Vector measurement system, method and application for phased array chip calibration

Abstract

This application provides a vector measurement system, method, and application for phased array chip calibration. The vector measurement system includes: a frequency output device for generating a first local oscillator signal, a second local oscillator signal, and a third local oscillator signal; a terahertz light source for receiving the second local oscillator signal and radiating terahertz waves after frequency doubling and amplification; a receiver for receiving the third local oscillator signal and using it as a fourth local oscillator signal after frequency doubling and amplification, wherein the fourth local oscillator signal is mixed with the terahertz signal to generate an intermediate frequency (IF) signal; an IQ demodulator for receiving the IF signal and the first local oscillator signal and demodulating them to obtain an output signal; and a wave-absorbing device disposed between the receiver and the terahertz light source to prevent unmodulated terahertz waves from aliasing with the terahertz signal and entering the receiver. The vector measurement system of this application has a simpler design and can effectively avoid measurement errors caused by signal aliasing.

Description

Technical Field

[0001] This application relates to the fields of micro / nano fabrication and terahertz measurement, and more particularly to vector measurement systems, methods and applications for phased array chip calibration. Background Technology

[0002] With the continuous development of communication technology, commercial spectrum has gradually expanded to millimeter waves, and terahertz will be applied to next-generation communication systems. However, as the carrier frequency increases, the path attenuation of electromagnetic waves intensifies, while the saturation output power of devices decreases, leading to a reduction in the operating distance of terahertz communication systems. To overcome this challenge, phased array technology is widely used in practical applications. Phased array technology can not only increase the directivity of electromagnetic wave radiation but also increase the total output power of the system, thereby significantly improving the system's operating distance. Accurate calibration of phased array chips is a prerequisite for ensuring their effective operation in practical applications; only after calibration can phased array chips be reliably applied to various systems.

[0003] Currently, commonly used phased array chip calibration methods are mainly divided into two categories: direct calibration and indirect calibration. Direct calibration uses a vector network analyzer (VNA) to analyze the amplitude and phase information of the network input and output signals to obtain the amplitude and phase modulation characteristics of the phased array chip. This method is the main method for calibrating low-frequency phased array systems, characterized by high accuracy and efficiency. However, in the terahertz band, a combination of VNA and a frequency extension module is required to complete the measurement. This increases the complexity of the link and exacerbates path parasitic effects, leading to numerous measurement errors. For example, parasitic capacitance can cause feedback paths in the terahertz signal, resulting in self-oscillation. Indirect calibration uses a superheterodyne RF link, employing one terahertz signal as the reference light and another as the measurement light. By comparing the amplitude and phase information of the reference and measurement lights, the amplitude and phase modulation characteristics of the phased array chip can be obtained. However, VNA measurement or superheterodyne measurement link measurements in related technologies suffer from problems such as complex optical and RF link designs and measurement errors caused by signal aliasing.

[0004] Based on this, this application provides a vector measurement system, method, and related equipment for phased array chip calibration. Summary of the Invention

[0005] To address the problems existing in the prior art, this application provides a vector measurement system, method, and application for phased array chip calibration.

[0006] The objective of this application is achieved through the following technical solution:

[0007] In a first aspect, this application provides a vector measurement system for calibrating a phased array chip, the system comprising:

[0008] A frequency output device, wherein the frequency output device is used to generate a first local oscillator signal, a second local oscillator signal and a third local oscillator signal;

[0009] A terahertz light source is used to receive the second local oscillator signal and radiate terahertz waves after frequency doubling and amplification. The terahertz waves are used to generate terahertz signals after being modulated by the phased array chip under test.

[0010] A receiver is used to receive the third local oscillator signal and the terahertz signal. The third local oscillator signal is amplified by frequency multiplication to become the fourth local oscillator signal. The fourth local oscillator signal is mixed with the terahertz signal to generate an intermediate frequency signal and output it.

[0011] An IQ demodulator is used to receive the intermediate frequency signal and the first local oscillator signal and demodulate them to obtain an output signal. The output signal is used to obtain the amplitude modulation characteristics and phase modulation characteristics of the phased array chip under test.

[0012] An absorbing device is disposed between the receiver and the terahertz light source to prevent unmodulated terahertz waves from aliasing with the terahertz signal and entering the receiver.

[0013] In some possible implementations, the frequency output device is a frequency synthesizer; or, the frequency output device includes a function generator and a microwave source, the function generator being used to generate a reference signal and a first local oscillator signal, and the microwave source being used to receive and generate a second local oscillator signal and a third local oscillator signal based on the reference signal; the reference signal and the first local oscillator signal are phase-synchronized.

[0014] In some possible implementations, the terahertz light source is used to receive the second local oscillator signal and, after frequency doubling and amplification, radiate terahertz waves through a horn.

[0015] In some possible implementations, the first local oscillator signal and the intermediate frequency signal have the same frequency.

[0016] In some possible implementations, the reference signal is a 10 MHz signal.

[0017] In some possible implementations, the phased array chip under test is placed on a displacement stage, and the system further includes an off-axis parabolic mirror disposed between the terahertz light source and the phased array chip under test, for focusing the terahertz wave onto the target array element of the phased array chip under test.

[0018] In some possible implementations, the system further includes a beam splitter disposed in the optical path between the phased array chip under test and the receiver, for separating the terahertz signal from the unmodulated terahertz wave.

[0019] Secondly, this application also provides a calibration method for a phased array chip based on the vector measurement system according to any one of the first aspects, the method comprising:

[0020] Perform calibration of the vector measurement system;

[0021] Based on the actual measured frequency points, set the output frequency and level of the first local oscillator signal of the frequency output device, and set the output frequency and power of the second and third local oscillator signals;

[0022] The output signal of the IQ demodulator is acquired and processed to obtain the amplitude modulation characteristics and phase modulation characteristics of the phased array chip under test.

[0023] In some possible implementations, the calibration of the vector measurement system includes: performing displacement calibration and time stability calibration of the vector measurement system.

[0024] Thirdly, this application also provides an electronic device including one or more processors and a memory; one or more programs are stored in the memory and configured to be executed by the one or more processors according to any one of the second aspects.

[0025] Fourthly, this application also provides a computer-readable storage medium having instructions stored thereon that, when executed by a processor, cause the processor to perform the method as described in any of the second aspects.

[0026] Fifthly, this application also provides a computer program product comprising a computer program that, when executed by at least one processor, implements the steps of the method described in any of the second aspects.

[0027] Compared with the prior art, this application has at least the following beneficial effects:

[0028] (1) The vector measurement system provided in this application includes a frequency output device, a terahertz light source, a receiver, an IQ demodulator and an absorbing device, which reduces the complexity of the link and makes the system design simpler.

[0029] (2) By setting up an absorbing device between the receiver and the terahertz light source, this application can effectively prevent unmodulated terahertz waves from aliasing with terahertz signals and entering the receiver, thereby avoiding measurement errors caused by signal aliasing. Attached Figure Description

[0030] The present application will be further described below with reference to the accompanying drawings and embodiments.

[0031] Figure 1 This is a schematic diagram of the structure of a vector measurement system provided in an embodiment of this application.

[0032] Figure 2 This is a schematic diagram of another vector measurement system provided in an embodiment of this application.

[0033] Figure 3 This is a schematic diagram of the phase calibration results of the vector measurement system provided in the embodiments of this application.

[0034] Figure 4 This is a schematic diagram of the amplitude calibration results of the vector measurement system provided in the embodiments of this application.

[0035] Figure 5 This is a schematic diagram of the time stability of the vector measurement system provided in the embodiments of this application.

[0036] Figure 6 This is a schematic diagram of the amplitude modulation characteristics and phase modulation characteristics measured by the vector measurement system provided in the embodiments of this application.

[0037] Figure 7 This is a flowchart illustrating a vector measurement method provided in an embodiment of this application.

[0038] Figure 8 This is a structural diagram of an electronic device provided in an embodiment of the present application. Detailed Implementation

[0039] The present application will now be further described in conjunction with the accompanying drawings and specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments. The implementation process of the present application will be described below with reference to the accompanying drawings and preferred embodiments. Those skilled in the art can easily understand other advantages and effects of the present application from the content disclosed in this specification. The present application can also be implemented or applied through other different specific implementation procedures, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present application. It should be understood that the preferred embodiments are only for illustrating the present application and not for limiting the scope of protection of the present application.

[0040] The technical field of the embodiments of this application will be briefly described below to facilitate understanding by those skilled in the art.

[0041] Phased array chips are a product of micro- and nano-manufacturing technologies, typically composed of micrometer- or nanometer-scale components, and capable of operating in the terahertz frequency band. The vector measurement system protected in this application can be used for quality control and performance testing during the micro- and nano-manufacturing process.

[0042] The relevant technologies employ VNA (Vibration Array Array) measurement, which presents the following challenges: 1. Measurement Frequency: Commercially available VNAs operate at a maximum frequency of 110 GHz, with 60 GHz being the most commonly purchased frequency. Therefore, higher-frequency terahertz vector measurements cannot be directly performed. While adding a frequency extension module can increase the VNA's measurement frequency, compatibility issues exist between the extension module and the VNA device. Typically, the presence of high-frequency parasitic capacitance creates a feedback path, generating self-excited signals that manifest as spikes and glitches in the scattering parameters, affecting measurement accuracy. 2. Calibration Error: Measurement accuracy is significantly affected by calibration precision. When measuring phased array chips, the RF signal path couples from the coaxial line to free space, and the lack of appropriate calibration components leads to substantial measurement errors. 3. Dynamic Range: VNAs have limited dynamic range, particularly in terms of maximum output power. VNAs are designed for small-signal measurements and therefore cannot perform vector measurements of large-signal electromagnetic fields. Based on this, a superheterodyne measurement link can be used.

[0043] However, the applicant found the following shortcomings in using superheterodyne measurement links: 1. Link complexity: Currently disclosed terahertz superheterodyne measurement links are quite complex. As an example, the terahertz beam optical field vector spatial distribution measurement method and test system disclosed in application number CN202310185159.4 adopts a dual-local oscillator architecture, that is, using a power divider to separate one signal from the local oscillator path and the RF path as the reference signal for IQ demodulation. The characteristic of this architecture is its strong universality; different types and different phase noise levels of microwave sources can use this architecture. However, the link is complex and the measurement accuracy is generally low. In other words, in the superheterodyne measurement link of related technologies, the IQ local oscillator signal link greatly increases the link complexity and increases hardware costs; and low-frequency noise signals are easily coupled into the IQ demodulator through this link, affecting the measurement accuracy; the IQ local oscillator link is separated from the microwave source, and the spectrum contains the phase noise of the two microwave sources, resulting in relatively large phase noise, thus the measurement accuracy is generally low. In addition, the terahertz superheterodyne vector measurement link in the related technology does not consider the measurement error caused by background signal aliasing, nor does it consider the measurement error caused by reference signal phase noise.

[0044] Based on this, this application provides a vector measurement system, method, and related equipment for phased array chip calibration, which is simpler, more flexible and reconfigurable, and more accurate. Simplicity is reflected in the design of the optical path and RF link; for example, compared to previously published patents, the technical solution provided in this application is simpler. Flexibility and reconfigurability refer to the fact that the equipment and optical components in the system can be replaced according to measurement requirements, such as IQ demodulators, AFGs, terahertz light sources, and terahertz receivers. High accuracy refers to the fact that this application improves IQ demodulation accuracy by suppressing background terahertz signals and low phase noise reference signals through an absorption device. The system will be described first, followed by the method, etc., in the following description.

[0045] System Implementation Example.

[0046] See Figure 1 and Figure 2 , Figure 1 This is a schematic diagram of the structure of a vector measurement system provided in an embodiment of this application. Figure 2 This is a schematic diagram of another vector measurement system provided in this application embodiment, illustrating the test optical path for a single element of a phased array chip.

[0047] This application provides a vector measurement system for phased array chip calibration, the system comprising:

[0048] A frequency output device, wherein the frequency output device is used to generate a first local oscillator signal, a second local oscillator signal and a third local oscillator signal;

[0049] A terahertz light source is used to receive the second local oscillator signal and, after frequency multiplication and amplification, radiate terahertz waves through a horn. The terahertz waves are used to generate terahertz signals after being modulated by the phased array chip under test.

[0050] A receiver is used to receive the third local oscillator signal and the terahertz signal. The third local oscillator signal is amplified by frequency multiplication to become the fourth local oscillator signal. The fourth local oscillator signal is mixed with the terahertz signal to generate an intermediate frequency signal and output it.

[0051] An IQ demodulator is used to receive the intermediate frequency signal and the first local oscillator signal and demodulate them to obtain an output signal. The output signal is used to obtain the amplitude modulation characteristics and phase modulation characteristics of the phased array chip under test.

[0052] An absorbing device is disposed between the receiver and the terahertz light source to prevent unmodulated terahertz waves from aliasing with the terahertz signal and entering the receiver.

[0053] In the technical solution provided in this embodiment, the frequency output device is responsible for generating three local oscillator signals: a first local oscillator signal, a second local oscillator signal, and a third local oscillator signal. A terahertz light source receives the second local oscillator signal, amplifies it by frequency multiplication, and then radiates a terahertz wave through a horn. The terahertz wave is used to interact with the phased array chip under test, generating a terahertz signal through modulation. This can be understood as the terahertz wave being modulated by the phased array chip, changing its amplitude and phase according to the chip's characteristics to generate a terahertz signal carrying chip characteristic information. Simultaneously, the receiver receives the third local oscillator signal and amplifies it by frequency multiplication to obtain the fourth local oscillator signal. The fourth local oscillator signal is mixed with the terahertz signal modulated by the phased array chip to generate an intermediate frequency (IF) signal. An IQ demodulator receives the IF signal and the first local oscillator signal and performs demodulation. The demodulated output signal contains the amplitude modulation and phase modulation characteristics of the phased array chip and is used to evaluate the chip's performance.

[0054] In addition, an absorbing device is installed between the receiver and the terahertz light source. Its function is to prevent the unmodulated terahertz waves from aliasing with the modulated terahertz signals and to prevent these unmodulated waves from entering the receiver, thereby avoiding interference with the measurement results.

[0055] Therefore, by using multiple local oscillator signals and IQ demodulators, the system can accurately measure the amplitude modulation and phase modulation characteristics of the phased array chip; the use of absorbing devices reduces the interference of unmodulated terahertz waves on the measurement, improving the system's stability and measurement accuracy; the system includes a frequency output device, a terahertz light source, a receiver, an IQ demodulator, and absorbing devices, reducing link complexity and making the system design simpler.

[0056] In practical applications, the system design allows for the replacement of components such as the frequency output device, terahertz light source, receiver, and IQ demodulator to adapt to different measurement needs and environments, enhancing the system's flexibility and reconfigurability. Compared to existing technologies, the system design provided in this application is simpler, reduces link complexity, lowers hardware costs, and improves the system's anti-interference capability.

[0057] In summary, this technical solution provides a high-precision, high-stability, flexible and reconfigurable terahertz phased array chip calibration vector measurement system, which can effectively evaluate the performance of phased array chips.

[0058] In some embodiments, the frequency output device is a frequency synthesizer; or, the frequency output device includes a function generator and a microwave source, the function generator being used to generate a reference signal and a first local oscillator signal, and the microwave source being used to receive and generate a second local oscillator signal and a third local oscillator signal according to the reference signal; the reference signal and the first local oscillator signal are phase-synchronized.

[0059] A frequency synthesizer is a device that generates precise frequency outputs, producing highly stable and accurate frequency signals suitable for applications requiring high-precision frequency control. In this case, the frequency synthesizer is responsible for generating the first local oscillator signal, the second local oscillator signal, and the third local oscillator signal.

[0060] In another embodiment, the frequency output device includes a function generator and a microwave source. The function generator generates a reference signal and a first local oscillator signal. The microwave source receives the reference signal generated by the function generator and generates a second local oscillator signal and a third local oscillator signal based on the reference signal.

[0061] Therefore, using a frequency synthesizer can provide a very high-precision and stable frequency output; by using a combination of a function generator and a microwave source, the system can flexibly adjust the output frequency to adapt to different measurement requirements and environmental conditions; the combination of the function generator and the microwave source ensures the synchronization and phase consistency between different local oscillator signals.

[0062] In some embodiments, the first local oscillator signal and the intermediate frequency signal have the same frequency; and / or, the reference signal is a 10MHz signal. The frequency of the first local oscillator signal is set to be the same as the frequency of the intermediate frequency signal to ensure that the IQ demodulator can effectively demodulate the intermediate frequency signal.

[0063] In some embodiments, the phased array chip under test is disposed on a displacement stage, and the system further includes an off-axis parabolic mirror disposed between the terahertz light source and the phased array chip under test, for converging the terahertz wave onto the target array element of the phased array chip under test.

[0064] This can be understood as the phased array chip under test being mounted on a displacement stage. The displacement stage precisely controls the chip's position and movement, which is crucial for adjusting the phased array chip's pointing and focus. The vector measurement system also includes one or more off-axis parabolic mirrors, positioned between the terahertz light source and the phased array chip under test. An off-axis parabolic mirror is an optical element designed to reflect and focus the incident terahertz wave onto a specific point, i.e., the target array element.

[0065] The terahertz waves generated by the terahertz light source are reflected and focused by the off-axis parabolic mirror and precisely converged onto the target element of the phased array chip under test. This ensures that the energy of the terahertz waves is concentrated on a specific part of the chip, thus enabling precise testing and analysis of a single element or a small number of elements.

[0066] Therefore, by using a displacement stage and an off-axis parabolic mirror, the system can precisely control the focusing position of the terahertz wave, enabling accurate testing of individual elements of a phased array chip.

[0067] In some embodiments, the system further includes a beam splitter disposed in the optical path between the phased array chip under test and the receiver, for separating the terahertz signal from the unmodulated terahertz wave.

[0068] A beam splitter is an optical element that can split an incident light wave into two or more beams, typically one beam being transmitted and the other one or more beams being reflected. In this case, the beam splitter is placed in the optical path between the phased array chip under test (TAD) and the receiver, allowing the terahertz wave to be refracted towards the TAD chip. The terahertz signal generated by the TAD chip after modulation is transmitted through the beam splitter to the receiver. Other off-axis parabolic mirrors can also be placed in the optical path after the terahertz signal has passed through the beam splitter to reflect the light, with the aim of transmitting the terahertz signal to the receiver.

[0069] Because beam splitters need to be able to distinguish between modulated signals and raw terahertz waves, they can ensure that they do not mix and reach the receiver. Furthermore, unmodulated terahertz waves are reflected or absorbed by the beam splitter, preventing them from continuing along the optical path to the receiver. This avoids unmodulated waves interfering with the measurement results of the modulated signal.

[0070] Therefore, the use of a beam splitter can effectively separate the modulated and unmodulated signals, thereby avoiding interference from the unmodulated signal on the measurement results and improving measurement accuracy. By ensuring that only the modulated signal is transmitted to the receiver, the beam splitter reduces variables that may affect the measurement results, thus contributing to improved system stability. Since the receiver only needs to process the modulated signal, rather than both modulated and unmodulated signals simultaneously, the signal processing is simplified. By blocking unmodulated terahertz waves, the beam splitter helps reduce background noise, thereby improving the signal-to-noise ratio and measurement reliability.

[0071] As an example, see Figure 1 A vector measurement system is provided, comprising: a function generator (AFG), a microwave source (MS), a terahertz light source (T, transmitter), a receiver (R, receiver), and an IQ demodulator. Optical components include an absorbing device composed of absorbing material, a beam splitter, and an off-axis parabolic mirror (OAP).

[0072] The connecting lines in the diagram illustrate the signal path. AFG contains two channels (Channel 1 AFG-CH1 and Channel 2 AFG-CH2), which are phase-synchronized. Channel 1 generates a 10MHz signal as the MS reference signal, and Channel 2 generates the first local oscillator signal S of the IQ demodulator as needed. LOAFGMS uses the 10MHz signal generated by AFG as a reference to generate two microwave signals. Channel 1 MS-CH1 serves as the second local oscillator signal S of the terahertz source. RF After being amplified by frequency multiplication (frequency multiplication factor of N1), it is radiated through a speaker, and channel 2MS-CH2 serves as the third local oscillator signal S of the receiver. LO After passing through the built-in frequency multiplier module (frequency multiplication factor of N2), it becomes the fourth local oscillator signal of the terahertz downconverter mixer, which is then mixed with the terahertz signal to generate the intermediate frequency signal S. IF S LOAFG With S IF The signal is demodulated in an IQ demodulator to obtain an output signal, which is used to obtain the amplitude and phase information in the terahertz optical path. This optical path calibrates the performance of the terahertz phased array chip under test by reflection. Figure 1 The solid arrows represent unmodulated terahertz waves, while the dashed arrows represent terahertz waves modulated by the phased array chip under test (terahertz signals). The absorbing material (i.e., the absorbing device) in the diagram is used to absorb the unmodulated terahertz waves, preventing them from aliasing with the modulated signal and entering the receiver, thus affecting measurement accuracy. This application does not restrict the selection of absorbing materials. Absorbing materials are materials capable of absorbing incident electromagnetic wave energy and converting it into other forms of energy (such as heat energy), such as carbon materials and rubber-based composite materials.

[0073] To facilitate understanding, the terahertz vector measurement principle using the above-described vector measurement system is provided:

[0074] Suppose that MS generates two signals with different frequencies but both initially have a phase of 0:

[0075]

[0076] Where A RF ω RF A LO ω LO Let N1 be the amplitude of channel 1, N2 be the frequency of channel 1, N2 be the amplitude of channel 2, and N2 be the frequency of channel 2. These two signals are multiplied by the transmitter and receiver respectively, with multiplication factors N1 and N2. Therefore, the transmitter signal and the receiver local oscillator terahertz signal are respectively:

[0077]

[0078] in These represent the amplitude and phase of the signal emitted by the terahertz light source, and the amplitude and phase of the receiver's local oscillator link, respectively. Figure 1 As can be seen from the optical path, S THzRF The signal is modulated by the phased array chip under test, reflected, and then passes through a beam splitter to reach the receiver. The signal under test reaching the receiver is:

[0079]

[0080] Where k MOD and The amplitude modulation and phase modulation characteristics of the phased array chip under test for terahertz waves are respectively, k s and These are amplitude attenuation and phase change caused by the optical path, respectively. After down-conversion by the receiver, the intermediate frequency signal is:

[0081]

[0082] The local oscillator signal of the IQ demodulator is generated by AFG:

[0083]

[0084] in These represent the amplitude, frequency, and phase of the local oscillator signal generated by the AFG for the IQ demodulator. Therefore, the output signal of the IQ demodulator is:

[0085]

[0086] Where ω IF =N1ω RF -N2ω LO , When is the initial phase of the system, and is a constant. k MOD When ω = 1, it represents the initial amplitude of the system and is a constant. To facilitate data acquisition and processing, ω is adjusted... LOAFG Make it with ω IF They are equal, at this time S I and S Q If the signal is a DC signal, then:

[0087]

[0088] Then the amplitude modulation characteristics and phase modulation characteristics k of the phased array chip under test can be solved. MOD and

[0089] As an example, the measurement optical path can be adjusted according to the actual test scenario. For example... Figure 2 As shown, to achieve single-element testing of a phased array chip, OAP can be used to focus terahertz light onto the target element, and the phased array chip can be mounted on a two-dimensional displacement stage for easy fine-tuning. The measurement principle is the same. To facilitate data acquisition and processing, ω can be set during measurement. LOAFG Make it with ω IF Only when they are equal can IQ demodulation be performed correctly. ω IF =N1ω RF -N2ωLO Therefore, ω RF and ω LO The number of decimal places needs to be less than the number of decimal places of the MS fractional divider, that is, the minimum settable frequency step size of the MS, and the ω generated by it. IF The number of decimal places must be less than the minimum frequency step size that AFG can set. The frequency setting must meet the above conditions to complete the measurement.

[0090] In this application Figure 1 and Figure 2 In the diagram, AFG is the function generator, MS is the microwave source, T is the terahertz source, R is the receiver, and OAP is the off-axis parabolic mirror.

[0091] The system's dynamic range is determined by the receiver sensitivity and the dynamic range of the IQ demodulator. Typically, the dynamic range of the IQ demodulator is relatively small; replacing the IQ demodulator with one suitable for different measurement power levels can expand the system's measurement dynamic range.

[0092] Method implementation examples.

[0093] This application provides a calibration method for a phased array chip based on the vector measurement system described in the system embodiment. The specific implementation method and the technical effects achieved are the same as those described in the above system embodiment, and some contents will not be repeated.

[0094] See Figure 7 , Figure 7 A flowchart illustrating a calibration method for a phased array chip is shown. The method includes:

[0095] S101, Perform calibration of the vector measurement system;

[0096] S102, based on the actual measured frequency point, set the output frequency and level of the first local oscillator signal of the frequency output device, and set the output frequency and power of the second and third local oscillator signals;

[0097] S103 acquires and processes the output signal of the IQ demodulator to obtain the amplitude modulation characteristics and phase modulation characteristics of the phased array chip under test.

[0098] Before S101, it may also include selecting the specific test optical path of the vector measurement system according to the actual test requirements.

[0099] In some embodiments, the calibration of the vector measurement system includes: performing displacement calibration and time stability calibration of the vector measurement system.

[0100] As an example, displacement calibration uses physical displacement to determine the phase measurement accuracy of the system. The phased array chip under test is mounted on a precision displacement stage with a known repeatability of 2 micrometers. The actual phase is calculated based on the measurement frequency and the displacement of the stage. Multiple measurements are performed, and the displacement calibration is considered complete when the phase error and amplitude fluctuation meet the requirements, such as a maximum phase measurement error of less than 10°, an average error of less than 4°, and an amplitude fluctuation of less than 2dB. If these requirements are not met, the optical path needs to be fine-tuned and re-aligned. The purpose of time stability calibration is to eliminate the influence of phase noise from the terahertz frequency multiplier used for frequency doubling in the MS, AFG, and terahertz light source on the measurement results. Excessive phase noise from the MS, or frequency drift over time, will reduce the system's measurement accuracy. Therefore, a phase drift of less than 1° / min is often defined as a complete system calibration. If this condition cannot be met, the ambient temperature needs to be stabilized, or a low-phase-noise device needs to be used.

[0101] Based on the actual measurement frequency, set the output frequency and level of the two AFG channels, and set the output frequency and power of the two MS channels. Control the phased array chip according to the measurement requirements, and simultaneously control the acquisition equipment to acquire and process the output signal of the IQ demodulator to obtain the amplitude modulation characteristics and phase modulation characteristics of the phased array chip.

[0102] A test instance with a frequency of 317GHz is provided, as follows:

[0103] choose Figure 1 The optical path shown is used for overall performance testing of the terahertz phased array chip.

[0104] After adjusting the optical path, displacement calibration was performed. The chip under test was mounted on the displacement stage of a stepper motor. The stepper motor moved 10 micrometers to the right each time, and the output signal of the IQ demodulator was collected. The results are as follows. Figure 3 and Figure 4 As shown, the maximum phase measurement error is less than 7°, the average error is less than 2°, and the amplitude fluctuation is less than 1.6dB, thus meeting the measurement requirements.

[0105] After displacement calibration, time stability calibration is performed. The IQ demodulator output signal is acquired without any operation, and the results are as follows. Figure 5 As shown, the total phase drift of the 20-minute system is 7°, approximately 0.35° / minute. Since the single data acquisition time is less than 1 minute, it meets the measurement requirements.

[0106] Calibration is now complete; chip testing will proceed. The measurement frequency is 317GHz, with a preset fI. F =50MHz. In this experiment, the transmitter's frequency multiplication factor N1 is 27, and the receiver's frequency multiplication factor is 24. Therefore, fL O =13.21GHz, f RF=11.743GHz, then the actual intermediate frequency is f IF =21MHz. Therefore, the frequency of AFG channel 2 is set to 21 MHz. The signal modulation capability of the phased array chip at this frequency is measured. The bias voltage range of the phased array chip is set to 0-6V with a step size of 0.2V. The measurement results are as follows. Figure 6 As shown, the amplitude and phase modulation performance of the chip is demonstrated.

[0107] Obviously, based on the aforementioned vector measurement system for phased array chip calibration and the calibration method for phased array chips, it can be understood that the technical solution provided in this application uses a beam splitter to separate the incident beam and the reflected beam in the terahertz optical path, thus completing the calibration of the reflective phased array chip. An absorbing device is added to the optical path to absorb unmodulated terahertz light, preventing unmodulated terahertz waves from aliasing with the terahertz signal into the receiver. In the RF link section, an AFG is used to generate the MS reference signal and the local oscillator signal of the IQ demodulator. Because the AFG has extremely low phase noise, the phase noise of the local oscillator signal of the IQ demodulator is very small and synchronized with the intermediate frequency signal, thus achieving extremely high measurement accuracy.

[0108] Compared to measurement methods using VNA:

[0109] Higher measurement frequency: This application can easily achieve higher frequency measurements with higher accuracy by using different combinations of terahertz transmitters and receivers.

[0110] Calibration error: This application uses optical path calibration, which results in smaller system errors.

[0111] Dynamic range: This application allows for the replacement of receivers and IQ demodulators with appropriate dynamic ranges according to measurement requirements, thereby achieving a larger measurement dynamic range.

[0112] Measurement accuracy: The measurement accuracy of this application is mainly determined by the phase noise levels of the AFG, MS and terahertz frequency multiplier, and is not affected by the link. Therefore, the measurement accuracy is higher than that of the VNA.

[0113] Compared to publicly available superheterodyne measurement links:

[0114] Simple signal link: The signal link of this application is simpler, requires fewer components, is more resistant to external interference, and has high stability.

[0115] Measurement accuracy: In the terahertz optical path, this application suppresses interference signals to the maximum extent, and the IQ demodulator uses the signal generated by AFG as the local oscillator, which has lower phase noise, thus achieving higher measurement accuracy.

[0116] Equipment implementation example.

[0117] This application provides an electronic device whose specific implementation and achieved technical effects are consistent with the implementation methods and system implementations described above, and some details will not be repeated. The electronic device includes one or more processors and a memory; one or more programs are stored in the memory and configured to be executed by the one or more processors using any of the methods described above.

[0118] See Figure 8 , Figure 8 This is a structural diagram of an electronic device provided in an embodiment of the present application.

[0119] Electronic devices may include, for example, at least one memory 11, at least one processor 12, and a bus 13 connecting different platform systems.

[0120] The memory 11 may include a readable medium in the form of volatile memory, such as random access memory (RAM) 111 and / or cache memory 112, and may further include read-only memory (ROM) 113.

[0121] The memory 11 also stores a computer program, which can be executed by the processor 12 to enable the processor 12 to implement the steps of any of the above methods.

[0122] The memory 11 may also include a utility 114 having at least one program module 115, including but not limited to: an operating system, one or more application programs, other program modules, and program data, each or some combination of these examples may include an implementation of a network environment.

[0123] Accordingly, processor 12 can execute the aforementioned computer program, and can also execute utility 114.

[0124] The processor 12 may employ one or more application-specific integrated circuits (ASICs), DSPs, programmable logic devices (PLDs), complex programmable logic devices (CPLDs), field-programmable gate arrays (FPGAs), or other electronic components.

[0125] Bus 13 can represent one or more of several types of bus structures, including a memory bus or memory controller, peripheral bus, graphics acceleration port, processor, or a local bus using any bus structure with multiple bus structures.

[0126] The electronic device can also communicate with one or more external devices 14, such as a keyboard, pointing device, Bluetooth device, etc., and with one or more devices capable of interacting with the electronic device, and / or with any device that enables the electronic device to communicate with one or more other computing devices (e.g., a router, modem, etc.). This communication can be performed via input / output interface 15. Furthermore, the electronic device can communicate with one or more networks (e.g., local area network (LAN), wide area network (WAN), and / or public networks, such as the Internet) via network adapter 16. Network adapter 16 can communicate with other modules of the electronic device via bus 13. It should be understood that, although not shown in the figures, in practical applications, other hardware and / or software modules can be used in conjunction with the electronic device, including but not limited to: microcode, device drivers, redundant processors, external disk drive arrays, RAID systems, tape drives, and data backup storage platforms.

[0127] Storage medium example.

[0128] This application also provides a computer-readable storage medium, the specific embodiments of which are consistent with the embodiments and technical effects achieved in the above method embodiments, and some contents will not be repeated.

[0129] The computer-readable storage medium stores a computer program that, when executed by at least one processor, implements the steps of any of the above methods or the functions of any of the above electronic devices.

[0130] A computer-readable medium can be a computer-readable signal medium or a computer-readable storage medium. In embodiments of this application, a computer-readable storage medium can be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, apparatus, or device. Computer-readable storage media can be, for example, but not limited to, electrical, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatus, or devices, or any combination thereof. More specific examples of computer-readable storage media (a non-exhaustive list) include: electrical connections having one or more wires, portable disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fibers, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof.

[0131] Computer-readable storage media may include data signals propagated in baseband or as part of a carrier wave, carrying readable program code. Such propagated data signals may take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. The computer-readable storage medium may also be any computer-readable medium capable of sending, propagating, or transmitting a program for use by or in conjunction with an instruction execution system, apparatus, or device. The program code contained on the computer-readable storage medium may be transmitted using any suitable medium, including but not limited to wireless, wired, optical fiber, RF, or any suitable combination thereof. Program code for performing operations of the present invention may be written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Java and C++, as well as conventional procedural programming languages ​​such as C or similar programming languages. The program code may be executed entirely on a user computing device, partially on a user device, as a standalone software package, partially on a user computing device and partially on a remote computing device, or entirely on a remote computing device or server. In cases involving remote computing devices, the remote computing devices can be connected to user computing devices via any type of network, including local area networks (LANs) or wide area networks (WANs), or they can be connected to external computing devices (e.g., via the Internet using an Internet service provider).

[0132] Example of a program product.

[0133] This application also provides a program product embodiment, wherein the computer program product includes a computer program, and when the computer program is executed by at least one processor, it implements the steps of the method described in any one of the method embodiments.

[0134] It should be noted that in the embodiments of this application, "at least one" refers to one or more, and "more than one" refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one of a, b, or c can represent: a, b, c, a and b, a and c, b and c, or a and b and c, where a, b, and c can be single or multiple. It is worth noting that "at least one" can also be interpreted as "one or more".

[0135] The terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this application are configured to distinguish similar objects and are not necessarily configured to describe a particular order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0136] This application describes the invention from the perspectives of purpose, performance, progress, and novelty, and it meets the functional enhancement and use requirements emphasized by the Patent Law. The above description and drawings are merely preferred embodiments of this application and are not intended to limit this application. Therefore, all structures, devices, features, etc., that are similar to or identical to those of this application, i.e., all equivalent substitutions or modifications made in accordance with the scope of this patent application, shall fall within the scope of protection of this patent application.

Claims

1. A vector measurement system for calibrating a phased array chip, characterized in that, The system includes: A frequency output device, wherein the frequency output device is used to generate a first local oscillator signal, a second local oscillator signal and a third local oscillator signal; A terahertz light source is used to receive the second local oscillator signal and radiate terahertz waves after frequency doubling and amplification. The terahertz waves are used to generate terahertz signals after being modulated by the phased array chip under test. A receiver is used to receive the third local oscillator signal and the terahertz signal. The third local oscillator signal is amplified by frequency multiplication to become the fourth local oscillator signal. The fourth local oscillator signal is mixed with the terahertz signal to generate an intermediate frequency signal and output it. An IQ demodulator is used to receive the intermediate frequency signal and the first local oscillator signal and demodulate them to obtain an output signal. The output signal is used to obtain the amplitude modulation characteristics and phase modulation characteristics of the phased array chip under test. An absorbing device is disposed between the receiver and the terahertz light source to prevent unmodulated terahertz waves from aliasing with the terahertz signal and entering the receiver.

2. The vector measurement system according to claim 1, characterized in that, The frequency output device is a frequency synthesizer; or, the frequency output device includes a function generator and a microwave source, the function generator being used to generate a reference signal and a first local oscillator signal, and the microwave source being used to receive and generate a second local oscillator signal and a third local oscillator signal according to the reference signal; the reference signal and the first local oscillator signal are phase synchronized.

3. The vector measurement system according to claim 2, characterized in that, The first local oscillator signal and the intermediate frequency signal have the same frequency; and / or, the reference signal is a 10 MHz signal.

4. The vector measurement system according to claim 1, characterized in that, The phased array chip under test is mounted on a displacement stage. The system also includes an off-axis parabolic mirror, which is positioned between the terahertz light source and the phased array chip under test to focus the terahertz wave onto the target element of the phased array chip under test; and / or, the terahertz light source is used to receive the second local oscillator signal and, after frequency doubling and amplification, radiate terahertz waves through a horn.

5. The vector measurement system according to claim 1, characterized in that, The system also includes a beam splitter, which is disposed in the optical path between the phased array chip under test and the receiver, for separating the terahertz signal from the unmodulated terahertz wave.

6. A calibration method for a phased array chip in a vector measurement system according to any one of claims 1-5, characterized in that, The method includes: Perform calibration of the vector measurement system; Based on the actual measured frequency, set the output frequency and level of the first local oscillator signal of the frequency output device, and set the output frequency and power of the second and third local oscillator signals; The output signal of the IQ demodulator is acquired and processed to obtain the amplitude modulation characteristics and phase modulation characteristics of the phased array chip under test.

7. The calibration method according to claim 6, characterized in that, The calibration of the vector measurement system includes: performing displacement calibration and time stability calibration of the vector measurement system.

8. An electronic device, characterized in that, It includes one or more processors and memory; one or more programs are stored in the memory and configured to be executed by the one or more processors according to any one of claims 6-7.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by at least one processor, implements the steps of the method according to any one of claims 6-7.

10. A computer program product, characterized in that, The computer program product includes a computer program that, when executed by at least one processor, implements the steps of the method according to any one of claims 6-7.

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