Optical detection circuit, wireless communication base station and system, and signal processing method

Abstract

The embodiment of the invention provides an optical detection circuit, a wireless communication base station, a system and a signal processing method, relates to the technical field of wireless communication, and is used for improving the rollback efficiency of the optical detection circuit. The optical detection circuit comprises a main circuit and an auxiliary circuit, the main circuit is conducted, the auxiliary circuit is conducted under the control of the power amplifier when the power is larger than a set value, the turn-on voltage effect similar to that of a triode can be achieved, and the output power of the optical detection circuit is improved. An impedance modulation network is adopted to carry out output load modulation on the optical detector in the main path and the optical detector in the auxiliary path, so that dynamic load conversion from a backoff point to a maximum output point is realized, and the main path optical detector and the auxiliary path optical detector can maintain relatively high output efficiency in an interval between the maximum power point and the backoff point; therefore, the purpose of improving the backspacing efficiency of the optical detection circuit is achieved.

Description

Technical Field

[0001] The present application relates to the field of wireless communication technology, and in particular to an optical detection circuit, a wireless communication base station and system, and a signal processing method. Background Art

[0002] Entering the era of the fifth generation (5G) communication system, the application of massive multiple input multiple output (Massive MIMO) technology has greatly improved the capacity and peak rate of wireless base stations. Compared with the high-power outdoor macro base stations in the fourth generation (4G) communication system, the active antenna unit (AAU) architecture base station based on Massive MIMO in 5G has eliminated the physical feeder port, increased the number of channels and antenna directional gain, and reduced the required single-channel RF output power to less than 10W while meeting the same coverage range. In the future, with the expansion of the working frequency band from sub-6G to higher frequency bands and the further development of Massive MIMO technology, the number of channels contained in a single AAU will be greater, and the single-channel RF output power will be further reduced to hundreds of mW.

[0003] RF photonic base stations use optoelectronic fusion technology to solve the performance bottleneck of pure electric systems, thereby realizing ultra-wideband, miniaturized and low-power wireless communication systems. When the RF output power of a single channel is reduced to the hundreds of mW level, the high-power photodiode (HPD) direct-driven antenna solution based on the RF photonic architecture will have more advantages in size and power consumption compared to the traditional power amplifier (PA) solution. This architecture not only has a very simple RF link and power supply solution, but also benefits from the large bandwidth characteristics of the HPD itself, which can realize an ultra-wideband RF head. However, the fallback efficiency of HPD has always been an important factor limiting the commercial use of HPD. Summary of the invention

[0004] Embodiments of the present application provide a light detection circuit, a wireless communication base station and system, and a signal processing method, which are used to improve the back-off efficiency of the light detection circuit.

[0005] In order to achieve the above objectives, this application adopts the following technical solutions:

[0006] According to a first aspect of an embodiment of the present application, there is provided an optical detection circuit, comprising: an optical input terminal, an RF output terminal, a first branch, a second branch, and an impedance modulation network. The optical input terminal is used to input an optical signal, and the optical signal includes a first optical signal and a second optical signal. The first branch includes a first optical detector, and the first optical detector is used to receive the first optical signal and output a first RF signal. The second branch includes a second optical detector and a first power amplifier, and the second detector is used to receive the second optical signal and output a second RF signal; the first power amplifier is coupled between the second optical detector and the impedance modulation network, and is used to amplify the second RF signal and control the on-off between the second optical detector and the impedance modulation network. The impedance modulation network is used to transform the output impedance of the first optical detector and the second optical detector, and couple the output terminal of the first optical detector and the output terminal of the second optical detector to the RF output terminal.

[0007] In the optical detection circuit provided by the embodiment of the present application, the first optical detector and the second optical detector are in parallel relationship, and whether the branch where the second optical detection is located is connected depends on whether the second radio frequency signal is greater than the threshold turn-on voltage of the first power amplifier PA1. The circuit structure in which the branch where the first optical detector is located is continuously turned on, and the branch where the second optical detector is located is turned on only when the second radio frequency signal reaches the set peak value can achieve a turn-on voltage effect similar to that of a triode, thereby improving the output power of the optical detection circuit. In addition, an impedance modulation network is used to combine the branch where the first optical detector is located and the branch where the second optical detector is located, so as to achieve a load modulation effect when the input power changes, thereby realizing a dynamic load transformation from the back-off point to the maximum output point, which is conducive to achieving that the first optical detector and the second optical detector maintain a high output efficiency within the range of the maximum power point and the back-off point, thereby achieving the purpose of improving the back-off efficiency of the optical detection circuit.

[0008] In a possible implementation, the first power amplifier is specifically used to control the disconnection between the second light detector and the impedance modulation network when the second RF signal is less than a set value; and to control the connection between the second light detector and the impedance modulation network when the second RF signal is greater than or equal to the set value. In this way, when the branch where the second light detection is located is not turned on (when the input RF signal power is small), the light detection circuit operates at the optimal efficiency point. When the branch where the second light detection is located is turned on (when the input RF signal power is large), the light detection circuit operates at the output power optimum point.

[0009] In a possible implementation, the optical detection circuit also includes an optical attenuator, and the second optical signal is attenuated by the optical attenuator and then transmitted to the second optical detector. By adjusting the power of the second optical signal with the aid of the optical attenuator, it is possible to achieve that the power of the first optical signal is greater than the power of the second optical signal, and the amplitude of the corresponding output first radio frequency signal is greater than the amplitude of the second radio frequency signal. After the second radio frequency signal is amplified by the first power amplifier, it is possible to achieve that the amplitude of the radio frequency signal output by the first branch is equal to the amplitude of the radio frequency signal output by the second branch, so as to reduce the problems of reduced efficiency and deterioration of signal quality caused by the inconsistent amplitude when the two signals are synthesized, and the optical attenuator has a high power adjustment accuracy for the optical signal.

[0010] In a possible implementation, the optical detection circuit also includes an electric attenuator, which is coupled between the second optical detector and the first power amplifier. By adjusting the power of the second RF signal with the aid of the electric attenuator, the amplitude of the first RF signal can be greater than the amplitude of the second RF signal. After the second RF signal is amplified by the first power amplifier, the amplitude of the RF signal output by the first branch can be equal to the amplitude of the RF signal output by the second branch, so as to reduce the problems of reduced efficiency and deteriorated signal quality caused by the inconsistent amplitude when the two signals are synthesized, and the integration difficulty and cost of the electric attenuator are low.

[0011] In a possible implementation, the optical detection circuit further includes a first optical delay device; the first optical signal is phase-shifted by the first optical delay device and then transmitted to the first optical detector. By arranging the first optical delay device before the first optical detector, the phase of the first optical signal is adjusted by optical adjustment, so that the optical detection circuit supports phase adjustment of broadband signals, and the phase adjustment accuracy of the optical delay device structure is high, the bandwidth is large, and the switching is fast.

[0012] In a possible implementation, the optical detection circuit further includes a second optical delay device; the second optical signal is phase-shifted by the second optical delay device and then transmitted to the second optical detector. By arranging the second optical delay device before the second optical detector, the phase of the second optical signal is adjusted by optical adjustment, so that the optical detection circuit supports phase adjustment of broadband signals, and the optical delay device structure has high phase adjustment accuracy, large bandwidth, and supports multi-band true delay fast switching.

[0013] In a possible implementation, the optical detection circuit further includes a first phase shifter; the first phase shifter is coupled between the first optical detector and the impedance modulation network. By arranging the first phase shifter after the first optical detector, the phase of the first radio frequency signal is adjusted by electrical adjustment, so that the optical detection circuit supports phase adjustment of broadband signals, and the integration difficulty and cost of the electrical phase shifter are low.

[0014] In a possible implementation, the optical detection circuit further includes a second phase shifter; the second phase shifter is coupled between the second optical detector and the first power amplifier. By arranging the second phase shifter after the second optical detector, the phase of the second radio frequency signal is adjusted by electrical adjustment, so that the optical detection circuit supports phase adjustment of broadband signals, and the integration difficulty and cost of the electrical phase shifter are low.

[0015] In a possible implementation, the optical detection circuit also includes a third optical detector and a second power amplifier; the third optical detector is used to receive a third optical signal and output a third radio frequency signal; the second power amplifier is coupled between the third optical detector and the impedance modulation network, and is used to control the on-off between the third optical detector and the impedance modulation network. By setting a plurality of conditional start circuits in the optical detection circuit, the optical detection circuit can increase a plurality of efficiency optimum points within the back-off interval, thereby improving the average efficiency of the entire back-off interval. For example, when the optical detection circuit works independently in the first branch, there is an efficiency optimum point; when the first branch and the second branch work synchronously, there is an efficiency optimum point; when the first branch and the third branch work synchronously, there is an efficiency optimum point; when the first branch, the second branch, and the third branch work synchronously, there is an efficiency optimum point.

[0016] In a possible implementation, the start-up voltage of the first power amplifier is not equal to the start-up voltage of the second power amplifier. In this way, the branch where the second photodetector is located and the branch where the third photodetector is located provide different efficiency optimum points, thereby improving the average efficiency in the back-off interval.

[0017] In a possible implementation, the power of the first optical signal is equal to the power of the second optical signal. In this way, the first optical signal and the second optical signal can be generated by using mature devices, without the need to develop new devices, and can be easily implemented.

[0018] In a possible implementation, the power of the first optical signal is greater than the power of the second optical signal. In this way, the optical detection circuit does not need to include the above-mentioned power adjustment structure to increase the power of the first radio frequency signal. As long as the phase adjustment structure is included, the first branch and the second branch can output radio frequency signals with equal amplitude and phase, which can simplify the structure of the optical detection circuit.

[0019] In one possible implementation, the optical detection circuit further includes an optical splitter; the optical splitter is used to receive an optical signal and split the optical signal into a first optical signal and a second optical signal. In this case, the optical detection circuit only needs to include one optical input terminal, and the optical splitter implements power division of the optical signal and outputs the first optical signal and the second optical signal. Compared with requiring two independent optical input terminals, the number of input interfaces of the optical detection circuit can be simplified, and power and efficiency can be improved without increasing the cost and complexity of the optical detection circuit.

[0020] In a possible implementation, the optical detection circuit further includes an impedance matching network, which is coupled between the second optical detector and the first power amplifier. The impedance matching network can match the output impedance of the second optical detector with the input impedance of the first power amplifier to reduce the excessive insertion loss caused by impedance mismatch when the second optical detector is cascaded with the first power amplifier.

[0021] In a possible implementation, the optical detection circuit further includes a first capacitor and a second capacitor; the first capacitor is coupled between the first optical detector and the impedance modulation network, and the second capacitor is coupled between the second optical detector and the first power amplifier. The first capacitor and the second capacitor can filter out DC signals to filter out interference signals.

[0022] According to a second aspect of an embodiment of the present application, a photoelectric conversion module is provided, comprising a light detection circuit and an electro-optical conversion circuit; the light detector is used to convert a received light signal into an electrical signal, and the electro-optical conversion circuit is used to convert a received electrical signal into an optical signal; the light detection circuit comprises the light detection circuit of any one of the first aspects.

[0023] In a third aspect of the embodiments of the present application, a photoelectric conversion chip is provided. The photoelectric conversion chip may be a bare chip, a bare chip packaged chip, or a chip system in which multiple chips (bare chips or packaged chips) are packaged together. The photoelectric conversion chip includes a light detection circuit and an electro-optical conversion circuit; the light detector is used to convert a received light signal into an electrical signal, and the electro-optical conversion circuit is used to convert a received electrical signal into an optical signal; the light detection circuit includes any light detection circuit of the first aspect.

[0024] According to a fourth aspect of an embodiment of the present application, a wireless communication base station is provided, comprising a photoelectric conversion module and an antenna unit, wherein the photoelectric conversion module is coupled to the antenna unit; the photoelectric conversion module comprises the photoelectric conversion module of the second aspect or the photoelectric conversion chip of the third aspect.

[0025] According to a fifth aspect of an embodiment of the present application, a wireless communication system is provided, comprising a baseband processing unit, a wireless communication base station and an optical fiber, wherein the baseband processing unit and the wireless communication base station are connected via the optical fiber; the wireless communication base station comprises the wireless communication base station of the fourth aspect.

[0026] The sixth aspect of the embodiment of the present application provides a signal processing method, including: a first optical detector receives a first optical signal and performs photoelectric conversion on the first optical signal to generate a first radio frequency signal, a second optical detector receives a second optical signal and performs photoelectric conversion on the second optical signal to generate a second radio frequency signal; a first power amplifier is turned on or off under the control of the second radio frequency signal, and amplifies the second radio frequency signal when the first power amplifier is turned on; an impedance modulation network transforms the output impedance of the first optical detector and the second optical detector, and combines the first radio frequency signal and the amplified second radio frequency signal for output. The beneficial effects of the signal processing method provided in the embodiment of the present application are the same as the beneficial effects of the above-mentioned optical detection circuit, which will not be repeated here.

[0027] In a possible implementation, the first power amplifier is turned off when the second RF signal is less than a set value, and turned on when the second RF signal is greater than or equal to the set value. In this way, when the second RF signal is small, the first optical detector works at the optimal efficiency point. When the second RF signal is large, the first optical detector and the second optical detector work at the output power optimum point.

[0028] In a possible implementation, the signal processing method further includes: performing phase sum modulation on the first optical signal, which helps to achieve that the first radio frequency signal and the amplified second radio frequency signal are radio frequency signals of equal amplitude and phase, so as to reduce loss.

[0029] In a possible implementation, the signal processing method further includes: performing phase and / or amplitude modulation on the second optical signal, which helps to ensure that the first radio frequency signal and the amplified second radio frequency signal are radio frequency signals with equal amplitude and phase, thereby reducing loss.

[0030] In a possible implementation, the signal processing method further includes: performing phase modulation on the first radio frequency signal, which helps to ensure that the first radio frequency signal and the amplified second radio frequency signal are radio frequency signals with equal amplitude and phase, thereby reducing loss.

[0031] In a possible implementation, the signal processing method further includes: performing phase and / or amplitude modulation on the second RF signal, which helps to ensure that the first RF signal and the amplified second RF signal are RF signals with equal amplitude and phase, thereby reducing loss.

[0032] In a possible implementation, the signal processing method further includes: receiving an optical signal, and processing the optical signal to generate a first optical signal and a second optical signal. In this way, only one optical signal can be received, simplifying the optical receiving path. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 An architecture diagram of a wireless communication system provided in an embodiment of the present application;

[0034] Figure 2 An architecture diagram of a wireless communication base station provided in an embodiment of the present application;

[0035] Figure 3 A curve diagram showing the relationship between the power conversion efficiency and the output power of a high-power photodetector provided in an embodiment of the present application;

[0036] Figure 4 A schematic diagram of the topological structure of a balanced photodetector provided in an embodiment of the present application;

[0037] Figure 5 A schematic diagram of a topological structure of a light detection circuit provided in an embodiment of the present application;

[0038] Figure 6 A curve diagram showing the change of efficiency with input power provided in an embodiment of the present application;

[0039] Fig. 7A and Figure 7B A schematic diagram of a topological structure of a light detection circuit provided in an embodiment of the present application;

[0040] Fig. 8A and Figure 8B A schematic diagram of a topological structure of a light detection circuit provided in an embodiment of the present application;

[0041] Fig.9A and Fig. 9B A schematic diagram of a topological structure of a light detection circuit provided in an embodiment of the present application;

[0042] Fig. 10A and Fig. 10B A schematic diagram of a topological structure of a light detection circuit provided in an embodiment of the present application;

[0043] Fig.11 A schematic diagram of a topological structure of a light detection circuit provided in an embodiment of the present application;

[0044] Figure 12A-12C A schematic diagram of a topological structure of a light detection circuit provided in an embodiment of the present application;

[0045] Fig.13 A schematic diagram of the structure of a first light detector provided in an embodiment of the present application. DETAILED DESCRIPTION

[0046] The technical solutions in the embodiments of the present application will be described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments.

[0047] In the following, the terms "second", "first", etc. are used only for convenience of description and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "second", "first", etc. may explicitly or implicitly include one or more of the feature. In the description of this application, unless otherwise specified, "plurality" means two or more.

[0048] In addition, in the embodiments of the present application, directional terms such as "up", "down", "left" and "right" may be defined including but not limited to the orientation relative to the schematic placement of the components in the drawings. It should be understood that these directional terms may be relative concepts, which are used for relative description and clarification, and may change accordingly according to changes in the orientation of the components in the drawings.

[0049] In the embodiments of the present application, unless otherwise clearly specified and limited, the term "connection" should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium. In addition, the term "coupled" can be a direct electrical connection or an indirect electrical connection through an intermediate medium. The term "contact" can be a direct contact or an indirect contact through an intermediate medium.

[0050] In the embodiments of the present application, "and / or" describes the association relationship of the associated objects, indicating that there may be three relationships. For example, A and / or B may represent: A exists alone, A and B exist at the same time, and B exists alone, where A and B may be singular or plural. The character " / " generally indicates that the associated objects are in an "or" relationship.

[0051] The optical detection circuit provided in the embodiment of the present application can be applied to base station systems, satellite communication systems, radar systems, optical sensor systems, etc. For example, when the optical detection circuit is applied to a base station system, the optical detection circuit can be a partial circuit structure in a photoelectric conversion module of the base station, which is used to realize the photoelectric conversion of signals in the base station. The embodiment of the present application does not limit the specific application scenario of the optical detection circuit.

[0052] The following uses the photoelectric conversion module in the base station system as an example to illustrate the application scenario. As the core component of the wireless communication system, the performance of the photoelectric conversion module directly affects the transmission distance and quality of the signal. Therefore, it is necessary to take into account indicators such as linearity and current efficiency to meet the application requirements of the base station system.

[0053] Figure 1 An architecture diagram of a wireless communication system provided in an embodiment of the present application.

[0054] The present application embodiment provides a wireless communication system, such as Figure 1As shown, the wireless communication system includes a baseband unit (BBU), an optical fiber and a wireless communication base station. The BBU is connected to the wireless communication base station through the optical fiber, and the optical fiber is used to achieve the extension of the radio frequency optical signal.

[0055] BBU is mainly used to process Radio Link Control (RLC), Medium Access Control (MAC), some Port Physical Layer (PHY) functions, Radio Resource Control (RRC), and Packet Data Convergence Protocol (PDCP). For example, BBU is also used to receive radio frequency signals, perform electrical-optical conversion on the received radio frequency signals, and transmit them through optical fibers.

[0056] The wireless communication base station is connected to the BBU. The wireless communication base station is mainly used to perform photoelectric conversion, transmission, and radiation of the received optical radio frequency signals to establish a downlink link from the base station to the terminal equipment, and to receive, transmit, and perform electro-optical conversion of the uplink signals from the terminal equipment to establish an uplink link from the terminal equipment to the base station.

[0057] A wireless communication base station can be a base transceiver station (BTS) in a global system for mobile communication (GSM) system or a code division multiple access (CDMA) network, a 3G base station NodeB in a wideband code division multiple access (WCDMA) system, or an evolutionary NodeB (eNB or eNodeB for short) in a long term evolution (LTE) system.

[0058] Figure 2 An architectural diagram of a wireless communication base station provided in an embodiment of the present application.

[0059] The present application embodiment provides a wireless communication base station, which may be a radio frequency photon base station architecture based on radio remote over fiber technology. Figure 2As shown, the wireless communication base station includes an optical detection circuit 10, an electro-optical conversion circuit 20, a low noise amplifier (LNA) and an antenna unit 30. The wireless communication base station provided in the embodiment of the present application simplifies the remote radio unit (RRU) on the basis of the traditional RRU architecture, and moves the digital signal processing unit, the digital-to-analog conversion unit, etc. to the BBU side under the tower.

[0060] The optical detection circuit 10 is mainly used to realize the high-efficiency photoelectric conversion of the optical signal of the transmission link to the electrical signal. The electro-optical (EO) conversion circuit 20 is mainly used to realize the conversion of the electrical signal of the receiving link to the optical signal. The electro-optical conversion circuit 20 may include, for example, a directly modulated laser or an externally modulated laser. The LNA is mainly used to realize the low-noise amplification of the small signal received by the receiving link. The antenna unit 30 is mainly used to realize the isolation, bidirectional transmission, filtering and radiation of the uplink and downlink signals. The antenna unit 30 is, for example, a filtering antenna unit.

[0061] Of course, the wireless communication base station may also include a switch unit or a duplexer structure to isolate the transmission link from the reception link to ensure that both reception and transmission can work normally at the same time. The switch unit or the duplexer structure may be independently provided or integrated in the antenna unit 30.

[0062] In some embodiments, the optical detection circuit 10, the electro-optical conversion circuit 20 and the LNA can be integrated into one module, and a photoelectric conversion module provided in an embodiment of the present application is applied to a wireless communication base station. For example, the optical detection circuit 10, the electro-optical conversion circuit 20 and the LNA can exist in the form of devices.

[0063] In other embodiments, the optical detection circuit 10, the electro-optical conversion circuit 20 and the LNA may be integrated into one chip, and applied to a wireless communication base station as an opto-electrical conversion chip provided in an embodiment of the present application.

[0064] The photoelectric conversion chip may be a bare chip, for example, the light detection circuit 10, the electro-optical conversion circuit 20 and the LNA are integrated on the same wafer. The photoelectric conversion chip may also be a bare chip packaged.

[0065] The photoelectric conversion chip can also be a chip that is a combination of multiple chips (bare chips or packaged chips). In this case, the photoelectric conversion chip can also be understood as a photoelectric conversion chip system, which includes multiple chips in the form of bare chips and / or packaged chips. For example, the light detection circuit 10 and the electro-optical conversion circuit 20 are two independent chips that are combined with the LNA to form the photoelectric conversion chip of the present application. Of course, the LNA can exist in the form of a device or in the form of a chip.

[0066] In some embodiments, a conventional PIN photodetector is used as the light detection circuit 10. The conventional PIN photodetector based on germanium material has a response speed exceeding 2 GHz, becoming the prototype of modern high-speed photodetectors. With the maturity of the indium phosphide (InP) material system, the bandwidth of the conventional PIN photodetector has been rapidly improved by continuously optimizing the material epitaxial structure and device structure.

[0067] As the demand for photodetector response speed increases, the device size is getting smaller and smaller, the current density in the device is getting higher and higher, and the device is increasingly affected by the space charge effect and thermal effect. The collapse of the electric field in the depletion region will not only reduce the bandwidth, but also saturate the microwave output power of the device. The saturation power of the photodetector will affect the gain, noise factor and dynamic range of the microwave photon link. Therefore, the saturation power of the traditional PIN photodetector can no longer meet the requirements of high speed and high power while taking into account the bandwidth.

[0068] Figure 3 A curve diagram showing the relationship between the power conversion efficiency and the output power of a high-power photodetector provided in an embodiment of the present application.

[0069] In some embodiments, a charge-compensated modified uni-travelling-carrier high power photodiode (CC-MUTC-HPD) is used as the light detection circuit 10. Currently, in the 10 GHz frequency band, when the RF output power of the CC-MUTC-HPD is 27.8 dBm, the corresponding peak efficiency can reach 50.7% to 60%.

[0070] For the scenario where a high power photodiode (HPD) directly drives the antenna unit 30, the RF output power of the HPD is generally in the range of 20dbm-25dbm, and the peak-to-average ratio of the modulated signal is generally around 8db-10db. After back-off, the efficiency of the HPD will be greatly reduced. For example, Figure 3The figure shows the variation trend of power conversion efficiency (PCE) with output power when the output power of HPD is in the range of 17dbm-27dbm and the bias voltage remains unchanged. It can be seen that when the saturated output power is close to 27dbm, the PCE of HPD can reach 29.6%. However, when the signal is backed off by 8db, the PCE is only 4.7%.

[0071] In the application process, due to the large peak-to-average ratio of the modulated signal, in order to meet the linearity of the peak value, the average output power of the HPD needs to be backed off by 6db-10db based on the peak value. After the 6db-10db signal peak-to-average ratio backoff, the RF output power of the HPD is difficult to reach 20dbm, and the corresponding backoff efficiency will be greatly reduced. However, to reduce the power consumption of the RRU on the tower, it is necessary to meet the peak linearity and improve the backoff efficiency of the HPD under the premise of the need for power backoff.

[0072] Figure 4 A schematic diagram of the topological structure of a balanced photodetector provided in an embodiment of the present application.

[0073] In some embodiments, a balanced photo detector (BPD) is used as the light detection circuit 10 .

[0074] BPD is widely used in space optical communication due to its high sensitivity and low noise. BPD uses dual photodiodes to input optical signals and suppress or eliminate common mode noise in the signal. It is one of the core devices of coherent optical communication. According to the different chip connection structures, it can be divided into current self-subtraction structure and differential amplification structure. Figure 4 A BPD with a differential amplification structure includes a differential amplifier, two photodiodes (PD), two capacitors C, and two resistors R. The differential amplifier is, for example, a trans-impedance amplifier (TIA) with dual input terminals. The resistor R, the capacitor C, and the PD form a current arm. The current difference between the two arms is obtained through the TIA to achieve a differential voltage output.

[0075] BPDs with differential amplification structures can also be divided into fiber-coupled BPDs and spatial optical coupling BPDs according to different optical coupling methods. BPDs with waveguide structures can eliminate the contradiction between light absorption efficiency and carrier transit time and are easy to integrate with other photonic components on a single chip. Although BPDs have the above advantages and can amplify differential signals and improve sensitivity, BPDs that have both high RF power of vertical irradiation structure and high bandwidth of waveguide structure have not yet been developed. Vertically irradiated BPDs can achieve high RF power, but the bandwidth will not be too large, while the bandwidth of waveguide integrated BPDs can be very large, but the RF power cannot reach the height of the vertical irradiation structure.

[0076] Based on this, although there are currently a variety of structures of the optical detection circuit 10, they all have shortcomings, and the optimization of the structure of the optical detection circuit 10 is still a difficult problem studied by those skilled in the art. The embodiment of the present application aims to propose an unbalanced optical detection circuit 10 to optimize the back-off efficiency of the optical detection circuit 10.

[0077] Figure 5 A schematic diagram of a topological structure of a light detection circuit provided in an embodiment of the present application.

[0078] The present application embodiment provides a light detection circuit 10, such as Figure 5 As shown, the optical detection circuit 10 includes an optical input terminal I, a first branch, a second branch, an impedance modulation network 13, and a radio frequency output terminal Ro. The first branch and the second branch are parallel branches, which are combined at the input end of the impedance modulation network 13. The output end of the impedance modulation network 13 is coupled to the radio frequency output terminal Ro. The radio frequency signals output by the first branch and the second branch are combined to form a final output radio frequency signal, which is output from the radio frequency output terminal Ro. The radio frequency output terminal Ro is used to couple with a load, and the load may include, for example, a resistor, a capacitor, an inductor, or an antenna unit 30.

[0079] The optical input terminal I is used to input an optical signal, and the optical signal includes a first optical signal and a second optical signal. For example, Figure 5 As shown, the optical input terminal I includes a first optical input terminal I1 and a second optical input terminal I2. The first optical input terminal I1 is used to input a first optical signal, and the second optical input terminal I2 is used to input a second optical signal.

[0080] The first branch includes a first optical detector 11, which is used to receive a first optical signal and output a first radio frequency signal. For example, the first optical detector 11 includes a first input end and a first output end, the first input end is used to receive the first optical signal, and the first output end is used to output the first radio frequency signal.

[0081] The second branch includes a second photodetector 12 and a first power amplifier PA1, and the second photodetector 12 is used to receive a second optical signal and output a second radio frequency signal. For example, the second photodetector 12 includes a second input terminal and a second output terminal, and the second input terminal is used to receive the second optical signal, and the second output terminal is used to output the second radio frequency signal. The first power amplifier PA1 is coupled between the second photodetector 12 and the impedance modulation network 13, and is used to amplify the second radio frequency signal and control the on-off between the second photodetector 12 and the impedance modulation network 13. For example, the first power amplifier PA1 includes a third input terminal and a third output terminal, and the third input terminal is coupled to the second output terminal of the second photodetector 12, and the third output terminal is connected to the fourth input terminal of the impedance modulation network 13. On the basis of amplifying the second radio frequency signal, the first power amplifier PA1 also controls the on-off between the second output terminal and the third input terminal.

[0082] In the embodiment of the present application, the first power amplifier PA1 works in a Class C amplifier state. The gate voltage of the first power amplifier PA1 can be adjusted so that it is in an on state when the second RF signal is greater than a certain threshold, and in an off state when the second RF signal is less than the threshold. The threshold turn-on effect of the phototransistor is realized by driving the first power amplifier PA1 with the second photodetector 12.

[0083] The first optical signal and the second optical signal are two optical signals obtained after the input radio frequency signal is processed. For example, the input radio frequency signal can be processed by branching, electro-optical conversion and amplification to obtain the first optical signal and the second optical signal. The first optical signal and the second optical signal can be optical signals with equal power, or the first optical signal and the second optical signal can be optical signals with unequal power. The first optical signal and the second optical signal can be optical signals with the same phase, or the first optical signal and the second optical signal can be optical signals with different phases.

[0084] The impedance modulation network 13 is used to transform the output impedance of the first photodetector 11 and the second photodetector 12, and couple the output end of the first photodetector 11 and the output end of the second photodetector 12 to the radio frequency output end Ro. For example, the impedance modulation network 13 includes a fourth input end and a fourth output end, the first output end of the first photodetector 11 and the third output end of the first power amplifier PA1 are coupled to the fourth input end, and the fourth output end is coupled to the radio frequency output end Ro. The impedance modulation network 13 is used to adjust the impedance load presented by the first photodetector 11 and the second photodetector 12 at the output end based on the power of the first optical signal and the second optical signal.

[0085] The impedance modulation network 13 is, for example, a microstrip line structure. For example, the impedance modulation network 13 may be a 1 / 4 wavelength impedance transformer or the like.

[0086] For example, the first power amplifier PA1 is used to control the disconnection between the second light detector 12 and the impedance modulation network 13 when the second RF signal (for example, the amplitude of the second RF signal) is less than the set value. For example, when the frequency of the second light signal is relatively small, the power of the second RF signal output by the second light detector 12 is also relatively small, and the second RF signal is not enough to turn on the first power amplifier PA1. The first power amplifier PA1 is turned off so that the second light detector 12 and the impedance modulation network 13 are in a disconnected state. The first branch includes the first light detector 11, and the first branch is a normally-on circuit. Then the impedance of the impedance modulation network 13 itself is all used as the output impedance of the first light detector 11, and the impedance modulation network 13 is the equivalent load of the first branch. For example, the impedance of the impedance modulation network 13 is 100 ohm, and the equivalent load of the first branch is increased to 100 ohm. In this scenario, the voltage of the first branch reaches saturation, the second branch is disconnected, and the light detection circuit 10 operates at the optimal efficiency point.

[0087] The first power amplifier PA1 is used to control the connection between the second light detector 12 and the impedance modulation network 13 when the second RF signal (for example, the amplitude of the second RF signal) is greater than or equal to the set value. For example, when the frequency of the second light signal is relatively large, the power of the second RF signal output by the second light detector 12 is also relatively large, and the second RF signal turns on the first power amplifier PA1, and the first power amplifier PA1 is turned on so that the second light detector 12 and the impedance modulation network 13 are in a path state. In this scenario, the first branch and the second branch are connected in parallel with the impedance modulation network 13, and the impedance modulation network 13 is a common equivalent load for the first branch and the second branch. At this time, the equivalent load of the first branch is reduced. For example, the equivalent load of the first branch gradually decreases from 100ohm, and the current of the first branch gradually increases. The load of the second branch decreases from the open circuit state, and the current of the second branch also gradually increases. When the intensity of the second optical signal reaches the saturation output point (or peak operating point) of the second branch, the first branch and the second branch share the impedance of the impedance modulation network 13, so that the loads of the first branch and the second branch are both the maximum power output impedance. For example, the loads of the first branch and the second branch are both 50 ohms. At this time, the currents of the first branch and the second branch both reach the maximum value, and the currents of the two branches are equal. When the phases of the first branch and the second branch are equal, the output power of the optical detection circuit 10 reaches the maximum.

[0088] Figure 6 A curve diagram showing the variation of efficiency with input power provided in an embodiment of the present application.

[0089] Figure 6 The middle dashed line is a curve showing the efficiency of the light detection circuit (conventional light detection circuit) including only the first light detector 11 as a function of input power. Figure 6The solid line in the middle is a curve showing the variation of the efficiency of the optical detection circuit 10 provided in the present application with the input power. Figure 6 The horizontal axis is input power, and the vertical axis is efficiency. Figure 6 It can be seen that the conventional optical detection circuit can achieve a power conversion efficiency of about 59% when the input power is 25dbm, but when the input power is backed off to 17dbm, the back-off efficiency can only reach about 25%. The optical detection circuit 10 provided in the embodiment of the present application can achieve a power conversion efficiency of about 54.5% when the input power is 25dbm, and when the input power is backed off to 17dbm, the back-off efficiency can reach about 41%.

[0090] In the optical detection circuit 10 provided in the embodiment of the present application, the first optical detector 11 and the second optical detector 12 are in parallel relationship, and whether the branch where the second optical detector 12 is located is connected or not depends on whether the second radio frequency signal is greater than the threshold turn-on voltage of the first power amplifier PA1. By adopting this circuit structure in which the branch where the first optical detector 11 is located is continuously turned on, and the branch where the second optical detector 12 is located is turned on only when the second radio frequency signal reaches the set peak value, a turn-on voltage effect similar to that of a triode can be achieved, thereby improving the output power of the optical detection circuit 10. In addition, by adopting an impedance modulation network 13 to combine the branch where the first optical detector 11 is located and the branch where the second optical detector 12 is located, a load modulation effect can be achieved when the input power changes, thereby realizing a dynamic load transformation from the back-off point to the maximum output point, which is conducive to achieving that the first optical detector 11 and the second optical detector 12 both maintain a high output efficiency within the range of the maximum power point and the back-off point, thereby achieving the purpose of improving the back-off efficiency of the optical detection circuit 10.

[0091] Regarding the way to make the phases of the first branch and the second branch equal, in some embodiments, the phases of the first optical signal and the second optical signal are adjusted before the first optical signal and the second optical signal are input to the optical detection circuit 10. Then, the first optical signal and the second optical signal received by the optical detection circuit 10 are optical signals with the same phase.

[0092] In other embodiments, the first optical signal and the second optical signal are optical signals with different phases, and a phase adjustment structure is provided in the optical detection circuit 10 so that the phases of the first RF signal and the second RF signal finally outputted are the same.

[0093] Fig. 7A and Figure 7B A schematic diagram of a topological structure of a light detection circuit provided in an embodiment of the present application.

[0094] In some embodiments, Fig. 7AAs shown, the optical detection circuit 10 also includes a first capacitor C1 and a second capacitor C2. The first capacitor C1 is coupled between the first optical detector 11 and the impedance modulation network 13, and the second capacitor C2 is coupled between the second optical detector 12 and the first power amplifier PA1. The first capacitor C1 and the second capacitor C2 are used to pass the AC signal and filter out the DC signal.

[0095] In some embodiments, Fig. 7A As shown, the optical detection circuit 10 further includes a first optical delay device 14 , and the first optical signal is transmitted to the first optical detector 11 after being phase-shifted by the first optical delay device 14 .

[0096] By adjusting the phase of the first optical signal with the help of the first optical delay device 14, the first optical signal and the second optical signal can be made into optical signals with the same phase, and the corresponding output first radio frequency signal and the second radio frequency signal are also made into radio frequency signals with the same phase, so as to reduce the problems of reduced efficiency and deteriorated signal quality caused by the inconsistent phase when the two signals are synthesized.

[0097] In other embodiments, Figure 7B As shown, the optical detection circuit 10 further includes a second optical delay device 15 , and the second optical signal is transmitted to the second optical detector 12 after being phase-shifted by the second optical delay device 15 .

[0098] By adjusting the phase of the second optical signal with the help of the second optical delay device 15, the first optical signal and the second optical signal can be made into optical signals with the same phase, and the corresponding output first radio frequency signal and second radio frequency signal are also made into radio frequency signals with the same phase, so as to reduce the problems of reduced efficiency and deteriorated signal quality caused by the phase inconsistency when the two signals are synthesized.

[0099] In some other embodiments, the optical detection circuit 10 includes a first optical delay device 14 and a second optical delay device 15. The first optical delay device 14 adjusts the phase of the first optical signal, and the synchronized second optical delay device 15 adjusts the phase of the second optical signal. This can achieve that the first optical signal and the second optical signal are optical signals with the same phase, and the corresponding output first radio frequency signal and the second radio frequency signal are also radio frequency signals with the same phase, so as to reduce problems such as reduced efficiency and deteriorated signal quality caused by phase inconsistency when the two signals are synthesized.

[0100] The optical detection circuit 10 provided in the embodiment of the present application, by setting an optical delay device before the first optical detector 11 and / or the second optical detector 12, adjusts the phase of the first optical signal and / or the second optical signal by optical adjustment, so that the optical detection circuit 10 supports phase adjustment of broadband signals, and the phase adjustment accuracy of the optical delay device structure is high, the bandwidth is large, and it can be switched quickly.

[0101] The first optical delay device 14 and the second optical delay device 15 can be adjustable optical delay devices, or they can be non-adjustable optical delay devices. The embodiment of the present application does not limit the structure of the first optical delay device 14 and the second optical delay device 15, and the optical delay devices in the related art are all applicable to the embodiment of the present application.

[0102] Fig. 8A and Figure 8B A schematic diagram of a topological structure of a light detection circuit provided in an embodiment of the present application.

[0103] In some embodiments, Fig. 8A As shown, the optical detection circuit 10 further includes a first phase shifter 16 , which is coupled between the first optical detector 11 and the impedance modulation network 13 .

[0104] By adjusting the phase of the first RF signal with the help of the first phase shifter 16, the first RF signal and the second RF signal can be made into RF signals with the same phase, so as to reduce the problems of reduced efficiency and deteriorated signal quality caused by the inconsistent phase when the two signals are synthesized.

[0105] In other embodiments, Figure 8B As shown, the optical detection circuit 10 further includes a second phase shifter 17 , which is coupled between the second optical detector 12 and the first power amplifier PA1 .

[0106] By adjusting the phase of the second RF signal with the help of the second phase shifter 17, the first RF signal and the second RF signal can be made into RF signals with the same phase, so as to reduce the problems of reduced efficiency and poor signal quality caused by the inconsistent phase when the two signals are synthesized.

[0107] In some other embodiments, the optical detection circuit 10 includes a first phase shifter 16 and a second phase shifter 17. The first phase shifter 16 adjusts the phase of the first RF signal, and the synchronized second phase shifter 17 adjusts the phase of the second RF signal, so that the first RF signal and the second RF signal can be RF signals with the same phase, so as to reduce the problems of reduced efficiency and deteriorated signal quality caused by the inconsistent phase when the two signals are synthesized.

[0108] The optical detection circuit 10 provided in the embodiment of the present application, by setting a phase shifter after the first optical detector 11 and / or the second optical detector 12, adjusts the phase of the first RF signal and / or the second RF signal by electrical adjustment, so that the optical detection circuit 10 supports phase adjustment of broadband signals, and the integration difficulty and cost of the electrical phase shifter are low.

[0109] The first phase shifter 16 and the second phase shifter 17 can be adjustable phase shifters, or they can be non-adjustable phase shifters. The embodiment of the present application does not limit the structure of the first phase shifter 16 and the second phase shifter 17, and the phase shifters in the related art are all applicable to the embodiment of the present application.

[0110] In the first scenario, the power of the first optical signal is equal to the power of the second optical signal.

[0111] Then, the amplitude of the first RF signal is equal to the amplitude of the second RF signal. However, the amplitude of the amplified RF signal output after the second RF signal is amplified by the first power amplifier PA1 is different from the amplitude of the first RF signal.

[0112] In the second scenario, the power of the first optical signal is less than the power of the second optical signal.

[0113] Then, the amplitude of the first RF signal is smaller than the amplitude of the second RF signal, and the amplitude of the amplified RF signal output after the second RF signal is amplified by the first power amplifier PA1 is greater than the amplitude of the first RF signal.

[0114] In some embodiments, the optical detection circuit 10 further includes a power adjustment structure for making the amplitude of the first RF signal equal to the amplitude of the amplified RF signal output by the first power amplifier PA1.

[0115] Fig.9A and Fig. 9B A schematic diagram of a topological structure of a light detection circuit provided in an embodiment of the present application.

[0116] In some embodiments, Fig.9A As shown, the optical detection circuit 10 further includes an optical attenuator 18 , and the second optical signal is attenuated by the optical attenuator 18 and then transmitted to the second optical detector 12 .

[0117] By adjusting the power of the second optical signal with the aid of the optical attenuator 18, the power of the first optical signal can be greater than the power of the second optical signal, and the amplitude of the corresponding output first radio frequency signal can be greater than the amplitude of the second radio frequency signal. After the second radio frequency signal is amplified by the first power amplifier PA1, the amplitude of the radio frequency signal output by the first branch can be equal to the amplitude of the radio frequency signal output by the second branch, so as to reduce the problems of reduced efficiency and deterioration of signal quality caused by the inconsistent amplitude when the two signals are synthesized, and the optical attenuator 18 has a high power adjustment accuracy for the optical signal.

[0118] The optical attenuator 18 may be an adjustable optical attenuator or a non-adjustable optical attenuator. The embodiment of the present application does not limit the structure of the optical attenuator 18, and the optical attenuators in the related art are all applicable to the embodiment of the present application.

[0119] In other embodiments, Fig. 9B As shown, the optical detection circuit 10 further includes an electrical attenuator 19 , which is coupled between the second optical detector 12 and the first power amplifier PA1 .

[0120] By adjusting the power of the second RF signal with the aid of the electric attenuator 19, the amplitude of the first RF signal can be made greater than the amplitude of the second RF signal. After the second RF signal is amplified by the first power amplifier PA1, the amplitude of the RF signal output by the first branch can be made equal to the amplitude of the RF signal output by the second branch, so as to reduce the problems of reduced efficiency and deteriorated signal quality caused by the inconsistent amplitude when the two signals are synthesized, and the integration difficulty and cost of the electric attenuator 19 are low.

[0121] In some other embodiments, the optical detection circuit 10 includes an optical attenuator 18 and an electrical attenuator 19. The optical attenuator 18 adjusts the power of the second optical signal before the second optical detector 12, and the electrical attenuator 19 adjusts the power of the second RF signal after the second optical detector 12. Ultimately, the first RF signal and the amplified RF signal can be made equal-amplitude RF signals to reduce losses.

[0122] In some further embodiments, the optical detection circuit 10 includes an optical enhancer and / or an electrical enhancer, wherein the optical enhancer is arranged before the first optical detector 11 and the electrical enhancer is arranged after the first optical detector 11, and is used to make the amplitude of the radio frequency signal output by the first branch equal to the amplitude of the radio frequency signal output by the second branch.

[0123] In the third scenario, the power of the first optical signal is greater than the power of the second optical signal.

[0124] Then, the amplitude of the first RF signal is greater than the amplitude of the second RF signal, and the amplitude of the amplified RF signal output after the second RF signal is amplified by the first power amplifier PA1 can be exactly equal to the amplitude of the first RF signal. In this scenario, there is no need to set a power adjustment structure in the optical detection circuit 10, which can simplify the structure of the optical detection circuit 10.

[0125] Fig. 10A and Fig. 10B A schematic diagram of a topological structure of a light detection circuit provided in an embodiment of the present application.

[0126] In some embodiments, Fig. 10A As shown, the optical detection circuit 10 further includes a third branch, which includes a third optical detector 12' and a second power amplifier PA2.

[0127] The optical input terminal I further includes a third optical input terminal I3, and the third optical input terminal I3 is used to input a third optical signal.

[0128] The third optical detector 12 ′ is used to receive a third optical signal and output a third radio frequency signal. The second power amplifier PA2 is coupled between the third optical detector 12 ′ and the impedance modulation network 13 , and is used to control the connection between the third optical detector 12 ′ and the impedance modulation network 13 .

[0129] The optical detection circuit 10 includes the first branch and the second branch, and can also include one or more third branches, and the third branch and the second branch are both conditionally open circuits. The RF signals output by the first branch, the second branch and the third branch are phase matched and combined for output through the impedance modulation network 13.

[0130] In some embodiments, the third branch may also include structures such as an optical delay device, a phase shifter, an optical attenuator, and an electrical attenuator. The configuration of the aforementioned structures in the third branch can refer to the above description of the structure in the second branch and will not be repeated here.

[0131] For example, Fig. 10B As shown, the first branch in the optical detection circuit 10 includes a first optical detector 11 and a first phase shifter 16, the second branch includes a second optical detector 12, a second phase shifter 17 and a first power amplifier PA1, the third branch includes a third optical detector 12', a third phase shifter 17' and a second power amplifier PA2, and the output end of the first phase shifter 16, the output end of the first power amplifier PA1, and the output end of the second power amplifier PA2 are combined at the input end of the impedance modulation network 13.

[0132] By setting a plurality of conditional start circuits in the optical detection circuit 10, the optical detection circuit 10 can increase a plurality of efficiency optimum points in the back-off interval, thereby improving the average efficiency of the entire back-off interval. For example, when the optical detection circuit 10 works independently in the first branch, there is an efficiency optimum point, when the first branch and the second branch work synchronously, there is an efficiency optimum point, when the first branch and the third branch work synchronously, there is an efficiency optimum point, and when the first branch, the second branch, and the third branch work synchronously, there is an efficiency optimum point.

[0133] In some embodiments, a turn-on voltage of the first power amplifier PA1 is not equal to a turn-on voltage of the second power amplifier PA2 .

[0134] In this way, the branch where the second light detector 12 is located and the branch where the third light detector 12 ′ is located provide different optimum efficiency points, thereby improving the average efficiency of the back-off interval.

[0135] Fig.11 A schematic diagram of a topological structure of a light detection circuit provided in an embodiment of the present application.

[0136] In some embodiments, Fig.11 As shown, the optical detection circuit 10 further includes an impedance matching network 40 , which is coupled between the second optical detector 12 and the first power amplifier PA1 .

[0137] The impedance matching network 40 can be, for example, a 1 / 4 microstrip line or a resistor-capacitor (RC) matching network. The impedance matching network 40 is used to match the output impedance of the second photodetector 12 with the input impedance of the first power amplifier PA1 to reduce the excessive insertion loss caused by impedance mismatch when the second photodetector 12 is cascaded with the first power amplifier PA1.

[0138] based on Figure 5-Figure 11 The optical detection circuit 10 shown is used to receive the first optical signal and the second optical signal. The optical detection circuit 10 includes two optical input ports, which are optical ports. The optical input ports can be, for example, fiber pigtail or pluggable optical fiber ports. The optical detection circuit 10 includes two unbalanced links, but they are finally combined to the RF output port Ro through the impedance modulation network 13. The RF output port Ro is used to output RF signals. The RF output port Ro can be connected to other circuits by coaxial connectors, pin welding, or surface mount welding.

[0139] Figure 12A-12C A schematic diagram of a topological structure of a light detection circuit provided in an embodiment of the present application.

[0140] In some embodiments, Fig. 12A As shown, the optical detection circuit 10 further includes an optical splitter 50, and the optical splitter 50 is used to split the received optical signal (optical radio frequency signal) into a first optical signal and a second optical signal.

[0141] In this case, if Fig. 12A As shown, the optical detection circuit 10 includes an optical input port I whose input port is an optical port, and the optical splitter 50 realizes power division of the optical signal and outputs a first optical signal and a second optical signal. Compared with requiring two independent optical input ports, the number of input interfaces of the optical detection circuit 10 can be simplified, and power and efficiency can be improved without increasing the cost and complexity of the optical detection circuit 10.

[0142] In some embodiments, Fig. 12B As shown, the optical splitter 50 is an equal-ratio power splitter.

[0143] The input RF signal is converted into an optical signal by a photodiode, and the optical signal is transmitted to the optical splitter 50 in the optical detection circuit 10 through an optical fiber. The optical splitter 50 divides the received signal into a first optical signal and a second optical signal in a 1:1 ratio.

[0144] In this way, the optical splitter 50 capable of realizing equal power division in the related art is applicable to the embodiment of the present application, and the optical splitter 50 is mature in technology and easy to realize. In this case, for example, the optical detection circuit 10 also includes the above-mentioned power adjustment structure (for example Fig. 12B The electrical attenuator 19) is used to achieve that the first branch and the second branch output radio frequency signals of equal amplitude and phase.

[0145] In other embodiments, Fig. 12C As shown, the optical splitter 50 is a non-uniform power splitter.

[0146] The optical splitter 50 splits the received optical signal into a first optical signal and a second optical signal in unequal proportions. For example, the proportion of the first optical signal is greater than the proportion of the second optical signal.

[0147] In this way, the optical detection circuit 10 need not include the above-mentioned power adjustment structure, but only needs to include a phase adjustment structure (eg Fig. 12C By using the first phase shifter 16 and the second phase shifter 17 in the optical detection circuit 10, the first branch and the second branch can output radio frequency signals with equal amplitude and phase, thereby simplifying the structure of the optical detection circuit 10.

[0148] Regardless of whether the optical splitter 50 is an equal-ratio power splitter or a non-equal-ratio power splitter, after the distribution ratio of the optical splitter 50 is determined, the gate voltage of the first power amplifier PA1 can be adjusted so that the first power amplifier PA1 is turned on when the power of the optical radio frequency signal received by the optical splitter 50 is greater than or equal to the average power. When the power of the optical radio frequency signal received by the optical splitter 50 is less than the average power, the first power amplifier PA1 is turned off.

[0149] It should be noted that when the power adjustment structure in the optical detection circuit 10 is an optical attenuator 18, and the phase adjustment structure in the optical detection circuit 10 is a first optical delay device 14 or a second optical delay device 15, one or more of the optical attenuator 18, the first optical delay device 14, and the second optical delay device 15 can be integrated in the optical splitter 50.

[0150] Regarding the structures of the first light detector 11 and the second light detector 12 , in some embodiments, the first light detector 11 and the second light detector 12 are high power photo detectors (HPDs).

[0151] Fig.13 A schematic diagram of the structure of a first light detector provided in an embodiment of the present application.

[0152] For example, Fig.13As shown, the first photodetector 11 includes an anti-reflection coating (ARC), a substrate, an N contact layer, a drift layer, a cliff layer, a depleted absorption layer, an undoped absorption layer, an N metal layer, a coplanar waveguide signal region, a coplanar waveguide ground, and a diamond submount. Of course, Fig.13 The structure of the first light detector 11 shown is only for illustration and is not intended to be limiting.

[0153] The first optical signal is incident on the first photodetector 11 from the side where the anti-reflection coating is located, and the photoelectric conversion is realized by using the internal photoelectric effect of the semiconductor material inside the first photodetector 11, and electron-hole pairs are generated by absorbing photons, thereby generating photocurrent in the external circuit. When the incident light is a radio frequency optical carrier signal, the output photocurrent contains DC and radio frequency components, wherein the radio frequency component is output through the coplanar waveguide signal area to form a first radio frequency signal, and the coplanar waveguide signal area is coupled to the impedance modulation network 13, and the coplanar waveguide ground is coupled to the reference ground voltage terminal.

[0154] In some embodiments, the structure of the second light detector 12 is the same as that of the first light detector 11 , and will not be described in detail herein.

[0155] The embodiment of the present application also provides a signal processing method, which can be performed by the above-mentioned light detection circuit 10. The signal processing method includes the following steps:

[0156] The first photodetector 11 receives a first optical signal and performs photoelectric conversion on the first optical signal to generate a first radio frequency signal. The second photodetector 12 receives a second optical signal and performs photoelectric conversion on the second optical signal to generate a second radio frequency signal.

[0157] Among them, the first optical signal and the second optical signal are two optical signals obtained after the input radio frequency signal is processed. Referring to the above description, the first optical signal and the second optical signal can be optical signals that have been split and processed before entering the optical detection circuit 10, or can be signals formed by processing after entering the optical detection circuit 10. In this case, the signal processing method also includes receiving the optical signal, processing the optical signal (such as power division processing) to generate the first optical signal and the second optical signal. This step can be performed, for example, by the above-mentioned optical splitter 50.

[0158] The first power amplifier PA1 is turned on or off under the control of the second radio frequency signal, and amplifies the second radio frequency signal when the first power amplifier PA1 is turned on.

[0159] For example, the first power amplifier PA1 is turned off when the second RF signal is less than a set value, and the amplified second RF signal output by the first power amplifier PA1 can be understood as 0. The first power amplifier PA1 is turned on when the second RF signal is greater than or equal to the set value.

[0160] The impedance modulation network 13 performs output impedance transformation on the first photodetector 11 and the second photodetector 12 , and combines the first radio frequency signal and the amplified second radio frequency signal for output.

[0161] The impedance modulation network 13 transforms the output impedance of the first photodetector 11 and the second photodetector 12 according to the power of the first RF signal and the power of the second RF signal. The specific process can be referred to the above description of the impedance modulation network 13, which will not be repeated here.

[0162] In some embodiments, the signal processing method further includes: performing phase modulation on the first optical signal. For example, the first optical delay device 14 is used to perform phase modulation on the first optical signal.

[0163] In some embodiments, the signal processing method further includes: performing phase modulation on the second optical signal. For example, the second optical delay device 15 is used to perform phase modulation on the second optical signal.

[0164] In some embodiments, the signal processing method further includes: performing amplitude modulation on the second optical signal. For example, the above-mentioned optical attenuator 18 is used to perform amplitude modulation on the second optical signal.

[0165] In some embodiments, the signal processing method further includes: performing phase modulation on the first radio frequency signal. For example, the first phase shifter 16 is used to perform phase modulation on the first radio frequency signal.

[0166] In some embodiments, the signal processing method further includes: performing phase modulation on the second radio frequency signal. For example, the second phase shifter 17 is used to perform phase modulation on the second radio frequency signal.

[0167] In some embodiments, the signal processing method further includes: performing amplitude modulation on the second radio frequency signal. For example, the above-mentioned electric attenuator 19 is used to perform amplitude modulation on the second radio frequency signal.

[0168] In the present application, under the premise of no logical contradiction, the various embodiments may reference each other, for example, the methods and / or terms between method embodiments may reference each other, for example, the functions and / or terms between device embodiments may reference each other, for example, the functions and / or terms between device embodiments and method embodiments may reference each other.

[0169] The above are only specific implementations of the present application, but the protection scope of the present application is not limited thereto, and any changes or substitutions within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A light detection circuit, characterized in that: include: An optical input end, used for inputting an optical signal, wherein the optical signal includes a first optical signal and a second optical signal; RF output terminal; a first optical detector, configured to receive the first optical signal and output a first radio frequency signal; a second optical detector, configured to receive the second optical signal and output a second radio frequency signal; an impedance modulation network, configured to transform the output impedance of the first photodetector and the second photodetector, and couple the output end of the first photodetector and the output end of the second photodetector to the radio frequency output end; The first power amplifier is coupled between the second photodetector and the impedance modulation network, and is used for amplifying the second radio frequency signal and controlling the connection between the second photodetector and the impedance modulation network.

2. The light detection circuit according to claim 1, characterized in that: The first power amplifier is specifically used to control the second light detector and the impedance modulation network to be disconnected when the second RF signal is less than a set value; and to control the second light detector and the impedance modulation network to be connected when the second RF signal is greater than or equal to the set value.

3. The light detection circuit according to claim 1 or 2, characterized in that: The optical detection circuit further includes an optical attenuator, and the second optical signal is attenuated by the optical attenuator and then transmitted to the second optical detector.

4. The light detection circuit according to claim 1 or 2, characterized in that: The optical detection circuit further includes an electrical attenuator coupled between the second optical detector and the first power amplifier.

5. The light detection circuit according to any one of claims 1 to 4, characterized in that: The optical detection circuit further includes a first optical delay device; the first optical signal is phase-shifted by the first optical delay device and then transmitted to the first optical detector; and / or, The optical detection circuit also includes a second optical delay device; the second optical signal is phase-shifted by the second optical delay device and then transmitted to the second optical detector.

6. The light detection circuit according to any one of claims 1 to 4, characterized in that: The optical detection circuit further includes a first phase shifter; the first phase shifter is coupled between the first optical detector and the impedance modulation network; and / or, The optical detection circuit further includes a second phase shifter; the second phase shifter is coupled between the second optical detector and the first power amplifier.

7. The light detection circuit according to any one of claims 1 to 6, characterized in that: The optical detection circuit also includes a third optical detector and a second power amplifier; The third optical detector is used to receive a third optical signal and output a third radio frequency signal; The second power amplifier is coupled between the third photodetector and the impedance modulation network, and is used to control the connection between the third photodetector and the impedance modulation network.

8. The light detection circuit according to claim 7, characterized in that: A turn-on voltage of the first power amplifier is not equal to a turn-on voltage of the second power amplifier.

9. The light detection circuit according to any one of claims 1 to 8, characterized in that: The power of the first optical signal is greater than or equal to the power of the second optical signal.

10. The light detection circuit according to any one of claims 1 to 9, characterized in that: The optical detection circuit further includes an optical splitter; the optical splitter is used to receive the optical signal and split the optical signal into the first optical signal and the second optical signal.

11. The light detection circuit according to any one of claims 1 to 10, characterized in that: The optical detection circuit further includes an impedance matching network coupled between the second optical detector and the first power amplifier.

12. The light detection circuit according to any one of claims 1 to 11, characterized in that: The light detection circuit also includes a first capacitor and a second capacitor; The first capacitor is coupled between the first photodetector and the impedance modulation network, and the second capacitor is coupled between the second photodetector and the first power amplifier.

13. A photoelectric conversion module, characterized in that: It comprises a light detection circuit and an electro-optical conversion circuit; the light detector is used to convert a received light signal into an electrical signal, and the electro-optical conversion circuit is used to convert a received electrical signal into an optical signal; the light detection circuit comprises the light detection circuit according to any one of claims 1 to 12.

14. A photoelectric conversion chip, characterized in that: It comprises a light detection circuit and an electro-optical conversion circuit; the light detector is used to convert a received light signal into an electrical signal, and the electro-optical conversion circuit is used to convert a received electrical signal into an optical signal; the light detection circuit comprises the light detection circuit according to any one of claims 1 to 12.

15. A wireless communication base station, characterized in that: It comprises a photoelectric conversion module and an antenna unit, wherein the photoelectric conversion module is coupled to the antenna unit; the photoelectric conversion module comprises the photoelectric conversion module according to claim 13 or the photoelectric conversion chip according to claim 14.

16. A wireless communication system, characterized in that: It comprises a baseband processing unit, a wireless communication base station and an optical fiber, wherein the baseband processing unit and the wireless communication base station are connected via the optical fiber; the wireless communication base station comprises the wireless communication base station according to claim 15.

17. A signal processing method, characterized in that: include: The first photodetector receives a first optical signal and performs photoelectric conversion on the first optical signal to generate a first radio frequency signal, and the second photodetector receives a second optical signal and performs photoelectric conversion on the second optical signal to generate a second radio frequency signal; The first power amplifier is turned on or off under the control of the second radio frequency signal, and amplifies the second radio frequency signal when the first power amplifier is turned on; The impedance modulation network transforms the output impedance of the first photodetector and the second photodetector, and combines the first radio frequency signal and the amplified second radio frequency signal for output.

18. The signal processing method according to claim 17, characterized in that: The first power amplifier is turned off when the second radio frequency signal is less than a set value, and is turned on when the second radio frequency signal is greater than or equal to the set value.

19. The signal processing method according to claim 17 or 18, characterized in that: The signal processing method further includes: performing phase sum modulation on the first optical signal; and / or, performing phase and / or amplitude modulation on the second optical signal; and / or, performing phase modulation on the first radio frequency signal; and / or, The second radio frequency signal is phase and / or amplitude modulated.

20. The signal processing method according to any one of claims 17 to 19, characterized in that: The signal processing method further includes: An optical signal is input, and the optical signal is processed to generate the first optical signal and the second optical signal.

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