Performance detection circuit and performance detection method of filter

Abstract

The present application relates to a performance detection circuit and a performance detection method for a filter. In the performance detection circuit, a main control module generates a signal excitation instruction and a synchronization control instruction; a signal generation module generates a local oscillator signal and a swept frequency signal; a first signal mixing module mixes the local oscillator signal with the swept frequency signal based on the signal excitation instruction, and outputs the first mixed signal to the filter under test; a second signal mixing module mixes the swept frequency signal with a second mixed signal output by the filter under test and extracts a target frequency component through filtering; a signal detection module measures the amplitude of the target frequency component to obtain an amplitude sequence of the target frequency component; a synchronization control module synchronizes the signal generation timing of the signal generation module with the signal detection timing of the signal detection module based on the synchronization control instruction; the main control module determines the insertion loss and / or bandwidth of the filter under test based on the amplitude sequence of the target frequency component, the amplitude of the local oscillator signal and the swept frequency signal.

Description

Technical Field

[0001] The present application relates to the field of microwave measurement technology, and in particular to a performance detection circuit and a performance detection method for a filter. Background Art

[0002] Filters are essential components in modern communication systems, and their performance directly impacts the overall performance of the communication system. With the rapid development of communication technology, higher requirements are being placed on the accuracy and efficiency of filter performance testing, especially for X-band (8GHz-12GHz) filters in the microwave frequency band.

[0003] Conventional filter performance testing typically relies on direct measurement of high-frequency RF signals using vector network analyzers or high-frequency ADC (Analog-to-Digital Converter) chips, resulting in high system cost and complex operation. However, even with expensive, high-performance ADC chips, testing in high-frequency bands like the X-band can still be limited by insufficient resolution, making it difficult to accurately measure key filter parameters such as insertion loss and bandwidth. Summary of the Invention

[0004] The embodiments of the present application provide a filter performance detection circuit and a performance detection method to solve at least one problem existing in the background technology.

[0005] In a first aspect, an embodiment of the present application provides a filter performance detection circuit, comprising:

[0006] Main control module, used to generate signal excitation instructions and synchronization control instructions;

[0007] a signal generating module, configured to generate a local oscillator signal and a frequency sweep signal based on the signal excitation instruction, wherein the frequency range of the frequency sweep signal covers the operating frequency band of the filter under test, the lowest frequency of the frequency sweep signal is at least one order of magnitude higher than the fixed frequency of the local oscillator signal, and the operating frequency band is within a target band within the microwave frequency band;

[0008] a first signal mixing module, configured to mix the local oscillator signal with the frequency sweep signal, and output a first mixed signal to the filter under test;

[0009] a second signal mixing module, configured to mix the frequency sweep signal with a second frequency mixing signal output by the filter under test, and extract a target frequency component by filtering, wherein the frequency of the target frequency component is equal to the fixed frequency of the local oscillator signal;

[0010] a signal detection module, configured to measure the amplitude of the target frequency component to obtain an amplitude sequence of the target frequency component, wherein the amplitudes in the amplitude sequence correspond one-to-one to the frequencies of the frequency sweep signal;

[0011] a synchronization control module, configured to synchronously control the signal generation timing of the signal generation module and the signal detection timing of the signal detection module based on the synchronization control instruction;

[0012] The main control module is further used to determine the insertion loss and / or bandwidth of the filter under test based on the amplitude sequence of the target frequency component, the amplitude of the local oscillator signal and the amplitude of the swept frequency signal.

[0013] In conjunction with the first aspect, in an optional implementation manner, the signal detection module is configured to:

[0014] During the dwell time corresponding to each frequency of the swept frequency signal, the amplitude of the target frequency component is measured.

[0015] In conjunction with the first aspect, in an optional implementation manner, the signal detection module includes an analog-to-digital converter, and the analog-to-digital converter is configured to:

[0016] During the dwell time corresponding to each frequency of the swept frequency signal, the target frequency component is digitally sampled, and the amplitude is measured based on the sampling result.

[0017] In conjunction with the first aspect, in an optional implementation manner, the first signal mixing module includes a first mixer for generating the first mixed signal;

[0018] The second signal mixing module includes:

[0019] a second mixer, configured to mix the swept frequency signal with a second mixed signal output by the filter under test after processing the first mixed signal, so as to output a third mixed signal containing a plurality of frequency components;

[0020] A low-pass filter is used to perform low-pass filtering on the third mixed signal to extract the target frequency component from the multiple frequency components.

[0021] In conjunction with the first aspect, in an optional implementation manner, the main control module is specifically configured to:

[0022] determining an amplitude sequence of the second mixing signal based on each amplitude in the amplitude sequence of the target frequency component and the amplitude of the frequency sweep signal;

[0023] determining the amplitude of the first mixing signal based on the amplitude of the local oscillator signal and the amplitude of the frequency sweep signal;

[0024] Insertion loss calculation is performed on each amplitude in the amplitude sequence of the second mixing signal and the amplitude of the first mixing signal to obtain an insertion loss value of the tested filter corresponding to each frequency of the swept frequency signal.

[0025] In combination with the first aspect, in an optional implementation manner, the filter under test is a bandpass filter, and the main control module is specifically configured to:

[0026] Determining, based on the insertion loss value of the filter under test corresponding to each frequency of the swept frequency signal, a first frequency and a second frequency at which the insertion loss value meets a bandwidth determination condition, wherein the bandwidth determination condition includes an insertion loss threshold;

[0027] A frequency width between the first frequency and the second frequency is determined as the bandwidth of the filter under test.

[0028] In combination with the first aspect, in an optional implementation manner, the target band is the X band.

[0029] In a second aspect, an embodiment of the present application provides a method for detecting performance of a filter, comprising:

[0030] Inputting a first mixed signal obtained by mixing a local oscillator signal with a swept frequency signal into the filter under test, wherein the swept frequency range of the swept frequency signal covers an operating frequency band of the filter under test, the lowest frequency of the swept frequency signal is at least one order of magnitude higher than a fixed frequency of the local oscillator signal, and the operating frequency band is within a target band within the microwave frequency band;

[0031] Mixing the swept frequency signal with a second mixed frequency signal output by the filter under test, and extracting a target frequency component by filtering, wherein the frequency of the target frequency component is equal to the fixed frequency of the local oscillator signal;

[0032] triggering the amplitude measurement of the target frequency component each time the frequency sweep signal scans to a frequency, to obtain an amplitude sequence of the target frequency component, wherein the detection timing of the target frequency component is synchronized with the generation timing of the local oscillator signal and the frequency sweep signal;

[0033] The insertion loss and / or bandwidth of the filter under test is determined based on the amplitude sequence of the target frequency component, the amplitude of the local oscillator signal, and the amplitude of the swept frequency signal.

[0034] In conjunction with the second aspect, in an optional implementation manner, triggering the amplitude measurement of the target frequency component each time the frequency sweep signal scans to a frequency to obtain the amplitude sequence of the target frequency component includes:

[0035] During the dwell time corresponding to each frequency of the frequency sweep signal, the amplitude of the target frequency component is measured by an analog-to-digital converter to generate an amplitude sequence of the target frequency component.

[0036] In conjunction with the second aspect, in an optional implementation manner, determining the insertion loss of the filter under test based on the amplitude sequence of the target frequency component, the amplitude of the local oscillator signal, and the amplitude of the swept frequency signal includes:

[0037] determining an amplitude sequence of the second mixing signal based on each amplitude in the amplitude sequence of the target frequency component and the amplitude of the frequency sweep signal;

[0038] determining the amplitude of the first mixing signal based on the amplitude of the local oscillator signal and the amplitude of the frequency sweep signal;

[0039] Insertion loss calculation is performed on each amplitude in the amplitude sequence of the second mixing signal and the amplitude of the first mixing signal to obtain an insertion loss value of the tested filter corresponding to each frequency of the swept frequency signal.

[0040] In conjunction with the second aspect, in an optional implementation manner, the filter under test is a bandpass filter, and the bandwidth of the filter under test is determined based on the following method:

[0041] Determining, based on the insertion loss value of the filter under test corresponding to each frequency of the swept frequency signal, a first frequency and a second frequency at which the insertion loss value meets a bandwidth determination condition, wherein the bandwidth determination condition includes an insertion loss threshold;

[0042] A frequency width between the first frequency and the second frequency is determined as the bandwidth of the filter under test.

[0043] In combination with the second aspect, in an optional implementation manner, the target band is the X band.

[0044] In a third aspect, an embodiment of the present application provides an electronic device, comprising a performance detection circuit for a filter as described in any optional implementation manner of the first aspect.

[0045] In a fourth aspect, an embodiment of the present application provides an electronic device, comprising a processor, wherein the processor is configured to call instructions so that the electronic device executes the filter performance detection method described in any optional implementation of the second aspect.

[0046] The present invention provides a filter performance testing circuit and method. By setting the frequency range of a swept frequency signal to cover the operating frequency band of the filter under test, with its lowest frequency at least one order of magnitude higher than the fixed frequency of the local oscillator signal, the higher-frequency swept frequency signal is down-converted to a target frequency component equal to the local oscillator signal frequency through two mixing processes and filtering. Consequently, when testing the performance of high-frequency filters, the amplitude of the target frequency component can be measured using a signal detection module designed for low-frequency detection, without relying on high-performance testing equipment such as high-frequency ADC chips, thereby effectively reducing the hardware cost of filter performance testing. Furthermore, a synchronous control mechanism is employed to align the generation timing of the local oscillator signal and the swept frequency signal with the detection timing of the target frequency component, ensuring a one-to-one correspondence between the amplitudes of the target frequency component and the frequency of the swept frequency signal. This ensures that the amplitude sequence of the target frequency component accurately reflects the transmission characteristics of the filter under test at different swept frequency frequencies. Furthermore, by combining the amplitude sequence of the target frequency component, the amplitudes of the local oscillator signal, and the swept frequency signal, accurate detection of filter insertion loss and bandwidth under low-frequency conditions can be achieved.

[0047] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0049] Figure 1 A block diagram of a filter performance detection circuit provided in an embodiment of the present application.

[0050] Figure 2 A schematic diagram of the structure of a performance detection circuit for a filter provided in an embodiment of the present application.

[0051] Figure 3 A flowchart of a filter performance detection method provided in an embodiment of the present application.

[0052] Figure 4 A schematic diagram of a flow chart for determining the insertion loss of a filter provided in an embodiment of the present application.

[0053] Figure 5 A schematic diagram of a filter bandwidth determination process provided in an embodiment of the present application. DETAILED DESCRIPTION

[0054] To make the technical solutions and beneficial effects of this application more clearly understood, the technical solutions in the embodiments of this application are clearly and completely described below by listing specific embodiments. Obviously, the embodiments described are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0055] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application pertains. The terms used in this specification are for the purpose of describing specific embodiments only and are not intended to limit this application.

[0056] It should be understood that the terms "first," "second," and so forth, as used herein, may be used to describe various elements, but these elements are not limited by these terms. These terms are used solely to distinguish a first element from another element. For example, a first resistor could be referred to as a second resistor, and similarly, a second resistor could be referred to as a first resistor, without departing from the scope of this application. A first resistor and a second resistor are both resistors, but they are not the same resistor. When describing "first," it does not necessarily imply the presence of a "second," nor does discussing "second" necessarily imply the presence of a first element, component, region, layer, or portion. When used herein, the singular forms "a," "an," and "the" are intended to include the plural forms, unless the context clearly indicates otherwise. "A plurality" means more than two, unless otherwise specifically defined. It should also be understood that the term "comprising," when used in this specification, specifies the presence of the stated features, but does not preclude the presence or addition of one or more other features. As used herein, the term "and / or" includes any and all combinations of the associated listed items.

[0057] It is understood that in the context of this application, "connection" means that electrical signals or data can be transmitted between the connected end and the connected end, and can be understood as "electrical connection", "communication connection", etc. In the context of this application, "A and B are directly connected" means that no components other than wires are between A and B.

[0058] X-band: This refers to the electromagnetic wave frequency range between 8 GHz and 12 GHz, part of the microwave band. This frequency band has high resolution and strong penetration capabilities, and is widely used in military target detection, air traffic control, weather monitoring, and other fields.

[0059] Insertion Loss (IL): refers to the signal power loss caused by inserting a component (such as a filter, attenuator, connector, etc.) in an electronic device or communication system. Insertion loss is usually expressed in decibels (dB) and is calculated as follows: IL = 20lg (V in / V out ) (unit: dB), where V in Indicates the input signal amplitude (such as the voltage amplitude before filtering), V out Indicates the output signal amplitude (such as the voltage amplitude after filtering).

[0060] Bandwidth: It is one of the important parameters to measure the performance of the filter. In electronic circuits, signal transmission and other scenarios, when a signal passes through a device (such as an amplifier, filter, etc.), its power or amplitude will change. "3dB bandwidth" refers to the frequency range width corresponding to the system gain (power amplification factor or amplitude amplification factor) dropping by 3dB relative to the center frequency (or a specific reference frequency). For voltage or current amplitude, the conversion relationship with dB is: dB=20lg(V1 / V2), where V1 and V2 represent the signal amplitudes in different states, respectively. A 3dB drop corresponds to the amplitude becoming the original .

[0061] DUT: It is the abbreviation of Device Under Test, which means "device under test". In the field of electronic testing, when performance testing is performed on various electronic components, modules or systems, the object under test is called DUT.

[0062] Microwave filters have widespread and critical applications in modern communications, radar, electronic countermeasures, and many other fields. Their primary function is to selectively pass or suppress signals within a specific frequency range, thereby improving the system's signal processing capabilities and anti-interference performance. Insertion loss and bandwidth are two core parameters that measure filter performance and directly impact the overall system performance.

[0063] Taking X-band (8GHz-12GHz) filters as an example, X-band filters offer high resolution and strong penetration, making them widely used in radar target detection, air traffic control, weather monitoring, and 5G communications. In radar systems, X-band filters can be used to filter echo signals of specific frequencies, thereby improving radar detection accuracy and anti-interference capabilities. In communications systems, they can ensure efficient signal transmission within a specific frequency band, enhancing communication quality and spectrum utilization.

[0064] Due to the high operating frequency of the X-band, the ADC chips and modules used in traditional detection methods must match this high frequency. To accurately measure key filter parameters such as insertion loss and bandwidth, these ADCs often require high resolution. However, when testing high-precision filters, using a low-resolution ADC will result in significant measurement errors and fail to meet the stringent parameter accuracy requirements of practical applications.

[0065] As performance requirements for microwave filters continue to increase across various fields, accurate testing of key parameters such as insertion loss and bandwidth has become increasingly important. For example, during the construction of 5G communication base stations, precise testing of key X-band filter parameters is required to ensure efficient wireless signal transmission and stable system operation. In the military, the performance of X-band filters in radar and other equipment directly impacts the overall operational efficiency of the equipment, making accurate testing of filter parameters crucial.

[0066] The present invention provides a filter performance detection circuit suitable for testing key performance parameters such as insertion loss and bandwidth of filters operating in a target microwave band (e.g., the X-band). This performance detection circuit can be applied to various communication systems, radar systems, satellite communication equipment, and radio frequency test platforms. It can also be embedded as a standalone functional module within a test platform. It can achieve high-precision detection of key filter performance parameters such as insertion loss and bandwidth without relying on high-performance detection equipment such as high-frequency ADC chips.

[0067] See Figure 1 , Figure 1 This is a block diagram of a filter performance detection circuit provided in an embodiment of the present application. The filter performance detection circuit includes: a main control module 100, a signal generation module 110, a first signal mixing module 120, a second signal mixing module 130, a signal detection module 140, and a synchronization control module 150; the first signal mixing module 120 is connected to the input end of the filter under test 200, and the second signal mixing module 130 is connected to the output end of the filter under test 200.

[0068] The main control module 100 is used to generate signal excitation instructions and synchronization control instructions;

[0069] A signal generating module 110 is configured to generate a local oscillator signal and a swept frequency signal based on the signal excitation instruction. The frequency range of the swept frequency signal covers the operating frequency band of the filter under test, the lowest frequency of the swept frequency signal is at least one order of magnitude higher than the fixed frequency of the local oscillator signal, and the operating frequency band is within a target band within the microwave frequency band.

[0070] A first signal mixing module 120 is configured to mix the local oscillator signal with the frequency sweep signal and output a first mixed signal to the filter under test;

[0071] The second signal mixing module 130 is used to mix the swept frequency signal with the second mixed signal output by the filter under test, and extract the target frequency component by filtering, where the frequency of the target frequency component is equal to the fixed frequency of the local oscillator signal;

[0072] The signal detection module 140 is used to measure the amplitude of the target frequency component and obtain an amplitude sequence of the target frequency component, where the amplitudes in the amplitude sequence correspond to the frequencies of the swept frequency signal.

[0073] A synchronization control module 150 is used to synchronize the signal generation timing of the signal generation module and the signal detection timing of the signal detection module based on the synchronization control instruction;

[0074] The main control module 100 is further configured to determine the insertion loss and / or bandwidth of the filter under test based on the amplitude sequence of the target frequency component, the amplitude of the local oscillator signal, and the amplitude of the swept frequency signal.

[0075] In this embodiment, the filter under test may be any type of microwave filter that requires performance parameter testing, such as an X-band bandpass filter or an X-band high-pass filter.

[0076] The operating frequency band of the filter under test is the actual operating frequency range of the filter under test, which is determined by its design specifications or application scenarios. The target band is the microwave frequency band category to which the operating frequency band of the filter under test belongs.

[0077] In some examples, the target band can be the X-band. The X-band frequency range typically ranges from 8 GHz to 12 GHz. By setting the target band to the X-band (8 GHz to 12 GHz), the performance detection circuit can be used to evaluate the performance of filters in systems such as X-band radar and satellite communications.

[0078] Of course, other bands can also be selected according to the application scenario of the filter under test, such as S-band (2GHz-4GHz), C-band (4GHz-8GHz), or Ku-band (12GHz-18GHz).

[0079] The main control module 100 may include a main controller. The main controller is connected to the signal generation module 110 and the synchronization control module 150, respectively, and is used to send signal excitation instructions to the signal generation module 110 and synchronization control instructions to the synchronization control module 150. In addition, the main control module 100 is also connected to the signal detection module 140.

[0080] Exemplarily, the signal excitation instruction may carry local oscillator signal parameters and frequency sweep signal parameters.

[0081] The local oscillator signal parameters are used to control the signal generating module 110 to generate the local oscillator signal. The local oscillator signal parameters may include the local oscillator signal frequency and the local oscillator signal amplitude (eg, a first preset amplitude).

[0082] The sweep signal parameters are used to control the signal generation module 110 to generate the sweep signal. The sweep signal parameters may include parameters such as the sweep signal amplitude (e.g., the second preset amplitude), the start frequency, the end frequency, the sweep step length, and the sweep step time. The sweep step length is the frequency interval between two adjacent frequencies during the sweep process, and the sweep step time is the time interval from the start of one frequency to the start of the next.

[0083] For example, in an application scenario where the target band is the X band, the start frequency of the sweep signal can be set to 8 GHz, the end frequency can be set to 12 GHz, the sweep step size can be set to 100 MHz, and the sweep step time can be set to 25 μs.

[0084] The frequency of the swept signal can be swept in a linear or logarithmic step mode, and the specific sweep step can be set based on the test requirements.

[0085] In a possible implementation, the main controller may be a Field-Programmable Gate Array (FPGA) or a Microcontroller Unit (MCU).

[0086] The signal generating module 110 may include a local oscillator signal source and a swept frequency signal source. The local oscillator signal source is configured to generate a local oscillator signal of a fixed frequency, the amplitude of which may be fixed to a first preset amplitude. The swept frequency signal source is configured to generate a swept frequency signal with a continuously varying frequency, the sweep frequency range of which covers the operating frequency band of the filter under test, and the amplitude of the swept frequency signal may be fixed to a second preset amplitude.

[0087] In one possible implementation, the local oscillator signal source may be a constant frequency sine wave circuit.

[0088] In one possible implementation, the sweep signal source can be a DDS (Direct Digital Synthesizer) or a DDS-based frequency synthesizer (DDS frequency synthesizer). For example, if the filter under test is an X-band filter, i.e., the target band is the X-band, the sweep signal frequency range can be set to 8 GHz to 12 GHz to fully cover the operating frequency band of the filter under test.

[0089] The lowest frequency of the swept frequency signal is at least one order of magnitude higher than the fixed frequency of the local oscillator signal. It should be understood that the lowest frequency of the swept frequency signal is at least m orders of magnitude higher than the fixed frequency of the local oscillator signal (m is an integer greater than 1), which means that the lowest frequency of the swept frequency signal is approximately 10 times the fixed frequency of the local oscillator signal. m times. That is, the swept frequency signal is a high-frequency signal compared to the local oscillator signal, while the local oscillator signal is a low-frequency signal. For example, the fixed frequency of the local oscillator signal can be set to the kilohertz level or lower, while the lowest frequency of the swept frequency signal can be set to the gigahertz level (e.g., 8 GHz).

[0090] The first signal mixing module 120 has its input connected to the signal generating module 110 and its output connected to the filter under test 200. The first signal mixing module 120 can mix the local oscillator signal with the swept-frequency signal via a mixer to generate a first mixed signal. The frequency components of the first mixed signal may include at least one of the following: a difference frequency between the swept-frequency signal and the local oscillator signal; or a sum frequency between the swept-frequency signal and the local oscillator signal. The first mixed signal can be input as an excitation signal to the filter under test 200 to stimulate the frequency selectivity of the filter under test 200.

[0091] The filter under test 200 performs frequency selective processing on the received first mixed signal, allowing only frequency components within its passband to pass through while suppressing all other frequencies. The second mixed signal output by the filter under test 200 is the second mixed signal after the first mixed signal has been processed by the filter under test 200.

[0092] The second signal mixing module 130 has its input connected to the filter under test 200 and its output connected to the signal detection module 140. It is configured to mix the swept-frequency signal with the second mixed signal output by the filter under test 200 and extract the target frequency component (also referred to as the "target frequency component signal") through filtering. For example, the second signal mixing module 130 mixes the second mixed signal with the swept-frequency signal through a mixer to generate multiple frequency components, including a low-frequency component having the same frequency as the local oscillator signal. By low-pass filtering the multiple frequency components, the low-frequency component serving as the target frequency component is obtained.

[0093] Signal detection module 140 is connected to second signal mixing module 130 and synchronization control module 150, respectively, and can be used to measure the amplitude of the target frequency component during the dwell time corresponding to each frequency of the swept frequency signal. For example, during the dwell time corresponding to each frequency of the swept frequency signal, the voltage or power amplitude of the target frequency component is measured to obtain an amplitude sequence of the target frequency component.

[0094] In one possible embodiment, the signal detection module 140 includes an analog-to-digital converter; the analog-to-digital converter is used to digitally sample the target frequency component during the dwell time corresponding to each frequency of the swept frequency signal, and perform amplitude measurement based on the sampling results to obtain an amplitude sequence of the target frequency component.

[0095] Here, the analog-to-digital converter can perform a digital sampling operation within the dwell time corresponding to each frequency of the swept frequency signal based on the synchronization signal sent by the synchronization control module. During this process, the analog-to-digital converter digitally samples the voltage amplitude of the target frequency component and performs amplitude measurement based on the sampling results. This allows the amplitude of the target frequency component corresponding to each frequency of the swept frequency signal to be measured, thereby forming an amplitude sequence of the target frequency components.

[0096] It is understandable that, in other embodiments, the signal detection module 140 may also perform analog amplitude detection through a detector (such as a peak detector or an average detector), or perform RF power measurement through a power detector to obtain an amplitude sequence of the target frequency component.

[0097] Since the frequency of the target frequency component is equal to the fixed frequency of the local oscillator signal, and the lowest frequency of the swept-frequency signal is at least one order of magnitude higher than the fixed frequency of the local oscillator signal, the frequency of the target frequency component is significantly lower than the lowest frequency of the swept-frequency signal. In this way, the amplitude measurement of the target frequency component can be completed with the help of the signal detection module for low-frequency detection without relying on high-performance detection equipment such as high-frequency ADC chips.

[0098] In this embodiment, each amplitude value in the target frequency component's amplitude sequence corresponds to the amplitude (i.e., signal strength) of the fixed-frequency signal extracted by filtering after two mixing cycles at different frequencies. The amplitudes in the amplitude sequence correspond one-to-one with the frequencies of the swept-frequency signal; that is, the order of the amplitudes in the amplitude sequence corresponds to the order of the frequencies the swept-frequency signal passes through within its sweep range. Because the generation of the target frequency component is related to the transmission characteristics of the filter under test at the corresponding frequency, the changing trend of this amplitude sequence can be used to reflect the changes in the insertion loss of the filter under test at different frequencies.

[0099] The synchronization control module 150 can be implemented using a controller such as an FPGA or MCU. Based on synchronization control instructions from the main control module 100, the synchronization control module 150 synchronizes the signal generation timing of the signal generation module 110 with the signal detection timing of the signal detection module 140. This allows for precise timing synchronization control of the signal generation module 110 and the signal detection module 140, thereby achieving precise synchronization between local oscillator signal generation, swept frequency signal generation, and amplitude measurement operations, thereby improving the accuracy and stability of filter performance testing.

[0100] The signal generation timing of the signal generating module 110 includes the frequency switching timing of the sweep frequency signal of the signal generating module 110 and the generation timing of the local oscillator signal, which is used to keep the sweep frequency signal and the local oscillator signal in time synchronization within the time window corresponding to each frequency of the sweep frequency signal.

[0101] The signal detection timing of the signal detection module 140 is used to trigger the signal detection module 140 to perform an amplitude measurement on the target frequency component within a time window corresponding to each frequency of the swept frequency signal.

[0102] The swept frequency signal changes frequency point by point according to a set sweep frequency step. Whenever the swept frequency signal stabilizes at a new frequency (referred to as the "sweep frequency"), the second mixed signal output by the filter under test 200 and the target frequency component output by the second signal mixing module 130 also stabilize. At this point, the synchronization control module 150 issues a synchronization signal, triggering the signal detection module 140 to measure the amplitude of the target frequency component corresponding to that frequency, thereby generating an amplitude sequence for the target frequency component. This synchronization mechanism ensures that each amplitude measurement is completed within the time window of signal stability, ensuring good timing coordination between the operations of each module, thereby improving the consistency and accuracy of the measurement results.

[0103] The main control module 100 can perform calculations based on the amplitude sequence of the target frequency component, the amplitude of the local oscillator signal, and the amplitude of the swept frequency signal to obtain the transmission gain or attenuation data of the tested filter 200 corresponding to different frequencies of the swept frequency signal, and then determine the insertion loss and / or bandwidth parameters of the tested filter 200 corresponding to each swept frequency.

[0104] Insertion loss indicates the power attenuation caused when the signal is transmitted within the passband range of the filter under test.

[0105] For example, the insertion loss is calculated as follows: Insertion loss (dB) = 20 × log10 (amplitude of the first mixing signal / amplitude of the second mixing signal). The amplitude of the first mixing signal is determined based on the amplitude of the local oscillator signal and the amplitude of the swept frequency signal. The second mixing signal is the signal output by the filter under test after processing the first mixing signal. The amplitude of the second mixing signal can be determined based on the amplitude of the target frequency component and the amplitude of the swept frequency signal.

[0106] In addition, a correction coefficient can be introduced to correct the insertion loss to compensate for the system path loss and the non-ideal characteristics of each module, thereby further improving the performance measurement accuracy.

[0107] The definition of bandwidth varies among different types of microwave filters. The bandwidth of a bandpass filter refers to the frequency range between two frequencies where the insertion loss within its passband is no greater than the insertion loss threshold (usually -3dB) defined by the bandwidth, and is used to reflect the frequency selectivity of the filter. The bandwidth of a lowpass filter is the range from its lowest responsive frequency to the cutoff frequency corresponding to when the insertion loss first reaches the above insertion loss threshold, representing the upper limit of the signal frequency it allows to pass. The bandwidth of a highpass filter usually refers to the effective passband range above the cutoff frequency corresponding to the insertion loss threshold, and is used to characterize its ability to suppress low-frequency interference. Bandstop filters use "stopband width" to describe the frequency range in which they suppress interfering signals in a specific frequency band.

[0108] In some optional implementations, the amplitudes of the target frequency components can be normalized or logarithmically transformed by combining the amplitudes of the local oscillator signal and the swept frequency signal. Each amplitude in the target frequency component amplitude sequence can be converted into a gain value corresponding to each frequency of the swept frequency signal to generate a frequency response curve for the filter under test. Based on this frequency response curve, the frequency range corresponding to the insertion loss value falling below the insertion loss threshold defined by the bandwidth is identified to obtain the bandwidth of the filter under test. The insertion loss threshold can be set to -3dB.

[0109] In some optional implementations, the process of determining the insertion loss and bandwidth of the filter under test can refer to the optional implementation methods provided in the embodiments below.

[0110] In some examples, the main control module 100 can also be used to compare the insertion loss and / or bandwidth of the filter under test with the insertion loss and / or bandwidth of a pre-acquired standard filter (also referred to as a "reference filter") to determine whether the performance parameters of the filter under test meet the index requirements.

[0111] In this embodiment, the frequency range of the swept frequency signal is set to cover the operating frequency band of the filter under test, with its lowest frequency at least an order of magnitude higher than the fixed frequency of the local oscillator signal. This allows the higher-frequency swept frequency signal to be down-converted to a target frequency component equal to the local oscillator signal frequency through two mixing processes and filtering. Consequently, when testing the performance of high-frequency filters, the amplitude of the target frequency component can be measured using a signal detection module designed for low-frequency detection, eliminating the need for high-performance testing equipment such as high-frequency ADC chips. This effectively reduces the hardware cost of filter performance testing. Furthermore, a synchronous control mechanism is employed to align the generation timing of the local oscillator signal and the swept frequency signal with the detection timing of the target frequency component, ensuring a one-to-one correspondence between the amplitudes of the target frequency component and the frequency of the swept frequency signal. This ensures that the amplitude sequence of the target frequency component accurately reflects the transmission characteristics of the filter under test at different swept frequency frequencies. Furthermore, by combining the amplitude sequence of the target frequency component, the amplitudes of the local oscillator signal, and the swept frequency signal, accurate testing of filter insertion loss and bandwidth can be achieved under low-frequency conditions.

[0112] In some embodiments, the signal detection module 140 is configured to:

[0113] During the dwell time corresponding to each frequency of the swept signal, the amplitude of the target frequency component is measured.

[0114] During the frequency sweep, the signal generation module uses a DDS to sequentially output corresponding frequencies fc1, fc2, ..., fcn at multiple different times t1, t2, ..., tn. Each time is determined based on a set sweep step time, and each frequency is determined based on the starting frequency of the sweep signal and the set sweep step.

[0115] At each set frequency, the swept frequency signal has a fixed period corresponding to that frequency, which is the time required to complete a complete waveform (usually a sine wave). It can be understood that the period is inversely proportional to the frequency: lower frequencies correspond to longer periods, while higher frequencies correspond to shorter periods.

[0116] The dwell time for a frequency is the duration that a swept signal remains stable at that frequency. Its start time typically lags behind the completion of the frequency switchover for that frequency. The length of the dwell time depends not only on the sweep step length between adjacent frequencies but also on the frequency switching time. Frequency switching time refers to the time it takes for a swept signal to transition from one frequency to the next and reach a stable state. To ensure measurement accuracy and stability, set a reasonable sweep step time based on expert experience or experimental results. While taking frequency switching time into account, provide a sufficiently long dwell time for each frequency (i.e., the swept frequency) so that the signal detection module can achieve effective amplitude measurements for each swept frequency.

[0117] In some examples, in order to ensure that the amplitude measurement of the target frequency component can be accurately triggered within the dwell time corresponding to each frequency, the synchronization control module 150 can start the internal timer when sending a first synchronization signal to the signal generating module 110 according to the set scanning step time and frequency switching time. The first synchronization signal is used to trigger the signal generating module 110 to generate a time-synchronized local oscillator signal and a swept frequency signal; it can be delayed for a fixed period of time based on the frequency switching time, and when the dwell time corresponding to the current frequency entering the swept frequency signal is determined, a second synchronization signal is sent to the signal detection module 140 to trigger an amplitude measurement operation of the target frequency component corresponding to the current swept frequency.

[0118] It is worth noting that the first synchronization signal is usually only sent once to trigger the signal generating module 110 to simultaneously start the output of the local oscillator signal and the continuous generation of the sweep frequency signal; and each frequency switching of the sweep frequency signal is completed autonomously by the signal generating module 110, without the need for the synchronization control module 150 to repeatedly send the synchronization signal.

[0119] In this embodiment, the above-mentioned synchronous control mechanism can ensure that each amplitude measurement occurs within a time window in which the frequency of the swept frequency signal is stable, thereby achieving accurate mapping between the amplitude measurement result and the swept frequency, thereby further improving the accuracy of the filter performance detection.

[0120] In some embodiments, the first signal mixing module 120 includes a first mixer for generating a first mixed signal, and the second signal mixing module 130 includes a second mixer and a filtering module.

[0121] a second mixer, configured to mix the swept frequency signal with a second mixed signal output by the filter under test after processing the first mixed signal, so as to output a third mixed signal containing a plurality of frequency components;

[0122] The low-pass filter is used to perform low-pass filtering on the third mixed signal to extract the target frequency component from the multiple frequency components.

[0123] Exemplarily, the first mixer and the second mixer may be implemented by using passive mixers or active mixers.

[0124] In one possible implementation, the third mixed signal includes a sum frequency component, a difference frequency component, and a target frequency component of the swept frequency signal and the second mixed signal. To extract the target frequency component, the filtering module performs a low-pass filtering operation on the third mixed signal, separating the target frequency component from multiple frequency components. The target frequency component has a fixed frequency value (i.e., the local oscillator signal frequency), and the amplitude sequence of the target frequency component accurately reflects the transmission characteristics of the filter under test at different swept frequencies.

[0125] In this embodiment, by employing the aforementioned two mixing operations in conjunction with low-pass filtering, high-precision extraction of the target frequency component is achieved. Furthermore, the high-frequency filter response signal can be effectively converted to a lower, fixed frequency (i.e., the local oscillator signal frequency) for amplitude measurement. This effectively reduces the complexity and measurement uncertainty associated with direct high-frequency signal processing, and improves the stability and reliability of performance testing of the filter under test.

[0126] See Figure 2 , Figure 2 A schematic diagram of the structure of a filter performance detection circuit provided by an embodiment of the present application. The main control module includes a main controller (e.g., an MCU or FPGA) that controls the entire circuit. For example, the main controller generates signal excitation instructions and synchronization control instructions. The signal excitation instructions trigger the signal generation module to generate a local oscillator signal and a swept frequency signal, while the synchronization control instructions control the synchronization control module to synchronize the signal generation timing of the signal generation module with the signal detection timing of the signal detection module. The signal generation module includes a fixed-frequency sine wave circuit and a DDS frequency synthesizer; the fixed-frequency sine wave circuit generates a fixed-frequency local oscillator signal S1. The signal detection module includes an ADC (digital-to-analog converter) for measuring the amplitude of a target frequency component. The synchronization control module includes a synchronization control circuit, which is connected to the fixed-frequency sine wave circuit, the DDS frequency synthesizer, and the ADC. Under the control of the main controller, it sends synchronization signals to the fixed-frequency sine wave circuit, the DDS frequency synthesizer, and the ADC to achieve timing alignment between the generation of the local oscillator signal and the swept frequency signal and the amplitude measurement of the target frequency component.

[0127] like Figure 2As shown, local oscillator signal S1 and swept frequency signal S2 are mixed by a first signal mixing module, which includes MIXER1 (i.e., the first mixer in the aforementioned embodiment). First mixed signal S3 is processed by the device under test (for example, an X-band filter as the DUT) to produce a second mixed signal S4. Second mixed signal S4 and swept frequency signal S2 are input to a second signal mixing module, which includes MIXER2 (i.e., the second mixer in the aforementioned embodiment) and a low-pass filter. Second mixed signal S4 and swept frequency signal S2 are mixed by MIXER2 to produce a third mixed signal S5. Third mixed signal S5 is low-pass filtered by a low-pass filter to produce a target frequency component S6. Target frequency component S6 is input to an ADC, which measures the amplitude of target frequency component S6 to obtain amplitude information. The amplitude information of the target frequency component S6 is fed back by the ADC to the main controller for calculation, and the final result (for example, the calculation results of performance parameters such as the insertion loss and bandwidth of the device under test) is output through the output circuit.

[0128] The two input terminals of the mixer can be called the radio frequency terminal (RF) and the local oscillator terminal (LO), and the output terminal is called the intermediate frequency terminal (IF). The mixer performs frequency conversion by multiplying the two input signals. If the input signal frequency is f RF 、f LO , then the output mixing signal frequency is |f RF -f LO | (downconversion) or f RF +f LO (Up-conversion).

[0129] The first mixing is to mix the high-frequency signal to be detected with the local oscillator signal with a relatively low frequency to obtain a frequency of |f RF -f LO The difference frequency signal of | is f RF +f LO The mixer can achieve up-conversion or down-conversion or both simultaneously. The output signal of the first mixing is passed through the X-band filter to output the filtered signal.

[0130] The second mixing is to mix the signal filtered by the X-band filter with the high-frequency signal to be detected again. Here, down-conversion is given priority, that is, the frequency of the difference frequency signal and the sum frequency signal after the first mixing is subtracted from f RF , and the frequency is |±f LO | signal, thereby converting the higher frequency filtered signal into a lower frequency signal for output. If the second mixing does not specifically select a down-mixer, the high frequency signal can also be filtered out by superimposing a low-pass filter, leaving only the frequency f LOTherefore, the X-band high-frequency signal in the filter is mixed twice. The mixer can convert the higher-frequency RF input signal into a lower-frequency output signal without changing the characteristics of the original signal, making it easier to detect the insertion loss and bandwidth of the X-band filter.

[0131] Continue reading Figure 2 , the working principle of the filter performance detection circuit is as follows:

[0132] The fixed frequency sine wave circuit is used to generate a fixed frequency f b The local oscillator signal S1 has an amplitude of a1, and the expression is: The main controller is used to control the DDS frequency synthesizer to generate a swept frequency signal (which can be used as a radio frequency signal). The main frequency range of the swept frequency signal is X-band (8GHz~12GHz).

[0133] When a single measurement is performed at time t, the output frequency of the sweep signal is f c , the sweep signal S2 with an amplitude of a2, assuming The frequency sweep process is to set the sweep step at different times {t1, t2, ...t n}The corresponding output frequency is {f c1 , f c2 ,…f cn}、A series of sine wave signals with constant amplitude, i.e., at time t n The corresponding output frequency is f cn Sweep signal , whose expression is: .

[0134] The local oscillator signal S1 and the swept frequency signal S2 pass through the mixer MIXER1 to generate the first mixed signal S3. The mixer MIXER1 multiplies the two input signals and performs frequency conversion to obtain the first mixed signal S3. The expression of the first mixed signal S3 is: .

[0135] After passing through the device under test (DUT), the first mixed signal S3 outputs the second mixed signal S4. Within the filtering band of the DUT's X-band filter, the first mixed signal S3 experiences amplitude attenuation, but its frequency remains unchanged. Assuming the amplitude becomes a3, the expression for the second mixed signal S4 is: .

[0136] The second mixed signal S4 and the swept signal S2 are mixed twice by the mixer MIXER2 to output a third mixed signal S5. The expression of the third mixed signal S5 is: .

[0137] The third mixed signal S5 contains three frequency components, namely: f b +2f c 、|f b -2f c |、f b .

[0138] Usually the local oscillator signal frequency is f b Much smaller than the RF signal frequency f c Therefore, after the third mixed signal S5 passes through the low-pass filter, the frequency f is filtered out. b +2f c 、|f b -2f c |The high-frequency component, only the frequency f b The low-frequency component of , thereby obtaining the target frequency component S6, which is expressed as: .

[0139] The amplitude of the target frequency component S6 is collected by the ADC, input to the main controller for calculation, and the result is finally output through the output circuit.

[0140] Since the frequency of the target frequency component S6 is the same as that of the local oscillator signal S1, a conventional ADC can be used to acquire the signal amplitude without relying on a high-frequency ADC for insertion loss and bandwidth detection.

[0141] Through the above working principle, the filter performance detection circuit can accurately measure the performance parameters of the filter under test under low frequency conditions.

[0142] In other embodiments, the first signal mixing module 120 includes a first mixer for generating a first mixing signal; the second signal mixing module 130 includes: a second mixer for down-mixing the swept signal with a second mixing signal output by the filter under test to output a target frequency component.

[0143] Here, the second mixer is internally integrated with a filtering unit configured to perform low-pass filtering on the signal obtained by mixing the swept frequency signal and the second mixing signal, so as to suppress high-frequency components and retain the desired target frequency components.

[0144] Unlike the previous embodiment, in this embodiment, the second signal mixing module 130 does not include a filtering module, and the signal mixing function is achieved solely through a second mixer with an integrated filtering unit. The second mixer performs a down-mixing operation on the swept signal and the second mixed signal output by the filter under test, so that the frequency difference between the mixing results is exactly equal to the fixed frequency of the local oscillator signal, thereby directly obtaining the target frequency component. In this embodiment, by adopting the aforementioned dual-mixing architecture and omitting the filtering module, efficient extraction of the target frequency component is achieved. The high-frequency filter response signal is simultaneously effectively converted to a fixed frequency (i.e., the local oscillator frequency) for measurement. This reduces the complexity and measurement uncertainty associated with direct processing of high-frequency signals, further improving the stability and practicality of filter performance testing.

[0145] In some optional implementations, the main control module 100 is specifically configured to:

[0146] determining an amplitude sequence of a second mixed signal based on each amplitude in the amplitude sequence of the target frequency component and the amplitude of the frequency sweep signal;

[0147] determining the amplitude of the first mixed signal based on the amplitude of the local oscillator signal and the amplitude of the frequency sweep signal;

[0148] Insertion loss calculation is performed on each amplitude in the amplitude sequence of the second mixing signal and the amplitude of the first mixing signal to obtain an insertion loss value of the measured filter corresponding to each frequency of the swept frequency signal.

[0149] In this embodiment, the target frequency component is a fixed-frequency signal obtained by mixing two signals and filtering them. Its amplitude reflects the strength of the output signal of the filter under test. By combining each amplitude in the target frequency component amplitude sequence with the known amplitude of the swept-frequency signal, the actual amplitude of the second mixed signal at each swept frequency can be inferred, thereby obtaining the amplitude sequence of the second mixed signal.

[0150] For example, referring to the description of the circuit working principle in the above embodiment, the amplitude of the target frequency component S6 is , for each amplitude in the amplitude sequence of the target frequency component, assuming that it corresponds to a certain sweep frequency f c , the actual measured amplitude of the target frequency component is a4, then it can be calculated a3 is the amplitude of the second mixed signal S4 output by the first mixed signal S3 after passing through the filter under test (DUT). The amplitude of the first mixed signal S3 can be calculated based on the known amplitude a1 of the local oscillator signal and the known amplitude a2 of the swept signal S2.

[0151] The insertion loss of the second mixing signal S4 and the first mixing signal S3 are calculated, and the measured filter corresponding to the sweep frequency f is obtained. c The insertion loss value of the filter under test corresponding to each frequency of the swept frequency signal can be calculated by analogy.

[0152] Insertion loss IL is expressed in decibels (dB) and is calculated as: IL = 20log (Vin / Vout), where Vin is the input signal amplitude and Vout is the output signal amplitude. For the filter under test, the input signal is the first mixed signal S3, and the output signal is the second mixed signal S4.

[0153] Based on the above insertion loss calculation, the frequency {f c1 , f c2 ,…f cn} Insertion loss values ​​{IL1, IL2, ... IL n}.

[0154] It can be understood that the insertion loss value is calculated based on the amplitude ratio between the first mixing signal (the input signal of the filter under test) and the second mixing signal (the output signal of the filter under test), and the frequency of the first mixing signal is determined by the frequency of the swept signal and the frequency of the local oscillator signal. Therefore, the insertion loss value can be regarded as the attenuation performance of the filter under test at the passband frequency corresponding to each frequency of the swept signal. In other words, the insertion loss value reflects the attenuation characteristics of the filter under test at the frequencies corresponding to each frequency of the swept signal within its operating frequency band.

[0155] In this embodiment, based on each amplitude of the target frequency component, combined with the known amplitudes of the swept frequency signal and the local oscillator signal, it is accurately converted into the amplitude of the first mixing signal and the amplitude of the second mixing signal, that is, the actual signal amplitudes at the input and output ends of the measured filter are obtained, thereby achieving accurate calculation of the insertion loss of the measured filter corresponding to each swept frequency.

[0156] In some optional implementations, the filter under test 200 is a bandpass filter, and the main control module 100 is further configured to:

[0157] Determining, based on the insertion loss value of the filter under test corresponding to each frequency of the swept frequency signal, a first frequency and a second frequency at which the insertion loss value meets the bandwidth determination condition;

[0158] The frequency width between the first frequency and the second frequency is determined as the bandwidth of the filter under test.

[0159] The bandwidth judgment condition includes an insertion loss threshold. The main control module 100 obtains the frequency {f c1 , f c2 ,…f cn} Insertion loss values ​​{IL1, IL2, ... IL n}, the first frequency (i.e., the lower boundary frequency) and the second frequency (i.e., the upper boundary frequency) that meet the bandwidth judgment condition can be determined based on the insertion loss threshold in the bandwidth judgment condition, and then the frequency width between the first frequency and the second frequency can be determined as the bandwidth of the filter under test.

[0160] The insertion loss threshold is usually set to -3dB. The frequency corresponding to the insertion loss value of -3dB indicates that the amplitude of the output signal of the tested filter is equal to the amplitude of the input signal of the tested filter. .

[0161] In addition, after the first frequency and the second frequency are determined, the arithmetic mean of the first frequency and the second frequency may be determined as the center frequency of the filter under test.

[0162] The first mixing signal and the two boundary frequencies corresponding to 3dB‌, when the filter under test is a bandpass filter, can be calculated according to the bandwidth formula BW=f upper -f lower , calculate the 3dB bandwidth of the X-band filter, BW represents the 3dB bandwidth, f lower Represents the lower boundary frequency, f upper Indicates the upper boundary frequency.

[0163] Based on the filter performance detection circuit in the aforementioned embodiment, the present application also provides a filter performance detection method. The various embodiments or implementation methods in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Similar or identical parts between the various embodiments can be referenced to each other. For example, the optional implementation methods in the filter performance detection method embodiment can refer to the relevant content of the filter performance detection circuit provided in the aforementioned embodiment, and vice versa, and will not be repeated here.

[0164] Figure 3 This is a flow chart of a filter performance detection method provided in an embodiment of the present application. Figure 3 As shown, the method includes steps S301 to S304.

[0165] S301: Input a first mixed signal obtained by mixing a local oscillator signal and a frequency sweep signal into a filter under test.

[0166] The sweep frequency range of the sweep frequency signal covers the working frequency band of the filter under test, the lowest frequency of the sweep frequency signal is at least one order of magnitude higher than the fixed frequency of the local oscillator signal, and the working frequency band is located in the target band in the microwave frequency band.

[0167] In some examples, the target band is the X-band.

[0168] For example, step S301 may be implemented by a first signal mixing module in a performance detection circuit of a filter.

[0169] S302: Mix the frequency sweep signal with a second mixed signal output by the filter under test, and extract the target frequency component through filtering.

[0170] The frequency of the target frequency component is equal to the fixed frequency of the local oscillator signal.

[0171] For example, step S302 may be implemented by a second signal mixing module in a performance detection circuit of the filter.

[0172] S303: triggering the amplitude measurement of the target frequency component every time the frequency sweep signal scans to a frequency, to obtain an amplitude sequence of the target frequency component.

[0173] The detection timing of the target frequency component is aligned with the generation timing of the local oscillation signal and the frequency sweep signal.

[0174] For example, step S303 may be implemented by a signal detection module in a performance detection circuit of the filter.

[0175] The synchronization control module can synchronize the signal generation timing of the signal generation module and the signal detection timing of the signal detection module based on the synchronization control instructions from the main control module, so that the detection timing of the target frequency component is aligned with the generation timing of the local oscillator signal and the swept frequency signal.

[0176] The signal generation timing of the signal generation module includes: the frequency switching timing of the sweep signal and the generation timing of the local oscillator signal, which is used to keep the sweep signal and the local oscillator signal in time synchronization within the time window corresponding to each frequency of the sweep signal.

[0177] The signal detection timing of the signal detection module is used to perform an amplitude measurement on the target frequency component within the time window corresponding to each frequency of the swept frequency signal.

[0178] S304: Determine the insertion loss and / or bandwidth of the filter under test based on the amplitude sequence of the target frequency component, the amplitude of the local oscillator signal, and the amplitude of the swept frequency signal.

[0179] For example, step S304 may be implemented by a main control module in a performance detection circuit of the filter.

[0180] In this embodiment, the frequency range of the swept frequency signal is set to cover the operating frequency band of the filter under test, with its lowest frequency at least an order of magnitude higher than the fixed frequency of the local oscillator signal. This allows the higher-frequency swept frequency signal to be down-converted to a target frequency component equal to the local oscillator signal frequency through two signal mixing processes. Consequently, when testing the performance of high-frequency filters, the amplitude of the target frequency component can be measured using a low-frequency signal detection module, eliminating the need for high-performance testing equipment such as high-frequency ADC chips. This effectively reduces the hardware cost of filter performance testing. Furthermore, a synchronous control mechanism is employed to trigger the amplitude measurement of the target frequency component each time the swept frequency signal reaches a certain frequency, generating an amplitude sequence of the target frequency component. This amplitude sequence of the target frequency component can be aligned with the frequency variation sequence of the swept frequency signal, thereby accurately reflecting the transmission characteristics of the filter under test at different swept frequencies. Furthermore, by combining the amplitude sequence of the target frequency component, the amplitude of the local oscillator signal, and the amplitude of the swept frequency signal, accurate detection of filter insertion loss and bandwidth can be achieved under low-frequency conditions.

[0181] In some optional implementations, in step S303, triggering the amplitude measurement of the target frequency component each time the frequency sweep signal scans to a frequency to obtain the amplitude sequence of the target frequency component may include:

[0182] During the dwell time corresponding to each frequency of the swept frequency signal, the amplitude of the target frequency component is measured by the ADC to generate an amplitude sequence of the target frequency component.

[0183] In some optional embodiments, such as Figure 4 As shown, in step S304, determining the insertion loss of the filter under test based on the amplitude sequence of the target frequency component, the amplitude of the local oscillator signal, and the amplitude of the swept frequency signal may include the following steps:

[0184] S401: Determine an amplitude sequence of a second mixed signal based on each amplitude in the amplitude sequence of the target frequency component and the amplitude of the frequency sweep signal;

[0185] S402: Determine the amplitude of the first mixed signal based on the amplitude of the local oscillator signal and the amplitude of the swept frequency signal;

[0186] S403: Perform insertion loss calculation on each amplitude in the amplitude sequence of the second mixing signal and the amplitude of the first mixing signal to obtain an insertion loss value of the tested filter corresponding to each frequency of the swept frequency signal.

[0187] In this embodiment, the execution order of step S401 and step S402 is not specifically limited. For example, executing step S401 and step S402 simultaneously is a preferred solution.

[0188] In this embodiment, the target frequency component is a fixed-frequency signal obtained by mixing two signals and filtering them. Its amplitude reflects the strength of the output signal of the filter under test. By combining each amplitude in the target frequency component amplitude sequence with the known amplitude of the swept-frequency signal, the actual amplitude of the second mixed signal at each swept frequency can be inferred, thereby obtaining the amplitude sequence of the second mixed signal.

[0189] For example, referring to the description of the circuit working principle in the above embodiment, the amplitude of the target frequency component S6 is , for each amplitude in the amplitude sequence of the target frequency component, assuming that it corresponds to a certain sweep frequency f c , the actual measured amplitude of the target frequency component is a4, then it can be calculated a3 is the amplitude of the second mixed signal S4 output by the first mixed signal S3 after passing through the filter under test (DUT). The amplitude of the first mixed signal S3 can be calculated based on the known amplitude a1 of the local oscillator signal and the known amplitude a2 of the swept signal S2.

[0190] The insertion loss of the second mixing signal S4 and the first mixing signal S3 are calculated, and the measured filter corresponding to the sweep frequency f is obtained. c The insertion loss value of the filter under test corresponding to each frequency of the swept frequency signal can be calculated by analogy.

[0191] Insertion loss IL is expressed in decibels (dB) and is calculated as: IL = 20log (Vin / Vout), where Vin is the input signal amplitude and Vout is the output signal amplitude. For the filter under test, the input signal is the first mixed signal S3, and the output signal is the second mixed signal S4.

[0192] Based on the above insertion loss calculation, the frequency {f c1 , f c2 ,…f cn} Insertion loss values ​​{IL1, IL2, ... IL n}.

[0193] It can be understood that the insertion loss value is calculated based on the amplitude ratio between the first mixing signal (the input signal of the filter under test) and the second mixing signal (the output signal of the filter under test), and the frequency of the first mixing signal is determined by the frequency of the swept signal and the frequency of the local oscillator signal. Therefore, the insertion loss value can be regarded as the attenuation performance of the filter under test at the passband frequency corresponding to each frequency of the swept signal. In other words, the insertion loss value reflects the attenuation characteristics of the filter under test at the frequencies corresponding to each frequency of the swept signal within its operating frequency band.

[0194] In this embodiment, based on each amplitude of the target frequency component, combined with the known amplitudes of the swept frequency signal and the local oscillator signal, it is accurately converted into the amplitude of the first mixing signal and the amplitude of the second mixing signal, that is, the actual signal amplitudes at the input and output ends of the measured filter are obtained, thereby achieving accurate calculation of the insertion loss of the measured filter corresponding to each swept frequency.

[0195] In some optional embodiments, such as Figure 5 As shown, the filter under test is a bandpass filter, and the bandwidth of the filter under test can be determined based on the following method:

[0196] Step S501: determining a first frequency and a second frequency at which the insertion loss value meets a bandwidth determination condition based on the insertion loss value of the filter under test corresponding to each frequency of the swept frequency signal;

[0197] Step S502: Determine the frequency width between the first frequency and the second frequency as the bandwidth of the filter under test.

[0198] The bandwidth judgment condition includes an insertion loss threshold. The main control module 100 obtains the frequency {f c1 , f c2 ,…f cn} Insertion loss values ​​{IL1, IL2, ... IL n}, the first frequency (i.e., the lower boundary frequency) and the second frequency (i.e., the upper boundary frequency) that meet the bandwidth judgment condition can be determined based on the insertion loss threshold in the bandwidth judgment condition, and then the frequency width between the first frequency and the second frequency can be determined as the bandwidth of the filter under test.

[0199] The insertion loss threshold is usually set to -3dB. The frequency corresponding to the insertion loss value of -3dB indicates that the amplitude of the output signal of the tested filter is equal to the amplitude of the input signal of the tested filter. .

[0200] In addition, after the first frequency and the second frequency are determined, the arithmetic mean of the first frequency and the second frequency may be determined as the center frequency of the filter under test.

[0201] For example, when the filter under test is a bandpass filter, the bandwidth can be calculated according to the formula BW=f upper -f lower , calculate the 3dB bandwidth of the X-band filter, BW represents the 3dB bandwidth, f lower Represents the lower boundary frequency, f upper Indicates the upper boundary frequency.

[0202] In this embodiment, by identifying the first frequency and the second frequency that meet the insertion loss threshold and defining the frequency band between the two as the filter bandwidth, the effective passband range of the tested filter under actual working conditions can be accurately reflected, thereby achieving a high-precision evaluation of its frequency response performance.

[0203] In summary, the embodiments of the present application provide a filter performance testing method particularly suitable for testing the insertion loss and bandwidth of double-frequency conversion X-band filters. By employing a double-frequency mixing method to convert a higher-frequency RF input signal into a lower-frequency output signal, signal acquisition no longer relies on high-frequency ADC chips, such as the expensive 24-bit ADS1220, for high-performance ADC chips. This reduces reliance on high-performance components and significantly reduces the cost of the testing system. Furthermore, compared to traditional testing systems, which are generally applicable to a wider operating frequency band and are not specifically optimized for the X-band, and are prone to introducing errors when testing X-band filters, the present application scheme enables more precise frequency scanning and measurement within the X-band, enabling accurate testing of the insertion loss and bandwidth of X-band filters and improving the accuracy of X-band filter performance testing.

[0204] An embodiment of the present application provides an electronic device, comprising a performance detection circuit for a filter provided by any one of the aforementioned embodiments.

[0205] An embodiment of the present application provides an electronic device, including a processor, wherein the processor is configured to call instructions so that the electronic device executes a filter performance detection method as provided in any one of the aforementioned embodiments.

[0206] The present application also provides a computer-readable storage medium, in which computer-executable instructions are stored. When a processor executes the computer-executable instructions, the filter performance detection method provided by any one of the aforementioned embodiments is implemented.

[0207] The computer-readable storage medium provided in this embodiment can execute the filter performance detection method provided in any of the aforementioned embodiments. The implementation principles and technical effects are similar and will not be described in detail in this embodiment.

[0208] The computer-readable storage medium mentioned above can be implemented by any type of volatile or non-volatile memory device, or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk. The computer-readable storage medium can be any available medium that can be accessed by a general-purpose or special-purpose computer.

[0209] An exemplary readable storage medium is coupled to a processor so that the processor can read information from the readable storage medium and write information to the readable storage medium. Of course, the readable storage medium can also be an integral part of the processor. The processor and the readable storage medium can be located in an application specific integrated circuit (ASIC). Of course, the processor and the readable storage medium can also exist as discrete components in an electronic device or a main control device.

[0210] Those skilled in the art will appreciate that all or part of the steps in the above-described method embodiments can be implemented using hardware associated with program instructions. The aforementioned program can be stored in a computer-readable storage medium. When executed, the program performs the steps of the above-described method embodiments. The aforementioned storage medium includes various media capable of storing program code, such as ROM, RAM, magnetic disks, or optical disks.

[0211] The various embodiments or implementation methods in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments, and the same or similar parts between the various embodiments can be referenced to each other.

[0212] Throughout this specification, references to "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples" mean that a specific feature, structure, material, or characteristic described in conjunction with an embodiment or example is included in at least one embodiment or example of the present application. In this specification, illustrative references to the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0213] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A filter performance detection circuit, characterized in that: include: Main control module, used to generate signal excitation instructions and synchronization control instructions; a signal generating module, configured to generate a local oscillator signal and a frequency sweep signal based on the signal excitation instruction, wherein the frequency range of the frequency sweep signal covers the operating frequency band of the filter under test, the lowest frequency of the frequency sweep signal is at least one order of magnitude higher than the fixed frequency of the local oscillator signal, and the operating frequency band is within a target band within the microwave frequency band; a first signal mixing module, configured to mix the local oscillator signal with the frequency sweep signal, and output a first mixed signal to the filter under test; a second signal mixing module, configured to mix the frequency sweep signal with a second frequency mixing signal output by the filter under test, and extract a target frequency component by filtering, wherein the frequency of the target frequency component is equal to the fixed frequency of the local oscillator signal; a signal detection module, configured to measure the amplitude of the target frequency component to obtain an amplitude sequence of the target frequency component, wherein the amplitudes in the amplitude sequence correspond one-to-one to the frequencies of the frequency sweep signal; a synchronization control module, configured to synchronously control the signal generation timing of the signal generation module and the signal detection timing of the signal detection module based on the synchronization control instruction; The main control module is further used to determine the insertion loss and / or bandwidth of the filter under test based on the amplitude sequence of the target frequency component, the amplitude of the local oscillator signal and the amplitude of the swept frequency signal.

2. The filter performance detection circuit according to claim 1, characterized in that: The signal detection module is used for: During the dwell time corresponding to each frequency of the swept frequency signal, the amplitude of the target frequency component is measured.

3. The filter performance detection circuit according to claim 2, characterized in that: The signal detection module includes an analog-to-digital converter, which is used to: During the dwell time corresponding to each frequency of the swept frequency signal, the target frequency component is digitally sampled, and the amplitude is measured based on the sampling result.

4. The filter performance detection circuit according to claim 1, characterized in that: The first signal mixing module includes a first mixer for generating the first mixed signal; The second signal mixing module includes: a second mixer, configured to mix the swept frequency signal with a second mixed signal output by the filter under test after processing the first mixed signal, so as to output a third mixed signal containing a plurality of frequency components; A low-pass filter is used to perform low-pass filtering on the third mixed signal to extract the target frequency component from the multiple frequency components.

5. The filter performance detection circuit according to claim 1, characterized in that: The main control module is specifically used for: determining an amplitude sequence of the second mixing signal based on each amplitude in the amplitude sequence of the target frequency component and the amplitude of the frequency sweep signal; determining the amplitude of the first mixing signal based on the amplitude of the local oscillator signal and the amplitude of the frequency sweep signal; Insertion loss calculation is performed on each amplitude in the amplitude sequence of the second mixing signal and the amplitude of the first mixing signal to obtain an insertion loss value of the tested filter corresponding to each frequency of the swept frequency signal.

6. The filter performance detection circuit according to any one of claims 1 to 5, characterized in that: The target band is the X band.

7. A filter performance detection method, characterized in that: include: Inputting a first mixed signal obtained by mixing a local oscillator signal with a swept frequency signal into the filter under test, wherein the swept frequency range of the swept frequency signal covers an operating frequency band of the filter under test, the lowest frequency of the swept frequency signal is at least one order of magnitude higher than a fixed frequency of the local oscillator signal, and the operating frequency band is within a target band within the microwave frequency band; Mixing the swept frequency signal with a second mixed frequency signal output by the filter under test, and extracting a target frequency component by filtering, wherein the frequency of the target frequency component is equal to the fixed frequency of the local oscillator signal; triggering amplitude measurement of the target frequency component each time the frequency sweep signal scans to a frequency, to obtain an amplitude sequence of the target frequency component, wherein a detection timing of the target frequency component is aligned with a generation timing of the local oscillator signal and the frequency sweep signal; The insertion loss and / or bandwidth of the filter under test is determined based on the amplitude sequence of the target frequency component, the amplitude of the local oscillator signal, and the amplitude of the swept frequency signal.

8. The filter performance detection method according to claim 7, characterized in that: The triggering of the amplitude measurement of the target frequency component each time the frequency sweep signal scans to a frequency, to obtain the amplitude sequence of the target frequency component, includes: During the dwell time corresponding to each frequency of the frequency sweep signal, the amplitude of the target frequency component is measured by an analog-to-digital converter to generate an amplitude sequence of the target frequency component.

9. The filter performance detection method according to claim 7 or 8, characterized in that: The determining of the insertion loss of the filter under test based on the amplitude sequence of the target frequency component, the amplitude of the local oscillator signal, and the amplitude of the swept frequency signal includes: determining an amplitude sequence of the second mixing signal based on each amplitude in the amplitude sequence of the target frequency component and the amplitude of the frequency sweep signal; determining the amplitude of the first mixing signal based on the amplitude of the local oscillator signal and the amplitude of the frequency sweep signal; Insertion loss calculation is performed on each amplitude in the amplitude sequence of the second mixing signal and the amplitude of the first mixing signal to obtain an insertion loss value of the tested filter corresponding to each frequency of the swept frequency signal.

10. The filter performance detection method according to claim 9, characterized in that: The filter under test is a bandpass filter, and the bandwidth of the filter under test is determined based on the following method: Determining, based on the insertion loss value of the filter under test corresponding to each frequency of the swept frequency signal, a first frequency and a second frequency at which the insertion loss value meets a bandwidth determination condition, wherein the bandwidth determination condition includes an insertion loss threshold; A frequency width between the first frequency and the second frequency is determined as the bandwidth of the filter under test.

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