Device and method for measuring scattering parameters based on microwave photonic mixing

Abstract

A scattering parameter measurement device based on microwave photonic mixing includes a microwave generation module 1, a signal loading module 2, a local oscillator frequency generation module 3, a multi-channel microwave photonic mixing module 4, an analog-to-digital converter (ADC) module 5, and a signal processing module 6. Along the signal output direction of the multi-channel microwave photonic mixing module 4, the ADC module 5 and the signal processing module 6 are sequentially arranged. This invention utilizes microwave photonic mixing technology and a local oscillator source with relatively small bandwidth to down-convert a high-frequency microwave signal to a fixed-frequency intermediate frequency (IF) signal. This reduces the bandwidth requirements of the receiver's electronic components and the sampling rate requirements of the ADC. It abandons the traditional superheterodyne structure and / or direct conversion structure, using a miniaturized continuous optical module as the light source for microwave photonic mixing, simplifying the system structure and reducing cost and power consumption.

Description

Technical Field

[0001] This invention relates to microwave photonic mixing, and in particular to a device and method for measuring scattering parameters based on microwave photonic mixing. Background Technology

[0002] With the development of information technology, the application of high-frequency signals is becoming increasingly widespread, a typical example being vector network analyzers. A vector network analyzer is a fundamental instrument used to accurately measure the scattering parameters (S-parameters) of microwave components, precisely measuring the amplitude and phase responses of the device under continuous wave excitation. Because amplitude and phase receivers have limited bandwidth and cannot directly acquire high-frequency signals, heterodyne or direct frequency conversion methods are typically used to receive high-frequency signals when measuring microwave devices. However, heterodyne reception and direct frequency conversion methods involve complex structures or can introduce problems such as local oscillator leakage and I / Q imbalance.

[0003] Furthermore, the reception and processing of high-frequency signals require high-bandwidth, high-sampling-rate analog-to-digital converters (ADCs), while traditional electrical analog-to-digital converters (EDCs) suffer from significant losses at high frequencies, making them difficult to meet current demands. Microwave photonic mixing technology can effectively utilize the large bandwidth advantage of photonics to down-convert high-frequency microwave signals into intermediate-frequency signals. Moreover, microwave photonic mixing technology reduces the bandwidth requirements of the local oscillator signal source. Therefore, microwave signals can be efficiently received and processed by low-bandwidth, low-sampling-rate EDCs. Summary of the Invention

[0004] To address the shortcomings of the existing technologies, this invention provides a scattering parameter measurement device and method based on microwave photonic mixing. This device utilizes microwave photonic mixing technology and a local oscillator with a small bandwidth to down-convert a high-frequency microwave signal to a fixed-frequency intermediate frequency signal. This reduces the bandwidth requirements of the receiver's electronic components and the sampling rate requirements of the analog-to-digital converter. It abandons the traditional superheterodyne structure and / or direct conversion structure, and uses a miniaturized continuous optical module as the light source for microwave photonic mixing, simplifying the system structure and reducing cost and power consumption.

[0005] The technical solution of the present invention is as follows:

[0006] A scattering parameter measurement device based on microwave photonic mixing, characterized in that it comprises a microwave generating module 1, a signal loading module 2, a local oscillator frequency generating module 3, a multi-channel microwave photonic mixing module 4, an analog-to-digital converter module 5, and a signal processing module 6; along the signal output direction of the multi-channel microwave photonic mixing module 4, the analog-to-digital converter module 5 and the signal processing module 6 are arranged sequentially; the local oscillator signal output terminal of the local oscillator frequency generating module 3 is connected to the local oscillator input terminal of the multi-channel microwave photonic mixing module 4; the microwave signal output terminal of the microwave generating module 1 is connected to the input terminal of the signal loading module 2, and the output terminal of the signal loading module 2 is connected to the microwave input terminal of the multi-channel microwave photonic mixing module 4; two test ports of the signal loading module 2 are connected to the device under test; the output terminal of the signal processing module 6 is connected to the control terminals of the microwave generating module 1 and the local oscillator frequency generating module 3 respectively; the reference clock output by the local oscillator frequency generating module 3 is connected to the reference clock input terminals of the microwave generating module 1 and the analog-to-digital converter module 5 respectively.

[0007] Signal processing module 6 controls microwave generator module 1 and local oscillator frequency generator module 3 to generate frequencies f0 and f2 respectively. The signal, where n is a positive integer greater than 1, f pb The frequency of the intermediate frequency signal output by the multi-channel microwave photonic mixer module 4 is greater than 0 and less than the bandwidth of the back-end circuit.

[0008] The multi-channel microwave photonic mixing module 4 is characterized in that it is a three-channel microwave photonic mixing module or a four-channel microwave photonic mixing module.

[0009] When the multi-channel microwave photonic mixing module 4 is a three-channel microwave photonic mixing module, it specifically includes a continuous light source 4-1, a local oscillator modulator 4-2, an optical splitter 4-3, a reference branch modulator 4-4, a first test branch modulator 4-5, a second test branch modulator 4-6, and a photoelectric conversion module 4-7; the electrical analog-to-digital converter module 5 is composed of three parallel branches of electrical analog-to-digital converters; the output terminal of the continuous light source 4-1 is connected to the optical input terminal of the local oscillator modulator 4-2, and the radio frequency input terminal of the local oscillator modulator is the local oscillator input terminal, which is connected to the local oscillator signal output of the local oscillator frequency generation module 3. The output terminals are connected; the output terminal of the local oscillator modulator 4-2 is connected to the input terminal of the optical splitter 4-3, which is divided into three output terminals, which are respectively connected to the optical input terminals of the reference branch modulator 4-4, the first test branch modulator 4-5, and the second test branch modulator 4-6. The radio frequency input terminals of these three modulators are microwave input terminals. The output terminals of the three modulators are respectively connected to the input terminals of the corresponding branches of the photoelectric converters in the photoelectric conversion module 4-7. The output terminals of the three photoelectric converters are respectively connected to the input terminals of the corresponding branches of the analog-to-digital converters in the analog-to-digital converter module 5.

[0010] When the multi-channel microwave photonic mixing module 4 is a four-channel microwave photonic mixing module, it specifically includes a continuous light source 4-1, a local oscillator modulator 4-2, an optical splitter 4-3, a first reference branch modulator 4-4, a first test branch modulator 4-5, a second reference branch modulator 4-7, a second test branch modulator 4-6, and a photoelectric conversion module 4-8; the photoelectric conversion module 4-8 is composed of an analog-to-digital converter with four parallel branches; the output terminal of the continuous light source 4-1 is connected to the optical input terminal of the local oscillator modulator 4-2, and the radio frequency input terminal of the local oscillator modulator 4-2 is the local oscillator input terminal, which generates a frequency with the local oscillator. The local oscillator signal output terminal of module 3 is connected; the output terminal of the local oscillator modulator 4-2 is connected to the input terminal of the optical splitter 4-3, which is divided into four output terminals, which are respectively connected to the optical input terminals of the first reference branch modulator 4-4, the first test branch modulator 4-5, the second reference branch modulator 4-7, and the second test branch modulator 4-6. The output terminals of the four modulators are respectively connected to the input terminals of the corresponding branches of the photoelectric converters in the photoelectric conversion module 4-8, and the output terminals of the four photoelectric converters are respectively connected to the input terminals of the corresponding branches of the analog-to-digital converters in the analog-to-digital converter module 5.

[0011] A device and method for measuring scattering parameters based on microwave photonic mixing, characterized in that, taking a three-channel structure as an example, the method includes the following steps:

[0012] 1) Connect the two ports of the device under test to test port one and test port two of signal loading module 2 respectively;

[0013] 2) Set the test frequency range as: f min ~f max With a resolution of Δf, the number of sampling points for each channel of the analog-to-digital converter module 5 is n. s Let f0 = f min ;

[0014] 3) The signal processing module 6 controls the microwave generating module 1 to generate a single-frequency signal with a frequency of f0. The single-frequency signal is incident on the device under test through the signal loading module 2. The signal loading module 2 inputs the single-frequency signal, the transmission signal of the device under test to the single-frequency signal, and the reflection signal into the radio frequency input terminals of the reference branch modulator 4-4, the second test branch modulator 4-5, and the first test branch modulator 4-6, respectively.

[0015] 4) The signal processing module 6 controls the local oscillator frequency generation module 3 to generate a frequency of... The single-frequency local oscillator signal is input to the radio frequency input terminal of the local oscillator modulator 4-2;

[0016] 5) The analog-to-digital converter module 5 converts the frequency output of the multi-channel microwave photonic mixer module 4 to f. pb The signal is converted from analog to digital to obtain the corresponding digital signal. The signal processing module 6 processes the digital signal and calculates the scattering parameters of the device under test at frequency point f0.

[0017] 6) Let f0 = f0 + Δf, when f0 ≤ f max (Return to step 3); otherwise proceed to the next step.

[0018] 7) Switch the connection direction of the device under test in signal loading module 2, and repeat steps 3)-6) to calculate a pair of scattering parameters of the device under test when it is excited in the opposite direction;

[0019] 8) Calibrate the two pairs of scattering parameters measured according to the existing calibration parameters and corresponding calibration methods.

[0020] Based on the above technical features, the present invention has the following advantages:

[0021] This invention provides a scattering parameter measurement device and method based on microwave photonic mixing. The device utilizes microwave photonic mixing technology and a local oscillator with a small bandwidth to down-convert a high-frequency microwave signal to a fixed-frequency intermediate frequency signal. This reduces the bandwidth requirements of the receiver's electronic components and the sampling rate requirements of the analog-to-digital converter. It abandons the traditional superheterodyne structure and / or direct conversion structure, and uses a miniaturized continuous optical module as the light source for microwave photonic mixing, simplifying the system structure and reducing cost and power consumption. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the module structure of the scattering parameter measurement device based on microwave photonic mixing according to the present invention.

[0023] Figure 2 This is a schematic diagram of the three-channel structure of the multi-channel microwave photonic mixing module of the present invention.

[0024] Figure 3 This is a schematic diagram of the four-channel structure of the multi-channel microwave photonic mixing module of the present invention.

[0025] Figure 4 This is a schematic diagram illustrating the principle of microwave photonic mixing in this invention.

[0026] Figure 5 This is a schematic diagram of the structure of Embodiment 1 of the scattering parameter measurement device based on microwave photonic mixing of the present invention.

[0027] Figure 6 This is a schematic diagram of the structure of Embodiment 2 of the scattering parameter measurement device based on microwave photonic mixing of the present invention. Detailed Implementation

[0028] The following detailed description is provided with reference to embodiments of the present invention: These embodiments are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention.

[0029] Please see, Figure 1 This is a schematic diagram of the scattering parameter measurement device based on microwave photonic mixing according to the present invention. As shown in the figure, a scattering parameter measurement device based on microwave photonic mixing includes a microwave generating module 1, a signal loading module 2, a local oscillator frequency generating module 3, a multi-channel microwave photonic mixing module 4, an analog-to-digital converter module 5, and a signal processing module 6. Along the signal output direction of the multi-channel microwave photonic mixing module 4, the analog-to-digital converter module 5 and the signal processing module 6 are sequentially connected. The local oscillator signal output terminal of the local oscillator frequency generating module 3 is connected to the local oscillator input terminal of the multi-channel microwave photonic mixing module 4. The microwave signal output terminal of the microwave generating module 1 is connected to the input terminal of the signal loading module 2, and the output terminal of the signal loading module 2 is connected to the microwave input terminal of the multi-channel microwave photonic mixing module 4. The two test ports of the signal loading module 2 are connected to the device under test. The output terminal of the signal processing module 6 is connected to the control terminals of the microwave generating module 1 and the local oscillator frequency generating module 3, respectively. The reference clock output by the local oscillator frequency generating module 3 is connected to the reference clock input terminals of the microwave generating module 1 and the analog-to-digital converter module 5, respectively.

[0030] Example 1:

[0031] Figure 5 This is a schematic diagram of the structure of Embodiment 1 of the scattering parameter measurement device based on microwave photonic mixing of the present invention. As shown in the figure, a scattering parameter measurement device based on microwave photonic mixing includes a microwave generating module 1, a signal loading module 2, a local oscillator frequency generating module 3, a multi-channel microwave photonic mixing module 4, an analog-to-digital converter module 5, and a signal processing module 6. Along the signal output direction of the multi-channel microwave photonic mixing module 4, the analog-to-digital converter module 5 and the signal processing module 6 are sequentially connected. The local oscillator signal output terminal of the local oscillator frequency generating module 3 is connected to the local oscillator input terminal of the multi-channel microwave photonic mixing module 4. The microwave signal output terminal of the microwave generating module 1 is connected to the input terminal of the signal loading module 2, and the output terminal of the signal loading module 2 is connected to the microwave input terminal of the multi-channel microwave photonic mixing module 4. The two test ports of the signal loading module 2 are connected to the device under test. The output terminal of the signal processing module 6 is connected to the control terminals of the microwave generating module 1 and the local oscillator frequency generating module 3, respectively. The reference clock output by the local oscillator frequency generating module 3 is connected to the reference clock input terminals of the microwave generating module 1 and the analog-to-digital converter module 5, respectively.

[0032] The multi-channel microwave photonic mixing module 4 includes a continuous light source 4-1, a local oscillator modulator 4-2, an optical splitter 4-3, a reference branch modulator 4-4, a first test branch modulator 4-5, a second test branch modulator 4-6, and a photoelectric conversion module 4-7. The output of the continuous light source 4-1 is connected to the optical input of the local oscillator modulator 4-2. The radio frequency input of the local oscillator modulator is the local oscillator input. The output of the local oscillator modulator 4-2 is connected to the input of the optical splitter 4-3. The optical splitter has three outputs, which are respectively connected to the optical inputs of the reference branch modulator 4-4, the first test branch modulator 4-5, and the second test branch modulator 4-6. The radio frequency inputs of these three modulators are microwave inputs. The outputs of the three modulators are respectively connected to the inputs of the photoelectric converters of the corresponding branches in the photoelectric conversion module 4-7.

[0033] This embodiment of the signal loading module 2 includes: a power divider 2-1, a microwave switch 2-2, a first directional coupler 2-3, and a second directional coupler 2-4. The input terminal of the power divider 2-1 is connected to the output terminal of the microwave generating module 1, and the power divider 2-1 has two output terminals. One output terminal is connected to the input terminal of the microwave switch 2-2, which is divided into two output terminals. The first output terminal ① is connected to the input terminal of the first directional coupler 2-3, and one output terminal of the first directional coupler 2-3 is the test port 1 of the signal loading module 2, which is connected to one end of the device under test. The other output terminal of the first directional coupler 2-3 is connected to the RF input terminal of the first test branch modulator 4-5; the second output terminal ② of the microwave switch 2-2 is connected to the input terminal of the second directional coupler 2-4; one output terminal of the second directional coupler 2-4 is the test port two of the signal loading module, connected to the other end of the device under test; the other output terminal of the second directional coupler 2-4 is connected to the RF input terminal of the second test branch modulator 4-6; the other output terminal of the power divider 2-1 is connected to the RF input terminal of the reference branch modulator 4-4.

[0034] The reference clock 1 and reference clock 2 output by the local oscillator frequency generation module 3 are respectively connected to the reference clock input terminals of the microwave generation module 1 and the analog-to-digital converter module 5; the signal processing module 6 is connected to the control terminals of the microwave generation module 1 and the local oscillator frequency generation module 3.

[0035] The testing process in this embodiment includes the following steps:

[0036] 1) Connect the two ports of the device under test to test port one and test port two of signal loading module 2 respectively;

[0037] 2) Set the test frequency range as: fmin ~f max The resolution is Δf, and the number of sampling points for each channel of the analog-to-digital converter module (5) is n. s Let f0 = f min ;

[0038] 3) The signal processing module 6 controls the microwave generating module 1 to generate a single-frequency signal with a frequency of f0. The single-frequency signal is incident on the device under test through the signal loading module (2). The signal loading module 2 inputs the single-frequency signal, the transmission signal of the device under test to the single-frequency signal, and the reflection signal of the device under test to the radio frequency input terminals of the reference branch modulator 4-4, the second test branch modulator 4-5, and the first test branch modulator 4-6, respectively.

[0039] 4) The signal processing module 6 controls the local oscillator frequency generation module 3 to generate a frequency of... The single-frequency local oscillator signal is input to the radio frequency input terminal of the local oscillator modulator 4-2;

[0040] 5) The analog-to-digital converter module 5 converts the frequency output of the multi-channel microwave photonic mixer module 4 to f. pb The signal is converted from analog to digital to obtain the corresponding digital signal. The signal processing module 6 processes the digital signal and calculates the scattering parameters of the device under test at frequency point f0.

[0041] 6) Let f0 = f0 + Δf, when f0 ≤ f max (Return to step 3); otherwise proceed to the next step.

[0042] 7) Switch microwave switch 2-2 and repeat steps 3)-6) to calculate a pair of scattering parameters of the device under test under reverse excitation;

[0043] 8) Calibrate the two pairs of scattering parameters measured according to the existing calibration parameters and corresponding calibration methods.

[0044] Example 2:

[0045] Figure 6This is a schematic diagram of the structure of Embodiment 2 of the scattering parameter measurement device based on microwave photonic mixing of the present invention. As shown in the figure, the difference between this embodiment 2 and embodiment 1 is that the multi-channel microwave photonic mixing module 4 includes a continuous light source 4-1, a local oscillator modulator 4-2, an optical splitter 4-3, a first reference branch modulator 4-4, a first test branch modulator 4-5, a second reference branch modulator 4-6, a second test branch modulator 4-7, and a photoelectric conversion module 4-8. The output end of the continuous light source 4-1 is connected to the optical input end of the local oscillator modulator 4-2. The radio frequency input end of the local oscillator modulator is the local oscillator input end. The output end of the local oscillator modulator 4-2 is connected to the input end of the optical splitter 4-3. The optical splitter is divided into four output ends, which are respectively connected to the optical input ends of the first reference branch modulator 4-4, the first test branch modulator 4-5, the second reference branch modulator 4-6, and the second test branch modulator 4-7. The radio frequency input ends of these four modulators are microwave input ends. The output ends of the four modulators are respectively connected to the input ends of the photoelectric converters of the corresponding branches in the photoelectric conversion module 4-8.

[0046] The signal loading module 2 includes: a microwave switch 2-1, a first power divider 2-2, a first directional coupler 2-3, a second power divider 2-5, and a second directional coupler 2-4. The input terminal of the microwave switch 2-1 is connected to the output terminal of the microwave generating module 1. The microwave switch 2-1 has two output terminals: the first output terminal ① is connected to the input terminal of the first power divider 2-2. The first power divider 2-2 has two output terminals: one output terminal is connected to the input terminal of the first directional coupler 2-3. One output terminal of the first directional coupler 2-3 is the test port 1 of the signal loading module 2, connected to one end of the device under test. The other output terminal of the first directional coupler 2-3 is connected to the first test branch modulator 4-5. The RF input terminal of the first power divider 2-2 is connected to the RF input terminal of the first reference branch modulator 4-4; the second output terminal ② of the microwave switch 2-1 is connected to the input terminal of the second fixed power divider 2-5. The second power divider 2-5 is divided into two output terminals: one output terminal is connected to the input terminal of the second directional coupler 2-4, one output terminal of the second directional coupler 2-4 is the test port two of the signal loading module 2, and is connected to the other end of the device under test; the other output terminal of the second directional coupler 2-4 is connected to the RF input terminal of the second test branch modulator 4-7; and the other output terminal of the second power divider 2-5 is connected to the RF input terminal of the second reference branch modulator 4-6.

[0047] The output terminal of the local oscillator frequency generation module 3 is connected to the radio frequency input terminal of the local oscillator modulator 4-2. The reference clock 1 and reference clock 2 output by the local oscillator frequency generation module 3 are respectively connected to the reference clock input terminals of the microwave generation module 1 and the analog-to-digital converter module 5. The signal processing module 6 is connected to the control terminals of the microwave generation module 1 and the local oscillator frequency generation module 3.

[0048] The testing process in this embodiment includes the following steps:

[0049] 1) Connect the two ports of the device under test to test port one and test port two of signal loading module 2 respectively;

[0050] 2) Set the test frequency range as: f min ~f max The resolution is Δf, and the number of sampling points for each channel of the analog-to-digital converter module (5) is n. s Let f0 = f min ;

[0051] 3) The signal processing module 6 controls the microwave generating module 1 to generate a single-frequency signal with a frequency of f0. The single-frequency signal is incident on the device under test through the signal loading module (2). The signal loading module 2 inputs the single-frequency signal, the transmission signal of the device under test to the single-frequency signal, and the reflection signal of the device under test to the radio frequency input terminals of the reference branch modulator 4-4, the second test branch modulator 4-5, and the first test branch modulator 4-6, respectively.

[0052] 4) The signal processing module 6 controls the local oscillator frequency generation module 3 to generate a frequency of... The single-frequency local oscillator signal is input to the radio frequency input terminal of the local oscillator modulator 4-2;

[0053] 5) The analog-to-digital converter module 5 converts the frequency output of the multi-channel microwave photonic mixer module 4 to f. pb The signal is converted from analog to digital to obtain the corresponding digital signal. The signal processing module 6 processes the digital signal and calculates the scattering parameters of the device under test at frequency point f0.

[0054] 6) Let f0 = f0 + Δf, when f0 ≤ f max (Return to step 3); otherwise proceed to the next step.

[0055] 7) Switch microwave switches 2-3 and repeat steps 3)-6) to calculate a pair of scattering parameters of the device under test under reverse excitation;

[0056] 8) Calibrate the two pairs of scattering parameters measured according to the existing calibration parameters and corresponding calibration methods.

[0057] Experiments show that this invention utilizes microwave photonic mixing technology and a local oscillator with a smaller bandwidth to downconvert high-frequency microwave signals to intermediate frequency signals of a fixed frequency. This reduces the bandwidth requirements of receiver electronic devices and the sampling rate requirements of the analog-to-digital converter. It abandons the traditional superheterodyne structure and / or direct conversion structure, and uses a miniaturized continuous optical module as the light source for microwave photonic mixing, simplifying the system structure and reducing cost and power consumption.

Claims

1. A microwave photon mixing based scattering parameter measurement device, comprising a microwave generation module, a signal loading module, a local oscillator frequency generation module, a multi-channel microwave photon mixing module, an electric analog-digital conversion module and a signal processing module; along the signal output direction of the multi-channel microwave photon mixing module, the electric analog-digital conversion module and the signal processing module are sequentially arranged; the local oscillator signal output end of the local oscillator frequency generation module is connected with the local oscillator input end of the multi-channel microwave photon mixing module; the microwave signal output end of the microwave generation module is connected with the input end of the signal loading module, and the output end of the signal loading module is connected with the microwave input end of the multi-channel microwave photon mixing module; the two test ports of the signal loading module are connected with a device to be measured; the output end of the signal processing module is respectively connected with the control end of the microwave generation module and the local oscillator frequency generation module; the reference clock output by the local oscillator frequency generation module is respectively connected with the reference clock input end of the microwave generation module and the electric analog-digital conversion module; characterized in that, The signal processing module controls the microwave generating module and the local frequency generating module to generate signals with frequencies of and respectively, wherein, is a positive integer greater than 1, is the frequency of the intermediate frequency signal output by the multi-channel microwave photon mixing module, greater than 0 and less than the bandwidth of the backend circuit; when the multi-channel microwave photon mixing module is a three-channel microwave photon mixing module, it specifically comprises a continuous light source, a local modulation device, an optical splitter, a reference branch modulation device, a first test branch modulation device, a second test branch modulation device, and an optical-electric conversion module; the electric analog-digital conversion module is composed of three parallel branch electric analog-digital converters; the output end of the continuous light source is connected with the optical input end of the local modulation device, the radio frequency input end of the local modulation device is the local input end, and is connected with the local signal output end of the local frequency generating module; the output end of the local modulation device is connected with the input end of the optical splitter, the optical splitter is divided into three output ends, and is connected with the optical input ends of the reference branch modulation device, the first test branch modulation device, and the second test branch modulation device respectively; the radio frequency input ends of the three modulation devices are microwave input ends, the output ends of the three modulation devices are connected with the input ends of the optical-electric converters in the corresponding branches of the optical-electric conversion module respectively, and the output ends of the three optical-electric converters are connected with the input ends of the electric analog-digital converters in the corresponding branches of the electric analog-digital conversion module respectively.

2. A microwave photon mixing based scattering parameter measurement device, comprising a microwave generation module, a signal loading module, a local oscillator frequency generation module, a multi-channel microwave photon mixing module, an electric analog-digital conversion module and a signal processing module; along the signal output direction of the multi-channel microwave photon mixing module, the electric analog-digital conversion module and the signal processing module are sequentially arranged; the local oscillator signal output end of the local oscillator frequency generation module is connected with the local oscillator input end of the multi-channel microwave photon mixing module; the microwave signal output end of the microwave generation module is connected with the input end of the signal loading module, and the output end of the signal loading module is connected with the microwave input end of the multi-channel microwave photon mixing module; the two test ports of the signal loading module are connected with a device to be measured; the output end of the signal processing module is respectively connected with the control end of the microwave generation module and the local oscillator frequency generation module; the reference clock output by the local oscillator frequency generation module is respectively connected with the reference clock input end of the microwave generation module and the electric analog-digital conversion module, characterized in that, The signal processing module controls the microwave generating module and the local frequency generating module to generate signals with frequencies of and respectively, wherein, is a positive integer greater than 1, is the frequency of the intermediate frequency signal output by the multi-channel microwave photon mixing module, greater than 0 and less than the bandwidth of the backend circuit; when the multi-channel microwave photon mixing module is a four-channel microwave photon mixing module, it specifically comprises a continuous light source, a local modulation device, an optical splitter, a first reference branch modulator, a first test branch modulator, a second reference branch modulator, a second test branch modulator, and an optical-electric conversion module; the optical-electric conversion module is composed of four parallel branches of electric analog-digital converters; the output end of the continuous light source is connected to the optical input end of the local modulation device, the radio frequency input end of the local modulation device is the local input end, and is connected to the local signal output end of the local frequency generating module; the output end of the local modulation device is connected to the input end of the optical splitter, which is divided into four output ends and connected to the optical input ends of the first reference branch modulator, the first test branch modulator, the second reference branch modulator, and the second test branch modulator respectively; the output ends of the four modulators are connected to the input ends of the corresponding optical-electric converters in the optical-electric conversion module respectively, and the output ends of the four optical-electric converters are connected to the input ends of the corresponding electric analog-digital converters in the electric analog-digital conversion module respectively.

3. A method based on the microwave photonic mixing based scatterometry apparatus of claim 1 or 2, characterized in that, The method comprises the following steps: 1) connecting two ports of the device under test to test port one and test port two of the signal loading module respectively; 2) Set the test frequency range as: , the resolution is , the sampling points of each channel of the electric analog-digital converter module are , let ; 3) the signal processing module controls the microwave generating module to generate a single frequency signal with a frequency of The single frequency signal is incident on the device under test through the signal loading module, which inputs the single frequency signal, the transmission signal and the reflection signal of the device under test into the RF input end of the reference branch modulator, the second test branch modulator and the first test branch modulator, respectively. 4) the signal processing module controls the local frequency generation module to generate a single-frequency local signal with a frequency of the single-frequency local signal is input to the RF input end of the local modulator; 5) The analog-to-digital converter module converts the frequency output of the multi-channel microwave photonic mixer module to... The signal is converted from analog to digital to obtain a corresponding digital signal. The signal processing module processes the digital signal and calculates the frequency of the device under test. scattering parameters; 6) Let , when , go to step 3); otherwise go to next step; 7) switching the connection direction of the device under test in the signal loading module, and repeating steps 3)-6) to calculate a pair of scattering parameters of the device under test under reverse excitation; 8) calibrating the two pairs of measured scattering parameters according to the existing calibration parameters and the corresponding calibration method.

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