Radio frequency signal processing system and method

Abstract

The present application relates to a radio frequency signal processing system and method. The system comprises a signal separation unit, electro-optical conversion units, a photodiode unit, and a matching compensation unit which are successively arranged; the signal separation unit is configured to decompose an input radio frequency signal into two paths of sub-input radio frequency signals; the electro-optical conversion units are configured to convert the received two paths of sub-input radio frequency signals into two paths of optical signals; the photodiode unit comprises two photodiodes connected in parallel, and the photodiodes are configured to convert the received optical signals into sub-output radio frequency signals; and the matching compensation unit is configured to fuse the two paths of sub-output radio frequency signals to form an output radio frequency signal and is also configured to implement matching of the impedance of the two photodiodes with the optimal impedance. The radio frequency signal processing system in the present application uses the Outphasing architecture on the basis of a photoelectric fusion link, thereby improving the power supply efficiency in a back-off state, reducing the complexity of the architecture, facilitating implementation, and facilitating full-band full-service flexible deployment of the radio frequency signal processing system.

Description

Radio frequency signal processing system and method

[0001] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office of China on October 31, 2023, with application number 202311443068.2 and invention name “A Radio Frequency Signal Processing System and Method”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of communication technology, and in particular to a radio frequency signal processing system and method. Background Art

[0003] Radio-over-Fiber (RoF) links effectively address issues such as RF signal extension and simplified base station deployment costs, offering advantages such as wide bandwidth, high data rates, low loss, and interference resistance. In response to the call for next-generation green wireless communications, RF photonic base station architectures employ high-power photodiode (PD) direct-drive antennas. Designing a suitable matching network for the high-power photodiode at the output of these links can effectively improve link performance, such as output power and efficiency. However, fifth-generation (5G) communication systems generally utilize orthogonal frequency division multiplexing (OFDM), the standard downlink signal modulation scheme. OFDM modulated signals have a high peak-to-average ratio (PAR). To ensure lossless signal transmission, functional modules within the communication link must operate within a back-off zone based on the PAR. Therefore, ensuring that high-power photodiodes maintain efficient operation during the back-off state is a core issue that must be addressed for the engineering and practical application of RF photonic base station architectures.

[0004] In existing technologies, the Doherty architecture is often applied to the downlink of RF photonic base stations to ensure that high-power photodiodes maintain high efficiency even in the back-off region. However, due to the different requirements for photodiodes in the carrier and peak paths, this Doherty architecture requires the design of two different electro-optical conversion units, making its implementation difficult.

[0005] Application Contents

[0006] In view of this, the present application provides a radio frequency signal processing system and method to solve the problem that the existing technical architecture is difficult to implement.

[0007] A first aspect of an embodiment of the present application provides a radio frequency signal processing system, comprising a signal separation unit, an electro-optical conversion unit, a photodiode unit, and a matching compensation unit, which are arranged in sequence. The signal separation unit is used to decompose an input radio frequency signal into two out-of-phase sub-input radio frequency signals, and output the two sub-input radio frequency signals to the electro-optical conversion unit. The electro-optical conversion unit is used to convert the two received sub-input radio frequency signals into corresponding two optical signals, and output the two optical signals to the photodiode unit. The photodiode unit includes two photodiodes connected in parallel, and the two photodiodes correspond one-to-one to the two optical signals. The photodiode is used to convert the received optical signal into a corresponding sub-output radio frequency signal, and output the sub-output radio frequency signal to the matching compensation unit. The matching compensation unit is used to fuse the two sub-output radio frequency signals to form an output radio frequency signal. The matching compensation unit is also used to adjust the impedance of the two photodiodes to achieve matching between the impedance of the two photodiodes and the optimal impedance value corresponding to the back-off output power.

[0008] In the present application, the link of the radio frequency signal processing system is an optoelectronic fusion link, which can reduce the loss during signal transmission and is conducive to long-distance signal transmission. On this basis, the radio frequency signal processing system in the embodiment of the present application adopts the Outphasing architecture. Compared with the Doherty architecture, the first photodiode and the second photodiode in the branch of the Outphasing architecture work in the same state, and there is no need to set a unique electro-optical conversion unit for a specific path to realize the opening and closing of the photodiode of the path. Therefore, the radio frequency signal processing system in the embodiment of the present application has the advantages of simple structure and easy implementation. It can improve the power efficiency of the photodiode unit in the fallback state while reducing the complexity of the architecture, which is conducive to the flexible deployment of the radio frequency signal processing system in all frequency bands and all services, and reduces the implementation cost of the radio frequency signal processing system.

[0009] In one possible design, the electro-optical conversion unit includes two laser modulators, which correspond one-to-one to the two sub-input RF signals. The laser modulator includes a first RF signal input terminal, a bias current receiving terminal, and a first optical signal output terminal. The first RF signal input terminal is connected to the signal separation unit, the bias current receiving terminal is used to receive a bias current, and the first optical signal output terminal is connected to the photodiode unit. The laser modulator is used to convert the received sub-input RF signal into the corresponding optical signal according to the bias current.

[0010] In this solution, when a direct-modulation electro-optical conversion unit is used, the DC bias point of the first laser modulator and the second laser modulator can be controlled by controlling the magnitude of the input bias current, thereby adjusting the power of the output first optical signal and the second optical signal, so that the first photodiode and the second photodiode at the back end can operate in a high-efficiency working state, thereby putting the entire RF signal processing system architecture in a high-efficiency working mode, further improving the power efficiency of the RF signal processing system. This control method is simple, reliable, and easy to implement. In addition, since the first laser modulator and the second laser modulator can generate laser light themselves, there is no need to arrange an external laser source, which further reduces the complexity of the architecture, makes the architecture easier to implement, and reduces implementation costs.

[0011] In one possible design, the electro-optical conversion unit includes a light source and two external modulators, the two external modulators correspond one-to-one to the two sub-input RF signals, the external modulator includes a second RF signal input terminal, a laser signal receiving terminal, a bias voltage receiving terminal and a second optical signal output terminal, the second RF signal input terminal is connected to the signal separation unit, the laser signal receiving terminal is connected to the light source, the bias voltage receiving terminal is used to receive the bias voltage, and the second optical signal output terminal is connected to the photodiode unit, the light source is used to generate a laser signal and output the laser signal to the two external modulators, and the external modulator is used to convert the received sub-input RF signal into the corresponding optical signal according to the laser signal and the bias voltage.

[0012] In this solution, when an externally modulated electro-optical conversion unit is used, the bias voltage operating point of the first external modulator and the second external modulator can be controlled by controlling the magnitude of the input bias voltage, thereby adjusting the power of the output first optical signal and the second optical signal, so that the first photodiode and the second photodiode at the back end can operate in a high-efficiency working state, thereby putting the entire RF signal processing system architecture in a high-efficiency working mode, further improving the power efficiency of the RF signal processing system. This control method is simple, reliable, and easy to implement. In addition, in the externally modulated electro-optical conversion unit, the light source, the first external modulator, and the second external modulator can all be controlled separately, further improving the conversion accuracy of the electro-optical conversion unit, and also improving the design freedom of the architecture, which is more conducive to the flexible deployment of the full-band and full-service RF signal processing system.

[0013] In one possible design, the electro-optical conversion unit also includes an optical power splitter, which includes an input end and two output ends, the input end is connected to the light source, and the two output ends are connected one-to-one with the two external modulators. The optical power splitter is used to decompose the laser generated by the light source into two laser signals, and output the two laser signals to the corresponding external modulators.

[0014] In this solution, the working requirements of the first external modulator and the second external modulator can be met. At the same time, the number of light sources in the structure is reduced, the control difficulty requirement of the electro-optical conversion unit is reduced, and the design freedom of the architecture can be further improved, which is more conducive to the flexible deployment of the full-band and full-service RF signal processing system.

[0015] In one possible design, the radio frequency signal processing system further includes an optical amplifier, wherein an input end of the optical amplifier is connected to the light source, and an output end of the optical amplifier is connected to the optical power splitter.

[0016] In this solution, the laser generated by the light source can be amplified by an optical amplifier first, and then decomposed into two laser signals by an optical power splitter. This can ensure that the power of the laser signal meets the control requirements of the first photodiode and the second photodiode at the back end. At the same time, this structure uses an optical amplifier at the front end of the externally modulated electro-optical conversion unit to amplify the two optical signals. This can reduce the number of transmission optical fibers and the imbalance in the amplitude and phase of the optical signal caused by multi-optical fiber transmission, which is beneficial to improving the quality of multi-channel optical signal transmission. In addition, it can further reduce the structural complexity of the architecture, making the architecture easy to implement.

[0017] In one possible design, the radio frequency signal processing system further includes an optical amplifier, wherein an input end of the optical amplifier is connected to an output end of the electro-optical conversion unit, and an output end of the optical amplifier is connected to an input end of the photodiode unit.

[0018] In this solution, the optical amplifier is arranged between the electro-optical conversion unit and the photodiode unit, and the first optical signal and the second optical signal can be amplified by the optical amplifier respectively, which can improve the control accuracy of each optical signal.

[0019] In one possible design, the radio frequency signal processing system further includes an optical multiplexer and an optical demultiplexer, wherein the input end of the optical multiplexer is connected to the output end of the electro-optical conversion unit, the output end of the optical multiplexer is connected to the input end of the optical amplifier, the input end of the optical demultiplexer is connected to the output end of the optical amplifier, and the output end of the optical demultiplexer is connected to the photodiode unit.

[0020] In this solution, the first and second optical signals are first combined into one optical signal through an optical multiplexer, then amplified by an optical amplifier. The amplified optical signal is then decomposed into the first and second optical signals by an optical demultiplexer. This structure, combining the amplifier, optical multiplexer, and optical demultiplexer to amplify and transmit optical signals, reduces the number of transmission fibers and the amplitude and phase imbalance of optical signals caused by multi-fiber transmission. This improves the transmission quality of multi-channel optical signals and further reduces the structural complexity of the architecture, making it easier to implement.

[0021] In a possible design, the radio frequency signal processing system further includes an optical delay device, the input end of the optical delay device is connected to the output end of the electro-optical conversion unit, and the output end of the optical delay device is connected to the photodiode unit.

[0022] In this solution, the optical delay device is used to adjust the phase delay of the first optical signal and the second optical signal to ensure that the two optical signals maintain the same phase, thereby improving the performance of signal transmission.

[0023] In a possible design, the radio frequency signal processing system further includes an electrical phase shifter, wherein an input end of the electrical phase shifter is connected to an output end of the signal separation unit, and an output end of the electrical phase shifter is connected to the electro-optical conversion unit.

[0024] In this solution, the electrical phase shifter can be used to adjust the phase of the two-way input RF signal, thereby ensuring that the phase of the two-way input RF signal meets the requirements of the Outphasing architecture.

[0025] In one possible design, the matching compensation unit is a Chireix synthesizer, thereby realizing a Chireix-Outphasing architecture to reduce the structural complexity of the architecture and further reduce the difficulty of implementation.

[0026] In one possible design, the matching compensation unit is a three-port structure composed of multiple microstrip lines, and the matching compensation unit includes a first branch and a second branch. The input ends of the first branch and the second branch are respectively two input ports of the matching compensation unit, and are connected one-to-one with the two photodiodes. The output ends of the first branch and the second branch are connected to form the output port of the matching compensation unit.

[0027] In this solution, the first branch and the second branch are connected to the first photodiode and the second photodiode, respectively, so that the first branch and the second branch can respectively match the impedance of the first photodiode and the second photodiode with the optimal impedance value corresponding to their back-off output power, thereby improving the efficiency of the first photodiode and the second photodiode in the back-off state. In addition, microstrip lines have a wide bandwidth, high stability, and are easy to simulate and control during circuit simulation. Therefore, using a microstrip line structure in the transmission circuit can provide controllable variables for circuit design and reduce the difficulty of circuit design of the matching compensation unit.

[0028] In a possible design, the matching compensation unit further includes a susceptance element, and the susceptance element is arranged in parallel on the first branch and the second branch.

[0029] In this solution, by connecting corresponding susceptance elements in parallel on the first branch and the second branch, the susceptance of the first photodiode and the second photodiode themselves can be compensated, so that the matching compensation unit can perform phase compensation on the link where the first photodiode is located and the link where the second photodiode is located. By improving the matching condition of the first photodiode and the second photodiode through compensation, the overall power balance of the RF signal processing system is achieved, the loss is reduced, and the power supply efficiency is improved.

[0030] In one possible design, the susceptance element includes a capacitor and / or an inductor.

[0031] A second aspect of the embodiments of the present application further provides a method for processing radio frequency signals, comprising the following steps:

[0032] Receives an input RF signal.

[0033] In this step, the signal separation unit may be used to receive the input radio frequency signal S(t) to facilitate the generation of two sub-input signals.

[0034] The radio frequency signal is decomposed into two sub-input radio frequency signals, where the two sub-input radio frequency signals are out-of-phase constant envelope signals.

[0035] In this step, the signal separation unit can decompose the received input RF signal S(t) into two out-of-phase constant envelope signals, namely the first input RF signal S1(t) and the second input RF signal S2(t), and output the first input RF signal S1(t) and the second input RF signal S2(t) to the electro-optical conversion unit.

[0036] The two sub-RF signals are converted into corresponding two optical signals.

[0037] In this step, the electro-optical conversion unit is used to convert the received first-path input RF signal S1(t) into a first-path optical signal, convert the received second-path input RF signal S2(t) into a second-path optical signal, and output the first-path optical signal and the second-path optical signal to the photodiode unit.

[0038] The two optical signals are converted into corresponding two-way output radio frequency signals.

[0039] In this step, the photodiode unit includes two parallel photodiodes, namely a first photodiode and a second photodiode, with the two photodiodes corresponding one-to-one to the two optical signals. The first photodiode is used to convert the received first optical signal into a first output RF signal and output the first output RF signal to the matching compensation unit. The second photodiode is used to convert the received second optical signal into a second output RF signal and output the second output RF signal to the matching compensation unit.

[0040] The impedances of the two photodiodes are adjusted to achieve matching between the impedances of the two photodiodes and the optimal impedance values ​​corresponding to the back-off output power.

[0041] In this step, the matching compensation unit is further configured to adjust the impedance of the first photodiode and the second photodiode to achieve matching between the impedance of the two photodiodes and the optimal impedance value corresponding to the fallback output power, thereby improving the power efficiency of the first photodiode and the second photodiode in the fallback state. The power efficiency in the fallback state is equal to the saturated power efficiency of the first photodiode and the second photodiode.

[0042] The two sub-RF signals are merged to form an output RF signal.

[0043] In this step, the matching compensation unit is used to merge the first-path output RF signal and the second-path output RF signal to form an output RF signal, and output the output RF signal to the terminal load.

[0044] In the embodiment of the present application, the link of the radio frequency signal processing system is an optoelectronic fusion link, which can reduce the loss during signal transmission and is conducive to long-distance signal transmission. On this basis, the radio frequency signal processing system in the embodiment of the present application adopts the Outphasing architecture. Compared with the Doherty architecture, the first photodiode and the second photodiode in the branch of the Outphasing architecture work in the same state, and there is no need to set a unique electro-optical conversion unit for a specific path to realize the opening and closing of the photodiode of the path. Therefore, the radio frequency signal processing system in the embodiment of the present application has the advantages of simple structure and easy implementation. It can improve the power efficiency of the photodiode unit in the fallback state while reducing the complexity of the architecture, which is conducive to the flexible deployment of the radio frequency signal processing system in all frequency bands and all services, and reduces the implementation cost of the radio frequency signal processing system.

[0045] In one possible design, adjusting the impedance of the two photodiodes includes the following steps:

[0046] A target compensation angle of the matching compensation unit is determined according to the peak-to-average ratio of the input radio frequency signal.

[0047] In this step, different compensation angles have different backoff capabilities. It is necessary to select an appropriate target compensation angle θ based on the actual requirements of the peak-to-average ratio of the input radio frequency signal S(t). comp , which can ensure efficiency while achieving the best fallback capability.

[0048] A compensation susceptance is determined according to the compensation angle.

[0049] In this step, the target compensation angle θ is determinedcomp After determination, according to the above formula Japanese style The equivalent output admittance Y1 of the output end of the first photodiode and the equivalent output admittance Y2 of the output end of the second photodiode can also be determined, so that the compensation susceptance can be determined based on the imaginary parts of Y1 and Y2, that is, the susceptance.

[0050] According to the compensation susceptance, susceptance elements are connected in parallel in the first branch and the second branch of the matching compensation unit respectively, so as to achieve matching of the load impedance of the two photodiodes with the optimal impedance value corresponding to the back-off output power.

[0051] In this solution, by connecting corresponding susceptance elements in parallel on the first branch and the second branch, the susceptance of the first photodiode and the second photodiode themselves can be compensated, so that the matching compensation unit can perform reactance compensation on the link where the first photodiode is located and the link where the second photodiode is located. By improving the matching condition of the first photodiode and the second photodiode through compensation, the overall power balance of the RF signal processing system is achieved, the loss is reduced, and the power supply efficiency is improved.

[0052] In one possible design, determining the target compensation angle of the matching compensation unit according to the peak-to-average ratio of the input RF signal includes the following steps:

[0053] The back-off amount is determined according to the peak-to-average ratio of the input radio frequency signal.

[0054] In this step, since the peak-to-average ratio of the signal is different, the back-off requirements are also different, so the back-off amount can be determined according to the peak-to-average ratio of the input RF signal S(t).

[0055] A target compensation angle is determined according to the retraction amount.

[0056] In this step, different compensation angles have different backoff capabilities. According to the actual backoff requirements of the peak-to-average ratio of the input radio frequency signal S(t), the appropriate target compensation angle θ is selected. comp , which can ensure efficiency while achieving the best fallback capability.

[0057] In one possible design, determining a target compensation angle according to the retraction amount includes the following steps:

[0058] Draw a curve of the power efficiency changing with the power back-off amount under different compensation angles of the matching compensation unit.

[0059] In this step, a curve diagram showing how the power efficiency changes with the power back-off amount under different compensation angles of the matching compensation unit can be drawn through simulation.

[0060] A target compensation angle is determined according to the backoff amount and a curve diagram of the power supply efficiency varying with the power backoff amount.

[0061] In this step, the target compensation angle θ comp This is the compensation angle corresponding to the curve with the highest power efficiency at this setback in the figure.

[0062] In this solution, the backoff capability of different compensation angles varies according to the backoff amount. The smaller the compensation angle, the greater the power backoff amount, but the efficiency between the two peak efficiency points is worse. The backoff amount can be determined based on the peak-to-average ratio of the input RF signal S(t), and the target compensation angle θ suitable for the matching compensation unit 4 under this backoff amount can be determined. comp , in order to ensure efficiency while achieving the best retreat capability, where the target compensation angle θ comp This is the compensation angle corresponding to the curve with the highest power efficiency at this setback in the figure.

[0063] In one possible design, determining the target compensation angle of the matching compensation unit according to the peak-to-average ratio of the input RF signal includes the following steps:

[0064] The back-off amount is determined according to the peak-to-average ratio of the input radio frequency signal.

[0065] In this step, since the peak-to-average ratio of the signal is different, the back-off requirements are also different, so the back-off amount can be determined according to the peak-to-average ratio of the input RF signal S(t).

[0066] An out-of-phase angle is determined according to the backoff amount.

[0067] In this step, since the signal works at the back-off point most of the time, the out-of-phase angle can be taken as the angle value at the back-off point during design.

[0068] A target compensation angle is determined according to the out-of-phase angle.

[0069] In this step, different compensation angles have different retraction capabilities. According to the size of the phase difference angle θ(t), the appropriate target compensation angle θ is selected. comp , which can ensure efficiency while achieving the best fallback capability.

[0070] In one possible design, determining a target compensation angle according to the out-of-phase angle includes the following steps:

[0071] Draw a curve of the synthetic efficiency of the matching compensation unit changing with the phase angle under different compensation angles.

[0072] In this step, a curve diagram showing how the synthesis efficiency of the matching compensation unit changes with the out-of-phase angle under different compensation angles can be drawn through simulation.

[0073] The target compensation angle is determined according to the out-of-phase angle and a curve diagram of the resultant efficiency varying with the out-of-phase angle.

[0074] In this step, the target compensation angle θ comp That is, the compensation angle corresponding to the curve with the highest synthesis efficiency of the matching compensation unit at the out-of-phase angle θ(t) in the figure.

[0075] In this solution, the power back-off capability of different compensation angles varies according to the different out-of-phase angles. For example, when the compensation angle is 10 degrees, the combined efficiency reaches its peak at out-of-phase angles of 10 degrees and 80 degrees. The two out-of-phase angles corresponding to the peak efficiency are symmetrical about 45 degrees. The target compensation angle θ of the matching compensation unit can be determined based on the out-of-phase angle θ(t) determined by the peak-to-average ratio of the input RF signal S(t). comp , in order to ensure efficiency while achieving the best retreat capability, where the target compensation angle θ comp That is, the compensation angle corresponding to the curve with the highest synthesis efficiency of the matching compensation unit at the out-of-phase angle θ(t) in the figure.

[0076] In one possible design, converting the two sub-RF signals into corresponding two optical signals includes the following steps:

[0077] Receive bias current.

[0078] In this step, the bias current receiving end of the first laser modulator receives the first bias current Id1, and the bias current receiving end of the second laser modulator receives the second bias current Id2.

[0079] The DC bias point of the electro-optical conversion unit is controlled according to the bias current to convert the received sub-input radio frequency signal into the corresponding optical signal.

[0080] In this step, the DC bias point of the first laser modulator can be controlled according to the magnitude of the first bias current Id1 received by the first laser modulator, thereby converting the input first-path RF signal into the desired first-path optical signal, thereby ensuring that the first photodiode can operate in a high-efficiency working state; and the DC bias point of the second laser modulator can be controlled according to the magnitude of the second bias current Id2 received by the second laser modulator, thereby converting the input second-path RF signal into the desired second-path optical signal, thereby ensuring that the second photodiode can operate in a high-efficiency working state.

[0081] In an embodiment of the present application, when a direct-modulation electro-optical conversion unit is used, the DC bias point of the first laser modulator and the second laser modulator can be controlled by controlling the magnitude of the input bias current, thereby adjusting the power of the output first optical signal and the second optical signal, so that the first photodiode and the second photodiode at the back end can operate in a high-efficiency working state, thereby putting the entire RF signal processing system architecture in a high-efficiency working mode, further improving the power efficiency of the RF signal processing system. This control method is simple, reliable, and easy to implement. In addition, because the first laser modulator and the second laser modulator can generate laser light themselves, there is no need to arrange an external laser source, which further reduces the complexity of the architecture, makes the architecture easier to implement, and reduces implementation costs.

[0082] In one possible design, converting the two sub-RF signals into corresponding two optical signals includes the following steps:

[0083] Receive bias voltage.

[0084] In this step, the bias voltage receiving terminal of the first external modulator receives the first bias voltage Vd1, and the bias low voltage receiving terminal of the second external modulator receives the second bias voltage Vd2.

[0085] The bias voltage operating point of the electro-optical conversion unit is controlled according to the bias voltage to convert the received sub-input radio frequency signal into the corresponding optical signal.

[0086] In this step, the bias voltage operating point of the first external modulator can be controlled according to the magnitude of the first bias voltage Vd1 received by the first external modulator, thereby converting the input first-path RF signal into the desired first-path optical signal, thereby ensuring that the first photodiode operates in a high-efficiency operating state; and the bias voltage operating point of the second external modulator can be controlled according to the magnitude of the second bias voltage Vd2 received by the second external modulator, thereby converting the input second-path RF signal into the desired second-path optical signal, thereby ensuring that the second photodiode operates in a high-efficiency operating state.

[0087] In this solution, when an externally modulated electro-optical conversion unit is used, the bias voltage operating point of the first external modulator and the second external modulator can be controlled by controlling the magnitude of the input bias voltage, thereby adjusting the power of the output first optical signal and the second optical signal, so that the first photodiode and the second photodiode at the back end can operate in a high-efficiency working state, thereby putting the entire RF signal processing system architecture in a high-efficiency working mode, further improving the power efficiency of the RF signal processing system. This control method is simple, reliable, and easy to implement. In addition, in the externally modulated electro-optical conversion unit, the light source, the first external modulator, and the second external modulator can all be controlled separately, further improving the conversion accuracy of the electro-optical conversion unit, and also improving the design freedom of the architecture, which is more conducive to the flexible deployment of the full-band and full-service RF signal processing system.

[0088] It should be understood that the foregoing general description and the following detailed description are merely illustrative and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0089] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0090] FIG1 is a block diagram of a Doherty architecture used in a radio frequency photonic base station link in the prior art;

[0091] FIG2 is a structural block diagram of a radio frequency signal processing system provided by a first embodiment of the present application;

[0092] FIG3 is a circuit block diagram of the first photodiode in FIG2 ;

[0093] FIG4 is a current-voltage characteristic curve diagram of the first photodiode in FIG3 ;

[0094] FIG5 is a structural block diagram of a radio frequency signal processing system provided by a second embodiment of the present application;

[0095] FIG6 is a circuit block diagram of the first laser modulator in FIG5 ;

[0096] FIG7 is a diagram showing the working principle of a direct-modulation electro-optical conversion unit;

[0097] FIG8 is a structural block diagram of a radio frequency signal processing system provided by a third embodiment of the present application;

[0098] FIG9 is a circuit block diagram of the first external modulator in FIG8 ;

[0099] FIG10 is a diagram showing the working principle of an externally modulated electro-optical conversion unit;

[0100] FIG11 is a structural block diagram of a radio frequency signal processing system provided by a fourth embodiment of the present application;

[0101] FIG12 is a structural block diagram of a radio frequency signal processing system provided in a fifth embodiment of the present application;

[0102] FIG13 is a structural block diagram of a radio frequency signal processing system provided by a sixth embodiment of the present application;

[0103] FIG14 is a structural block diagram of a radio frequency signal processing system provided by a seventh embodiment of the present application;

[0104] FIG15 is a circuit structure diagram of a matching compensation unit;

[0105] FIG16 is a waveform diagram of a signal separation unit and a signal vector decomposition diagram;

[0106] FIG17 is a graph showing a change in power efficiency with power backoff under different compensation angles of the matching compensation unit;

[0107] FIG18 is a graph showing how the combined efficiency of the matching compensation unit changes with the out-of-phase angle at different compensation angles;

[0108] FIG19 is a graph showing a change in power efficiency of a radio frequency signal processing system according to an embodiment of the present application as a function of the out-of-phase angle;

[0109] FIG20 is a graph showing a change in power efficiency versus output power for a radio frequency signal processing system according to an embodiment of the present application;

[0110] FIG21 is a flowchart of a radio frequency signal processing method in an embodiment of the present application.

[0111] Reference numerals: 1-signal separation unit; 2-electro-optical conversion unit; 21-first laser modulator; 211-first RF signal input terminal; 212-bias current receiving terminal; 213-first optical signal output terminal; 22-second laser modulator; 23-first external modulator; 231-second RF signal input terminal; 232-laser signal receiving terminal; 233-bias voltage receiving terminal; 234-second optical signal output terminal; 24-second external modulator; 25-light source; 26-optical power splitter; 3-photodiode unit; 31-first photodiode; 311-optical signal input terminal; 312-DC power supply terminal; 313-RF signal output terminal; 32-second photodiode; 4-matching compensation unit; 41-first branch; 42-second branch; 43-susceptance element; 51-first optical amplifier; 52-second optical amplifier; 53 - third optical amplifier; 61 - first optical delay device; 62 - second optical delay device; 71 - first electrical phase shifter; 72 - second electrical phase shifter; 81 - optical multiplexer; 82 - optical demultiplexer.

[0112] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application. DETAILED DESCRIPTION

[0113] In order to better understand the technical solution of the present application, the embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0114] In the description of this application, unless otherwise specified or limited, the terms "first" and "second" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance; unless otherwise specified or explained, the term "plurality" refers to two or more; the terms "connected" and "fixed" should be understood in a broad sense. For example, "connected" can mean a fixed connection, a detachable connection, an integral connection, or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For those skilled in the art, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0115] The terms used in the embodiments of the present application are for the purpose of describing specific embodiments only and are not intended to limit the present application. The singular forms "a", "an", "the" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms unless the context clearly indicates otherwise.

[0116] It should be understood that the term "and / or" as used herein simply describes a relationship between associated objects, indicating that three possible relationships exist. For example, "A and / or B" can represent: A alone, A and B together, or B alone. Furthermore, the character " / " in this document generally indicates an "or" relationship between the associated objects.

[0117] Radio-over-Fiber (RoF) links effectively address issues such as RF signal extension and simplified base station deployment costs, offering advantages such as wide bandwidth, high speed, low loss, and interference resistance. In response to the call for next-generation green wireless communications, RF photonic base station architectures employ high-power photodiode (PD) direct-drive antennas. Designing a suitable matching network for the high-power photodiode at the output of these links can effectively improve link performance, such as output power and efficiency. However, fifth-generation (5G) communication systems generally utilize orthogonal frequency division multiplexing (OFDM), the standard downlink signal modulation scheme. OFDM modulated signals have a high peak-to-average ratio (PAR). To ensure linear signal transmission, functional modules within the communication link must operate within a back-off zone based on the PAR. Therefore, ensuring that high-power photodiodes maintain efficient operation during the back-off state is a core issue that must be addressed for the engineering and practical application of RF photonic base station architectures.

[0118] Please refer to Figure 1, which is a block diagram of the Doherty architecture used for the RF photonic base station link in the prior art. As shown in Figure 1, the Doherty architecture is usually applied to the downlink of the RF photonic base station in the prior art. In the traditional Doherty architecture, the first path is the carrier path, and the second path is the peak path. The first path is usually biased in Class AB as the main power amplifier, and the second path usually works in Class C as an auxiliary power amplifier. When the power of the input signal is relatively small, only the first photodiode of the first path works and outputs a signal. At this time, the load impedance is large and the power efficiency is high, while the second photodiode is turned off, reducing the power consumption of the second photodiode, thereby improving the power efficiency in the fallback state; when the power of the input signal gradually increases and reaches the threshold of the second photodiode, the second photodiode of the second path will start to work. At this time, the load is reduced, thereby increasing the output power and improving the power efficiency in the saturation state.

[0119] Although this solution can improve efficiency in the fallback state, since the photodiode will turn on when there is light, regardless of the size of the signal it carries, in the Doherty architecture, the first path does not need to set the on and off states of the first photodiode, and the second path's second photodiode needs to be set to only start working when the power of the input signal reaches a certain threshold. Therefore, the second path requires a unique electro-optical conversion unit to realize the turning on and off of the second photodiode, thereby ensuring the reliability of the architecture. It can be seen from this that the working requirements of the photodiodes in the first and second paths are completely different. Therefore, when implementing the Doherty architecture, it is necessary to design two different electro-optical conversion units, which makes the architecture difficult to implement and limits its practicality.

[0120] In addition, the second photodiode on the second path is usually biased in a Class C state. However, when the second photodiode is biased in a Class C state, the corresponding linear performance is extremely poor, which may result in a low signal-to-noise ratio of the link.

[0121] In order to solve this technical problem, an embodiment of the present application provides a radio frequency signal processing system, in which an outphasing architecture is adopted in the optoelectronic fusion circuit of the radio frequency signal processing system to reduce the implementation difficulty of the overall architecture and reduce the implementation cost. As an application scenario, the radio frequency signal processing system in the embodiment of the present application can be applied to various communication systems, such as the fifth generation (5G) system or the new wireless (NR), the sixth generation (6G) communication system, etc., and can also be applied to, for example, radio frequency photon base stations, fifth generation (5G) wireless base stations, sixth generation (6G) wireless base stations, radio frequency fiber optic extension systems, etc. Of course, the radio frequency signal processing system in the embodiment of the present application can also be used in various network devices, terminal devices, vehicle-mounted devices, and other devices that can be used for wireless communication, without limitation here.

[0122] The present application is further described in detail below through specific embodiments and in conjunction with the accompanying drawings.

[0123] Please refer to FIG. 2 , which is a structural block diagram of a radio frequency signal processing system provided by a first embodiment of the present application.

[0124] As shown in FIG2 , the radio frequency signal processing system of the embodiment of the present application includes a signal separation unit 1 , an electro-optical conversion unit 2 , a photodiode unit 3 and a matching compensation unit 4 , which are arranged in sequence.

[0125] The signal separation unit 1 is used to decompose the input RF signal S(t) into two out-of-phase constant envelope signals, namely the first input RF signal S1(t) and the second input RF signal S2(t), and output the first input RF signal S1(t) and the second input RF signal S2(t) to the electro-optical conversion unit 2.

[0126] The electro-optical conversion unit 2 is used to convert the received first input RF signal S1(t) into a first optical signal, convert the received second input RF signal S2(t) into a second optical signal, and output the first optical signal and the second optical signal to the photodiode unit 3.

[0127] Photodiode unit 3 includes two parallel photodiodes: a first photodiode 31 and a second photodiode 32. The two photodiodes correspond one-to-one to the two optical signals. First photodiode 31 is used to convert the received first optical signal into a first output RF signal, and then output the first output RF signal to matching compensation unit 4. Second photodiode 32 is used to convert the received second optical signal into a second output RF signal, and then output the second output RF signal to matching compensation unit 4.

[0128] Matching compensation unit 4 is used to combine the first and second RF output signals to form an output RF signal, and then output the output RF signal to the terminal load. Matching compensation unit 4 is also used to adjust the impedance of first photodiode 31 and second photodiode 32 to achieve matching between the impedance of the two photodiodes and the optimal impedance value corresponding to the fallback output power, thereby improving the power efficiency of first photodiode 31 and second photodiode 32 in the fallback state. The fallback power efficiency is equal to the saturated power efficiency of first photodiode 31 and second photodiode 32.

[0129] The outphasing architecture converts the amplitude modulated and phase modulated signal into two constant envelope signals, amplifies the two branch signals through a high-efficiency amplifier, and finally synthesizes the two signals for output.

[0130] As shown in Figure 2, the link of the RF signal processing system in the embodiment of the present application is an optoelectronic fusion link, which can reduce the loss during signal transmission and is conducive to long-distance signal transmission. On this basis, the RF signal processing system in the embodiment of the present application adopts the Outphasing architecture. Compared with the Doherty architecture, the first photodiode 31 and the second photodiode 32 in the branch of the Outphasing architecture work in the same state. There is no need to set a unique electro-optical conversion unit for a specific path to realize the opening and closing of the photodiode of the path. Therefore, the RF signal processing system in the embodiment of the present application has the advantages of simple structure and easy implementation. It can improve the power efficiency of the photodiode unit 3 in the fallback state while reducing the complexity of the architecture, which is conducive to the flexible deployment of the RF signal processing system in all frequency bands and all services, and reduces the implementation cost of the RF signal processing system.

[0131] Among them, the saturated power efficiency of the RF signal processing system is the same as the saturated power efficiency of a single first photodiode 31 and a second photodiode 32. In order to improve the power efficiency of the RF signal processing system, as shown in Figure 2, in the RF signal processing system in the embodiment of the present application, the first photodiode 31 and the second photodiode 32 both operate in Class AB or Class B states with higher power efficiency, so that the first photodiode 31 and the second photodiode 32 are both photodiodes in a high-efficiency working state, thereby putting the entire RF signal processing system in a high-efficiency working mode, further improving the power efficiency, and the corresponding linear performance when the first photodiode 31 and the second photodiode 32 operate in Class AB or Class B states is higher, which can improve the signal-to-noise ratio of the RF signal processing system, thereby improving the overall performance of the RF signal processing system.

[0132] For example, the operating states of the first photodiode 31 and the second photodiode 32 in the photodiode unit 3 can be controlled by the optical signal output by the electro-optical conversion unit 2. Since the first photodiode 31 and the second photodiode 32 have the same or similar structure, the following description will take the first photodiode 31 as an example.

[0133] Please refer to FIG. 3 and FIG. 4 . FIG. 3 is a circuit block diagram of the first photodiode, and FIG. 4 is a current-voltage characteristic curve diagram of the first photodiode in FIG. 3 .

[0134] As shown in Figure 3, the first photodiode 31 includes an optical signal input terminal 311, a DC power supply terminal 312, and an RF signal output terminal 313. The optical signal input terminal 311 is connected to the output terminal of the electro-optical conversion unit 2 for receiving the first optical signal. The DC power supply terminal 312 is used to receive a reverse DC power supply voltage to ensure the normal operation requirements of the first photodiode 31. The RF signal output terminal 313 is connected to the input terminal of the matching compensation unit to achieve reactance compensation of the first photodiode 31 by the matching compensation unit, thereby maximizing the RF signal output efficiency of the first photodiode 31.

[0135] As shown in FIG4 , each curve represents the power of a light signal. Depending on the power of the received light signal, the position of the current bias point of the photodiode varies, and the operating state of the photodiode varies. Therefore, by controlling the power state of the first light signal input to the first photodiode 31, the DC bias point of the first photodiode 31 can be controlled, causing the first photodiode 31 to operate in different modes, such as Class A, Class B, or Class AB, thereby ensuring the output efficiency of the first photodiode 31. For example, when the power of the first light signal is changed so that the DC bias point of the first photodiode 31 controlled by the first light signal is Q1, the operating state of the first photodiode 31 can be equivalent to the Class A operating state. When the power of the first light signal is changed so that the DC bias point of the first photodiode 31 controlled by the first light signal is Q2, the operating state of the first photodiode 31 can be equivalent to the Class B operating state. The specific setting can be made according to actual needs and is not limited here.

[0136] At the same time, as shown in FIG4 , the load slope of the first photodiode 31 can be changed by the matching compensation unit, thereby achieving a match between the impedance of the first photodiode 31 and the optimal impedance value corresponding to the back-off output power, thereby maximizing the output power of the first photodiode 31. In addition, during the operation of the first photodiode 31, an excessively large or small reverse DC supply voltage (i.e., reverse bias voltage) will affect the impedance of the first photodiode 31, thereby affecting the output capacity and power efficiency of the first photodiode 31. Therefore, by inputting a sufficient reverse DC supply voltage to the DC power supply terminal of the first photodiode 31, the output power of the first photodiode 31 can be ensured.

[0137] It should be noted that the structure and principle of the second photodiode 32 are the same as those of the first photodiode 31. By controlling the power state of the second optical signal input to the second photodiode 32, the DC bias point of the second photodiode 32 can be controlled, so that the second photodiode 32 can operate in different modes, such as Class A state, Class B state or Class AB state, etc., thereby ensuring the output capacity of the second photodiode 32. No further details will be given here.

[0138] Furthermore, in the RF signal processing system of the embodiment of the present application, a directly modulated electro-optical conversion unit or an externally modulated electro-optical conversion unit can be used to generate the above-mentioned first optical signal and / or second optical signal. The specific settings can be made according to actual needs and are not limited here.

[0139] In a specific embodiment, please refer to Figures 5, 6, and 7. Figure 5 is a structural block diagram of the radio frequency signal processing system provided by the second embodiment of the present application, Figure 6 is a circuit block diagram of the first laser modulator in Figure 5, and Figure 7 is a working principle diagram of the direct-modulation electro-optical conversion unit. As shown in Figure 5, when the electro-optical conversion unit 2 is a direct-modulation electro-optical conversion unit, the electro-optical conversion unit 2 includes two laser modulators, namely a first laser modulator 21 and a second laser modulator 22. The first laser modulator 21 is used to receive a first-path input radio frequency signal S1(t) and convert the first-path input radio frequency signal S1(t) into a first-path optical signal. The second laser modulator 22 is used to receive a second-path input radio frequency signal S2(t) and convert the second-path input radio frequency signal S2(t) into a second-path optical signal.

[0140] Furthermore, since the structures of the first laser modulator 21 and the second laser modulator 22 are identical, the first laser modulator 21 will be used as an example for description. As shown in FIG6 , the first laser modulator 21 includes a first RF signal input terminal 211, a bias current receiving terminal 212, and a first optical signal output terminal 213. The first RF signal input terminal 211 is connected to the signal separation unit 1, the bias current receiving terminal 212 is used to receive the first bias current Id1, and the first optical signal output terminal 213 is connected to the first photodiode unit 31. The first laser modulator 21 is used to convert the received first input RF signal into the desired first optical signal based on the first bias current Id1 and output it.

[0141] As shown in Figure 7, for a directly modulated electro-optical conversion unit, the size of its DC bias point is proportional to the output optical signal power. Under the same input RF signal, the DC bias point C of the electro-optical conversion unit is different, and its corresponding minimum light output point a and maximum light output point b are also different. Therefore, the output optical power AC signal size is different, thereby generating different optical signals.

[0142] Therefore, as shown in Figures 5 and 6, according to the size of the first bias current Id1 received by the first laser modulator 21, the DC bias point of the first laser modulator 21 can be controlled, so that the input first-path RF signal can be converted into the required first-path optical signal to ensure that the first photodiode 31 can operate in a high-efficiency working state.

[0143] The structure and principle are the same as those of the first laser modulator 21. As shown in FIG5 , according to the size of the second bias current Id2 received by the second laser modulator 22, the DC bias point of the second laser modulator 22 can be controlled, thereby converting the input second-path RF signal into the required second-path optical signal to ensure that the second photodiode 32 operates in a high-efficiency working state.

[0144] In an embodiment of the present application, as shown in FIG5 , when a direct-modulation electro-optical conversion unit is used, the DC bias point of the first laser modulator 21 and the second laser modulator 22 can be controlled by controlling the magnitude of the input bias current, thereby adjusting the power of the output first optical signal and the second optical signal, so that the first photodiode 31 and the second photodiode 32 at the back end can operate in a high-efficiency working state, thereby putting the entire RF signal processing system architecture in a high-efficiency working mode, further improving the power efficiency of the RF signal processing system. This control method is simple, reliable, and easy to implement. In addition, since the first laser modulator 21 and the second laser modulator 22 can generate laser light themselves, there is no need to arrange an external laser source, thereby further reducing the complexity of the architecture, making the architecture easier to implement, and reducing the implementation cost.

[0145] In another specific embodiment, please refer to Figures 8, 9, and 10. Figure 8 is a structural block diagram of the radio frequency signal processing system provided in the third embodiment of the present application, Figure 9 is a circuit block diagram of the first external modulator in Figure 8, and Figure 10 is a working principle diagram of the external modulation electro-optical conversion unit. As shown in Figure 8, when the electro-optical conversion unit 2 is an external modulation electro-optical conversion unit, the electro-optical conversion unit 2 includes a light source 25 and two external modulators, wherein the light source 25 is used to generate a laser signal and output the laser signal to the first external modulator 23 and the second external modulator 24 respectively. The two external modulators are the first external modulator 23 and the second external modulator 24. The first external modulator 23 is used to receive the first input radio frequency signal S1(t) and convert the first input radio frequency signal S1(t) into a first optical signal. The second external modulator 24 is used to receive the second input radio frequency signal S2(t) and convert the second input radio frequency signal S2(t) into a second optical signal. That is, the two external modulators correspond one-to-one to the two input radio frequency signals.

[0146] Furthermore, since the first external modulator 23 and the second external modulator 24 have the same structure, the first external modulator 23 is used as an example for description. As shown in Figure 9, the first external modulator 23 includes a second RF signal input terminal 231, a laser signal receiving terminal 232, a bias voltage receiving terminal 233, and a second optical signal output terminal 234. The second RF signal input terminal 231 is connected to the signal separation unit 1, the laser signal receiving terminal 232 is connected to the light source 25, the bias voltage receiving terminal 233 is used to receive the bias voltage, and the second optical signal output terminal 234 is connected to the first photodiode 31. The first external modulator 23 is used to convert the received first-path input RF signal into the desired first-path optical signal based on the laser signal and the first bias voltage Vd1, and output it.

[0147] As shown in Figure 10, for an externally modulated electro-optical conversion unit, the magnitude of its bias voltage operating point is proportional to the output optical signal power. Under the same input RF signal, different bias voltage operating points F of the electro-optical conversion unit correspond to different minimum transmission points d and maximum transmission points e. Therefore, the magnitude of the output optical power AC signal is different, thereby generating different optical signals.

[0148] Therefore, as shown in Figures 8 and 9, according to the size of the first bias voltage Vd1 received by the first external modulator 23, the bias voltage operating point of the first external modulator 23 can be controlled, so that the input first-path RF signal can be converted into the required first-path optical signal to ensure that the first photodiode 31 operates in a high-efficiency working state.

[0149] The structure and principle are the same as those of the first external modulator 23. As shown in FIG8 , according to the size of the second bias voltage Vd2 received by the second external modulator 24, the bias voltage operating point of the second external modulator 24 can be controlled, so that the input second-path RF signal can be converted into the required second-path optical signal to ensure that the second photodiode 32 can operate in a high-efficiency working state.

[0150] In the embodiment of the present application, as shown in FIG8 , when an externally modulated electro-optical conversion unit is used, the bias voltage operating point of the first external modulator 23 and the second external modulator 24 can be controlled by controlling the magnitude of the input bias voltage, thereby adjusting the power of the output first optical signal and the second optical signal, so that the first photodiode 31 and the second photodiode 32 at the back end can operate in a high-efficiency working state, thereby putting the entire RF signal processing system architecture in a high-efficiency working mode, further improving the power efficiency of the RF signal processing system, and the control method is simple, reliable, and easy to implement. In addition, in the externally modulated electro-optical conversion unit, the light source 25, the first external modulator 23, and the second external modulator 24 can all be controlled separately, further improving the conversion accuracy of the electro-optical conversion unit, and also improving the design freedom of the architecture, which is more conducive to the flexible deployment of the full-band and full-service RF signal processing system.

[0151] The light source 25 may be one or more, and the number can be set according to actual needs and is not limited here. For example, there may be multiple light sources 25, that is, a light source may be connected to the laser signal receiving end of each external modulator in the RF signal processing system, thereby further improving the design freedom of the architecture.

[0152] For example, as shown in FIG8 , there is only one light source 25. In this case, the optoelectronic conversion unit 2 may further include an optical power splitter 26. The light source 25 is connected to the input end of the optical power splitter 26, and the two output ends of the optical power splitter 26 are connected to the first external modulator 23 and the second external modulator 24, respectively, so that the laser light generated by the light source 25 can be decomposed into two laser signals by the optical power splitter 26, thereby meeting the working requirements of the first external modulator 23 and the second external modulator 24. At the same time, this structure reduces the number of light sources 25, reduces the control difficulty requirements of the electro-optical conversion unit 2, and can further improve the design freedom of the architecture, thereby being more conducive to the flexible deployment of the full-band and full-service RF signal processing system.

[0153] In a specific embodiment, the RF signal processing system also includes an optical amplifier for amplifying the power of the optical signal to meet the working requirements of the architecture. The optical amplifier is flexibly set up and can be set up in the electro-optical conversion unit 2 or between the electro-optical conversion unit 2 and the photodiode unit 3. The specific setting of the optical amplifier in the RF signal processing system architecture can be set according to the actual needs of the electro-optical conversion unit 2 and is not limited here.

[0154] For the RF signal processing system using a direct-modulation electro-optical conversion unit, please refer to Figures 11 and 12. Figure 11 is a structural block diagram of the RF signal processing system provided by the fourth embodiment of the present application, and Figure 12 is a structural block diagram of the RF signal processing system provided by the fifth embodiment of the present application.

[0155] For example, in the specific embodiment shown in FIG11 , the RF signal processing system may include a first optical amplifier 51 and a second optical amplifier 52. The input end of the first optical amplifier 51 is connected to the first optical signal output end of the first laser modulator 21, and the output end of the first optical amplifier 51 is connected to the optical signal input end of the first photodiode 31, so that the first optical signal output by the first laser modulator 21 can be amplified by the first optical amplifier 51, so that the power of the first optical signal can meet the requirement of controlling the first photodiode 31 in the back-end to operate in a high-efficiency working state. The input end of the second optical amplifier 52 is connected to the first optical signal output end of the second laser modulator 22, and the output end of the second optical amplifier 52 is connected to the optical signal input end of the second photodiode 32, so that the second optical signal output by the second laser modulator 22 can be amplified by the second optical amplifier 52, so that the power of the second optical signal can meet the requirement of controlling the second photodiode 32 in the back-end to operate in a high-efficiency working state.

[0156] In this embodiment, the first optical amplifier 51 and the second optical amplifier 52 are both arranged after the electro-optical conversion unit 2 and the photodiode unit 3. The first optical signal and the second optical signal are amplified by the first optical amplifier 51 and the second optical amplifier 52 respectively, which can improve the control accuracy of each optical signal.

[0157] For example, in the specific embodiment shown in Figure 12, the RF signal processing system may include only one third optical amplifier 53. In this case, the RF signal processing system may also include an optical multiplexer 81 and an optical demultiplexer 82. The input end of the optical multiplexer 81 is connected to the first optical signal output end of the first laser modulator 21 and the second laser modulator 22, the output end of the optical multiplexer 81 is connected to the input end of the third optical amplifier 53, the input end of the optical demultiplexer 82 is connected to the output end of the third optical amplifier 53, and the output end of the optical demultiplexer 82 is connected to the photodiode unit 3.

[0158] In this embodiment, as shown in FIG12 , the optical signals generated by the first laser modulator 21 and the second laser modulator 22 can first be combined into one optical signal through an optical multiplexer 81, then uniformly amplified by a third optical amplifier 53, and then decomposed into a first optical signal and a second optical signal through an optical demultiplexer 82. In this structure, the third amplifier 53, the optical multiplexer 81, and the optical demultiplexer 82 are combined to achieve optical signal amplification and transmission, which can reduce the number of transmission optical fibers and the imbalance in optical signal amplitude and phase caused by multi-fiber transmission, thereby improving the quality of multi-channel optical signal transmission. In addition, it can further reduce the structural complexity of the architecture, making the architecture easier to implement.

[0159] Of course, for the RF signal processing system using a direct-modulated electro-optical conversion unit, the optical amplifier can also be set up in other ways, as long as it can amplify the first optical signal and the second optical signal and meet the working requirements of the first photodiode 31 and the second photodiode 32 at the back end, there is no restriction here.

[0160] For the RF signal processing system using an externally modulated electro-optical conversion unit, please refer to Figures 13 and 14. Figure 13 is a structural block diagram of the RF signal processing system provided by the sixth embodiment of the present application, and Figure 14 is a structural block diagram of the RF signal processing system provided by the seventh embodiment of the present application.

[0161] For example, in the specific embodiment shown in FIG13 , the RF signal processing system may include a first optical amplifier 51 and a second optical amplifier 52. The input end of the first optical amplifier 51 is connected to the second optical signal output end of the first external modulator 23, and the output end of the first optical amplifier 51 is connected to the optical signal input end of the first photodiode 31, so that the first optical signal output by the first external modulator 23 can be amplified by the first optical amplifier 51, so that the power of the first optical signal can meet the requirement of controlling the first photodiode 31 in the back-end to operate in a high-efficiency working state. The input end of the second optical amplifier 52 is connected to the first optical signal output end of the second external modulator 24, and the output end of the second optical amplifier 52 is connected to the optical signal input end of the second photodiode 32, so that the second optical signal output by the second external modulator 24 can be amplified by the second optical amplifier 52, so that the power of the second optical signal can meet the requirement of controlling the second photodiode 32 in the back-end to operate in a high-efficiency working state. In this embodiment, the first optical amplifier 51 and the second optical amplifier 52 are both arranged after the electro-optical conversion unit 2 and the photodiode unit 3. The first optical signal and the second optical signal are amplified by the first optical amplifier 51 and the second optical amplifier 52 respectively, which can improve the control accuracy of each optical signal.

[0162] Exemplarily, in the specific embodiment shown in Figure 14, the RF signal processing system may include only one third optical amplifier 53, the input end of the third optical amplifier 53 is connected to the output end of the light source 25, and the output end of the third amplifier 53 is connected to the input end of the optical power splitter 26.

[0163] In this embodiment, as shown in Figure 14, the laser generated by the light source 25 can be amplified by the third optical amplifier 53 first, and then decomposed into two laser signals by the optical power splitter 26. This can ensure that the power of the laser signal meets the control requirements of the first photodiode 31 and the second photodiode 32 at the back end. At the same time, this structure uses the third optical amplifier 53 at the front-end light source 25 of the externally modulated electro-optical conversion unit to amplify the two optical signals, which can reduce the number of transmission optical fibers and the imbalance of the optical signal amplitude and phase caused by multi-optical fiber transmission, which is beneficial to improving the quality of multi-channel optical signal transmission. In addition, it can further reduce the structural complexity of the architecture, making the architecture easy to implement.

[0164] Of course, for the RF signal processing system using an externally modulated electro-optical conversion unit, the optical amplifier can also be set up in other ways, as long as it can amplify the first optical signal and the second optical signal and meet the working requirements of the first photodiode 31 and the second photodiode at the back end, and there is no restriction here.

[0165] In a specific embodiment, the radio frequency signal processing system also includes an optical delay device, the input end of the optical delay device is connected to the output end of the electro-optical conversion unit 2, and the output end of the optical delay device is connected to the input end of the photodiode unit 3. The optical delay device is used to adjust the phase delay of the first optical signal and the second optical signal to ensure that the two optical signals maintain the same phase, thereby improving the performance of signal transmission.

[0166] The radio frequency signal processing system may include a first optical delay device 61 and a second optical delay device 62. For a radio frequency signal processing system using a direct-modulation electro-optical conversion unit, exemplarily, in the specific embodiment shown in FIG11 , the input end of the first optical delay device 61 is connected to the output end of the first optical amplifier 51, the output end of the first optical delay device 61 is connected to the optical signal input end of the first photodiode 31, the input end of the second optical delay device 62 is connected to the output end of the second optical amplifier 52, and the output end of the second optical delay device 62 is connected to the optical signal input end of the second photodiode 32; exemplarily, in the specific embodiment shown in FIG12 , the input ends of the first optical delay device 61 and the second optical delay device 62 are connected to the output end of the optical demultiplexer 82, and the output ends of the first optical delay device 61 and the second optical delay device 62 are connected to the optical signal input ends of the first photodiode 31 and the second photodiode 32, respectively.

[0167] For a radio frequency signal processing system using an externally modulated electro-optical conversion unit, exemplarily, in the specific embodiment shown in FIG13 , the input end of the first optical delay device 61 is connected to the output end of the first optical amplifier 51, the output end of the first optical delay device 61 is connected to the optical signal input end of the first photodiode 31, the input end of the second optical delay device 62 is connected to the output end of the second optical amplifier 52, and the output end of the second optical delay device 62 is connected to the optical signal input end of the second photodiode 32; exemplarily, in the specific embodiment shown in FIG14 , the input end of the first optical delay device 61 is directly connected to the second optical signal output end of the first external modulator 23, the output end of the first optical delay device 61 is connected to the optical signal input end of the first photodiode 31, the input end of the second optical delay device 62 is directly connected to the second optical signal output end of the second external modulator 24, and the output end of the second optical delay device 62 is connected to the optical signal input end of the second photodiode 32.

[0168] Of course, depending on the actual structure of the RF signal processing system, the optical delay device can also be configured in other ways, as long as it can adjust the delay between the first optical signal and the second optical signal to ensure that the phases of the first optical signal and the second optical signal are the same. There is no limitation here.

[0169] In a specific embodiment, as shown in Figures 11 and 12, the RF signal processing system may further include an electrical phase shifter, wherein the input end of the electrical phase shifter is connected to the output end of the signal separation unit 1, and the output end of the electrical phase shifter is connected to the RF signal input end of the electro-optical conversion unit 2. The electrical phase shifter is used to adjust the phase of the two-path input RF signal, thereby ensuring that the phase of the two-path input RF signal meets the Outphasing architecture requirements.

[0170] Furthermore, as shown in Figures 11 and 12, the RF signal processing system includes a first electrical phase shifter 71 and a second electrical phase shifter 72. After the signal separation unit 1 decomposes the input RF signal S(t) into two equal-amplitude constant envelope modulated signals, namely the first input RF signal S1(t) and the second input RF signal S2(t), the first electrical phase shifter 71 can adjust the phase of the first input RF signal S1(t), and the second electrical phase shifter 72 can adjust the phase of the second input RF signal S2(t) to ensure that the phases of the first input RF signal S1(t) and the second input RF signal S2(t) meet the requirements of the Outphasing architecture, thereby improving the reliability of the architecture.

[0171] In the above embodiments, the matching compensation unit 4 in the radio frequency signal processing system may be a Chireix synthesizer, thereby realizing a Chireix-Outphasing architecture to reduce the structural complexity of the architecture and further reduce the difficulty of implementation.

[0172] Furthermore, the Chireix synthesizer may be a non-isolated synthesizer to further reduce the impact of isolation resistance on power efficiency. Of course, the matching compensation unit 4 may also be other types of synthesizers, which is not limited here.

[0173] Further, referring to Figure 15 , which illustrates a circuit structure of a matching compensation unit, as shown in Figure 15 , the matching compensation unit 4 can be a three-port structure composed of multiple microstrip lines. The matching compensation unit 4 includes a first branch 41 and a second branch 42 . The input ends of the first branch 41 and the second branch 42 are the two input ports of the matching compensation unit 4 and are connected to the two photodiodes in a one-to-one correspondence. The output ends of the first branch 41 and the second branch 42 are connected to form the output port of the matching compensation unit 4 .

[0174] In this embodiment, as shown in FIG15 , the first branch 41 and the second branch 42 are connected to the first photodiode 31 and the second photodiode 32, respectively, so that the first branch 41 and the second branch can respectively match the impedance of the first photodiode 31 and the second photodiode 32 with the optimal impedance value corresponding to their back-off output power, thereby improving the efficiency of the first photodiode 31 and the second photodiode 32 in the back-off state. In addition, microstrip lines have a wide bandwidth, high stability, and are easy to simulate and control during circuit simulation. Therefore, using a microstrip line structure in a transmission circuit can provide controllable variables for circuit design and reduce the difficulty of circuit design of the matching compensation unit.

[0175] Furthermore, as shown in FIG15 , the matching compensation unit 4 further includes a susceptance element 43 , which is provided in parallel on the first branch 41 and the second branch 42 .

[0176] Please refer to Figure 16, which is a waveform diagram and signal vector decomposition diagram of the signal separation unit, that is, a waveform diagram and signal vector decomposition diagram of the input RF signal S(t), the first path input RF signal S1(t) and the second path input RF signal S2(t). The signal separation unit 1 decomposes the input RF signal S(t) with amplitude modulation information into the first path input RF signal S1(t) and the second path input RF signal S2(t). As shown in Figure 16, the decomposed first path input RF signal S1(t) and the second path input RF signal S2(t) are constant envelope signals. is the initial phase of the input RF signal S(t), and θ(t) is called the phase shift angle. After separation by signal separation unit 1, the phase difference between the first-path input RF signal S1(t) and the second-path input RF signal S2(t) is twice the phase shift angle. The power backoff amount of the input RF signal can be determined based on the peak-to-average power ratio of the input RF signal S(t), and the phase shift angle θ(t) can be determined based on the backoff amount.

[0177] The equivalent output admittance Y1 of the output end of the first photodiode 31 and the equivalent output admittance Y2 of the output end of the second photodiode 32 are respectively:

[0178] In formula (1) and formula (2), θ comp To match the target compensation angle of compensation unit 4, R L For terminal load.

[0179] Assuming that the first photodiode 31 and the second photodiode 32 operate in the Class B state, the power efficiency η of the RF signal processing system is:

[0180] In formula (3), η B The saturated power efficiency of the photodiode working in Class B state is 78.5%.

[0181] As can be seen from equations (1) to (3), the equivalent output admittance Y1 at the output of the first photodiode 31 and the equivalent output admittance Y2 at the output of the second photodiode 32 are conjugate, where the real part of the admittance is conductance and the imaginary part is susceptance. Without the parallel connection of susceptance element 43 in the first branch 41 and the second branch 42, the imaginary parts of Y1 and Y2 cannot be offset, resulting in a complex impedance value. This can easily cause the architecture to be mismatched, affecting the performance of the entire architecture and reducing the power efficiency η.

[0182] In this embodiment, as shown in Figure 15, by connecting corresponding susceptance elements 43 in parallel to the first branch 41 and the second branch 42, the susceptance of the first photodiode 31 and the second photodiode 32 themselves can be compensated, so that the matching compensation unit 4 can perform reactance compensation on the link where the first photodiode 31 is located and the link where the second photodiode 32 is located. By compensating, the matching condition of the first photodiode 31 and the second photodiode 32 is improved, thereby achieving overall power balance of the RF signal processing system, reducing losses, and improving power supply efficiency.

[0183] The susceptance element 43 may include a capacitor and / or an inductor.

[0184] Furthermore, according to equations (1) and (2), the first branch 41 and the second branch 42 are connected in parallel with corresponding conjugate susceptances, which can offset the imaginary component and achieve high efficiency.

[0185] The target compensation angle θ of the matching compensation unit 4 can be determined according to the peak-to-average ratio of the compensated input RF signal S(t). comp , so that the target compensation angle θ can be calculated compThe compensation susceptance is determined, and the susceptance elements 43 are connected in parallel in the first branch 41 and the second branch 42 according to the compensation susceptance to match the load impedance of the first photodiode 31 and the second photodiode 32 with the optimal impedance value corresponding to the back-off output power, thereby improving the power supply efficiency.

[0186] For example, the backoff amount can be determined according to the peak-to-average ratio of the input RF signal S(t). By simulation, a curve diagram of the power efficiency of the matching compensation unit 4 changing with the power backoff amount under different compensation angles is drawn. The target compensation angle θ can be determined according to the backoff amount and the curve diagram of the power efficiency changing with the power backoff amount. comp .

[0187] Please refer to Figure 17, which shows a graph of the power efficiency of the matching compensation unit as a function of the power back-off amount when the compensation angle is 0 degrees, 10 degrees, 20 degrees, and 30 degrees. As shown in Figure 17, the back-off capabilities of different compensation angles vary depending on the back-off amount. The smaller the compensation angle, the greater the power back-off amount, but the efficiency between the two peak efficiency points is worse. The back-off amount can be determined based on the peak-to-average ratio of the input RF signal S(t), and the target compensation angle θ suitable for the matching compensation unit 4 under this back-off amount can be determined. comp , in order to ensure efficiency while achieving the best retreat capability, where the target compensation angle θ comp This is the compensation angle corresponding to the curve with the highest power efficiency at this setback in the figure.

[0188] For example, the back-off amount can also be determined according to the peak-to-average ratio of the input RF signal S(t), and the out-of-phase angle θ(t) can be determined according to the back-off amount. A curve diagram showing the variation of the synthesis efficiency of the matching compensation unit 4 with the out-of-phase angle θ(t) under different compensation angles can be drawn by simulation. The target compensation angle θ can be determined according to the out-of-phase angle θ(t) and the curve diagram showing the variation of the synthesis efficiency with the out-of-phase angle. comp .

[0189] Please refer to Figure 18, which is a graph showing the change in synthesis efficiency of the matching compensation unit with the out-of-phase angle when the compensation angle is 0 degrees, 10 degrees, 20 degrees, and 30 degrees. As shown in Figure 18, the power back-off capabilities of different compensation angles are different depending on the out-of-phase angle. For example, when the compensation angle is 10 degrees, the synthesis efficiency reaches its peak value when the out-of-phase angle is 10 degrees and 80 degrees, and the two out-of-phase angles corresponding to the peak efficiency are symmetrical about 45 degrees. The target compensation angle θ of the matching compensation unit 4 can be determined based on the out-of-phase angle θ(t) determined by the peak-to-average ratio of the input RF signal S(t). comp , in order to ensure efficiency while achieving the best retreat capability, where the target compensation angle θ comp That is, it is the compensation angle corresponding to the curve with the highest synthesis efficiency of the matching compensation unit 4 at the out-of-phase angle θ(t) in the figure.

[0190] Determine the target compensation angle θ through the above steps comp After determination, the equivalent output admittance Y1 of the output end of the first photodiode 31 and the equivalent output admittance Y2 of the output end of the second photodiode 32 can also be determined according to equations (1) and (2), so that the compensation susceptance can be determined according to the imaginary parts of Y1 and Y2, that is, the susceptance, and the susceptance elements 43 are connected in parallel in the first branch 41 and the second branch 42 according to the compensation susceptance to achieve matching of the load impedance of the first photodiode 31 and the second photodiode 32 with the optimal impedance value corresponding to the back-off output power, thereby improving the power supply efficiency.

[0191] Please refer to Figures 19 and 20. Figure 19 is a graph showing the power efficiency of the RF signal processing system according to an embodiment of the present application as a function of the outphasing angle; Figure 20 is a graph showing the power efficiency of the RF signal processing system according to an embodiment of the present application as a function of the output power. As can be seen from Figures 19 and 20, the efficiency curves generally match the theoretical efficiency curves of the outphasing architecture. The use of the RF signal processing system provided by the embodiment of the present application can significantly improve the back-off efficiency and enhance the power efficiency of the RF signal processing system.

[0192] Please refer to Figure 21, which is a flowchart of a radio frequency signal processing method in an embodiment of the present application.

[0193] As shown in FIG21 , the radio frequency signal processing method in the embodiment of the present application includes the following steps:

[0194] S1, receives input RF signal.

[0195] In this step, as shown in FIG2 , the signal separation unit 1 may be used to receive an input radio frequency signal S(t) to facilitate the generation of two-path sub-input signals.

[0196] S2, decomposing the radio frequency signal into two sub-input radio frequency signals, where the two sub-input radio frequency signals are out-of-phase constant envelope signals.

[0197] In this step, the signal separation unit 1 can decompose the received input RF signal S(t) into two out-of-phase constant envelope signals, namely the first input RF signal S1(t) and the second input RF signal S2(t), and output the first input RF signal S1(t) and the second input RF signal S2(t) to the electro-optical conversion unit 2.

[0198] S3, converting the two-way RF signal into two corresponding optical signals.

[0199] In this step, the electro-optical conversion unit 2 is used to convert the received first-path input RF signal S1(t) into a first optical signal, convert the received second-path input RF signal S2(t) into a second optical signal, and output the first optical signal and the second optical signal to the photodiode unit 3.

[0200] S4, converting the two optical signals into corresponding two-way output RF signals.

[0201] In this step, the photodiode unit 3 includes two parallel photodiodes, namely a first photodiode 31 and a second photodiode 32, with the two photodiodes corresponding one-to-one to the two optical signals. The first photodiode 31 is used to convert the received first optical signal into a first output RF signal and output the first output RF signal to the matching compensation unit 4. The second photodiode 32 is used to convert the received second optical signal into a second output RF signal and output the second output RF signal to the matching compensation unit 4.

[0202] S5, adjusting the impedance of the two photodiodes to achieve matching between the impedance of the two photodiodes and an optimal impedance value corresponding to the back-off output power.

[0203] In this step, the matching compensation unit 4 is further configured to adjust the impedance of the first photodiode 31 and the second photodiode 32 to achieve matching between the impedance of the two photodiodes and the optimal impedance value corresponding to the fallback output power, thereby improving the power efficiency of the first photodiode 31 and the second photodiode 32 in the fallback state. The fallback power efficiency is equal to the saturated power efficiency of the first photodiode 31 and the second photodiode 32.

[0204] S6: The two sub-RF signals are combined to form an output RF signal.

[0205] In this step, the matching compensation unit 4 is used to merge the first-path output RF signal and the second-path output RF signal to form an output RF signal, and output the output RF signal to the terminal load.

[0206] As shown in Figure 2, the link of the RF signal processing system in the embodiment of the present application is an optoelectronic fusion link, which can reduce the loss during signal transmission and is conducive to long-distance signal transmission. On this basis, the RF signal processing system in the embodiment of the present application adopts the Outphasing architecture. Compared with the Doherty architecture, the first photodiode 31 and the second photodiode 31 in the branch of the Outphasing architecture work in the same state, and there is no need to set a unique electro-optical conversion unit for a specific path to realize the opening and closing of the photodiode of the path. Therefore, the RF signal processing system in the embodiment of the present application has the advantages of simple structure and easy implementation. It can improve the power efficiency of the photodiode unit 3 in the fallback state while reducing the complexity of the architecture, which is conducive to the flexible deployment of the RF signal processing system in all frequency bands and all services, and reduces the implementation cost of the RF signal processing system.

[0207] Among them, the saturated power efficiency of the RF signal processing system is the same as the saturated power efficiency of a single first photodiode 31 and a second photodiode 32. In order to improve the power efficiency of the RF signal processing system, as shown in Figure 2, in the RF signal processing system in the embodiment of the present application, the first photodiode 31 and the second photodiode 32 both operate in Class AB or Class B states with higher power efficiency, so that the first photodiode 31 and the second photodiode 32 are both photodiodes in a high-efficiency working state, thereby putting the entire RF signal processing system in a high-efficiency working mode, further improving the power efficiency, and the corresponding linear performance when the first photodiode 31 and the second photodiode 32 operate in Class AB or Class B states is higher, which can improve the signal-to-noise ratio of the RF signal processing system, thereby improving the overall performance of the RF signal processing system.

[0208] Please refer to Figures 19 and 20. Figure 19 is a graph showing the power efficiency of the RF signal processing system according to an embodiment of the present application as a function of the outphasing angle; Figure 20 is a graph showing the power efficiency of the RF signal processing system according to an embodiment of the present application as a function of the output power. As can be seen from Figures 19 and 20, the efficiency curves generally match the theoretical efficiency curves of the outphasing architecture. The use of the RF signal processing system provided by the embodiment of the present application can significantly improve the back-off efficiency and enhance the power efficiency of the RF signal processing system.

[0209] Exemplarily, the working states of the first photodiode 31 and the second photodiode 32 in the photodiode unit 3 may be controlled by the optical signal output by the electro-optical conversion unit 2 .

[0210] In a specific embodiment, when the electro-optical conversion unit 2 in the radio frequency signal processing system is a direct-modulation electro-optical conversion unit, as shown in FIG5 , the electro-optical conversion unit 2 includes two laser modulators, namely a first laser modulator 21 and a second laser modulator 22. The first laser modulator 21 is used to receive a first-path input radio frequency signal S1(t) and convert the first-path input radio frequency signal S1(t) into a first-path optical signal, and the second laser modulator 22 is used to receive a second-path input radio frequency signal S2(t) and convert the second-path input radio frequency signal S2(t) into a second-path optical signal. In this case, the above-mentioned step S3, converting the two-path radio frequency signals into corresponding two-path optical signals, may include the following steps:

[0211] S31, receiving bias current.

[0212] In this step, the bias current receiving end of the first laser modulator 21 receives the first bias current Id1 , and the bias current receiving end of the second laser modulator 22 receives the second bias current Id2 .

[0213] S32 , controlling a DC bias point of the electro-optical conversion unit according to the bias current, and converting the received sub-input RF signal into a corresponding optical signal.

[0214] In this step, according to the magnitude of the first bias current Id1 received by the first laser modulator 21, the DC bias point of the first laser modulator 21 can be controlled, thereby converting the input first-path RF signal into the desired first-path optical signal to ensure that the first photodiode 31 can operate in a high-efficiency working state; according to the magnitude of the second bias current Id2 received by the second laser modulator 22, the DC bias point of the second laser modulator 22 can be controlled, thereby converting the input second-path RF signal into the desired second-path optical signal to ensure that the second photodiode 32 operates in a high-efficiency working state.

[0215] In an embodiment of the present application, as shown in FIG5 , when a direct-modulation electro-optical conversion unit is used, the DC bias point of the first laser modulator 21 and the second laser modulator 22 can be controlled by controlling the magnitude of the input bias current, thereby adjusting the power of the output first optical signal and the second optical signal, so that the first photodiode 31 and the second photodiode 32 at the back end can operate in a high-efficiency working state, thereby putting the entire RF signal processing system architecture in a high-efficiency working mode, further improving the power efficiency of the RF signal processing system. This control method is simple, reliable, and easy to implement. In addition, since the first laser modulator 21 and the second laser modulator 22 can generate laser light themselves, there is no need to arrange an external laser source, thereby further reducing the complexity of the architecture, making the architecture easier to implement, and reducing the implementation cost.

[0216] In a specific embodiment, when the electro-optical conversion unit 2 in the radio frequency signal processing system is an externally modulated electro-optical conversion unit, as shown in FIG8 , the electro-optical conversion unit 2 includes a light source 25 and two external modulators, wherein the light source 25 is used to generate a laser signal and output the laser signal to a first external modulator 23 and a second external modulator 24, respectively. The two external modulators are a first external modulator 23 and a second external modulator 24, wherein the first external modulator 23 is used to receive a first-path input radio frequency signal S1(t) and convert the first-path input radio frequency signal S1(t) into a first-path optical signal, and the second external modulator 24 is used to receive a second-path input radio frequency signal S2(t) and convert the second-path input radio frequency signal S2(t) into a second-path optical signal, that is, the two external modulators correspond one-to-one to the two-path input radio frequency signals. At this time, the above-mentioned step S3, converting the two-path radio frequency signals into corresponding two-path optical signals, includes the following steps:

[0217] S33, receiving a bias voltage.

[0218] In this step, the bias voltage receiving terminal of the first external modulator 23 receives the first bias voltage Vd1 , and the bias low voltage receiving terminal of the second external modulator 24 receives the second bias voltage Vd2 .

[0219] S34 , controlling the bias voltage operating point of the electro-optical conversion unit according to the bias voltage, and converting the received sub-input RF signal into a corresponding optical signal.

[0220] In this step, the bias voltage operating point of the first external modulator 23 can be controlled according to the magnitude of the first bias voltage Vd1 received by the first external modulator 23, thereby converting the input first-path RF signal into the desired first-path optical signal to ensure that the first photodiode 31 operates in a high-efficiency operating state; and the bias voltage operating point of the second external modulator 24 can be controlled according to the magnitude of the second bias voltage Vd2 received by the second external modulator 24, thereby converting the input second-path RF signal into the desired second-path optical signal to ensure that the second photodiode 32 operates in a high-efficiency operating state.

[0221] In the embodiment of the present application, as shown in FIG8 , when an externally modulated electro-optical conversion unit is used, the bias voltage operating point of the first external modulator 23 and the second external modulator 24 can be controlled by controlling the magnitude of the input bias voltage, thereby adjusting the power of the output first optical signal and the second optical signal, so that the first photodiode 31 and the second photodiode 32 at the back end can operate in a high-efficiency working state, thereby putting the entire RF signal processing system architecture in a high-efficiency working mode, further improving the power efficiency of the RF signal processing system, and the control method is simple, reliable, and easy to implement. In addition, in the externally modulated electro-optical conversion unit, the light source 25, the first external modulator 23, and the second external modulator 24 can all be controlled separately, further improving the conversion accuracy of the electro-optical conversion unit, and also improving the design freedom of the architecture, which is more conducive to the flexible deployment of the full-band and full-service RF signal processing system.

[0222] The light source 25 may be one or more, and the number can be set according to actual needs and is not limited here. For example, there may be multiple light sources 25, that is, a light source may be connected to the laser signal receiving end of each external modulator in the RF signal processing system, thereby further improving the design freedom of the architecture.

[0223] In a specific embodiment, as shown in FIG15 , the above step S5 of adjusting the impedance of the two photodiodes includes the following steps:

[0224] S51 , determining a target compensation angle of a matching compensation unit according to a peak-to-average ratio of an input radio frequency signal.

[0225] In this step, different compensation angles have different backoff capabilities. It is necessary to select an appropriate target compensation angle θ based on the actual requirements of the peak-to-average ratio of the input radio frequency signal S(t). comp , which can ensure efficiency while achieving the best fallback capability.

[0226] S52, determining the compensation susceptance according to the target compensation angle.

[0227] In this step, the target compensation angle θ is determined comp After determination, according to the above formula Japanese style The equivalent output admittance Y1 of the output end of the first photodiode 31 and the equivalent output admittance Y2 of the output end of the second photodiode 32 can also be determined, so that the compensation susceptance can be determined based on the imaginary parts of Y1 and Y2, that is, the susceptance.

[0228] S53 , according to the compensation susceptance, connecting susceptance elements 43 in parallel to the first branch 41 and the second branch 42 of the matching compensation unit 4 , respectively, to achieve matching of the load impedance of the two photodiodes with the optimal impedance value corresponding to the back-off output power.

[0229] In this embodiment, as shown in Figure 15, by connecting corresponding susceptance elements 43 in parallel to the first branch 41 and the second branch 42, the susceptance of the first photodiode 31 and the second photodiode 32 themselves can be compensated, so that the matching compensation unit 4 can perform reactance compensation on the link where the first photodiode 31 is located and the link where the second photodiode 32 is located. By compensating, the matching condition of the first photodiode 31 and the second photodiode 32 is improved, thereby achieving overall power balance of the RF signal processing system, reducing losses, and improving power supply efficiency.

[0230] The susceptance element 43 may include a capacitor and / or an inductor.

[0231] In a specific embodiment, S51, determining a target compensation angle of the matching compensation unit 4 according to the peak-to-average ratio of the input radio frequency signal, includes the following steps:

[0232] S511 : Determine a back-off amount according to a peak-to-average ratio of the input radio frequency signal.

[0233] In this step, since the peak-to-average ratio of the signal is different, the back-off requirements are also different, so the back-off amount can be determined according to the peak-to-average ratio of the input RF signal S(t).

[0234] S512: Determine a target compensation angle according to the retraction amount.

[0235] In this step, different compensation angles have different backoff capabilities. According to the actual backoff requirements of the peak-to-average ratio of the input radio frequency signal S(t), the appropriate target compensation angle θ is selected. comp , which can ensure efficiency while achieving the best fallback capability.

[0236] Furthermore, the above step S512, determining the target compensation angle according to the rollback amount, includes the following steps:

[0237] S5121 , as shown in FIG17 , draws a curve diagram of how the power efficiency of the matching compensation unit changes with the power back-off amount under different compensation angles.

[0238] In this step, a curve diagram showing how the power efficiency changes with the power back-off amount under different compensation angles of the matching compensation unit can be drawn through simulation.

[0239] S5122: Determine a target compensation angle according to the backoff amount and a curve diagram showing a change in power efficiency with the power backoff amount.

[0240] In this step, the target compensation angle θ comp This is the compensation angle corresponding to the curve with the highest power efficiency at this setback in the figure.

[0241] In this embodiment, as shown in FIG17 , the back-off capabilities of different compensation angles vary depending on the back-off amount. The smaller the compensation angle, the greater the power back-off amount, but the worse the efficiency between the two peak efficiency points. The back-off amount can be determined based on the peak-to-average ratio of the input RF signal S(t), and the target compensation angle θ suitable for the matching compensation unit 4 under the back-off amount can be determined. comp , in order to ensure efficiency while achieving the best retreat capability, where the target compensation angle θ comp This is the compensation angle corresponding to the curve with the highest power efficiency at this setback in the figure.

[0242] In another specific embodiment, the above step S51, determining the target compensation angle of the matching compensation unit according to the peak-to-average ratio of the input RF signal, includes the following steps:

[0243] S513: Determine a back-off amount according to the peak-to-average ratio of the input radio frequency signal.

[0244] In this step, since the peak-to-average ratio of the signal is different, the back-off requirements are also different, so the back-off amount can be determined according to the peak-to-average ratio of the input RF signal S(t).

[0245] S514: Determine the out-of-phase angle according to the retraction amount.

[0246] In this step, since the signal works at the back-off point most of the time, the out-of-phase angle can be taken as the angle value at the back-off point during design.

[0247] S515: Determine a target compensation angle according to the out-of-phase angle.

[0248] In this step, different compensation angles have different retraction capabilities. According to the size of the phase difference angle θ(t), the appropriate target compensation angle θ is selected. comp , which can ensure efficiency while achieving the best fallback capability.

[0249] Furthermore, the above step S515, determining the target compensation angle according to the out-of-phase angle, includes the following steps.

[0250] S5151 , as shown in FIG18 , plots a curve of how the combined efficiency of the matching compensation unit changes with the out-of-phase angle at different compensation angles.

[0251] In this step, a curve diagram showing how the synthesis efficiency of the matching compensation unit changes with the out-of-phase angle under different compensation angles can be drawn through simulation.

[0252] S5152: Determine a target compensation angle according to a curve diagram of the out-of-phase angle and the combined efficiency varying with the out-of-phase angle.

[0253] In this step, the target compensation angle θ compThat is, it is the compensation angle corresponding to the curve with the highest synthesis efficiency of the matching compensation unit 4 at the out-of-phase angle θ(t) in the figure.

[0254] In this embodiment, as shown in FIG18 , the power back-off capabilities of different compensation angles vary depending on the out-of-phase angle. For example, when the compensation angle is 10 degrees, the combined efficiency reaches its peak value at out-of-phase angles of 10 degrees and 80 degrees, and the two out-of-phase angles corresponding to the peak efficiencies are symmetrical about 45 degrees. The target compensation angle θ of the matching compensation unit 4 can be determined based on the out-of-phase angle θ(t) determined by the peak-to-average ratio of the input RF signal S(t). comp , in order to ensure efficiency while achieving the best retreat capability, where the target compensation angle θ comp That is, it is the compensation angle corresponding to the curve with the highest synthesis efficiency of the matching compensation unit 4 at the out-of-phase angle θ(t) in the figure.

[0255] In this specification, reference can be made to the same or similar parts between the various embodiments. In particular, for the device embodiment and the terminal embodiment, since they are basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the description in the method embodiment.

[0256] The above description is merely a specific implementation of the embodiments of the present application, but the scope of protection of the embodiments of the present application is not limited thereto. Any changes or substitutions within the technical scope disclosed in the embodiments of the present application shall be included in the scope of protection of the embodiments of the present application. Therefore, the scope of protection of the embodiments of the present application shall be based on the scope of protection of the claims.

Claims

1. A radio frequency signal processing system, characterized in that: It includes a signal separation unit, an electro-optical conversion unit, a photodiode unit and a matching compensation unit which are arranged in sequence; The signal separation unit is used to decompose the input radio frequency signal into two out-of-phase sub-input radio frequency signals, and output the two sub-input radio frequency signals to the electro-optical conversion unit; The electro-optical conversion unit is used to convert the received two-path sub-input RF signals into corresponding two-path optical signals, and output the two-path optical signals to the photodiode unit; The photodiode unit includes two photodiodes connected in parallel, and the two photodiodes correspond to the two optical signals one by one; the photodiode is used to convert the received optical signal into a corresponding sub-output radio frequency signal, and output the sub-output radio frequency signal to the matching compensation unit; The matching compensation unit is used to merge the two sub-output RF signals to form an output RF signal. The matching compensation unit is also used to adjust the impedance of the two photodiodes to achieve matching between the impedance of the two photodiodes and the optimal impedance value corresponding to the back-off output power.

2. The radio frequency signal processing system according to claim 1, characterized in that: The electro-optical conversion unit includes two laser modulators, and the two laser modulators correspond one to one to the two sub-input radio frequency signals; The laser modulator comprises a first radio frequency signal input terminal, a bias current receiving terminal and a first optical signal output terminal, wherein the first radio frequency signal input terminal is connected to the signal separation unit, the bias current receiving terminal is used to receive the bias current, and the first optical signal output terminal is connected to the photodiode unit; The laser modulator is used for converting the received sub-input radio frequency signal into the corresponding optical signal according to the bias current.

3. The radio frequency signal processing system according to claim 1, characterized in that: The electro-optical conversion unit comprises a light source and two external modulators, and the two external modulators correspond one to one with the two sub-input radio frequency signals; The external modulator includes a second RF signal input terminal, a laser signal receiving terminal, a bias voltage receiving terminal and a second optical signal output terminal, wherein the second RF signal input terminal is connected to the signal separation unit, the laser signal receiving terminal is connected to the light source, the bias voltage receiving terminal is used to receive the bias voltage, and the second optical signal output terminal is connected to the photodiode unit; The light source is used to generate a laser signal and output the laser signal to the two external modulators; The external modulator is used to convert the received sub-input radio frequency signal into the corresponding optical signal according to the laser signal and the bias voltage.

4. The radio frequency signal processing system according to claim 3, characterized in that: The electro-optical conversion unit further includes an optical power splitter, which includes an input end and two output ends; The input end is connected to the light source, and the two output ends are connected to the two external modulators in a one-to-one correspondence; The optical power splitter is used to split the laser light generated by the light source into two laser signals, and output the two laser signals to the corresponding external modulators.

5. The radio frequency signal processing system according to claim 4, characterized in that: The radio frequency signal processing system further comprises an optical amplifier, an input end of the optical amplifier is connected to the light source, and an output end of the optical amplifier is connected to the optical power divider.

6. The radio frequency signal processing system according to any one of claims 1 to 4, characterized in that: The radio frequency signal processing system further comprises an optical amplifier, an input end of the optical amplifier is connected to an output end of the electro-optical conversion unit, and an output end of the optical amplifier is connected to an input end of the photodiode unit.

7. The radio frequency signal processing system according to claim 6, characterized in that: The radio frequency signal processing system also includes an optical multiplexer and an optical demultiplexer; The input end of the optical multiplexer is connected to the output end of the electro-optical conversion unit, and the output end of the optical multiplexer is connected to the input end of the optical amplifier; The input end of the optical demultiplexer is connected to the output end of the optical amplifier, and the output end of the optical demultiplexer is connected to the photodiode unit.

8. The radio frequency signal processing system according to any one of claims 1 to 7, characterized in that: The radio frequency signal processing system further comprises an optical delay device, the input end of the optical delay device is connected to the output end of the electro-optical conversion unit, and the output end of the optical delay device is connected to the photodiode unit.

9. The radio frequency signal processing system according to any one of claims 1 to 7, characterized in that: The radio frequency signal processing system further includes an electrical phase shifter, an input end of the electrical phase shifter is connected to an output end of the signal separation unit, and an output end of the electrical phase shifter is connected to the electro-optical conversion unit.

10. The radio frequency signal processing system according to any one of claims 1 to 9, characterized in that: The matching compensation unit is a Chireix synthesizer.

11. The radio frequency signal processing system according to claim 10, characterized in that: The matching compensation unit is a three-port structure composed of multiple microstrip lines, and the matching compensation unit includes a first branch and a second branch; The input ends of the first branch and the second branch are two input ports of the matching compensation unit, and are connected to the two photodiodes in a one-to-one correspondence; The output ends of the first branch and the second branch are connected to form an output port of the matching compensation unit.

12. The radio frequency signal processing system according to claim 11, characterized in that: The matching compensation unit further includes a susceptance element, and the susceptance element is arranged in parallel on the first branch and the second branch.

13. The radio frequency signal processing system according to claim 12, characterized in that: The susceptance element includes a capacitor and / or an inductor.

14. A radio frequency signal processing method, characterized in that: The following steps are involved: receiving an input radio frequency signal; Decomposing the radio frequency signal into two sub-input radio frequency signals, wherein the two sub-input radio frequency signals are out-of-phase constant envelope signals; Convert the two sub-RF signals into two corresponding optical signals; Convert the two optical signals into corresponding two sub-output radio frequency signals; Adjusting the impedance of the two photodiodes to achieve matching between the impedance of the two photodiodes and an optimal impedance value corresponding to the back-off output power; The two sub-RF signals are merged to form an output RF signal.

15. The method according to claim 14, characterized in that The step of adjusting the impedance of the two photodiodes comprises the following steps: Determining a target compensation angle of the matching compensation unit according to the peak-to-average ratio of the input radio frequency signal; determining a compensation susceptance according to the compensation angle; According to the compensation susceptance, susceptance elements are connected in parallel in the first branch and the second branch of the matching compensation unit respectively, so as to achieve matching of the load impedance of the two photodiodes with the optimal impedance value corresponding to the back-off output power.

16. The method according to claim 15, characterized in that Determining the target compensation angle of the matching compensation unit according to the peak-to-average ratio of the input radio frequency signal comprises the following steps: Determining a back-off amount according to a peak-to-average ratio of the input radio frequency signal; A target compensation angle is determined according to the retraction amount.

17. The method according to claim 16, characterized in that Determining the target compensation angle according to the retraction amount comprises the following steps: Draw a curve of power efficiency changing with power back-off amount under different compensation angles of the matching compensation unit; A target compensation angle is determined according to the back-off amount and a curve diagram of the power supply efficiency changing with the power back-off amount.

18. The method according to claim 15, characterized in that Determining the target compensation angle of the matching compensation unit according to the peak-to-average ratio of the input radio frequency signal comprises the following steps: Determining a back-off amount according to a peak-to-average ratio of the input radio frequency signal; determining an out-of-phase angle according to the backoff amount; A target compensation angle is determined according to the out-of-phase angle.

19. The method according to claim 18, characterized in that Determining the target compensation angle according to the out-of-phase angle comprises the following steps: Draw a curve of the synthetic efficiency of the matching compensation unit changing with the out-of-phase angle at different compensation angles; The target compensation angle is determined according to the out-of-phase angle and the curve diagram of the resultant efficiency varying with the out-of-phase angle.

20. The method according to any one of claims 14 to 19, characterized in that The step of converting the two sub-RF signals into corresponding two optical signals comprises the following steps: receiving bias current; The DC bias point of the electro-optical conversion unit is controlled according to the bias current to convert the received sub-input RF signal into a corresponding The optical signal.

21. The method according to any one of claims 14 to 19, characterized in that The step of converting the two sub-RF signals into corresponding two optical signals comprises the following steps: receiving a bias voltage; The bias voltage operating point of the electro-optical conversion unit is controlled according to the bias voltage to convert the received sub-input radio frequency signal into the corresponding optical signal.

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