used to detect the voltage, and hence the power loss, across the matching circuit. The processor may also determine a bit error rate (BER) for the signals of each signal port. Alternatively, there is disclosed a tuning circuit, or a method of tuning an antenna device, comprising: a monitor circuit connected across a matching circuit where the monitor circuit includes an amplifier and an analogue to digital converter which detects the voltage across the matching circuit and the controller 5 then tunes the matching circuit to reduce the power loss across the matching circuit.

Description

TUNING RECONFIGURABLE MULTI-PORT ANTENNAS
[0001] This invention relates to a tuning a reconfigurable antenna. Particularly, but not exclusively, the invention relates to a tuning control circuit for a reconfigurable multiple-input multiple-output (MIMO) antenna for use in a portable electronic device such as a mobile phone handset, laptop, tablet, femtocell, wireless router or other radio communications device.
BACKGROUND
[0002] Multiple-input multiple-output (MIMO) wireless systems exploiting multiple antennas as both transmitters and receivers have attracted increasing interest due to their potential for increased capacity in rich multipath environments. Such systems can be used to enable enhanced communication performance (i.e. improved signal quality and reliability) by use of multi-path propagation without additional spectrum requirements. This has been a well-known and well-used solution to achieve high data rate communications in relation to 2G and 3G communication standards. Multi-port antennas can be used to improve the performance of the whole system, and it would be desirable to configure these antennas to operate with several frequency bands simultaneously. However, multi-port antennas in a MIMO system are much more complex to control than conventional one port or two port antenna systems. Accordingly, there is a need for a tuning control circuit and a tuning method for a reconfigurable multi-port antenna.
BRIEF SUMMARY OF THE DISCLOSURE
[0003] Viewed from a first aspect, there is provided a tuning control circuit configured for use with a reconfigurable antenna having multiple signal ports each connected to a respective matching circuit by way of a respective switch, the respective matching circuits in turn being connected to a transceiver, wherein the tuning control circuit comprises: i) a digital controller operatively connected to the respective switches so as to allow the switches to be independently operated, the digital controller also being operatively connected to the respective matching circuits so as to allow the matching circuits to be independently tuned; and ii) a baseband processor configured to determine a received signal strength indication, RSSI, and a signal-to-noise ratio, SNR, for signals received at each signal port; wherein the baseband processor is configured to send the determined RSSI and SNR values to the digital controller, and wherein the digital controller is configured to operate the switches and/or the matching circuits so as to obtain RSSI and SNR values that meet predetermined RSSI and SNR requirements for the transceiver.
[00041 The baseband processor may be connected to the transceiver, and may determine the RSSI and SNR of the received signals after they have been passed from the respective signal ports to the transceiver.
[0005] The baseband processor may additionally be configured to determine a bit error rate, BER, for signals at each signal port, and the digital controller may be configured to operate the switches and/or tune the matching circuits so as to obtain BER values that meet predetermined requirements.
[0006] The digital controller may be provided with a lookup table and measured RSSI, SNR and, optionally, BER values may be saved in the lookup table together with their related switch and/or matching circuit settings. For any given situation, the digital controller may subsequently select the best RSSI, SNR and, optionally, BER values from the lookup table and set the switches and/or tune the matching circuits accordingly. This can result in improved speed of control. The lookup table can be frequently updated to adapt to changing operating conditions of the antenna.
[0007] The digital controller may be configured as a microcontroller, a field-programmable gate array, FPGA, a PlC, a digital signal processor, DSP or any other suitable device. The digital controller may be implemented on a chip or integrated circuit.
[0008] The matching circuits may be monolithic microwave integrated circuits, MMICs, low-temperature co-fired ceramic circuits, LTCCs, surface mount component circuits or any other suitable tuneable circuits.
[0009] For a given signal port, the digital controller may monitor the matching circuit by way of a monitor circuit. The monitor circuit may be connected across the matching circuit, and may comprise an operational amplifier and an analogue/digital converter in combination with appropriate capacitors and diodes.
[0010] The operational amplifier is used to detect a potential difference across the matching circuit. The potential difference will be substantially zero if the matching circuit is able to match the antenna input impedance to a standard 50 ohm transmission line. If there is a mismatch, the potential difference will be non-zero, and will increase as the mismatch increases. Accordingly, if the digital controller detects that the output signal from the operational amplifier, converted to digital format by the A/D converter is increasing as the matching circuit is tuned, this will indicate that the matching circuit is being tuned in the wrong direction. In response, the digital controller can tune the matching circuit in the other direction. If the digital controller detects that the output signal from the operational amplifier, converted to digital format by the AID converter is decreasing as the matching circuit is tuned, this will indicate that the matching circuit is being tuned in the correct direction.
[0011] The digital controller may tune the matching circuit by adjusting one or more variable capacitors in the matching circuit, or by any other tuning mechanism as will be known to those of ordinary skill in the art.
[0012] For each operational signal port and matching circuit, it is desired to match the signal port to a standard 50 ohm transmission line.
[0013] Viewed from a second aspect, there is provided a tuning control circuit configured for use with an antenna device having at least one signal port connected to a matching circuit, the matching circuit in turn being connected to a transceiver, wherein the tuning control circuit comprises: i) a monitor circuit connected across the matching circuit, the monitor circuit comprising an operational amplifier and an analogueldigital converter, wherein the operational amplifier is configured to detect a potential difference representative of power loss across the matching circuit, and wherein the analogue/digital converter is configured to output a digital signal representative of power loss across the matching circuit; and U) a digital controller connected to the analogue/digital converter and also to the matching circuit, wherein the digital controller is configured to tune the matching circuit in response to the detected power loss across the matching circuit so as to reduce the detected power loss.
[0014] The circuit may further comprise a baseband processor configured to determine a received signal strength indication, RSSI, and a signal-to-noise ratio, SNR, for signals at the signal port; wherein the baseband processor is configured to send the determined RSSI and SNR values to the digital controller, and wherein the digital controller is configured to tune the matching circuit so as to obtain RSSl and SNR values that meet predetermined RSSI and SNR requirements for the transceiver.
[0015] The digital controller may be provided with a lookup table, and measured RSSI and SNR values may be saved in the lookup table together with their related switch and/or matching circuit settings.
[0016] The first and second aspects are to some extent complementary to each other, and may be combined or implemented separately.
[0017] Viewed from a third aspect, there is provided a method of tuning a reconfigurable antenna device having multiple signal ports each connected to a respective matching circuit by way of a respective switch, the respective matching circuits in turn being connected to a transceiver, the method comprising: i) with a digital controller, switching on a first switch to connect a first signal port to the transceiver by way of a first matching circuit; ii) with a baseband processor, determining a received signal strength indication, RSSI, and a signal-to-noise ratio, SNR, for signals at the first signal port; Ui) determining, by the digital controller, if the RSSI and SNR at the first signal port meet the requirements of the transceiver; iv) if the RSSI and SNR at the first port do not meet the requirements of the transceiver, the digital controller switching off the first switch and switching on a second switch to connect a second signal port to the transceiver by way of a second matching circuit; v) with the baseband processor, determining the RSSI and SNR for signals at the second signal port; vi) determining by the digital controller if the RSSl and SNR at the second signal port meet the requirements of the transceiver; and vii) if the RSSI and SNR at the second port do not meet the requirements of the transceiver, repeating steps iv) to vi) for all of the signal ports in turn.
[00181 In the event that none of the signal ports is able to provide an RSSI and SNR that meet the transceiver requirements, the method may further comprise: vUi) selecting the signal port and matching circuit with the best RSSI and SNR; ix) monitoring a potential difference across the selected matching circuit; x) tuning the selected matching circuit by way of the digital controller so as substantially to minimise the potential difference across the selected matching circuit; xi) determining if the RSSI and SNR at the selected signal port meet the requirements of the transceiver; xii) if the RSSI and SNR at the selected port do not meet the requirements of the transceiver, operating the switches with the digital controller so as to select the signal port and matching circuit with the next best RSSI and SNR; and xiU) repeating steps ix) to xU) until an RSSI and SNR meeting the requirements of the transceiver are obtained.
[0019] Viewed from a fourth aspect, there is provided a method of tuning an antenna device having at least one signal port connected to a matching circuit, the matching circuit in turn being connected to a transceiver, the method comprising: i) with a monitoring circuit, detecting a potential difference corresponding to a power loss across the matching circuit and generating a signal representative of the power loss; ii) inputting the signal representative of the power loss to a digital controller; iii) with the digital controller, determining whether or not the potential difference is above a predetermined value; and iv) if the potential difference is above the predetermined value, retuning the matching circuit under control of the digital controller so as to reduce the detected potential difference to below the predetermined value.
[0020] In order to illustrate how the present tuning control circuit may be implemented, an example will now be described. All the switches between the signal ports and the matching circuits may initially be switched off except for the switch connecting a first signal port to a first matching circuit. The baseband processor will then measure the RSSI and SNR values for the first signal port. If the measured RSSI and SNR values meet the requirements of the transceiver at that particular time, then the control process need go no fuither (at least while the measured RSSI and SNR values continue to meet transceiver requirements). If, on the other hand, the measured RSSI and SNR values do not meet transceiver requirements, the digital controller can then switch off the first switch and switch on a second switch to connect a second signal port to a second matching circuit.
The RSSI and SNR values for the second signal pod will then be measured by the baseband processor. This process can be repeated for all the signal pods and their associated matching circuits until acceptable RSSI and SNR values are obtained.
However, if none of the signal ports and matching circuits is able to provide adequate RSSI and SNR, then the digital controller will select the signal port with the best RSSI and SNR values, and then tune the associated matching circuit by using the monitoring circuit so as to obtain RSSI and SNR values that meet the requirements of the transceiver. If it is still not possible to obtain adequate RSSI and SNR values, then the digital controller will try switching in the other signal ports in turn, tuning their matching circuits until the best RSSI and SNR values are obtained.
[00211 By storing measured RSSI and SNR (and optionally BER) values in the lookup table so that they are correlated with particular signal ports and matching circuits, the efficiency of the control process may be improved by allowing the digital controller to try the most promising signal port and matching circuit first.
[0022] Likewise, tuning efficiency may be improved by configuring the digital controller to apply differently-sized tuning steps to the matching circuits depending on the output received from the operational amplifier and AID converter in the monitor circuit. A large tuning step may be set initially. If the detected potential difference across the matching circuit decreases when the tuning step is applied, then a further tuning step of the same magnitude may be applied. On the other hand, if the detected potential difference across the matching circuit increases when the tuning step is applied, then a further tuning step of half the magnitude and in the opposite direction may be applied. This process is repeated until the matching circuit is sufficiently tuned.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] Embodiments of the invention are further described hereinafter with reference to the accompanying drawings, in which: Figure 1 shows a mismatched antenna; Figure 2 shows a matched antenna; Figure 3 shows an equivalent circuit of the mismatched antenna; Figure 4 shows an equivalent circuit of the mismatched antenna after it has been rematched; Figure 5 shows the return loss of the matched antenna and the mismatched antenna; Figure 6 shows the return loss of mismatched antenna after it has been rematched; Figure 7 shows a system block including the antenna(s), signal ports, matching circuits and transceiver, as well as the tuning control circuit of a first embodiment; Figure 8 shows how antenna mismatch may be detected; and Figure 9 shows an exemplary circuit diagram for a monitor circuit for one matching circuit.
DETAILED DESCRIPTION
[0024] In order to show the importance of impedance matching and the consequences of impedance mismatch, reference is now made to Figure 1, which shows an ideal antenna having a complex impedance 7 = a +jb. The antenna 100 is connected to a power amplifier 101 having an output with a standard impedance of 50 ohms, the power amplifier 101 being in turn connected to a transceiver 102. The complex impedance Z = a +jb of the antenna 100 is clearly mismatched with the standard output of the power amplifier 101.
[0025] If the mismatched antenna 100 is directly connected to the output of the power amplifier 101, then a part of the forward power PF from the power amplifier 101 is reflected back to amplifier as PR. The reflected power PR is dissipated as heat in the amplifier 101 and is wasted [0026] In order to minimise the reflected power, the antenna 100 impedance has to be matched to output impedance of the amplifier 101, this process being known as complex conjugate matching. The imaginary part of the antenna impedance is neutralised and the real part is transformed to match 50 ohms, this being the output impedance of the amplifier 101. Figure 2 shows how impedance matching may be achieved between the antenna 100 and the amplifier 101.
[0027] Matching elements c and d server to transforming the real pad a" of the antenna impedance to 50 ohms. Looking from the amplifier 101 side in the direction of the antenna 100, an impedance of 50 ohms should be visible. When the antenna 100 is matched to the output of the amplifier 101 (50 ohms), losses should be minimised with relatively low reflected power from antenna 100.
[0028] Signal losses due to impedance mismatch, otherwise known as mismatch loss ML, can be calculated from: Mt = iOlogfi -(iO)} where RL = return loss.
[0029] The higher the numerical value of RL, the lower the mismatch loss, as shown in
Table 1 below.
[0030] A matched antenna can be easily detuned such that it is no longer matched to a front end of a radio system. In this case, the return loss drops and signal losses result in a degradation of radio performance. Causes of detuning include the presence of objects that can interfere with the radiation pattern of the antenna at close proximity, e.g. metallic objects, a user's hand (body effects), a user's hand and head in the case of a mobile handset. The amount of detuning will depend on the electrical properties of the interfering material and its proximity to the antenna. In this case, looking into the antenna port will reveal that its impedance has changed considerably and is no longer properly matched.
This can be seen in Figure 3, which shows an example of a detuned antenna. The imaginary part of the antenna impedance has shifted form -jb to +jy For complex conjugate matching, the first element +jb is now incorrect and needs to change to -jy in order to rematch the antenna, as shown in Figure 4.
Table 1:
Return Loss dB Signal Loss dB Comment 0.043 Very good match 0.14 Good Match
0.46 Acceptable Match
6 1.26 "Lossy" Match 3 3.02 bad' Match
2 4.33 Unacceptable Match
[0031] The effect of detuning and consequential mismatch can be seen in Figure 5, which shows a return loss plot for a detuned and hence mismatched antenna (in dashed lines) compared to a return loss for a properly matched antenna (solid line). The detuned antenna has been detuned by -Af from the desired frequency of f0. It can be seen that the return loss RL is much lower at frequency f0 for the detuned antenna than for the properly matched antenna, which means that the signal loss is much higher (see Table 1).
[0032] Figure 6 shows the effect of rematching the antenna of Figure 5. The real part of the antenna impedance has not changed in the tuning process, and therefore the matching elements (c and d in Figure 4) do not need to be changed. The impedance mismatch can be represented by a plot of return loss versus frequency as in Figure 5. By changing the matching impedance to rematch the antenna (antenna tuning), the return loss will revert to its original state as shown in Figure 6.
[0033] Figure 7 shows how an embodiment of the invention may be implemented. A plurality of antenna elements la, ib, ic is connected to a plurality of signal ports 2a, 2b, 2c. The antenna elements la, lb, ic may all form part of a single antenna device (not shown), or may indeed represent a single antenna element operating in several bands.
Constructional details of the antenna elements or antenna device are not of relevance to the present invention -what is important is that there is a plurality of signal ports 2a, 2b, 2c etc. that may operate in the same or different frequency bands. Each signal port 2a, 2b, 2c is connected to a respective matching circuit 3a, 3b, 3c by way of a respective switch 4a, 4b, 4c. The switches 3a, 3b, 3c are each controlled by a digital controller, here shown as a microcontroller 5, although other digital controllers such as FPGAs may equally be used, which is in turn connected to a baseband processor 6. Each matching circuit 3a, 3b, 3c is also connected to and controlled by the microprocessor 5. In addition, each matching circuit 3a, 3b, 3c is connected to a transceiver 7 to allow RE signals to be received or transmitted. The transceiver 7 is connected to the baseband processor 6 to allow the baseband processor 6 to analyse the signals from the signal ports 2a, 2b, 2c.
[00341 As hereinbefore described, the baseband processor 6 measures RSSI, SNR and optionally BER values for signals received by the transceiver 7 from each signal pod 2a, 2b, 2c when these are connected to the matching circuits 3a, 3b, 3c by the switches 4a, 4b, 4c. The microcontroller 5 operates the switches 4a, 4b, 4c in turn to determine which signal pod 2a, 2b, 2c gives the best RSSI, SNR and optionally BER for the transceiver 7.
The microcontroller 5 includes a lookup table for storing the measured RSSI, SNR and optionally BER values correlated against the respective signal pods 2a, 2b, 2c and/or matching circuits 3a, 3b, 3c.
[0035] A lookup table, for example as shown in Table 2 below, is created by the microprocessor 5 to store the performance of each antenna element la, ib, ic. The selection criterion is to select the antenna element la, ib, ic with the highest RSSI and the highest SNR at any given time. There may be circumstances where RSSI is high and SNR is low, for example in the case of in-band interference. The lookup table is updated every time there is a detected degradation in the performance of any of the antenna elements la, ib, ic.
Table 2:
Antenna Element RSSI (dB) S/N (dB) 1 RSSI1 S/N1 2 RSSI2 SIN2 3 RSSI3 S/N3 4 RSSI4 S/N4 N RSSIN S/NN [0036] In order to speed up the selection process, another lookup table may be built, for example as shown in Table 3 below. This lookup table order the antenna elements by performance, and has the best performing antenna element in the first position, and the worst performing antenna element in the last position.
Table 3:
Antenna Element SIN 3 Highest Best Performance 1 Next highest N Lowest Lowest Performance [0037] Further tables similar to Tables 2 and 3 could be created.
[0038] Certain embodiments further allow each antenna element la, lb ic to be tuned by adjusting the matching circuit 3a, 3b, 3c. For example, when selection of one of the signal ports 2a, 2b, 2c by way of the switches 4a, 4b, 4c does not allow adequate RSSI, SNR and optionally BER values to be obtained, the microcontroller 5 can select the signal port 2a, 2b, 2c with the best values, and then seek to tune the matching circuit 3a, 3b, 3c associated with that signal port in order to improve the RSSI, SNR and optionally the BER values.
[0039] Moreover, for antenna tuning to be effective, it is necessary to provide a means for detecting antenna mismatch or detuning. The means should indicate the severity of mismatch or detuning, and enable corrective measures to be taken to correct the mismatch and/or retune the antenna. Due to commercial and design pressures, the means should be simple in design and small in size so as to facilitate processor integration, while still being effective.
[0040] In the case of transmission, mismatch detection can be achieved by looking at the power output of the power amplifier and the power transferred to the antenna for radiation.
In theory, a directional coupler could be used, but such a device is typically too large for chip integration. Accordingly, an alternative approach is proposed in the present application.
[0041] The power output of the power amplifier 101 can be sampled and compared with the sampled power going into the antenna 100. When the antenna 100 is properly matched, these sampled powers should be substantially or nearly equal, indicating low loss and good impedance matching. The sampled powers can be used to drive peak/envelope detectors so as to generate voltages that can be compared in order to indicate mismatch. Figure 8 shows an example of how this may be achieved. Taking first the case where the antenna 100 is properly matched, it can be seen that the power output from the power amplifier 101 will be transferred to the antenna 100 via the matching network 3 with minimum loss. Accordingly, the power input to the antenna 100 will be equal or almost equal to the power output by the amplifier 101 when the antenna 100 is properly matched. This can be detected by sampling the potentials Vp and VA on either side of the matching network 3 using peak/envelope detectors 103, 104 so as to provide detection potentials V1 and V2. In the matched condition, V1 and V2 will be substantially equal, and the difference between V1 and V2 will increase with increasing power loss, indicative of increasing mismatch.
[0042] Figure 9 shows the general architecture for tuning a single antenna element la. It will be understood that this architecture may be extended for multiple antennas la, ib, ic.
There are four main parts involved in antenna tuning: match and tune 200, power detector 300, mixed signal application-specific integrated circuit, ASIC, 400 and microcontroller 5.
[0043] The power detector 300, which is shown in more detail in Figure 8, looks at the output of the transceiver 7 and the power transferred to the antenna la. The power detector includes peak/envelope detectors 103, 104 and outputs the detected voltages V1 and V2 (see Figure 8).
[0044] The mixed signal ASIC 400 comprises an operational amplifier 16 connected to an analogue/digital converter 17. The AID converter 17 is in turn connected to a signal processor 18.
[0045] If the antenna la is well-matched to the transceiver 7, then V1 and V2 will be substantially equal, and the operational amplifier will output a low or zero signal. The A/D converter 17 is configured to output a zero value, indicating good matching.
[0046] If, on the other hand, the antenna la is not well-matched (for example, it may have become detuned due to the proximity of a user's hand, or some other external influence), then the power transferred to the antenna la will drop. This means that V1 will be less than V2, and the larger the difference, the larger the mismatch. The operational amplifier will thus output a high signal, and this will be converted by the AID converter 17 to a positive value or digital code. The digital code preferably includes an indication of the magnitude of the difference between V1 and V2. The digital code is acted on by the signal processor 18, which sends a message to the microcontroller 5 to start the tuning process.
[0047] Tuning is achieved in the match and tune section 200 by applying or changing a potential difference on variable element C (which may be a variable capacitor or other variable component). Element C is adjusted until the output of the AID converter reverts to zero, thus indicating that good matching has been regained.
[0048] If the microcontroller 5 detects that the output signal from the operational amplifier 16, converted to digital format by the AID converter 17 is increasing as the voltage applied across variable element C is adjusted, this will indicate that tuning is in the wrong direction.
In response, the microcontroller 5 can adjust the voltage applied across variable element C in the other direction (e.g. decreasing the applied voltage in the event that increasing the voltage results in an increase in the output signal from the operational amplifier 16). If the microcontroller 5 detects that the output signal from the operational amplifier 16 is decreasing as voltage applied across variable element C is adjusted in a given direction, this will indicate that tuning is taking place in the correct direction.
[0049] Tuning may also be undertaken by the baseband processor 6 by way of a serial peripheral interface SPI bus 19. This is useful when there is no transmit signal and the transceiver 7 is running in receive mode. In this scenario, some receiver performance parameters will be required, namely the RSSI and SNR. These are sent to the microcontroller 5 by way of the SPI bus 19.
[0050] A well-matched antenna la will give a high RSSI and SNR, in which case no retuning is required.
[0051] A poorly-matched antenna la will give a low RSSI and SNR, indicating that retuning is required. In this case, retuning is achieved by adjusting the potential across variable element C in the match and tune section 200. Element C is adjusted until the RSSI and SNR indicate that a good match is obtained. This can be done with reference to
the lookup tables.
[0052] Furthermore, the architecture of Figure 9 can be used to detect if an antenna la, ib, ic is performing badly, and this antenna may be switched out temporarily, thus helping to reduce power consumption. The antenna can be periodically re-checked, and switched back in again once its performance has improved.
[0053] Throughout the description and claims of this specification, the words "comprise" and "contain" and variations of them mean "including but not limited to", and they are not intended to (and do not) exclude other moieties, additives, components, integers or steps.
Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.
[0054] Features, integers, characteristics, compounds, chemical moieties or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. The invention is not restricted to the details of any foregoing embodiments.
The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.
[0055] The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

Claims (18)

  1. CLAIMS: 1. A tuning control circuit configured for use with a reconfigurable antenna device having multiple signal ports each connected to a respective matching circuit by way of a respective switch, the respective matching circuits in turn being connected to a transceiver, wherein the tuning control circuit comprises: i) a digital controller operatively connected to the respective switches so as to allow the switches to be independently operated, the digital controller also being operatively connected to the respective matching circuits so as to allow the matching circuits to be independently tuned; and U) a baseband processor configured to determine a received signal strength indication, RSSI, and a signal-to-noise ratio, SNR, for signals at each signal port; wherein the baseband processor is configured to send the determined RSSI and SNR values to the digital controller, and wherein the digital controller is configured to operate the switches and/or the matching circuits so as to obtain RSSI and SNR values that meet predetermined RSSI and SNR requirements for the transceiver.
  2. 2. A circuit as claimed in claim 1, wherein the digital controller is provided with a lookup table, and wherein measured RSSI and SNR values are saved in the lookup table together with their related switch and/or matching circuit settings.
  3. 3. A circuit as claimed in any preceding claim, wherein a monitor circuit is connected across each matching circuit.
  4. 4. A circuit as claimed in claim 3, wherein the monitor circuit comprises an operational amplifier and an analogue/digital converter.
  5. 5. A circuit as claimed in claim 4, wherein operational amplifier is configured to detect a potential difference representative of power loss across the matching circuit.
  6. 6. A circuit as claimed in claim 5, wherein the digital controller is configured to tune the matching circuit so as to reduce the detected potential difference.
  7. 7. A circuit as claimed in any preceding claim, wherein the baseband processor is additionally configured to determine a bit error rate, BER, for signals at each signal port.
  8. 8. A circuit as claimed in claim 7, wherein the digital controller is configured to operate the switches and/or tune the matching circuits so as to obtain BER values that meet predetermined requirements.
  9. 9. A circuit as claimed in any preceding claim, wherein the digital controller includes a memory for storing at least the determined RSSI and SNR values for each signal port.
  10. 10. A circuit as claimed in claim 9, wherein the memory comprises a lookup table.
  11. 11. A tuning control circuit configured for use with an antenna device having at least one signal port connected to a matching circuit, the matching circuit in turn being connected to a transceiver, wherein the tuning control circuit comprises: i) a monitor circuit connected across the matching circuit, the monitor circuit comprising an operational amplifier and an analogue/digital converter, wherein the operational amplifier is configured to detect a potential difference representative of power loss across the matching circuit, and wherein the analogue/digital converter is configured to output a digital signal representative of power loss across the matching circuit; and U) a digital controller connected to the analogue/digital converter and also to the matching circuit, wherein the digital controller is configured to tune the matching circuit in response to the detected power loss across the matching circuit so as to reduce the detected power loss.
  12. 12. A circuit as claimed in claim 11, further comprising a baseband processor configured to determine a received signal strength indication, RSSI, and a signal-to-noise ratio, SNR, for signals at the signal port; wherein the baseband processor is configured to send the determined RSSI and SNR values to the digital controller, and wherein the digital controller is configured to tune the matching circuit so as to obtain RSSI and SNR values that meet predetermined RSSI and SNR requirements for the transceiver.
  13. 13. A circuit as claimed in claim 11 or 12, wherein the digital controller is provided with a lookup table, and wherein measured RSSI and SNR values are saved in the lookup table together with their related switch and/or matching circuit settings.
  14. 14. A method of tuning a reconfigurable antenna device having multiple signal ports each connected to a respective matching circuit by way of a respective switch, the respective matching circuits in turn being connected to a transceiver, the method comprising: i) with a digital controller, switching on a first switch to connect a first signal port to the transceiver by way of a first matching circuit; ii) with a baseband processor, determining a received signal strength indication, RSSI, and a signal-to-noise ratio, SNR, for signals at the first signal port; Ui) determining, by the digital controller, if the RSSI and SNR at the first signal port meet the requirements of the transceiver; iv) if the RSSI and SNR at the first port do not meet the requirements of the transceiver, the digital controller switching off the first switch and switching on a second switch to connect a second signal port to the transceiver by way of a second matching circuit; v) with the baseband processor, determining the RSSI and SNR for signals at the second signal port; vi) determining, by the digital controller, if the RSSI and SNR at the second signal port meet the requirements of the transceiver; and vii) if the RSSI and SNR at the second port do not meet the requirements of the transceiver, repeating steps iv) to vi) for all of the signal ports in turn.
  15. 15. A method according to claim 14, wherein, should none of the signal ports be able to provide an RSSI and SNR that meet the transceiver requirements, the method further comprises: viU) selecting the signal port and matching circuit with the best RSSI and SNR; ix) monitoring a potential difference across the selected matching circuit; x) tuning the selected matching circuit by way of the digital controller so as substantially to minimise the potential difference across the selected matching circuit; xi) determining if the RSSI and SNR at the selected signal port meet the requirements of the transceiver; xU) if the RSSI and SNR at the selected port do not meet the requirements of the transceiver, operating the switches with the digital controller so as to select the signal port and matching circuit with the next best RSSI and SNR; and xiii) repeating steps ix) to xii) until an RSSI and SNR meeting the requirements of the transceiver are obtained.
  16. 16. A method of tuning an antenna device having at least one signal port connected to a matching circuit, the matching circuit in turn being connected to a transceiver, the method comprising: i) with a monitoring circuit, detecting a potential difference corresponding to a power loss across the matching circuit and generating a signal representative of the power loss; ii) inputting the signal representative of the power loss to a digital controller; iii) with the digital controller, determining whether or not the potential difference is above a predetermined value; and iv) if the potential difference is above the predetermined value, retuning the matching circuit under control of the digital controller so as to reduce the detected potential difference to below the predetermined value.
  17. 17. A tuning control circuit configured for use with an antenna device substantially as hereinbefore described with reference to or as shown in the accompanying drawings.
  18. 18. A method of tuning an antenna device substantially as hereinbefore described with reference to or as shown in the accompanying drawings.Amendments to the claims have been filed as follows CLAIMS: 1. A tuning control circuit configured for use with an antenna device having at least one signal port connected to a matching circuit, the matching circuit in turn being connected to a transceiver, wherein the matching circuit includes a tuneable component that can be adjusted so as to allow the at least one signal port to be impedance matched to the transceiver, wherein the tuning control circuit comprises: i) a monitor circuit connected across the matching circuit, the monitor circuit comprising an operational amplifier and an analogue/digital converter, wherein the operational amplifier is configured to detect a potential difference representative of power loss across the matching circuit, and wherein the analogue/digital converter is configured to output a digital signal representative of power loss across the matching circuit; and ii) a digital controller connected to the analogue/digital converter and also to the matching circuit, wherein the digital controller is configured to tune the matching circuit by adjusting the tuneable component in response to the detected power loss across the matching circuit so as to reduce the detected power loss. IC)2. A circuit as claimed in claim 1, further comprising a baseband processor configured to determine a received signal strength indication, RSSI, and a signal-to-noise ratio, SNR, for signals at the signal port; CO wherein the baseband processor is configured to send the determined RSSI and SNR values to the digital controller, and wherein the digital controller is configured to tune the matching circuit by adjusting the tuneable component so as to obtain RSSI and SNR values that meet predetermined RSSl and SNR requirements for the transceiver.3. A circuit as claimed in claim 2, wherein the digital controller is provided with a lookup table, and wherein measured RSSI and SNR values are saved in the lookup table together with their related matching circuit settings.4. A circuit as claimed in any preceding claim, wherein the reconfigurable antenna device has multiple signal ports each connected to a respective matching circuit by way of a respective switch, the respective matching circuits in turn being connected to the transceiver.5. A circuit as claimed in claim 4, wherein the digital controller is operatively connected to the respective switches so as to allow the switches to be independently operated.6. A circuit as claimed in claim 5 depending through claim 2, wherein the digital controller is additionally configured to operate the switches so as to obtain RSSI and SNR values that meet predetermined RSSl and SNR requirements for the transceiver.7. A circuit as claimed in any one of claims 4 to 6, wherein the baseband processor is additionally configured to determine a bit error rate, BER, for signals at each signal pod.8. A circuit as claimed in claim 7, wherein the digital controller is configured to operate the switches and/or tune the matching circuits by adjusting the tuneable components so as to obtain BER values that meet predetermined requirements.9. A method of tuning an antenna device having at least one signal port connected to a matching circuit, the matching circuit in turn being connected to a transceiver, wherein the matching circuit includes a tuneable component that can be adjusted so as to allow the at least one signal pod to be impedance matched to the transceiver, the method IC) comprising: i) with a monitoring circuit, detecting a potential difference corresponding to a power loss across the matching circuit and generating a signal representative of the power loss; C) U) inputting the signal representative of the power loss to a digital controller; Ui) with the digital controller, determining whether or not the potential difference is above a predetermined value; and iv) if the potential difference is above the predetermined value, retuning the matching circuit by adjusting the tuneable component under control of the digital controller so as to reduce the detected potential difference to below the predetermined value.10. A method according to claim 8, wherein the reconfigurable antenna device has multiple signal ports each connected to a respective matching circuit by way of a respective switch, the respective matching circuits in turn being connected to the transceiver, the method comprising: i) with the digital controller, switching on a first switch to connect a first signal port to the transceiver by way of a first matching circuit; U) with the baseband processor, determining a received signal strength indication, RSSI, and a signal-to-noise ratio, SNR, for signals at the first signal pod; Ui) determining, by the digital controller, if the RSSI and SNR at the first signal port meet the requirements of the transceiver; iv) if the RSSI and SNR at the first port do not meet the requirements of the transceiver, the digital controller switching off the first switch and switching on a second switch to connect a second signal port to the transceiver by way of a second matching circuit; v) with the baseband processor, determining the RSSI and SNR for signals at the second signal port; vi) determining, by the digital controller, if the RSSI and SNR at the second signal port meet the requirements of the transceiver; and vu) if the RSSl and SNR at the second port do not meet the requirements of the transceiver, repeating steps iv) to vi) for all of the signal pods in turn.11. A tuning control circuit configured for use with an antenna device substantially as hereinbefore described with reference to or as shown in the accompanying drawings.12. A method of tuning an antenna device substantially as hereinbefore described with reference to or as shown in the accompanying drawings. IC) Co r
GB1415784.6A 2014-09-05 2014-09-05 Antenna impedance matching circuit tuning system Active GB2529887B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB1415784.6A GB2529887B (en) 2014-09-05 2014-09-05 Antenna impedance matching circuit tuning system

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB1415784.6A GB2529887B (en) 2014-09-05 2014-09-05 Antenna impedance matching circuit tuning system
PCT/GB2015/052563 WO2016034893A1 (en) 2014-09-05 2015-09-04 Tuning reconfigurable multi-port antennas

Publications (3)

Publication Number Publication Date
GB201415784D0 GB201415784D0 (en) 2014-10-22
GB2529887A true GB2529887A (en) 2016-03-09
GB2529887B GB2529887B (en) 2019-06-19

Family

ID=51796296

Family Applications (1)

Application Number Title Priority Date Filing Date
GB1415784.6A Active GB2529887B (en) 2014-09-05 2014-09-05 Antenna impedance matching circuit tuning system

Country Status (2)

Country Link
GB (1) GB2529887B (en)
WO (1) WO2016034893A1 (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2018182505A (en) * 2017-04-11 2018-11-15 株式会社デンソーテン Antenna amplifier unit and receiving system
DE102021102208A1 (en) 2021-02-01 2022-08-04 Diehl Metering Systems Gmbh Method for improving antenna matching

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US11258412B2 (en) 2020-05-28 2022-02-22 Eagle Technology, Llc Radio frequency (RF) device having tunable RF power amplifier and associated methods

Citations (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050003771A1 (en) * 2002-11-01 2005-01-06 Integration Associates Inc. Method and apparatus for automatic tuning of a resonant loop antenna in a transceiver circuit
DE102006007475A1 (en) * 2006-02-17 2007-08-30 Wiesemann & Theis Gmbh Circuit arrangement for automatically adjusting high frequency generator, has current sensor measuring supply direct current of generator, and digital control calculating optimal adjustment of tuning units based on analysis result
US20080129610A1 (en) * 2006-12-01 2008-06-05 Texas Instruments Incorporated Adaptive antenna matching for portable radio operating at VHF with single-chip based implementation
US20100073103A1 (en) * 2008-09-24 2010-03-25 Spears John H Methods for tuning an adaptive impedance matching network with a look-up table
US20100124890A1 (en) * 2008-10-27 2010-05-20 Marco Schwarzmueller Circuit for a loop antenna and method for tuning
US20110116423A1 (en) * 2009-11-17 2011-05-19 Nokia Corporation Antenna Impedance Stabilization With Stabilization Load In Second Antenna Circuitry
US20110299431A1 (en) * 2010-06-03 2011-12-08 Broadcom Corporation Front end module with a tunable balancing network
US20120135681A1 (en) * 2010-11-26 2012-05-31 Damon Adams Multi-mode communication system for a mobile phone
US8320850B1 (en) * 2009-03-18 2012-11-27 Rf Micro Devices, Inc. Power control loop using a tunable antenna matching circuit
US20130069737A1 (en) * 2011-09-19 2013-03-21 Qualcomm Incorporated Adaptive tuning of an impedance matching circuit in a wireless device
GB2502787A (en) * 2012-06-06 2013-12-11 Samsung Electronics Co Ltd Adaptive Antenna Impedance Matching
US20140113679A1 (en) * 2012-10-22 2014-04-24 Research In Motion Limited Method and apparatus for radio frequency tuning utilizing a determined use case

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH11251928A (en) * 1998-02-26 1999-09-17 Nec Eng Ltd Automatic antenna matching circuit and method
WO2006038167A1 (en) * 2004-10-06 2006-04-13 Koninklijke Philips Electronics N.V. Impedance detector
US8963611B2 (en) * 2009-06-19 2015-02-24 Qualcomm Incorporated Power and impedance measurement circuits for a wireless communication device

Patent Citations (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050003771A1 (en) * 2002-11-01 2005-01-06 Integration Associates Inc. Method and apparatus for automatic tuning of a resonant loop antenna in a transceiver circuit
DE102006007475A1 (en) * 2006-02-17 2007-08-30 Wiesemann & Theis Gmbh Circuit arrangement for automatically adjusting high frequency generator, has current sensor measuring supply direct current of generator, and digital control calculating optimal adjustment of tuning units based on analysis result
US20080129610A1 (en) * 2006-12-01 2008-06-05 Texas Instruments Incorporated Adaptive antenna matching for portable radio operating at VHF with single-chip based implementation
US20100073103A1 (en) * 2008-09-24 2010-03-25 Spears John H Methods for tuning an adaptive impedance matching network with a look-up table
US20100124890A1 (en) * 2008-10-27 2010-05-20 Marco Schwarzmueller Circuit for a loop antenna and method for tuning
US8320850B1 (en) * 2009-03-18 2012-11-27 Rf Micro Devices, Inc. Power control loop using a tunable antenna matching circuit
US20110116423A1 (en) * 2009-11-17 2011-05-19 Nokia Corporation Antenna Impedance Stabilization With Stabilization Load In Second Antenna Circuitry
US20110299431A1 (en) * 2010-06-03 2011-12-08 Broadcom Corporation Front end module with a tunable balancing network
US20120135681A1 (en) * 2010-11-26 2012-05-31 Damon Adams Multi-mode communication system for a mobile phone
US20130069737A1 (en) * 2011-09-19 2013-03-21 Qualcomm Incorporated Adaptive tuning of an impedance matching circuit in a wireless device
GB2502787A (en) * 2012-06-06 2013-12-11 Samsung Electronics Co Ltd Adaptive Antenna Impedance Matching
US20140113679A1 (en) * 2012-10-22 2014-04-24 Research In Motion Limited Method and apparatus for radio frequency tuning utilizing a determined use case

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2018182505A (en) * 2017-04-11 2018-11-15 株式会社デンソーテン Antenna amplifier unit and receiving system
DE102021102208A1 (en) 2021-02-01 2022-08-04 Diehl Metering Systems Gmbh Method for improving antenna matching

Also Published As

Publication number Publication date
GB201415784D0 (en) 2014-10-22
GB2529887B (en) 2019-06-19
WO2016034893A1 (en) 2016-03-10

Similar Documents

Publication Publication Date Title
EP2612445B1 (en) Apparatus and method for controlling a tunable matching network in a wireless network
US8521107B2 (en) Minimizing mutual coupling
EP2638640B1 (en) Method and appartus for tuning antennas in a communication device
CN103297077B (en) Adjustment resonance frequency and judge the method for impedance variation and circuit thereof and communication device
EP2557688B1 (en) A controller for a radio circuit
US7831219B2 (en) Matching network
US9049664B2 (en) Wireless communications circuit for improving current consumption and RF performance
US8611829B2 (en) Tunable filter feedback to control antenna switch diversity
US9054772B2 (en) Adaptive impedance matching circuit and method for matching for duplex operation standards
TWI540788B (en) Wireless communication device and method of adjusting antenna matching
WO2013176893A1 (en) Method and apparatus for compensating for phase shift in a communication device
CN107852249B (en) Method and apparatus for calibration in a radio frequency module
GB2529887B (en) Antenna impedance matching circuit tuning system
US9100109B2 (en) Apparatus for wirelessly transmitting information, communication terminal for wirelessly transmitting information and impedance matching method
US9014245B2 (en) Method and apparatus for compensating for phase shift in a communication device
EP2498407B1 (en) Mobile wireless communications device with adjustable impedance matching network and associated methods
CN110677168A (en) 5G terminal signal transceiving device and method and terminal
CN104303416A (en) Integrated technique for enhanced power amplifier forward power detection
US9130534B2 (en) Impedance matching circuit capable of broadband operation
CN114665907A (en) Radio frequency system and communication equipment

Legal Events

Date Code Title Description
732E Amendments to the register in respect of changes of name or changes affecting rights (sect. 32/1977)

Free format text: REGISTERED BETWEEN 20191010 AND 20191016