High-frequency front-end device based on OIP3 test and test method

Abstract

According to the high-frequency front-end device based on the OIP3 test and the test method, two radio frequency sources are divided into a high-output channel and a low-output channel, a manual adjustable attenuator is arranged in the high-output channel to control and deploy the output amplitude, the high-output channel and the low-output channel are both provided with isolators, leakage signals are suppressed, and the high-frequency front-end device based on the OIP3 test is obtained. The two-channel radio frequency signals are combined into one signal through the combiner to be output, meanwhile, the combined signal outputs a coupling signal and an output signal through the coupler, the coupling signal is used for monitoring the magnitude and amplitude of the output signal in real time, and the output signal finally passes through the programmable attenuator to achieve linear output modulation. The magnitude and amplitude of the output signal can be flexibly adjusted, real-time monitoring is supported, various application scenes are adapted, different power requirements are met, a high dynamic range is achieved, high-precision and stable linear modulation is supported, and the reliability under a high-power signal is ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of high-frequency radio communication, and particularly relates to a high-frequency front-end device and a test method based on OIP3 test. Background Art

[0002] E (60GHz - 90GHz), due to its short wavelength and wide frequency band, is used as a millimeter wave application, which makes the E-band millimeter wave have broad application prospects in the fields of communication, radar, remote sensing, etc. The OIP3 performance of the millimeter wave system is a key index for these applications. In signal transmission and reception, the output third-order intercept point OIP3 (Output Third-Order Intercept Point) and the third-order intermodulation IM3 (Third-Order Intermodulation) are two important parameters in the design and test of radio frequency circuits, especially for high-dynamic-range systems. In low-frequency OIP3 and IM3 tests, we can directly use two independent signal sources to output signals. However, with the development of communication and the increase in frequency, ordinary signal sources cannot meet the frequency requirements, and the suppression of high-frequency interference, harmonics, and the amplitude balance of signals are all the keys to affecting signal linearity, making it difficult to perform accurate and systematic tests. Summary of the Invention

[0003] To overcome the deficiencies of the prior art, the present invention proposes a high-frequency front-end device and a test method based on OIP3 test. By matching a high-directivity combiner and an isolator, the problem of signal crosstalk is solved, unnecessary intermodulation products are avoided, and the accuracy of the test results is improved.

[0004] To achieve the above object, a high-frequency front-end device based on OIP3 test of the present invention includes a 6-fold frequency multiplier 1 for the high-power channel, whose output power is +17dBm; a manually adjustable attenuator 3 for the high-power channel; an E-band isolator 4 for the high-power channel; a 6-fold frequency multiplier 2 for the low-power channel, whose output power is +15dBm; an E-band isolator 5 for the low-power channel; a combiner 6; an E-band coupler 7; an E-band programmable attenuator 8, wherein:

[0005] The input signal of the high-power channel, after passing through the 6-fold frequency multiplier 1, is sent to the manually adjustable attenuator 3, and then enters the IN1 port of the combiner 6 through the E-band isolator 4;

[0006] The input signal of the low-power channel, after passing through the 6-fold frequency multiplier 2, is sent to the IN2 port of the combiner 6 through the E-band isolator 5;

[0007] The combiner 6 combines and outputs the two signals and sends them to the E-band single-directional coupler 7;

[0008] The E-band coupler 7 monitors the power and sends it to the E-band programmable attenuator 8 through the through output, and outputs after attenuation, so as to achieve linear output modulation.

[0009] Furthermore, the input channels are two independent channels, namely the high-power channel and the low-power channel; both the high-power channel and the low-power channel adopt a sixth-order frequency multiplier. The output power of the high-power output channel is +17 dBm, the output power of the low-power output channel is +15 dBm, and the output frequency range is 60 GHz to 90 GHz.

[0010] Furthermore, a manually adjustable attenuator is provided in the high-power output channel, and its attenuation range is 0 dB to -30 dB.

[0011] Furthermore, E-band isolators are provided in both the high-power output channel and the low-power output channel.

[0012] Furthermore, the E-band programmable attenuator is a high-linearity programmable attenuator, and its attenuation range is 0 dB to -35 dB.

[0013] Furthermore, the specifications of the combiner are as follows:

[0014] Operating frequency: E-band 60 GHz to 90 GHz;

[0015] In-band insertion loss: ≤1 dB;

[0016] Output port isolation: ≥30 dB;

[0017] VSWR at the input and output ends: ≤1.6.

[0018] Furthermore, the coupling value of the E-band single directional coupler is 10 dB, and its specifications are as follows:

[0019] Operating frequency: E-band 60 GHz to 90 GHz;

[0020] In-band insertion loss: ≤1 dB;

[0021] Coupling flatness: ≤1 dB;

[0022] VSWR at the input end, output end and coupling end: ≤1.20.

[0023] Furthermore, the specifications of the E-band isolator are as follows:

[0024] Operating frequency: E-band 60 GHz to 90 GHz;

[0025] In-band insertion loss: ≤1 dB;

[0026] Reverse isolation: ≥25 dB.

[0027] Furthermore, the E-band programmable attenuator is a high-linearity programmable attenuator with an attenuation range of 0 dB to -35 dB.

[0028] A test method for a high-frequency front-end device based on OIP3 testing is applicable to any one of the high-frequency front-end devices based on OIP3 testing described above.

[0029] Step 1: Accurately calibrate the non-linear characteristics, channel synchronization, and temperature effects of the system through dual-tone signal injection, time-delay measurement, and temperature compensation modeling.

[0030] Step 2: Adopt dual-loop power control, time-delay tracking, and intermodulation component extraction technologies to ensure signal stability, phase synchronization, and accurate intermodulation component analysis.

[0031] Step 3: Precisely calculate OIP3 and evaluate the reliability of the results by processing multi-dimensional data through the three-slope method and weighted averaging.

[0032] Step 4: Design a multi-stage over-power protection and phase-locked loop re-capture process to ensure the stable operation and automatic recovery of the system under abnormal conditions.

[0033] Furthermore, Step 1 is specifically as follows:

[0034] Step 11: Input the fundamental frequency signal into both the high channel and the low channel simultaneously. Through the frequency doubling process, convert the fundamental frequency signal into the target frequency; then, increase or decrease a certain frequency offset on the fundamental frequency, with a range from 1 MHz to 50 MHz, to capture the non-linear effects of the system.

[0035] Step 12: Collect five key frequency points at the output end, including the two signals after frequency offset, intermodulation components, and the center frequency. The data is used for subsequent non-linear coefficient extraction; according to the collected data, solve the coefficient matrix reflecting the non-linear relationship of the signal through the least squares method. These coefficients describe the non-linear transfer characteristics between the input and output signals; the frequency calculation is as follows:

[0036] f 1 = 6·(f base + Δf);

[0037] f 2 = 6·(f base - Δf);

[0038] where, f base : Fundamental frequency (10 GHz);

[0039] Δf: Frequency offset, with a range of 1 MHz to 50 MHz (step 1 MHz);

[0040] f 1 and f 2: The frequency of the dual-tone signal after frequency offset;

[0041] Intermodulation component calculation:

[0042] IM3 1 = 2·f 1 -f 2 ;

[0043] IM3 2 = 2·f 2 -f 1 ;

[0044] Among them, IM3 1 and IM3 2 : Intermodulation products, representing the distortion frequencies generated by the non-linear action of the fundamental frequency signals;

[0045] Center frequency calculation:

[0046]

[0047] Among them, f c : Center frequency, which is the average value of the dual-tone signal frequencies and is used as the reference frequency for subsequent calculations.

[0048] Calculation of the non-linear coefficient matrix H:

[0049] V out = H·V 3 in ;

[0050] Among them, V out : Amplitude vector of the output signal.

[0051] V 3 in : Cubic direction vector of the input signal, used to capture the non-linear characteristics of the signal.

[0052] H = [α,β,γ,δ] T : Non-linear coefficient matrix, containing four coefficients, reflecting the non-linear influence of the signal, and solved by the least squares method.

[0053] Step 13: By injecting a chirp signal and using the cross-correlation algorithm to calculate the time delay difference between the high channel and the low channel. The cross-correlation algorithm helps to detect the signal peak, thereby determining the time delay difference; according to the calculated time delay difference, a corresponding phase compensation table is generated for each frequency point. The compensation table is used to adjust the phase of the system to correct the signal distortion caused by the time delay difference;

[0054] The time delay difference measurement is as follows:

[0055] Cross-correlation function:

[0056] Rxy R(τ) = ∫x(t)·y(t - τ)dt;

[0057] Wherein, R xy R(τ): Cross - correlation function, representing the similarity between two signals.

[0058] τ: Time - delay difference;

[0059] The time - delay difference Δτ is determined by maximizing the cross - correlation function, and the resolution is 5 picoseconds;

[0060] Phase compensation table calculation:

[0061] Φ comp Φ(f) = 2πfΔτ+Φ(f); offset (f);

[0062] Wherein, Φ comp Φ(f): Phase compensation amount at frequency f.

[0063] Δτ: Time - delay difference,

[0064] Φ offset Φ(f): System static phase offset obtained from measured S - parameter data.

[0065] Step 14: Under different temperature conditions (from 25°C to 85°C), heat the frequency multiplier and record the change in output power. By recording the temperature change, obtain the relationship between the output power and the temperature. Fit a compensation curve based on the temperature change data. According to this curve, the influence of temperature on power can be calculated, and the corresponding compensation coefficient can be obtained for subsequent temperature correction;

[0066] Temperature compensation formula:

[0067] ΔP = a(T - T 0 ) 2 +b(T - T 0 )+c;

[0068] Wherein, ΔP: Change in output power.

[0069] T: Current temperature.

[0070] T 0 : Calibration temperature (generally 25°C)

[0071] a, b, c: Compensation coefficients obtained through experiments, fitting the influence of temperature on power.

[0072] Furthermore, Step 2 is specifically as follows:

[0073] Step 21: Adopt a dual-loop control structure. The outer loop is responsible for coarse power adjustment and adjusts the gain by comparing the actual power and the target power. The inner loop performs fine adjustment and continuously adjusts the power at the auxiliary coupling end through the PID control algorithm to ensure that the system reaches a stable state;

[0074] Dual-loop control structure: Outer loop (coarse power adjustment) gain adjustment

[0075]

[0076] Among them, A manual : Manual gain adjustment amount; This formula is used for coarse gain adjustment according to the power difference.

[0077] Inner loop (fine adjustment) gain adjustment

[0078] ΔA = 0.8·e(t) + 0.05·∫e(t)dt + 0.2·(e(t) - e(t - 1));

[0079] Among them, e(t): Error function, representing the difference between the power at the auxiliary coupling end and the target auxiliary power.

[0080] This formula uses the PID algorithm to achieve fine adjustment, where 0.8, 0.05, and 0.2 are the proportional, integral, and differential coefficients respectively.

[0081] Actual power compensation:

[0082]

[0083] Among them, P real : Compensated actual power

[0084] P meas : Measured power

[0085] V high : High-channel voltage

[0086] V linear : Linear operating point voltage.

[0087] Step 22: To compensate for the power distortion caused by the nonlinear effect, adjust the output power in real time, and compensate the power through the correction factor to ensure that the measured power is close to the ideal value;

[0088] Time-delay dynamic tracking:

[0089] Δτ new =(t peak HP -t peak LP )×0.87;

[0090] Among them, tpeak HP and t peak LP : The peak times of the high channel and the low channel respectively;

[0091] 0.87: The velocity factor of the microstrip line, considering the propagation speed of the signal in the microstrip line;

[0092] Phase compensation calculation:

[0093]

[0094] where, ΔΦ: Phase difference compensation amount

[0095] f current : The current frequency

[0096] Δτ new : The updated time delay difference.

[0097] Step 23: Every 10 ms, inject a pulse signal, update the time delay difference by detecting the peak time of the signal, and precisely adjust the time delay difference of the signal according to this updated information. After updating the time delay difference, calculate the required phase compensation and perform real-time adjustment of the phase of the system to ensure signal synchronization.

[0098] Step 24: Adopt a blind source separation algorithm to extract the intermodulation components from the collected signals. This process can separate the intermodulation components generated by non-linear effects and other noise components. After extracting the intermodulation components, remove the noise floor through an adaptive threshold algorithm to obtain the power of the true intermodulation components, thereby calculating OIP3 more accurately.

[0099] Blind source separation algorithm:

[0100] Calculation of the demixing matrix:

[0101] Y = W·X;

[0102] where, X: Observation matrix, containing intermodulation components and noise floor

[0103] W: Demixing matrix, calculated through the FastICA algorithm

[0104] Y: Independent component, which is the intermodulation component extracted from the original signal;

[0105] Noise floor deduction:

[0106] Calculation of the power of the intermodulation component after denoising:

[0107]

[0108] where, P IM3true : The power of the intermodulation component after removing noise

[0109] P IM3meas : Measured intermodulation component power

[0110] P noise : Noise floor power.

[0111] Further, step 3 is specifically as follows:

[0112] Step 31: At different power levels, use the three-slope method to calculate OIP3. OIP3 is estimated by the difference between the fundamental frequency power and the intermodulation component power, which is used to measure the linear range of the system. Through three different calculation methods, the two-tone equal-amplitude method, the power extrapolation method, and the noise floor method, the OIP3 values are weighted and averaged to obtain the final OIP3 value; Three-slope method calculation:

[0113] OIP3 calculation:

[0114]

[0115] Among them, P find : Fundamental frequency power

[0116] P IM3 : Intermodulation component power

[0117] CF: Correction factor, considering bandwidth and device correction;

[0118] Comprehensive result weighting, take the comprehensive result of the three methods:

[0119] Two-tone equal-amplitude method: Weight 0.6

[0120] Power extrapolation method: Weight 0.3

[0121] Noise floor method: Weight 0.1.

[0122] Step 32: Calculate the uncertainty of the measurement result, including the measurement errors of power, phase, and temperature. Through the analysis of these error sources, the total uncertainty is obtained; Total uncertainty calculation:

[0123]

[0124] Among them, u pwr 、u phase and u temp respectively represent the measurement uncertainties of power, phase, and temperature;

[0125] If it satisfies:

[0126] Three-time measurement standard deviation < 0.2dB

[0127] Intermodulation ratio IMR > 15dB

[0128] Output the final OIP3 value; otherwise, trigger a retest.

[0129] Step 33: Determine whether the OIP3 calculation result is valid by judging whether the standard deviation and intermodulation ratio IMR of the three measurements meet the set standards. If they meet:

[0130] The standard deviation of the three measurements < 0.2 dB

[0131] The intermodulation ratio IMR > 15 dB

[0132] Output the final OIP3 value; otherwise, trigger a retest.

[0133] Furthermore, Step 4 is specifically as follows:

[0134] Step 41: Design a multi-level over-power protection mechanism. When the output power is detected to exceed the limit, take step-by-step response measures. For example, when the power exceeds 18 dBm, the system will automatically introduce attenuation; when it continues to exceed the limit, the low channel will be closed; in extreme cases, the system will perform a hard cut-off;

[0135] The response mechanism is as follows:

[0136] Level1(P out >+18 dBm): The programmable attenuator cuts in -3 dB

[0137] Level2: Close the low channel when the limit is exceeded continuously for 10 ms

[0138] Level3: When the instantaneous limit exceeds +20 dBm, the relay performs a hard cut-off.

[0139] Step 42: When the system has a phase lock loss, start the phase-locked loop re-capture process. Through steps such as reducing the bias voltage, injecting a reference signal, and scanning the tuning voltage, restore the stability of the system, ensure that the output signal is re-locked and the normal power output is restored; Steps of the phase-locked loop re-capture process:

[0140] 1. Reduce the multiplier bias voltage to 50%

[0141] 2. Inject a reference signal of -30 dBm

[0142] 3. Scan the VCO tuning voltage (in 10 MHz steps)

[0143] 4. Restore the lock and restore full power.

[0144] Compared with the prior art, the beneficial effects of the present invention are:

[0145] 1. The present invention provides a high-frequency front-end device and a test method based on OIP3 test. The high-frequency front-end device supports single-channel use and serves as a frequency expansion source. It also supports the combined output of signals with the same frequency or any frequency difference within the bandwidth when two channels are input simultaneously, featuring high flexibility and adjustability. It can effectively implement the test of OIP3 and IM3 in the E-band (60 GHz - 90 GHz), providing strong support for the evaluation of the linear characteristics of high-frequency signals.

[0146] 2. The present invention provides a high-frequency front-end device and a test method based on OIP3 test. By adopting the 6th high-harmonic suppression frequency doubling technology, it can effectively suppress harmonic components, reduce nonlinear distortion, and make the output signal purer. Through the combination of a high-directivity combiner and an isolator, the signal crosstalk problem is solved, unnecessary intermodulation products are avoided, and the accuracy of the test results is improved.

[0147] 3. The present invention provides a high-frequency front-end device and a test method based on OIP3 test, which can accurately test OIP3 and IM3 in the E-band, optimize the performance of the high-frequency front-end device, and is suitable for high-precision signal analysis. Combining the 6th frequency doubling technology and the high-directivity isolation design, it effectively reduces signal crosstalk and nonlinear distortion, ensuring the accuracy and reliability of the measurement results.

[0148] 4. The present invention provides a high-frequency front-end device and a test method based on OIP3 test. The method realizes real-time monitoring and adjustment, enabling flexible control of the output power and frequency, ensuring the stable operation of the system within a high dynamic range, supporting the linear modulation and frequency expansion of high-frequency signals, and can adapt to the test requirements of different bandwidths and frequencies through appropriate adjustment methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0149] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0150] Figure 1 is the circuit schematic diagram of the present invention;

[0151] Figure 2 is the test connection schematic diagram of OIP3 and IM3 of the present invention;

[0152] Figure 3 is the OIP3 characteristic of the present invention;

[0153] Figure 4 is the output power curve of the present invention;

[0154] Figure 5 Steps diagram of the method of the present invention

[0155] Figure 1 Among them: it includes a high-power channel sixth harmonic multiplier (1); a high-power channel manually adjustable attenuator (3); a high-power channel E-band isolator (4); a low-power channel sixth harmonic multiplier (2); a low-power channel E-band isolator (5); a combiner (6); an E-band coupler (7); an E-band programmable attenuator (8). Specific implementation mode

[0156] Next, the technical solution of the present invention will be described more clearly and completely by combining with the drawings and through the description of the preferred implementation mode of the present invention.

[0157] As Figure 1 shown, in the implementation of the present invention, a high-frequency front-end device based on OIP3 measurement includes a high-power channel sixth harmonic multiplier 1; a high-power channel manually adjustable attenuator 3; a high-power channel E-band isolator 4; a low-power channel sixth harmonic multiplier 2; a low-power channel E-band isolator 5; a combiner 6; an E-band coupler 7; an E-band programmable attenuator 8. The input signal of the high-power channel is sent to the manually adjustable attenuator 3 after being frequency multiplied six times by 1 and then sent to the IN1 port of the combiner 6 through the E-band isolator 4; the input signal of the low-power channel is sent to the IN2 port of the combiner 6 after being frequency multiplied six times by 2 and then through the E-band isolator 5. The combiner 6 combines the two signals and outputs them to the E-band coupler 7. The E-band coupler 7 couples and outputs for power monitoring, and the direct output is output after being programmed and attenuated to achieve linear output modulation.

[0158] To achieve linear output power and perform high-frequency OIP3 measurement, two low-frequency signal sources (upper line 15 GHz) are used to input signals to the high-output channel and the low-output channel respectively. Two continuous wave (CW) signals with different frequencies are generated. The two low-frequency signal sources synchronize the reference clock to ensure consistent phase. The output high and low signals are combined into one signal and sent to the spectrum analyzer. The high-output signal and the low-output signal are adjusted to the same amplitude and level by using the manual attenuator of the high-output channel. The combined power passes through a single directional coupler, and the coupled path is sent to the power meter to monitor the combined power value. The direct path signal is then linearly adjusted by the programmed attenuator to change the final output power. The appropriate power is input to the device under test (DUT), and the output power of the device is monitored in real time to ensure linear output. Finally, the spectrum analyzer collects and analyzes the output signal of the device under test (DUT). The fundamental wave and third-order intermodulation products (IM3) in the signal are analyzed, and OIP3 is calculated. OIP3 = Pout + ΔP / 2, where Pout is the fundamental wave power and ΔP is the difference between the fundamental wave power and the third-order intermodulation product power.

[0159] Please refer to Figure 1, in the embodiment of the present invention, at the input end of the device, the frequency and power are input to the high and low output channels through the low-frequency signal source 1 and the low-frequency signal source 2 respectively, and the low-frequency signal sources 1 and 2 are synchronized with the clock reference. The two signals are synthesized into one signal and output through this device. At the combined output end, a single directional coupler couples one path to a power meter to monitor the power value, and finally the power size is controlled by a programmable attenuator for output.

[0160] Please refer to Figure 2 , in the embodiment of the present invention, at the output end of the device, a schematic diagram of the OIP3 and IM3 test connections, the coupling port is connected to a power meter for real-time power monitoring, and the output port is connected to a spectrum analyzer for signal analysis.

[0161] Please refer to Figure 3 , in the embodiment of the present invention, the input frequency of the high-power channel is f1 = 76 GHz, the input frequency of the low-power channel is = 76.1 GHz, f1 - f2 = 100 MHz, and the output amplitude balance is adjusted by a manually adjustable attenuator, and the OIP3 characteristics at an output power of +15 dBm are utilized.

[0162] Please refer to Figure 4 , in the embodiment of the present invention, the output power curves of the high-power and low-power channels are respectively tested.

[0163] The working principle of the present invention is as follows: The high-frequency front-end device based on OIP3 testing supports single-channel use and serves as a frequency extension source; it can also input signals of the same frequency or any frequency difference within the bandwidth simultaneously in two channels and output them after combining. A manually adjustable attenuator is set on the high-power channel to adjust the output amplitude balance. A power meter is connected to the coupling port of the coupler to monitor the output power in real time, and a programmable attenuator with high linear dynamics is set at the output port to achieve linear output modulation. Currently, there are very few devices for OIP3 testing at the high-frequency module level, the systems are scattered, multiple power calibrations and repeated adjustments are required, and the test process is complex. The device of the present invention is highly integrated, can flexibly transform between single and dual channels, precisely level, real-time monitor the output power size, and automatically control the output. It greatly improves the test efficiency and meets the high-frequency application requirements.

[0164] As a specific implementation, a high-frequency front-end device based on OIP3 testing uses two low-frequency (with an upper limit of 15 GHz) signal sources. These are divided into high and low output channels through two RF sources and can be used individually as a frequency extension source. They can also simultaneously input signals of the same frequency or any frequency difference within the bandwidth in the two channels and combine the outputs. A manually adjustable attenuator is set in the high-output channel to control and adjust the output amplitude. Isolators are set in both the high and low output channels to suppress leakage signals. The RF output signals of the two channels are combined into one signal through a combiner. At the same time, the combined signal is also output as a coupled signal and an output signal through a coupler. The coupled signal is sent to a power meter to monitor the magnitude of the output signal in real time. The output signal finally passes through a programmable attenuator to achieve linear output modulation.

[0165] In the high-frequency front-end device based on OIP3 testing, a 6th-order frequency multiplier is used in the high-output channel. The input drive power is +5 dBm, and the input frequency is 10 GHz - 15 GHz; the output frequency is 60 GHz - 90 GHz, the output power is +17 dBm, the 5th harmonic is suppressed to -40 dBc, and the 7th harmonic is suppressed to -30 dBc.

[0166] In the high-frequency front-end device based on OIP3 testing, a 6th-order frequency multiplier is also used in the low-output channel. The input drive power is +5 dBm, and the input frequency is 10 GHz - 15 GHz; the output frequency is 60 GHz - 90 GHz, the output power is +15 dBm, the 5th harmonic is suppressed to -30 dBc, and the 7th harmonic is suppressed to -30 dBc.

[0167] In the high-frequency front-end device based on OIP3 testing, when using a single channel alone, both the high and low output channels can be independently used as a frequency extension source. The high-output channel can change the output power magnitude through a manually adjustable attenuator (located in the high-output channel), and the output power range can be changed between -13 dBm and +17 dBm.

[0168] In the high-frequency front-end device based on OIP3 testing, when using the two channels simultaneously with different frequencies, a manually adjustable attenuator is set in the high-output channel to finely adjust the amplitude in the spectrum, balance the power amplitude with the low-output channel, and achieve leveling of the output amplitudes at different frequencies.

[0169] In the high-frequency front-end device based on OIP3 testing, two low-frequency (with an upper limit of 15 GHz) signal sources drive the high and low channels with a synchronous clock reference to ensure signal phase consistency.

[0170] In the high-frequency front-end device based on OIP3 testing, the combiner is an E-band high-directivity combiner, which is used in conjunction with an isolator to suppress signal crosstalk. The isolation between the two ports of the combiner is 30 dB, the port VSWR ≤ 1.6, and the insertion loss ≤ 1 dB. The reverse isolation of the isolator is ≥ 25 dB, and the insertion loss ≤ 1.5 dB.

[0171] In the high-frequency front-end device based on OIP3 testing, the coupler is an E-band 10 dB coupler, which divides the output signal into a coupled signal for power monitoring by a power meter and output signal transmission testing. The power meter monitors the power to compensate for the coupling degree of the coupler. The coupling flatness is ±1 dB, the port VSWR ≤ 1.2, and the insertion loss ≤ 1 dB.

[0172] In the high-frequency front-end device based on OIP3 testing, the programmable attenuator is an E-band high-linear programmable attenuator with a dynamic range up to -35 dB, which realizes linear modulation of the output signal.

[0173] In the high-frequency front-end device based on OIP3 testing, the programmable attenuator is remotely controlled through a GPIB interface. After installing the driver, control commands are sent through an automated testing software to set the attenuation amount, usually in dB. In OIP3 testing, the parameter settings can be in the form of stepped attenuation, with a 1 dB step, and adjusted within the power range of -22 dBm to +12 dBm.

[0174] In the high-frequency front-end device based on OIP3 testing, to ensure the overall linearity, the combiner, coupler, and isolator all adopt waveguide cavity structures to ensure the accuracy and consistency of internal connections of the devices. The device structures are optimized through electromagnetic simulation software to reduce reflection and radiation losses.

[0175] In the high-frequency front-end device based on OIP3 testing, the combiner adopts the Magic-T form and consists of 4 ports. The horizontal arm is used for input or output of signals; the vertical arm is used for input or output of signals; the symmetric arms (ports 1 and 2) are usually used for signal distribution or synthesis. In the internal waveguide of the Magic-T, a stepped impedance transformer is used to gradually change the impedance of the waveguide to reduce reflection and achieve matching. The high and low output channels are input to the symmetric arms (ports 1 and 2) of the combiner, and the in-phase signals are combined and output at the vertical arm.

[0176] In the high-frequency front-end device based on OIP3 testing, the coupler adopts a waveguide structure with coupling holes to achieve signal transmission through electromagnetic field coupling. It consists of three ports. Port 1 (input end) is used for signal input; Port 2 (output end) is used for signal output; Port 3 (coupling end) is for coupled signal output. When the signal passes through the main transmission line, the electromagnetic field will leak into the auxiliary transmission line through the coupling holes. Due to the design and position of the coupling holes, the signal propagates in only one direction in the auxiliary transmission line, thus achieving directional coupling. The coupling holes are circular holes, and impedance transformation is achieved through a λ / 4 transmission line to match the impedance of the input and output ports.

[0177] In the high-frequency front-end device based on OIP3 testing, the isolator adopts a waveguide structure and a ferrite material with high-frequency characteristics to achieve unidirectional transmission. It consists of two ports. Port 1 (input end) is used for signal input; Port 2 (output end) is used for signal output; ensuring low loss in the forward direction and high isolation in the reverse direction.

[0178] As Figure 5 shown, the method is as follows:

[0179] Step 1: Through dual-tone signal injection, time-delay measurement, and temperature compensation modeling, accurately calibrate the nonlinear characteristics, channel synchronization, and temperature influence of the system.

[0180] Step 2: Adopt dual-loop power control, time-delay tracking, and intermodulation component extraction technologies to ensure signal stability, phase synchronization, and accurate intermodulation component analysis.

[0181] Step 3: Through the three-slope method and weighted average to process multi-dimensional data, accurately calculate OIP3 and evaluate the reliability of the results.

[0182] Step 4: Design a multi-stage over-power protection and phase-locked loop re-capture process to ensure the stable operation and automatic recovery of the system under abnormal conditions.

[0183] As a specific implementation, in the high-frequency front-end device of the present invention, first, the input signal is divided into two channels, namely the high-power channel and the low-power channel. The input signal of the high-power channel is converted to the target frequency through a six-times multiplier, and the output power is +17 dBm. This signal is power-adjusted through a manually adjustable attenuator and sent to the IN1 port of the combiner through an E-band isolator. The low-power channel converts the input signal to the target frequency through another six-times multiplier, with an output power of +15 dBm, and is sent to the IN2 port of the combiner after passing through an E-band isolator. The combiner combines the signals of the two channels and outputs them, and sends the combined signal to an E-band single directional coupler.

[0184] The E-band coupler is used for power monitoring and can obtain the signal power after combining in real time. At the same time, its through output signal is adjusted by an E-band programmable attenuator, and the attenuation range is from 0 dB to -35 dB to achieve precise adjustment of the output signal. This process enables the amplitude of the output signal to be flexibly adjusted while maintaining a high dynamic range and stable linear modulation, avoiding non-linear distortion of the signal.

[0185] In practical applications, users can select the single-channel mode as the frequency expansion source, or input signals with the same frequency or any frequency difference in the dual-channel mode for combined output, thereby completing the tests of E-band OIP3 and IM3. By adopting the 6-fold frequency multiplication technology, the device can effectively suppress high-order harmonics and reduce the influence of harmonic components on the signal quality. The design of the high-directivity combiner and isolator ensures the independence between signals, avoiding signal crosstalk and unnecessary intermodulation products.

[0186] When conducting OIP3 and IM3 tests, each stage of the signal can be monitored in real time. By precisely adjusting various components, such as manually adjustable attenuators and programmable attenuators, it is ensured that the amplitude, power, and frequency of the output signal are within the predetermined range and can meet different test requirements. This solution has high flexibility and can be optimized and adjusted according to specific test scenarios.

[0187] The above specific embodiments only describe the preferred embodiments of the present invention and do not limit the protection scope of the present invention. Without departing from the design concept and spirit scope of the present invention, various deformations, substitutions, and improvements made by those of ordinary skill in the art to the technical solutions of the present invention based on the written description and drawings provided by the present invention shall fall within the protection scope of the present invention. The protection scope of the present invention is determined by the claims.

Claims

1. A high frequency front end device based on OIP3 test, characterized in that: The invention comprises a high-power channel sixth-order frequency multiplier (1), whose output power is +17dBm; a high-power channel manually adjustable attenuator (3); a high-power channel E-band isolator (4); a low-power channel sixth-order frequency multiplier (2), whose output power is +15dBm; a low-power channel E-band isolator (5); a combiner (6); an E-band coupler (7); and an E-band programmable attenuator (8), wherein: The high-power channel input signal passes through the 6-fold frequency multiplier (1), is sent to the manually adjustable attenuator (3), and is sent to the IN1 port of the combiner (6) after passing through the E-band isolator (4); The low-power channel input signal passes through the 6-time frequency multiplier (2) and is then sent to the IN2 port of the combiner (6) through the E-band isolator (5); The combiner (6) combines the two signals and outputs them to the E-band single directional coupler (7); The E-band coupler (7) performs power monitoring and sends the power to the E-band programmable attenuator (8) through a direct output, and outputs the power after attenuation, thereby realizing linear output modulation.

2. A high frequency front end device based on OIP3 test according to claim 1, characterized in that: The input channels are two independent channels, namely a high-power channel and a low-power channel; both the high-power channel and the low-power channel use a 6th-time frequency multiplier, where the output power of the high-power output channel is +17dBm, the output power of the low-power output channel is +15dBm, and the output frequency range is 60GHz to 90GHz.

3. A high frequency front end device based on OIP3 test according to claim 1, characterized in that: A manually adjustable attenuator is provided in the high power output channel, and its attenuation range is 0dB to -30dB.

4. A high frequency front end device based on OIP3 test according to claim 1, characterized in that: E-band isolators are provided in both the high-power output channel and the low-power output channel.

5. A high frequency front end device based on OIP3 test according to claim 1, characterized in that: The E-band programmable attenuator is a high-linearity programmable attenuator, and its attenuation range is 0dB to -35dB.

6. A method for testing a high-frequency front-end device based on an OIP3 test, applicable to a high-frequency front-end device based on an OIP3 test according to any one of claims 1 to 5, characterized in that: Step 1: Accurately calibrate nonlinear characteristics, channel synchronization, and temperature effects through dual-tone signal injection, delay measurement, and temperature compensation modeling; Step 2: Use dual-loop power control, delay tracking and intermodulation component extraction technology to ensure signal stability, phase synchronization and accurate intermodulation component analysis; Step 3: Process multi-dimensional data through the three-slope method and weighted average to accurately calculate OIP3 and evaluate the reliability of the results; Step 4: Design multi-level over-power protection and phase-locked loop recapture process to ensure stable operation and automatic recovery of the system under abnormal conditions.

7. A method for testing a high frequency front-end device based on OIP3 testing according to claim 6, characterized in that: Step 1 is as follows: Step 11: Input the baseband signal to both the high channel and the low channel, and convert the baseband signal to the target frequency through the frequency multiplication process; then, add or subtract a certain frequency deviation from the baseband, ranging from 1 MHz to 50 MHz, to capture the nonlinear effects of the system; Step 12: Collect five key frequency points at the output end, including two signals after frequency deviation, intermodulation components and center frequency. The data is used for subsequent nonlinear coefficient extraction. Based on the collected data, the coefficient matrix reflecting the nonlinear relationship of the signal is solved by the least squares method. Step 13: By injecting a linear frequency modulation signal and using a cross-correlation algorithm to calculate the time delay difference between the high channel and the low channel, the cross-correlation algorithm helps detect the signal peak, thereby determining the time delay difference; based on the calculated time delay difference, a corresponding phase compensation table is generated for each frequency point; Step 14: Under different temperature conditions (25°C to 85°C), heat the frequency doubler and record the change in output power; by recording the temperature change, obtain the relationship between output power and temperature, fit a compensation curve through the temperature change data, calculate the influence of temperature on power based on the curve, and obtain the corresponding compensation coefficient for subsequent temperature correction.

8. A method for testing a high frequency front-end device based on OIP3 testing according to claim 6, characterized in that: Step 2 is as follows: Step 21: A dual-loop control structure is adopted, where the outer loop is responsible for coarse power adjustment and adjusts the gain by comparing the actual power with the target power; the inner loop performs fine adjustment and continuously adjusts the auxiliary coupling end power through the PID control algorithm to ensure that the system reaches a stable state; Step 22: In order to compensate for the power distortion caused by the nonlinear effect, the system adjusts the output power in real time and compensates the power through the correction factor to ensure that the measured power is close to the ideal value; Step 23: Every 10 ms, a pulse signal is injected, and the delay difference is updated by detecting the peak time of the signal. Based on the updated information, the delay difference of the signal is accurately adjusted. After the delay difference is updated, the required phase compensation is calculated, and the phase of the system is adjusted in real time to ensure the synchronization of the signal; Step 24: Use a blind source separation algorithm to extract intermodulation components from the collected signal. This process separates the intermodulation components and other noise components caused by nonlinear effects. After extracting the intermodulation components, the noise floor is removed through an adaptive threshold algorithm to obtain the true intermodulation component power, thereby calculating OIP3 more accurately.

9. A method for testing a high frequency front-end device based on OIP3 testing according to claim 6, characterized in that: Step 3 is as follows: Step 31: At different power levels, the three-slope method is used to calculate OIP3. OIP3 is estimated by the difference between the fundamental frequency power and the intermodulation component power. It is used to measure the linear range of the system. The OIP3 values ​​are weighted averaged by three different calculation methods: two-tone equal amplitude method, power extrapolation method, and noise floor method to obtain the final OIP3 value. Step 32: Calculate the uncertainty of the measurement result, including the measurement errors of power, phase and temperature, and obtain the total uncertainty by analyzing these error sources; Step 33: Determine whether the OIP3 calculation result is valid by judging whether the standard deviation and the intermodulation ratio IMR of the three measurements meet the set standards.

10. A method for testing a high frequency front-end device based on OIP3 testing according to claim 6, characterized in that: Step 4 is as follows: Step 41: Design a multi-level over-power protection mechanism to take step-by-step response measures when the output power exceeds the limit; Step 42: When the system loses phase lock, the phase-locked loop recapture process is started.

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