Interference suppression circuit, transmission / reception circuit, and wireless device

Abstract

Provided is an interference suppression circuit which, in a transmission / reception circuit that separates and processes a transmission signal and a reception signal transmitted and received via a shared antenna, is capable of reducing interference due to noise leakage in a reception band from a transmission path to a reception path, even when there are temperature fluctuations. An interference suppression circuit according to the present invention comprises: a signal extraction unit that extracts a part of a transmission signal being transmitted toward an antenna via a circulator in a transmission path of a transmission / reception circuit; a band-pass filter that selectively allows, among the extracted signal, a signal in a reception band to pass; a vector modulation unit that performs vector modulation on the signal in the reception band output from the band-pass filter to generate an interference suppression signal, on the basis of a value of a vector modulation parameter determined according to an ambient temperature or on the basis of a control voltage corresponding to the value of the vector modulation parameter; and a signal superimposition unit that superimposes the interference suppression signal in the reception band on a reception signal received from the antenna via the circulator in a reception path of the transmission / reception circuit.

Description

Interference suppression circuit, transmission / reception circuit, and radio device

[0001] The present invention relates to an interference suppression circuit, a transmission / reception circuit, and a wireless device.

[0002] BACKGROUND ART Conventionally, as a wireless device that separates and processes a transmission signal and a reception signal in wireless communication such as an FDD (frequency division multiplexing) system or a full duplex system, a wireless device equipped with a transmission / reception circuit configured using circuit elements such as a duplexer, an isolator, a circulator, and a bandpass filter has been known.

[0003] For example, Patent Document 1 discloses a transceiver device (wireless device) that includes a duplexer connected to an antenna, a low-noise amplifier circuit that amplifies the output signal of the duplexer, a power amplifier that amplifies the transmission signal, and an isolator inserted between the duplexer and the power amplifier.

[0004] Japanese Patent Application Laid-Open No. 2006-166277

[0005] In the above-described transmission / reception circuit, there is a need to reduce interference caused by noise sneaking from the transmission path to the reception path in the reception band even when there is a temperature fluctuation.

[0006] An interference suppression circuit according to one aspect of the present invention is an interference suppression circuit provided in a transmission / reception circuit that separates and processes a transmission signal and a reception signal transmitted and received via a shared antenna, the interference suppression circuit including: a signal extraction unit in a transmission path of the transmission / reception circuit that extracts a portion of the transmission signal transmitted to the antenna via a circulator, a band-pass filter that selectively passes a reception band signal from the signals extracted by the signal extraction unit, a vector modulation unit that vector-modulates the reception band signal output from the band-pass filter based on a control voltage of a vector modulation parameter determined in accordance with an environmental temperature to generate an interference suppression signal, and a signal superposition unit in a reception path of the transmission / reception circuit that superposes the interference suppression signal in the reception band generated by the vector modulation unit on a reception signal received from the antenna via the circulator.

[0007] A transceiver circuit according to another aspect of the present invention is a transceiver circuit that separates and processes a transmission signal and a reception signal transmitted and received via a shared antenna and a circulator, and includes the interference suppression circuit, a circulator connected to the shared antenna, a transmission circuit including the transmission path connected to the circulator, and a reception circuit including the reception path connected to the circulator.

[0008] In the transceiver circuit, the transmitter circuit may have a power amplifier, a transmitter band-pass filter, and an isolator in the transmission path, the receiver circuit may have a first receiver band-pass filter, a low-noise amplifier, and a second receiver band-pass filter in the reception path, the signal extraction unit may be provided between the isolator and the circulator in the transmission path, and the signal superposition unit may be provided between the first receiver band-pass filter and the low-noise amplifier in the reception path.

[0009] In the transmission / reception circuit, the signal extraction unit may be a directional coupler coupled to the transmission path, and the signal superimposition unit may be a directional coupler coupled to the reception path.

[0010] A wireless device according to yet another aspect of the present invention comprises the transceiver circuit, a shared antenna used for transmission and reception, and a signal processing unit that processes a transmission signal transmitted by the transceiver circuit and a reception signal received by the transceiver circuit.

[0011] In the wireless device, the vector modulation parameters may be a control voltage by which an in-phase signal component is multiplied and a control voltage by which a quadrature-phase signal component is multiplied in the vector modulation.

[0012] The wireless device may be provided with a first thermometer that detects the temperature of a power amplifier provided in the transceiver circuit, and the signal processing unit may determine a control voltage for the vector modulation parameter based on the temperature of the power amplifier detected by the first thermometer, and output the control voltage for the vector modulation parameter to the vector modulation unit.

[0013] In the wireless device, the signal processing unit may store a data table created in advance for multiple temperatures of the power amplifier, showing the relationship between the temperature of the power amplifier and the control voltage of the vector modulation parameter, and determine the control voltage of the vector modulation parameter based on the data table and the temperature of the power amplifier detected by the first thermometer.

[0014] The wireless device may further include an output level detection unit that detects the output level of the power amplifier, and the signal processing unit may store a data table that shows the relationship between the temperature of the power amplifier, the output level of the power amplifier, and the control voltage of the vector modulation parameter, the data table being created in advance for combinations of multiple temperatures of the power amplifier and multiple output levels of the power amplifier, and may determine the control voltage of the vector modulation parameter based on the data table, the temperature of the power amplifier detected by the first thermometer, and the output level of the power amplifier detected by the output level detection unit.

[0015] The wireless device may be provided with a second thermometer that detects the temperature of the interference suppression circuit, and the signal processing unit may determine a control voltage for the vector modulation parameter based on the temperature of the interference suppression circuit detected by the second thermometer, and output the control voltage for the vector modulation parameter to the vector modulation unit.

[0016] In the wireless device, the signal processing unit may store a data table that is created in advance for multiple combinations of temperatures of the interference suppression circuit and shows the relationship between the temperature of the interference suppression circuit and the control voltage of the vector modulation parameter, and determine the control voltage of the vector modulation parameter based on the data table and the temperature of the interference suppression circuit detected by the second thermometer.

[0017] The wireless device may further include an output level detection unit that detects the output level of a power amplifier provided in the transceiver circuit, and the signal processing unit may store a data table that shows the relationship between the temperature of the interference suppression circuit, the output level of the power amplifier, and the control voltage of the vector modulation parameter, the data table being created in advance for combinations of multiple temperatures of the interference suppression circuit and multiple output levels of the power amplifier, and may determine the control voltage of the vector modulation parameter based on the data table, the temperature of the interference suppression circuit detected by the second thermometer, and the output level of the power amplifier detected by the output level detection unit.

[0018] The wireless device may be provided with a first thermometer that detects the temperature of a power amplifier provided in the transceiver circuit, and a second thermometer that detects the temperature of the interference suppression circuit, and the signal processing unit may determine a control voltage for the vector modulation parameter based on the temperature of the power amplifier detected by the first thermometer and the temperature of the interference suppression circuit detected by the second thermometer, and output the control voltage for the vector modulation parameter to the vector modulation unit.

[0019] In the wireless device, the signal processing unit may store a data table that is created in advance for combinations of multiple temperatures of the power amplifier and multiple temperatures of the interference suppression circuit, and shows the relationship between the temperature of the power amplifier, the temperature of the interference suppression circuit, and the value of the vector modulation parameter, and determine the control voltage of the vector modulation parameter based on the data table, the temperature of the power amplifier detected by the first thermometer, and the temperature of the interference suppression circuit detected by the second thermometer.

[0020] The wireless device may include an output level detection unit that detects the output level of the power amplifier, and the signal processing unit may store a data table that is created in advance for combinations of multiple temperatures of the power amplifier, multiple temperatures of the interference suppression circuit, and multiple output levels of the power amplifier, and that shows the relationship between the temperature of the power amplifier, the temperature of the interference suppression circuit, the output level of the power amplifier, and the control voltage of the vector modulation parameter, and may determine the control voltage of the vector modulation parameter based on the data table, the temperature of the power amplifier detected by the first thermometer, the temperature of the interference suppression circuit detected by the second thermometer, and the output level of the power amplifier detected by the output level detection unit.

[0021] In addition, the program that performs at least one of the processes of creating the data table, creating the calculation formula, and determining the value of the vector modulation parameter may include a machine-learned model.

[0022] The wireless device including the transceiver may be a wireless device that performs FDD (Frequency Division Duplex) wireless communication or full-duplex wireless communication, or may be a wireless device mounted on an aircraft or floating object that can move, fly, or stay in the sky.

[0023] According to the present invention, in a transmission / reception circuit that separates and processes transmission signals and reception signals transmitted and received via a shared antenna, interference caused by noise leakage in the reception band from the transmission path to the reception path can be reduced even when there are temperature fluctuations.

[0024] Fig. 1 is an explanatory diagram showing an example of a schematic configuration of a wireless device according to an embodiment. Fig. 2A is an explanatory diagram showing an example of the relationship between the transmission band (DL Band 8), the reception band (UL Band 8), and the intermodulation distortion signals (IM11, IM9) of the power amplifier when the frequency band used by the wireless device in an aerial repeating type wireless repeater device is the 900 MHz band (Band 8). Fig. 2B is an explanatory diagram showing an example of the relationship between the transmission band (DL Band 3), the reception band (UL Band 3), and the intermodulation distortion signals (IM21, IM19) of the power amplifier when the frequency band used by the wireless device is the 1700 MHz band (Band 3). Fig. 2B is a frequency characteristic graph showing an example of the spectrum of a transmission signal including interference caused to a receiving circuit (receiving system) by a power amplifier (transmission system power amplifier) ​​in a transmitting circuit (transmission system). 5A is a graph of frequency characteristics showing an example of evaluation results of the effectiveness of an interference suppression circuit (interference canceller) that suppresses interference caused to a receiving circuit (receiving system) by a power amplifier (transmission system power amplifier) ​​in a transmitting circuit (transmission system). FIG. 5A is a graph showing an example of a change in gain with respect to temperature change of a power amplifier in a transmitting circuit. FIG. 5B is a graph showing an example of a change in phase with respect to temperature change of the same power amplifier. FIG. 5C is a graph showing an example of the relationship between the level difference between an interference signal and an interference suppression signal and the amount of interference suppression (cancellation amount). FIG. 6 is an explanatory diagram showing an example of the overall configuration of a wireless device according to an embodiment. FIG. 7 is an explanatory diagram showing an example of a control data table used in a signal processing unit in a wireless device. FIG. 8 is an explanatory diagram showing another example of the configuration of an interference suppression circuit in a wireless device. FIG. 9 is an explanatory diagram showing yet another example of the configuration of an interference suppression circuit in a wireless device. FIG. 10 is an explanatory diagram showing an example of a vector modulator circuit in an interference suppression circuit.

[0025] Hereinafter, embodiments of the present invention will be described with reference to the drawings. A transceiver circuit according to the embodiments described herein is a transceiver circuit that separates and processes a transmit signal and a receive signal transmitted and received via a shared antenna, and includes an interference suppression circuit for reducing interference due to noise leakage in the receive band (receive frequency band) from the transmit path to the receive path. One example of the interference suppression circuit extracts a portion of the transmit signal transmitted to the antenna via a circulator in the transmit path, vector-modulates the receive band signal from the extracted signal that has passed through a band-pass filter based on a vector modulation parameter value or control voltage determined according to the environmental temperature to generate an interference suppression signal, and superimposes the generated receive band interference suppression signal on the receive signal received from the antenna via the circulator. This makes it possible to reduce interference due to noise leakage in the receive band from the transmit path to the receive path even when there are temperature fluctuations.

[0026] Fig. 1 is an explanatory diagram showing an example of a schematic configuration of a wireless device 10 according to this embodiment. In Fig. 1, the wireless device 10 includes an antenna 20, a circulator 30, a transmission / reception circuit 40, and a signal processing unit 50. The transmission / reception circuit 40 includes a transmission circuit 410 including a transmission path connected to the circulator 30, and a reception circuit 420 including a reception path connected to the circulator. The transmission circuit 410 includes a power amplifier (PA) 411 that amplifies a transmission signal output from the signal processing unit 50 and transmitted via the antenna 20 and the circulator 30. The reception circuit 420 includes a low-noise amplifier (LNA) 422 that amplifies a reception signal received via the antenna 20 and the circulator 30 and before being input to the signal processing unit 50.

[0027] The circulator 30 has three ports arranged in a circular fashion to allow one-way transmission between adjacent ports. In the circulator 30, the transmitter circuit 410, the antenna 20, and the receiver circuit 420 are connected to the three ports in that order.

[0028] The signal processing unit 50 includes, for example, a modulation unit that modulates transmission data to generate a digital transmission signal, a DA converter that converts the digital transmission signal output from the modulation unit into an analog transmission signal that is passed to the transmission circuit, an AD converter that converts the analog reception signal received from the reception circuit 420 into a digital reception signal, a demodulation unit that demodulates the digital reception signal to generate reception data, and a control unit for controlling each unit. The signal processing unit 50 may also include a transmission system frequency conversion unit and a reception system frequency conversion unit. The transmission system frequency conversion unit converts the baseband frequency or intermediate frequency of the transmission signal generated by the signal processing unit 50 into a high frequency in a predetermined frequency band of the transmission signal processed by the transmission circuit 410 and transmitted from the antenna 20. The reception system frequency conversion unit converts the high frequency in a predetermined frequency band of the reception signal received from the antenna 20 into the baseband frequency or intermediate frequency of the reception signal processed by the signal processing unit 50.

[0029] The wireless device 10 is a device that transmits and receives high-frequency wireless signals used in mobile communications and the like via an antenna 20. The frequency band of the wireless signals may be, for example, a microwave frequency band below 20 GHz (e.g., low band, mid band, or Sub6 band), or a millimeter wave frequency band from 20 GHz to 300 GHz (e.g., 28 GHz band, 31 GHz band, 38 GHz band, or 39 GHz band). Here, the low band refers to a frequency band of 3.5 GHz or less (e.g., 900 MHz band (Band 8) or 1.7 GHz band (Band 3)), and the mid band refers to a frequency band above 3.5 GHz and below 6 GHz (e.g., 3.7 GHz band or 4.5 GHz band). The low band and mid band are collectively referred to as the Sub6 band.

[0030] The wireless device 10 may be, for example, a wireless device mounted on a high altitude platform station (HAPS) (also referred to as a "high altitude pseudosatellite" or "stratospheric platform") having an airborne repeater-type wireless repeater that constitutes an airborne platform, and performing wireless communication of at least one of a service link and a feeder link. The wireless device 10 may also be a wireless device mounted on a gateway device (also referred to as a "feeder station"; hereinafter referred to as a "GW station") for the HAPS that is provided on the ground (or on the sea, etc.) and performing wireless communication of the feeder link with the HAPS wireless repeater. The wireless device 10 may also be a wireless device mounted on a terminal device (user device) that performs wireless communication of the service link with an airborne repeater-type wireless repeater or a terrestrial base station.

[0031] A HAPS is an airborne or floating communications platform that is positioned in an airspace at a predetermined altitude and forms a three-dimensional cell (three-dimensional area) in a cell formation target airspace at a predetermined altitude toward a target service area.

[0032] The HAPS is a wireless relay device (hereinafter also referred to as a "relay communication station") equipped with the wireless device of this embodiment on the fuselage of an aircraft or floating body that is controlled by autonomous control or external control to float or fly in a high-altitude airspace (floating airspace) 100 km or less above ground or sea level. The airspace in which the HAPS is located may be, for example, stratospheric airspace at an altitude of 18 km or more and 50 km or less. This airspace may also be an airspace with relatively stable weather conditions at an altitude of 15 km or more and 25 km or less, and particularly may be an airspace at an altitude of approximately 20 km.

[0033] HAPS, which functions as an airborne platform, can provide ultra-wide area mobile communication services directly to UE (terminal equipment) on the ground from the stratosphere at altitudes of 18 km or more and 50 km or less (especially around 20 km). Airborne platforms consisting of HAPS are attracting attention as a new form of communication for use in large-scale disasters and other situations.

[0034] The HAPS may be equipped with at least one of a battery and a solar power generation system and fly using electric power. The HAPS may be a solar plane-type HAPS or an airship-type HAPS. The HAPS may also be an artificial satellite (e.g., a communications satellite), a balloon, or an unmanned aerial vehicle (UAV) such as a drone or an unmanned aircraft system (UAS). The HAPS may also fly using at least one of a battery and an engine as a power source. The UAV may be, for example, an unmanned aircraft that flies using fuel or a drone that flies using a battery or the like.

[0035] The wireless device 10 configured as described above faces the challenge of reducing the size and weight of the device. This is particularly important for wireless devices 10 intended for airborne platforms such as UAVs and HAPS. In this embodiment, a common antenna for transmission and reception is used as the antenna 20 of the wireless device 10, and a circulator 30, which can be made smaller and lighter than a cavity filter or duplexer, is used as a switching circuit for the transmission path and reception path connected to the antenna 20.

[0036] Furthermore, the wireless device 10 configured as described above has a problem of interference due to noise leakage in the reception band from the transmission path of the transmitter circuit 410 to the reception path of the receiver circuit 420. In a wireless device that performs wireless communication using FDD (Frequency Division Duplexing) technology, which divides the transmission signal and reception signal on the frequency axis and is used in mobile communications, etc., unlike TDD technology, which uses different time slots for transmission and reception, if the frequency separation between the transmission band and the reception band is narrow, noise leakage interference in the reception band from the transmitter circuit 410 to the receiver circuit 420 may occur. In the wireless device 10 configured as described above, the power of the high-frequency transmission signal (RF transmission power) amplified and transmitted by the power amplifier 411 of the transmitter circuit 410 is high, and the power of the reception signal (reception power) received by the receiver circuit 420 is low. Furthermore, the circulator 30 to which the transmitter circuit 410 and the receiver circuit 420 are connected has lower isolation between ports than a cavity filter or a duplexer. Because the high-gain power amplifier 411 provided in the transmission circuit 410 has nonlinear input / output characteristics, intermodulation distortion signals (signals generated between higher-order harmonic signals and the fundamental signal or higher-order harmonic signals) generated by the power amplifier 411 leak as noise into the reception circuit 420, causing noise leakage in the reception band. Intermodulation distortion is distortion that occurs when multiple signals of different frequencies are input to an amplifier with nonlinear input / output characteristics. For the same transmission band bandwidth, the lower the fundamental frequency of the frequency band used by the wireless device 10, the greater the impact of this intermodulation distortion generated by the power amplifier 411 on the reception circuit 420. For example, as shown in FIG. 2A , when the frequency band used by radio device 10 of an aerial repeater type radio repeater is the 900 MHz band (Band 8), the transmission band (DL Band 8) with a bandwidth of 10 MHz is 945 to 960 MHz, and the reception band (UL Band 8) is 900 to 915 MHz, the 11th-order intermodulation distortion signal (IM11) and the 9th-order intermodulation distortion signal (IM9), which have relatively high signal levels from power amplifier 411, are located in the reception band (UL Band 8).2B , when the frequency band used by radio device 10 of an aerial repeater type radio repeater is the 1700 MHz band (Band 3), the 10 MHz bandwidth transmission band (DL Band 3) is 1845 to 1860 MHz, and the reception band (UL Band 3) is 1750 to 1765 MHz, the 21st order intermodulation distortion signal (IM21) and the 19th order intermodulation distortion signal (IM19), which have relatively low signal levels from power amplifier 411, are located in the reception band (UL Band 8). As shown in FIGS. 2A and 2B , when the bandwidths of the transmission bands (DL Band 8, DL Band 3) are both 10 MHz, the impact of the intermodulation distortion signal generated by power amplifier 411 on receiving circuit 420 is greater in Band 8, which is the lower frequency band used by radio device 10, than in Band 3.

[0037] 1 , in the radio device (radio equipment) 10 having the same transmitting and receiving ports connected to the antenna 20, noise leakage from the receiving path of the transmitting circuit (transmitting system) 410 to the receiving path of the receiving circuit (receiving system) 420 causes degradation of the demodulation performance of the received signal. In order to prevent noise leakage, it is conceivable to implement a bandpass filter (BPF) or the like that sharply suppresses the receiving band (receiving frequency band) in the output from the power amplifier 411 in the final stage of the transmitting circuit (transmitting system) 410, but there are RF section configurations that are difficult to implement due to weight restrictions in HAPS radio equipment used in the above-mentioned HAPS and the like, a large difference in RF power levels between transmitting and receiving, and the like.

[0038] Therefore, in this embodiment, in order to reduce interference due to noise leakage in the reception band from the transmission path of the transmission circuit 410 to the reception path of the reception circuit 420, an interference suppression circuit (interference canceller) that suppresses the interference is provided between the transmission circuit 410 and the reception circuit 420 in the transmission / reception circuit 40 of the wireless device 10. Instead of implementing a BPF with a steep band pass characteristic in the transmission circuit (transmission system) 410, this interference suppression circuit (interference canceller) suppresses (cancels) the leakage noise by using a vector modulator to add the opposite phase of the noise signal in the reception band to the reception circuit (reception system) 420.

[0039] FIG. 3 is a graph showing an example of the spectrum of a transmission signal including interference caused to a receiving circuit (receiving system) 420 by a power amplifier (transmitting system power amplifier) ​​411 in a transmitting circuit (transmitting system) 410. Here, taking into account the actual implementation in a wireless device (radio equipment) 10, the interference noise output from the power amplifier 411 is considered as the output level when DPD (digital predistortion) control, which performs distortion compensation to reduce the distortion of the power amplifier 411, is performed. The power value indicated by symbol S101 in FIG. 3 is the output level of the transmission signal from the power amplifier 411 when DPD control is not performed, and the power value indicated by symbol S102 in FIG. 3 is the output level of the transmission signal from the power amplifier 411 when DPD control is performed. The frequency range indicated by symbol S103 in FIG. 3 is the receiving band. The signal components of pre-interference that sneak into this receiving band signal via the circulator (CIR) 30 are suppressed (canceled) by the receiving circuit (receiving system) 420. The interference suppression signal (cancellation signal) used for this suppression (cancellation) is combined with the received signal via the coupled port of the directional coupler of the receiving circuit (receiving system) 420, as will be exemplified later.

[0040] FIG. 4 is a frequency characteristic graph showing an example of evaluation results of the effect of an interference suppression circuit (interference canceller) that suppresses interference from a power amplifier (transmission system power amplifier) ​​411 in a transmission circuit (transmission system) 410 to a reception circuit (reception system) 420. FIG. 4 shows the results of an evaluation conducted targeting Band 8 (transmission side: 945 to 960 MHz, reception side: 900 to 915 MHz) as the frequency band of the transmission and reception frequency. The result indicated by symbol S201 in FIG. 4 is the level of the interference signal when interference suppression by the interference suppression circuit (interference canceller) is turned off, and the result indicated by symbol S202 in FIG. 4 is the level of the interference signal when interference suppression by the interference suppression circuit (interference canceller) is turned on. As shown in FIG. 4, when interference suppression is turned on and interference suppression correction is performed, it was confirmed that loop interference can be canceled by up to 20.6 dB at a frequency of 905 MHz compared to when interference suppression correction is not performed. As an example, when a modulated wave with a center frequency of 905 MHz and a bandwidth of 10 MHz was input to the received signal at -43 dBm and the modulation accuracy (EVM: Error Vector Magnitude) was measured, it was confirmed that the EVM was 41.5% without interference suppression correction and 16.1% with interference suppression correction, which is an improvement of 25.4% (8.23 dB).

[0041] The present inventors conducted further experiments, simulations, and studies on the case where an interference suppression circuit (interference canceller) having such an effect is provided to suppress (cancele) the above-mentioned loop noise. As a result, they found that it is necessary to adjust the interference suppression circuit (interference canceller) taking into account changes in gain and phase due to changes in the environmental temperature of the device (e.g., changes in the temperature of the power amplifier 411 of the transmission circuit 410). For example, as shown in Figures 5A and 5B, as the temperature of the power amplifier 411 increases, the gain of the power amplifier 411 decreases and the phase changes. In particular, when the radio device 10 is mounted on an airborne repeater-type radio repeater that moves horizontally and vertically in the airspace at the aforementioned altitude, the environmental temperature of the radio device 10 changes, and the gain and phase of the power amplifier 411 of the radio device 10 are likely to change. When the gain and phase of the power amplifier 411 change in response to changes in the temperature of the power amplifier 411, a level difference occurs, for example, between an interference signal due to loop noise included in the total reception signal and the interference suppression signal that the interference suppression circuit (interference canceller) applies to the received signal, reducing the amount of interference suppression (cancellation) suppressed by the interference suppression circuit (interference canceller). For example, as shown in FIG. 5C, if the interference signal due to noise leakage and the interference suppression signal differ by 1 dB, the amount of interference suppression (cancellation amount) decreases by 20 dB or more.

[0042] In light of the above, the wireless device 10 of this embodiment detects the environmental temperature (for example, the temperature of the power amplifier or the temperature of the components of the interference suppression circuit) and adjusts the interference suppression circuit (interference canceller) that reduces interference due to noise sneaking in the reception band based on the temperature measurement result. This reduces interference due to noise sneaking in the reception band from the transmission path of the transmission circuit 410 to the reception path of the reception circuit 420 even when the environmental temperature of the wireless device fluctuates.

[0043] FIG. 6 is an explanatory diagram showing an example of the overall configuration of a wireless device 10 according to an embodiment. Note that in FIG. 6, components common to those in FIG. 1 are assigned the same reference numerals and will not be described again. In the wireless device 10 of FIG. 6, a transmission circuit 410 includes a power amplifier 411, a transmission bandpass filter (hereinafter also referred to as a "transmission band BPF") 412, and an isolator 413 in a transmission path 410A, in this order from the signal processing unit 50 toward the circulator 30. The power amplifier 411 amplifies a transmission signal received from the signal processing unit 50 to a predetermined signal power level. The transmission band BPF 412 selectively passes transmission signals in a predetermined transmission band among signals output from the power amplifier 411. The isolator 413 blocks transmission of signals in the direction opposite to the predetermined transmission direction of the transmission path 410A (from the circulator 30 toward the power amplifier 411).

[0044] The receiving circuit 420 has a first receiving band-pass filter (hereinafter "receiving band BPF") 421, a low-noise amplifier 422, and a second receiving band-pass filter (hereinafter "receiving band BPF") 423 on a receiving path 420A, in that order from the circulator 30 toward the signal processing unit 50. The receiving band BPF 421 selectively passes received signals of a predetermined receiving band from the signals received from the circulator 30. The low-noise amplifier 422 amplifies the received signals that have passed through the receiving band BPF 421 to a predetermined signal power level. Furthermore, the receiving band BPF 423 selectively passes received signals of a predetermined receiving band from the signals output from the low-noise amplifier 422.

[0045] An interference suppression circuit 430 that reduces interference due to noise leakage in the reception band from a transmission path 410A of the transmission circuit 410 to a reception path 420A of the reception circuit 420 is provided between the transmission path 410A and the reception path 420A. The interference suppression circuit 430 has a directional coupler 431 as a signal extraction unit, a band-pass filter (hereinafter referred to as a "reception band BPF") 432, a vector modulation unit 433, and a directional coupler 434 as a signal superposition unit.

[0046] The directional coupler (signal extraction unit) 431 extracts a portion of the transmission signal transmitted via the circulator 30 to the antenna 20 in the transmission path 410A. The reception band BPF 432 selectively passes the reception band signal from the signals extracted by the directional coupler (signal extraction unit) 431. The signal output from the reception band BPF 432 is a signal corresponding to the reception band noise sneaking signal (interference signal to be suppressed) sneaking from the transmission path 410A to the reception path 420A via the circulator 30, and is an interference replica signal before being adjusted by the vector modulation unit 433 to generate an interference suppression signal.

[0047] The vector modulation unit 433 vector-modulates the reception band signal output from the reception band BPF 432 based on the value of a vector modulation parameter determined according to the environmental temperature or a control voltage corresponding to the value of the vector modulation parameter to generate an interference suppression signal. The interference suppression signal is a signal obtained by inverting the phase of a replica of an interference signal to be suppressed. As the vector modulation unit 433, for example, a commercially available device (e.g., HMC630LP3 by Analog Devices) can be used.

[0048] In the receiving path 420A, the directional coupler (signal superposition unit) 434 superimposes the interference suppression signal (a signal with the phase of the interference replica inverted) of the receiving band generated by the vector modulation unit 433 onto the receiving signal received from the antenna 20 via the circulator 30.

[0049] The directional coupler (signal extraction unit) 431 is provided between the isolator 413 and the circulator 30 of the transmission path 410A, and the directional coupler (signal superposition unit) 434 is provided between the reception band BPF (first reception bandpass filter) and the low-noise amplifier 422 of the reception path 420A.

[0050] In this embodiment, the wireless device 10 includes a first thermometer (hereinafter also referred to as an "amplifier thermometer") 415 that detects the temperature of the power amplifier 411 of the transmission circuit 410. Furthermore, the wireless device 10 may include a second thermometer (hereinafter also referred to as a "modulator thermometer") 435 that detects the temperature of the vector modulation unit 433 as a second thermometer that detects the temperature of the interference suppression circuit 430. Various temperature sensors can be used as the amplifier thermometer 415 and the modulator thermometer 435.

[0051] In this embodiment, the wireless device 10 includes a directional coupler 414 as an output level detector that detects the output level of the power amplifier 411 of the transmission circuit 410. A detection signal of the detected output level of the power amplifier 411 extracted by the directional coupler 414 is input to the signal processing unit 50 via a predetermined feedback path (for example, a feedback path for DPD (Digital Pre-Distortion)) and is used to generate values ​​of vector modulation parameters or control voltages for controlling the vector modulation unit 433, control DPD (Digital Pre-Distortion) that reduces distortion of the power amplifier 411, etc.

[0052] 6 , the signal processing unit 50 includes a transmission signal processing unit 510 that processes a transmission signal to be transmitted to the transmission circuit 410, and a reception signal processing unit 520 that processes a reception signal received from the reception circuit 420. The signal processing unit 50 further includes a storage unit 530, a control voltage determination unit 540, and a control voltage output unit 550.

[0053] The storage unit 530 stores a data table indicating the relationship between temperature and the control voltage of the vector modulation parameter used for vector modulation in the vector modulation unit 433. The data table is, for example, one of the following data tables A1 to A6. A1: A data table created in advance for a plurality of temperatures of the power amplifier 411, showing the relationship between the temperature of the power amplifier 411 and the control voltage of the vector modulation parameters (I, Q). A2: A data table created in advance for a plurality of combinations of temperatures of the power amplifier 411 and a plurality of output levels (RF output levels) of the power amplifier, showing the relationship between the temperature of the power amplifier 411, the output level (RF output level) of the power amplifier, and the control voltage of the vector modulation parameters (I, Q) (see Figure 7). A3: A data table created in advance for a plurality of temperatures of the vector modulation unit 433, showing the relationship between the temperature of the vector modulation unit 433 and the control voltage of the vector modulation parameters (I, Q). A4: A data table created in advance for a plurality of combinations of temperatures of the vector modulation unit 433 and a plurality of output levels (RF output levels) of the power amplifier 411, showing the relationship between the temperature of the vector modulation unit 433, the output level (RF output level) of the power amplifier 411, and the control voltage of the vector modulation parameters (I, Q). A5: A data table created in advance for a plurality of temperatures of the power amplifier 411 and a plurality of temperatures of the vector modulation unit 433, showing the relationship between the temperature of the power amplifier 411, the temperature of the vector modulation unit 433, and the control voltage of the vector modulation parameters (I, Q). A6: A data table created in advance for a plurality of combinations of temperatures of the power amplifier 411, a plurality of temperatures of the vector modulation unit 433, and a plurality of output levels (RF output levels) of the power amplifier 411, showing the relationship between the temperature of the power amplifier 411, the temperature of the vector modulation unit 433, the output level (RF output level) of the power amplifier 411, and the control voltage of the vector modulation parameters (I, Q).

[0054] The control voltage determiner 540 determines the control voltage of the vector modulation parameters (I, Q) to be applied to the vector modulator 433, for example, by one of the following methods B1 to B6. B1: Determine the control voltage of the vector modulation parameters (I, Q) based on the data table of A1 above and the temperature of the power amplifier 411 detected by the amplifier thermometer 415. B2: Determine the control voltage of the vector modulation parameters (I, Q) based on the data table of A2 above, the temperature of the power amplifier 411 detected by the amplifier thermometer 415, and the output level of the power amplifier 411 detected by the directional coupler (output level detector) 414. B3: Determine the control voltage of the vector modulation parameters (I, Q) based on the data table of A3 above and the temperature of the vector modulator 433 detected by the modulator thermometer 435. B4: Determine the control voltages of the vector modulation parameters (I, Q) based on the data table of A4 above, the temperature of the vector modulation unit 433 detected by the modulator thermometer 435, and the output level of the power amplifier 411 detected by the directional coupler (output level detector) 414. B5: Determine the control voltages of the vector modulation parameters (I, Q) based on the data table of A5 above, the temperature of the power amplifier 411 detected by the amplifier thermometer 415, and the temperature of the vector modulation unit 433 detected by the modulator thermometer 435. B6: Determine the control voltages of the vector modulation parameters (I, Q) based on the data table of A6 above, the temperature of the power amplifier 411 detected by the amplifier thermometer 415, the temperature of the vector modulation unit 433 detected by the modulator thermometer 435, and the output level of the power amplifier 411 detected by the directional coupler (output level detector) 414.

[0055] The control voltage output unit 550 outputs the control voltage of the vector modulation parameters (I, Q) determined by the control voltage determination unit 540 to the vector modulation unit 433 of the interference suppression circuit 430 .

[0056] In the wireless device 10 of this embodiment, the amount of gain correction for the power amplifier 411 may be determined based on the temperature of the power amplifier 411 detected by the amplifier thermometer 415 and the output level of the power amplifier 411 detected by the directional coupler (output level detection unit) 414.

[0057] 8 and 9 are explanatory diagrams showing other exemplary configurations of the interference suppression circuit 430. As shown in FIG. 8 , the interference suppression circuit 430 may include a signal level adjustment unit 436 between the reception band BPF 432 and the vector modulation unit 433. The signal level adjustment unit 436 adjusts the signal level of the unadjusted interference replica signal input to the vector modulation unit 433 to a predetermined level. The signal level adjustment unit 436 may be configured, for example, with an impedance element (attenuator) or a power amplifier. Furthermore, as shown in FIG. 9 , the interference suppression circuit 430 may include a directional coupler 437 as a signal detector for monitoring reception band noise signals between the signal level adjustment unit 436 and the vector modulation unit 433. The directional coupler (signal detector) 437 detects the signal (reception band noise signal) output from the signal level adjustment unit 436 and input to the vector modulation unit 433. The signal (reception band noise signal) input to the vector modulation unit 433 can be monitored based on the detection result of the directional coupler (signal detection unit) 437. The detection result of the directional coupler (signal detection unit) 437 may be used to control the amount of signal level adjustment in the signal level adjustment unit 436. For example, if the signal level adjustment unit 436 is configured to be able to switch between multiple impedance elements (attenuators), the switching may be controlled based on the detection result of the directional coupler (signal detection unit) 437 so that the signal (reception band noise signal) input to the vector modulation unit 433 falls within a predetermined level range. Furthermore, if the signal level adjustment unit 436 is configured with a power amplifier, the gain of the power amplifier may be controlled based on the detection result of the directional coupler (signal detection unit) 437 so that the signal (reception band noise signal) input to the vector modulation unit 433 falls within a predetermined level range. In addition, the detection result of the directional coupler (signal detection unit) 437 may be fed back to the control voltage determination unit 540 and used to determine the control voltage of the vector modulation parameters (I, Q) together with or instead of the output level of the power amplifier 411.

[0058] FIG. 10 is an explanatory diagram showing an example of the circuit of the vector modulator (vector modulation unit) 433. In FIG. 10, the vector modulator (vector modulation unit) 433 includes an input transformer 4331, an IQ signal generator 4332, multipliers 4333 and 4334, and an adder 4335. The input transformer 4331 generates a first signal with a phase of 0° and a second signal with a phase of −180° or +180°, which are inverted from each other but have equal amplitude, from a high-frequency input signal. The IQ signal generator 4332 generates an in-phase (I) signal component and a quadrature-phase (Q) signal component of the input signal, which are orthogonal to each other in predetermined orthogonal coordinates, based on the inverted first and second signals output from the input transformer 4331. The multiplier 4333 multiplies the in-phase (I) signal component output from the IQ signal generator 4332 by an in-phase (I) control voltage corresponding to the temperature received from the signal processing unit 50, and outputs the adjusted in-phase (I) signal component. The multiplier 4334 multiplies the quadrature-phase (Q) signal component output from the IQ signal generator 4332 by a quadrature-phase (Q) control voltage corresponding to the temperature received from the signal processing unit 50, and outputs an adjusted quadrature-phase (Q) signal component. The adder 4335 adds the adjusted in-phase (I) signal component and the adjusted quadrature-phase (Q) signal component, and outputs an adjusted interference suppression signal (a signal obtained by inverting the phase of the interference replica signal) whose amplitude and phase have been adjusted according to the temperature.

[0059] As described above, according to this embodiment, it is possible to reduce the size and weight of the wireless device 10, and even if the temperature of the device fluctuates, it is possible to reduce interference caused by noise leakage in the reception band from the transmission path 410A of the transceiver circuit 40 having the power amplifier 411 to the reception path 420A according to the temperature of the device.

[0060] Furthermore, the present invention can provide a transceiver circuit and a wireless device that are smaller and lighter in size and weight and have an interference suppression circuit that can reduce interference caused by noise leakage in the reception band from the transmission path 410A of the transceiver circuit 40 to the reception path 420A, thereby contributing to the achievement of Goal 9 of the Sustainable Development Goals (SDGs), which is to "build resilient infrastructure, promote inclusive and sustainable industrialization and foster innovation."

[0061] It should be noted that the processing steps and components of the interference suppression circuit, transceiver circuit, transmitter circuit, receiver circuit, wireless device, and communication system described herein can be implemented by various means. For example, these steps and components may be implemented in hardware, firmware, software, or a combination thereof.

[0062] For hardware implementations, the processing units and other means used to implement the above steps and components in an entity (e.g., various circuit elements, transmitters, receivers, transceivers, amplifiers, filters, controllers, antennas, hard disk drives, or optical disk drives) may be implemented in one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processors (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), processors, controllers, microcontrollers, microprocessors, electronic devices, other electronic units designed to perform the functions described herein, computers, or combinations thereof.

[0063] Furthermore, with regard to firmware and / or software implementations, the means, such as a processing unit, used to realize the above components may be implemented with a program (e.g., code, such as procedures, functions, modules, instructions, etc.) that performs the functions described herein. In general, any computer / processor-readable medium tangibly embodying firmware and / or software code may be used to implement the means, such as a processing unit, used to realize the above steps and components described herein. For example, the firmware and / or software code may be stored in a memory and executed by a computer or processor, such as in a control device. The memory may be implemented within the computer or processor, or external to the processor. The firmware and / or software code may also be stored on a computer or processor readable medium such as, for example, random access memory (RAM), read-only memory (ROM), non-volatile random access memory (NVRAM), programmable read-only memory (PROM), electrically erasable programmable read-only memory (EEPROM), flash memory, floppy disk, compact disk (CD), digital versatile disk (DVD), magnetic or optical data storage device, etc. The code may be executed by one or more computers or processors and may cause the computers or processors to perform certain aspects of the functionality described herein.

[0064] The medium may be a non-transitory recording medium. The program code may be in any format as long as it can be read and executed by a computer, processor, or other device or machine. For example, the program code may be in any of source code, object code, and binary code, or may be a mixture of two or more of these codes.

[0065] Moreover, the description of the embodiments disclosed herein is provided to enable any person skilled in the art to make or use the present disclosure. Various modifications to the present disclosure will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other variations without departing from the spirit or scope of the present disclosure. Thus, the present disclosure is not intended to be limited to the examples and designs described herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0066] DESCRIPTION OF SYMBOLS 10: Radio device 20: Antenna (shared antenna) 30: Circulator 40: Transmitting / receiving circuit 50: Signal processing unit 410: Transmitting circuit 410A: Transmitting path 411: Power amplifier 412: Transmitting band BPF 413: Isolator 414: Directional coupler 415: Thermometer 420: Receiving circuit 420A: Receiving path 421: Receiving band BPF 422: Low noise amplifier 423: Receiving band BPF 430: Interference suppression circuit 431: Directional coupler (signal extraction unit) 432: Receiving band BPF 433: Vector modulation unit 434: Directional coupler (signal superposition unit) 435: Thermometer 436: Signal level adjustment unit 437: Directional coupler (signal detection unit for receiving band noise signal monitor) 510: Transmission signal processing unit 520: Reception signal processing unit 530: Storage unit 540: Control voltage determination unit 550: Control voltage output unit

Claims

1. An interference suppression circuit provided in a transmission / reception circuit that separates and processes transmission signals and reception signals transmitted and received via a shared antenna, comprising: a signal extraction unit in the transmission path of the transmission / reception circuit that extracts a portion of the transmission signal transmitted towards the antenna via a circulator; a band-pass filter that selectively passes signals in a reception band from the signals extracted by the signal extraction unit; a vector modulation unit that vector-modulates the signal in the reception band output from the band-pass filter based on a control voltage of a vector modulation parameter determined according to the environmental temperature to generate an interference suppression signal; and a signal superposition unit in the reception path of the transmission / reception circuit that superposes the interference suppression signal in the reception band generated by the vector modulation unit onto a reception signal received from the antenna via the circulator.

2. A transmission / reception circuit that separates and processes transmission signals and reception signals transmitted and received via a shared antenna and circulator, comprising: the interference suppression circuit of claim 1; a circulator connected to the shared antenna; a transmission circuit including the transmission path connected to the circulator; and a reception circuit including the reception path connected to the circulator.

3. A transmitter / receiver circuit according to claim 2, wherein the transmitter circuit has a power amplifier, a transmitter band-pass filter, and an isolator in the transmission path; the receiver circuit has a first receiver band-pass filter, a low-noise amplifier, and a second receiver band-pass filter in the reception path; the signal extractor is provided between the isolator and the circulator in the transmission path; and the signal superimposing unit is provided between the first receiver band-pass filter and the low-noise amplifier in the reception path.

4. A transmission / reception circuit according to claim 3, wherein the signal extraction unit is a directional coupler coupled to the transmission path, and the signal superposition unit is a directional coupler coupled to the reception path.

5. A radio device comprising: a transmission / reception circuit according to claim 2, 3 or 4; a common antenna used for transmission and reception; and a signal processing unit that processes transmission signals transmitted by said transmission / reception circuit and reception signals received by said transmission / reception circuit.

6. A radio device according to claim 5, wherein the vector modulation parameters are a control voltage by which an in-phase signal component in the vector modulation is multiplied and a control voltage by which a quadrature-phase signal component is multiplied.

7. A radio device according to claim 5, further comprising a first thermometer for detecting the temperature of a power amplifier provided in the transmitting / receiving circuit, wherein the signal processing unit determines a control voltage for the vector modulation parameter based on the temperature of the power amplifier detected by the first thermometer, and outputs the control voltage for the vector modulation parameter to the vector modulation unit.

8. A radio device according to claim 7, wherein the signal processing unit stores a data table which is prepared in advance for a plurality of temperatures of the power amplifier and indicates the relationship between the temperature of the power amplifier and the control voltage of the vector modulation parameter, and determines the control voltage of the vector modulation parameter based on the data table and the temperature of the power amplifier detected by the first thermometer.

9. A radio device according to claim 7, further comprising an output level detection unit that detects the output level of the power amplifier, wherein the signal processing unit stores a data table that indicates the relationship between the temperature of the power amplifier, the output level of the power amplifier, and the control voltage of the vector modulation parameter, the data table being created in advance for a combination of a plurality of temperatures of the power amplifier and a plurality of output levels of the power amplifier, and determines the control voltage of the vector modulation parameter based on the data table, the temperature of the power amplifier detected by the first thermometer, and the output level of the power amplifier detected by the output level detection unit.

10. A radio device according to claim 5, further comprising a second thermometer for detecting the temperature of the interference suppression circuit, wherein the signal processing unit determines a control voltage for the vector modulation parameter based on the temperature of the interference suppression circuit detected by the second thermometer, and outputs the control voltage for the vector modulation parameter to the vector modulation unit.

11. A radio device according to claim 10, wherein the signal processing unit stores a data table showing the relationship between the temperature of the interference suppression circuit and the control voltage of the vector modulation parameter, the data table being created in advance for a plurality of combinations of temperatures of the interference suppression circuit, and determines the control voltage of the vector modulation parameter based on the data table and the temperature of the interference suppression circuit detected by the second thermometer.

12. A radio device according to claim 10, further comprising an output level detection unit that detects the output level of a power amplifier provided in the transmitting / receiving circuit, wherein the signal processing unit stores a data table that shows the relationship between the temperature of the interference suppression circuit, the output level of the power amplifier, and the control voltage of the vector modulation parameter, the data table being created in advance for a combination of a plurality of temperatures of the interference suppression circuit and a plurality of output levels of the power amplifier, and determines the control voltage of the vector modulation parameter based on the data table, the temperature of the interference suppression circuit detected by the second thermometer, and the output level of the power amplifier detected by the output level detection unit.

13. A radio device according to claim 5, comprising a first thermometer for detecting the temperature of a power amplifier provided in the transmitting / receiving circuit, and a second thermometer for detecting the temperature of the interference suppression circuit, wherein the signal processing unit determines a control voltage for the vector modulation parameter based on the temperature of the power amplifier detected by the first thermometer and the temperature of the interference suppression circuit detected by the second thermometer, and outputs the control voltage for the vector modulation parameter to the vector modulation unit.

14. A radio device according to claim 13, wherein the signal processing unit stores a data table which is created in advance for a combination of a plurality of temperatures of the power amplifier and a plurality of temperatures of the interference suppression circuit and which indicates the relationship between the temperature of the power amplifier, the temperature of the interference suppression circuit and the value of the vector modulation parameter, and determines the control voltage of the vector modulation parameter based on the data table, the temperature of the power amplifier detected by the first thermometer and the temperature of the interference suppression circuit detected by the second thermometer.

15. A radio device according to claim 13, further comprising an output level detection unit that detects the output level of the power amplifier, wherein the signal processing unit stores a data table that indicates the relationship between the temperature of the power amplifier, the temperature of the interference suppression circuit, the output level of the power amplifier, and the control voltage of the vector modulation parameter, the data table being created in advance for combinations of multiple temperatures of the power amplifier, multiple temperatures of the interference suppression circuit, and multiple output levels of the power amplifier, and determines the control voltage of the vector modulation parameter based on the data table, the temperature of the power amplifier detected by the first thermometer, the temperature of the interference suppression circuit detected by the second thermometer, and the output level of the power amplifier detected by the output level detection unit.

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