A K-band tracking receiver local oscillator device

Abstract

The utility model discloses a K wave band tracking receiver local oscillator device, including frequency synthesis module, temperature compensation module, adaptive control module and shielding shell. Frequency synthesis module contains reference source unit, direct digital synthesizer, first phase-locked loop unit and frequency multiplication amplification unit that electrically connect gradually, and the closed loop calibration is realized in cooperation with second phase-locked loop unit, and temperature compensation module restrains temperature drift through temperature sensor, thermostatic control unit and thermoelectric refrigerator, and adaptive control module realizes phase noise monitoring and spurious suppression with the help of microprocessor, digital signal processor etc. The device solves the frequency stability of prior art, phase noise high, weak anti -interference and other problems, is applicable to radar, satellite communication and other scenes.

Description

Technical Field

[0001] This utility model provides a local oscillator device, and particularly relates to a local oscillator device for a K-band tracking receiver. Background Technology

[0002] The local oscillator (LO) of a K-band tracking receiver is the core component for realizing the down-conversion of radio frequency signals. Its main function is to provide the receiver with a stable and accurate local oscillation signal. Its performance directly determines the receiver's frequency resolution, sensitivity, and anti-interference capability. It is widely used in scenarios such as radar detection, satellite communication, and 5G millimeter-wave base stations that require high-precision signal tracking in the 16-24GHz frequency band. It is a key device for ensuring signal demodulation and data transmission in complex electromagnetic environments.

[0003] Existing K-band tracking receiver local oscillator devices typically consist of a reference source, a phase-locked loop (PLL) unit, a frequency multiplier, and control circuitry. The reference source often uses a common crystal oscillator, the PLL unit is usually a single PLL structure (including a phase detector, a voltage-controlled oscillator, and a simple loop filter), and the frequency multiplier uses a single-stage amplifier circuit. Overall, there is a lack of targeted spurious suppression and temperature control design. This type of structure has significant shortcomings: poor reference source frequency stability (temperature drift can reach ±50ppm), making it difficult to provide a high-precision reference; high phase noise in the PLL unit (typically above -100dBc / Hz at 10kHz) and insufficient spurious signal suppression (spurious ratio is often below 50dBc); lack of a real-time temperature compensation mechanism, resulting in significant frequency drift of the voltage-controlled oscillator over a wide temperature range (-40~85℃); and the absence of an independent shielded chamber and adaptive calibration module, leading to severe electromagnetic interference between modules (EMI attenuation less than 20dB) and the inability to dynamically correct output frequency errors. This makes it difficult to meet the high requirements of K-band tracking receivers for signal purity, stability, and anti-interference capabilities in complex environments. Utility Model Content

[0004] To address the aforementioned problems, this application provides a local oscillator device for a K-band tracking receiver, which solves issues such as poor frequency stability, high phase noise, insufficient spurious suppression, significant temperature drift, and weak anti-interference.

[0005] To solve the above-mentioned technical problems, this utility model provides the following technical solution: a local oscillator device for a K-band tracking receiver, comprising:

[0006] A frequency synthesis module, comprising a reference source unit, a direct digital synthesizer, a first phase-locked loop unit, and a frequency multiplier unit that are electrically connected in sequence.

[0007] A temperature compensation module, comprising a temperature sensor, a constant temperature control unit, and a thermoelectric cooler, wherein the temperature sensor is attached to the surface of the voltage-controlled oscillator of the first phase-locked loop unit, and the thermoelectric cooler is disposed below the voltage-controlled oscillator and electrically connected to the constant temperature control unit;

[0008] An adaptive control module, comprising a microprocessor, a memory, and a digital signal processor, wherein the microprocessor is electrically connected to the reference source unit, the direct digital synthesizer, the first phase-locked loop unit, the temperature sensor, and the constant temperature control unit, respectively.

[0009] The output of the direct digital synthesizer is electrically connected to the phase detector input of the first phase-locked loop unit via a first bandpass filter. The output of the voltage-controlled oscillator of the first phase-locked loop unit is electrically connected to the input of the frequency multiplier unit via a second bandpass filter. The output of the frequency multiplier unit is connected to a directional coupler. The coupling end of the directional coupler is connected to the phase detector input of the second phase-locked loop unit via a third bandpass filter. The output of the second phase-locked loop unit is electrically connected to the microprocessor.

[0010] Preferably, the reference source unit is a temperature-controlled crystal oscillator with an output frequency of 100MHz±0.1ppm. The temperature-controlled crystal oscillator is electrically connected to the microprocessor through a power management unit, which is a low-dropout linear regulator with an output voltage of 3.3V±1%.

[0011] Preferably, the direct digital synthesizer uses a 14-bit phase accumulator and integrates a 16-bit digital-to-analog converter. Its output frequency range is 0-500MHz and its frequency resolution is 0.01Hz. The direct digital synthesizer is connected to the microprocessor via an SPI bus with a data transmission rate of 10MHz.

[0012] Preferably, the first phase-locked loop unit includes a phase detector, a charge pump, a loop filter, and a voltage-controlled oscillator connected in sequence. The voltage-controlled oscillator uses a GaNHEMT device with an operating frequency range of 8-12 GHz and a tuning voltage range of 0-5 V. The loop filter uses a third-order passive RC filter with a cutoff frequency of 10 kHz.

[0013] Preferably, the frequency multiplier unit includes a frequency multiplier, a driver amplifier, and a power amplifier connected in sequence. The frequency multiplier adopts a balanced Schottky diode frequency multiplier circuit with an input frequency of 8-12GHz and an output frequency of 16-24GHz. The power amplifier adopts a two-stage cascaded structure with an output power ≥15dBm and a noise figure ≤3dB.

[0014] Preferably, the temperature sensor is a platinum resistance temperature sensor with a measurement range of -55℃ to +125℃ and an accuracy of ±0.1℃; the constant temperature control unit adopts a PID control circuit with a control accuracy of ±0.05℃; and the maximum cooling power of the thermoelectric cooler is 5W.

[0015] Preferably, the microprocessor uses a 32-bit ARM Cortex-M4 core with a working frequency of 168MHz, and has a built-in 12-bit ADC and DAC. The digital signal processor uses a floating-point arithmetic unit with a processing speed of ≥1GFLOPS for real-time calculation of phase noise compensation parameters.

[0016] Preferably, the shielding housing is also included. The shielding housing is made of aluminum alloy and has multiple partitioned chambers inside. The frequency synthesis module, temperature compensation module and adaptive control module are respectively located in different chambers. Electromagnetic shielding partitions are provided between adjacent chambers. Heat dissipation fins are provided on the outer surface of the shielding housing.

[0017] Preferably, the second phase-locked loop unit adopts a fractional-frequency-division phase-locked loop with a phase detection frequency of 10MHz and an adjustable division ratio range of 800-1200. The output signal of the second phase-locked loop unit is sampled by a 16-bit ADC and then transmitted to the microprocessor for closed-loop calibration of the output frequency.

[0018] Preferably, the adaptive control module further includes:

[0019] A phase noise monitoring unit is used to collect phase noise data of the output signal in real time.

[0020] The spurious signal suppression unit is used to analyze and suppress spurious components in the output signal;

[0021] Temperature drift compensation unit is used to adjust the control voltage of the voltage-controlled oscillator in real time based on temperature sensor data;

[0022] The phase noise monitoring unit is connected to the coupling terminal of the directional coupler via a high-speed comparator, and the spurious suppression unit is electrically connected to the frequency control terminal of the direct digital synthesizer.

[0023] One or more technical solutions provided in the embodiments of this application have at least the following technical effects or advantages:

[0024] This device primarily addresses the problems of poor frequency stability, high phase noise, insufficient spurious signal suppression, weak environmental adaptability (temperature drift, electromagnetic interference), and insufficient frequency accuracy in existing K-band tracking receiver local oscillator devices. The solutions are as follows: A temperature-controlled crystal oscillator (TCC) in the reference source unit provides a highly stable reference signal of 100MHz ± 0.1ppm, laying the foundation for the frequency accuracy of the entire device and resolving the reference drift problem. The direct digital synthesizer uses a 14-bit phase accumulator and a 16-bit digital-to-analog converter to achieve an ultra-high frequency resolution of 0.01Hz. Combined with the 10MHz high-speed data transmission of the SPI bus, it quickly responds to the microprocessor's frequency adjustment commands, resolving the contradiction between rapid frequency switching and fine stepping within a wide bandwidth. The third-order passive RC loop filter (cutoff frequency 10kHz) in the first phase-locked loop unit effectively suppresses phase detection spurious signals. The GaN-based voltage-controlled oscillator operates stably in the 8-12GHz frequency band, providing a frequency doubling capability. The 16-24GHz K-band provides a clean intermediate frequency signal, overcoming the high phase noise of high-frequency oscillators. The balanced Schottky diode frequency multiplier circuit of the frequency multiplier unit efficiently achieves frequency doubling, and the two-stage cascaded power amplifier ensures an output power ≥15dBm and a noise figure ≤3dB, meeting the requirements of tracking receivers for local oscillator signal power and noise performance. The second phase-locked loop unit adopts a fractional frequency division design (phase detection frequency 10MHz, division ratio 800-1200), combined with 16-bit ADC sampling feedback to the microprocessor, forming a closed-loop calibration mechanism to correct the output frequency error in real time and solve the problem of accumulated error in the frequency synthesis process. The first, second, and third bandpass filters selectively filter out spurious components at different stages of the signal link, significantly improving the spurious rejection ratio of the output signal. The temperature compensation module uses a temperature sensor (±0.1℃ accuracy) to capture the temperature change of the voltage-controlled oscillator in real time, and the PID control circuit of the constant temperature control unit (±0.1℃ accuracy) is used for temperature control.The 0.05℃ control accuracy drives a thermoelectric cooler (5W maximum cooling power) to quickly regulate the temperature, effectively suppressing the frequency drift of the voltage-controlled oscillator caused by temperature fluctuations (reducing it from the traditional ±50ppm to within ±5ppm), solving the frequency stability problem in a wide temperature range environment; in the adaptive control module, the digital signal processor (≥1GFLOPS computing speed) analyzes the data collected by the phase noise monitoring unit in real time, and combines it with the correction amount generated by the temperature drift compensation unit. The microprocessor dynamically adjusts the control parameters of the first phase-locked loop unit, while the spurious suppression unit specifically adjusts the output frequency of the direct digital synthesizer to suppress spurious signals. The signal suppression ratio is improved by more than 15dB, overcoming the shortcomings of traditional local oscillator devices in dynamically suppressing stray noise. The shielded shell is made of aluminum alloy, and the frequency synthesis module, temperature compensation module, and adaptive control module are independently housed in separate chambers. Electromagnetic shielding partitions between adjacent chambers block electromagnetic coupling between modules (EMI attenuation ≥40dB). The heat dissipation fins on the outer surface increase the heat dissipation area, enabling the device to maintain a stable operating temperature even at high power, solving the problems of signal interference and high-temperature reliability in strong electromagnetic environments. The synergistic effect of all components allows the device to maintain high frequency accuracy, low phase noise, and strong anti-interference capability even in complex environments.

[0025] Other advantages, objectives and features of this invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination or study, or may be taught from the practice of this invention. Attached Figure Description

[0026] Figure 1 This is a block diagram of the overall structure of a local oscillator device for a K-band tracking receiver according to the present invention;

[0027] Figure 2 This is a timing diagram of the temperature compensation control for the local oscillator device of a K-band tracking receiver according to this utility model;

[0028] Figure 3 This is a flowchart illustrating the adaptive spurious suppression process of a local oscillator device for a K-band tracking receiver according to this invention.

[0029] Figure 4 This is a flowchart illustrating the closed-loop frequency calibration process of a local oscillator device for a K-band tracking receiver according to this utility model.

[0030] Figure 5 This is a schematic diagram of the local oscillator device of a K-band tracking receiver according to this utility model. Detailed Implementation

[0031] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0032] It should be noted that the terms "vertical," "horizontal," "up," "down," "left," "right," and similar expressions used in this article are for illustrative purposes only and do not represent the only possible implementation.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains; the terminology used herein in the description of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention; the term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0034] like Figure 1 and Figure 2 As shown, a local oscillator device for a K-band tracking receiver includes a frequency synthesis module. This module comprises a reference source unit, a direct digital synthesizer, a first phase-locked loop (PLL) unit, and a frequency doubling amplifier unit, all electrically connected in sequence. The output of the direct digital synthesizer is electrically connected to the phase detector input of the first PLL unit via a first bandpass filter. The output of the voltage-controlled oscillator (VCO) of the first PLL unit is electrically connected to the input of the frequency doubling amplifier unit via a second bandpass filter. The output of the frequency doubling amplifier unit is connected to a directional coupler. The coupling terminal of the directional coupler is connected to the phase detector of the second PLL unit via a third bandpass filter. The input terminal of the device and the output terminal of the second phase-locked loop unit are electrically connected to the microprocessor. The reference source unit adopts a temperature-controlled crystal oscillator and is electrically connected to the microprocessor through the power management unit. The direct digital synthesizer adopts a 14-bit phase accumulator and is connected to the microprocessor through the SPI bus. The first phase-locked loop unit includes a phase detector, a charge pump, a loop filter and a voltage-controlled oscillator connected in sequence. The frequency multiplier unit includes a frequency doubler, a driver amplifier and a power amplifier connected in sequence. The second phase-locked loop unit adopts a fractional-frequency-division phase-locked loop and its output signal is sampled by a 16-bit ADC and then transmitted to the microprocessor.

[0035] In this implementation, the reference signal output from the reference source unit is transmitted to the direct digital synthesizer (DDS). The signal generated by the DDS is filtered for spurious signals by a first bandpass filter and then input to the phase detector of the first phase-locked loop (PLL) unit. Within the first PLL unit, the phase detector output signal is processed sequentially by a charge pump and a loop filter to drive a voltage-controlled oscillator (VCO). The VCO output signal is filtered by a second bandpass filter and then sent to a frequency multiplier unit. After being processed sequentially by a frequency multiplier, a driver amplifier, and a power amplifier, the signal is split into a main output path and a coupling feedback path by a directional coupler. The coupling feedback path signal is filtered by a third bandpass filter and then input to the phase detector of the second PLL unit. The output signal of the second PLL unit is sampled by an ADC and then fed back to the microprocessor. The DDS interacts with the microprocessor via an SPI bus. The reference source unit is electrically connected to the microprocessor via a power management unit and is controlled by it.

[0036] The reference source unit employs a temperature-controlled crystal oscillator, providing a highly stable reference signal of 100MHz ± 0.1ppm, laying the foundation for the frequency accuracy of the entire device and solving the problem of traditional local oscillator reference drift. The 14-bit phase accumulator and 16-bit digital-to-analog converter of the direct digital synthesizer achieve an ultra-high frequency resolution of 0.01Hz. Combined with the 10MHz high-speed data transmission of the SPI bus, it can quickly respond to the microprocessor's frequency adjustment instructions, resolving the contradiction between rapid frequency switching and fine stepping within a wide bandwidth. The third-order passive RC loop filter (cutoff frequency 10kHz) of the first phase-locked loop unit effectively suppresses phase detection spurious signals. The GaN-based voltage-controlled oscillator operates stably in the 8-12GHz frequency band, providing a clean intermediate frequency signal for the frequency doubling to the 16-24GHz K-band, overcoming the high phase noise defect of high-frequency oscillators. The balanced Schottky diode frequency doubling circuit of the frequency multiplier amplification unit... The system efficiently achieves double frequency harmonics, with two cascaded power amplifiers ensuring an output power ≥15dBm and a noise figure ≤3dB, meeting the requirements of tracking receivers for local oscillator signal power and noise performance. The second phase-locked loop unit employs a fractional-order frequency division design (phase detection frequency 10MHz, division ratio 800-1200), combined with 16-bit ADC sampling feedback to the microprocessor, forming a closed-loop calibration mechanism to correct output frequency errors in real time, solving the problem of accumulated errors in the frequency synthesis process. The first, second, and third bandpass filters selectively filter out spurious components at different stages of the signal link, significantly improving the spurious rejection ratio of the output signal. The microprocessor coordinates the control of each module, enabling the units to work together, allowing the device to achieve high frequency accuracy, low phase noise, and fast tuning capability in the K-band range, effectively addressing the shortcomings of traditional K-band local oscillator devices in terms of frequency stability, spurious rejection, and dynamic response.

[0037] like Figure 3 , 4As shown in Figure 5, the local oscillator device of the K-band tracking receiver also includes a temperature compensation module and an adaptive control module. The temperature compensation module includes a temperature sensor, a constant temperature control unit, and a thermoelectric cooler. The temperature sensor is attached to the surface of the voltage-controlled oscillator of the first phase-locked loop unit. The thermoelectric cooler is located below the voltage-controlled oscillator and is electrically connected to the constant temperature control unit. The adaptive control module includes a microprocessor, a memory, a digital signal processor, a phase noise monitoring unit, a spurious suppression unit, and a temperature drift compensation unit. The microprocessor is electrically connected to the reference source unit, the direct digital synthesizer, the first phase-locked loop unit, the temperature sensor, and the constant temperature control unit, respectively. The phase noise monitoring unit is connected to the coupling end of the directional coupler through a high-speed comparator. The spurious suppression unit is electrically connected to the frequency control end of the direct digital synthesizer. The device also includes a shielded shell made of aluminum alloy and has multiple partitioned chambers inside. Each module is located in a different chamber, and an electromagnetic shielding partition is provided between adjacent chambers. The outer surface is provided with heat dissipation fins.

[0038] In this embodiment, a temperature sensor is attached to the surface of the voltage-controlled oscillator (VCO) of the first phase-locked loop (PLL) unit to collect its temperature data in real time. This data is transmitted to a constant temperature control unit, which is electrically connected to a thermoelectric cooler located below the VCO, forming a closed-loop temperature control link. In the adaptive control module, a microprocessor serves as the control core, establishing electrical connections with the reference source unit, the direct digital synthesizer (DDS), the first PLL unit, the temperature sensor, and the constant temperature control unit to enable command issuance and data interaction. A phase noise monitoring unit connects to the coupling end of a directional coupler via a high-speed comparator to collect the phase noise information of the output signal. A spurious emission suppression unit is electrically connected to the frequency control end of the DDS to adjust its output parameters. A temperature drift compensation unit generates a control voltage correction for the VCO based on the temperature sensor data. The shielding shell is made of aluminum alloy, and the frequency synthesis module, temperature compensation module, and adaptive control module are independently housed in separate chambers. Electromagnetic shielding partitions between adjacent chambers block electromagnetic coupling between modules, and heat dissipation fins on the outer surface enhance the overall heat dissipation capacity of the device.

[0039] The beneficial effects and functions of each component combination are as follows: The temperature compensation module captures the temperature changes of the voltage-controlled oscillator in real time through a temperature sensor (±0.1℃ accuracy). The PID control circuit of the constant temperature control unit (±0.05℃ control accuracy) drives the thermoelectric cooler (5W maximum cooling power) to quickly adjust the temperature, effectively suppressing the frequency drift of the voltage-controlled oscillator caused by temperature fluctuations (the temperature drift of traditional devices can reach ±50ppm, while this solution can reduce it to within ±5ppm through closed-loop control), solving the frequency stability problem in a wide temperature range environment; In the adaptive control module, the digital signal processor (≥1GFLOPS computing speed) analyzes the data collected by the phase noise monitoring unit in real time, and... The correction value generated by the temperature drift compensation unit is dynamically adjusted by the microprocessor to control the parameters of the first phase-locked loop unit. Simultaneously, the spurious signal suppression unit specifically adjusts the output frequency of the direct digital synthesizer, improving the spurious signal suppression ratio by more than 15dB. This overcomes the shortcomings of traditional local oscillator devices in dynamically suppressing spurious signals. The aluminum alloy material of the shielded shell and the partitioned chamber design, combined with the electromagnetic shielding partition, significantly reduce electromagnetic interference between modules (EMI attenuation ≥40dB). The external heat dissipation fins increase the heat dissipation area, enabling the device to maintain a stable operating temperature even under high power operation (e.g., power amplifier output ≥15dBm), solving the problems of signal interference and high-temperature reliability in strong electromagnetic environments. The synergistic effect of these three elements allows the device to maintain high frequency accuracy, low phase noise, and strong anti-interference capability in complex environments, significantly improving the overall performance of the K-band tracking receiver.

[0040] In actual use, this device requires a 12V DC power adapter (such as Mean Well SD-15B-12) to power the power management unit. The main output is connected to the mixer input of the tracking receiver via an RG-405 semi-rigid RF cable. The phase noise and spurious characteristics of the output signal should be calibrated periodically using an Agilent N9020A spectrum analyzer. The contact surfaces of the thermoelectric cooler and the voltage-controlled oscillator should be coated with Shin-Etsu 7783 thermal grease (thermal conductivity 6.0W / m•K) to enhance heat conduction. The microprocessor communicates with an external computer via an FTDIFT232H USB to SPI adapter to configure parameters. The shielded shell and the receiver chassis are connected via a copper grounding plate (0.3mm thick) to ensure common ground. The shielding wires between each module should use silver-plated copper core wire (0.8mm in diameter) and be fitted with ferrite magnetic rings to suppress high-frequency interference.

[0041] Specifically, during installation, this device is secured to the receiver chassis using M3 stainless steel screws (8mm in length) through the pre-drilled mounting holes in the shielded housing. A torque wrench is used to tighten the screws to 8 N•m to ensure mechanical stability. During the commissioning phase, the 100MHz standard signal output from the Keysight E8257D signal generator needs to be connected to the calibration port of the reference source unit. The Agilent N9020A spectrum analyzer is controlled via the GPIB bus to synchronously acquire data with this device, comparing and correcting the frequency compensation coefficients within the microprocessor. When integrated with a tracking receiver, the main output is connected via SMA... Connect the K / F adapter to the mixer input port and use a Rohde & Schwarz ZNB40 network analyzer to test the port VSWR, ensuring impedance matching (50Ω) and VSWR ≤ 1.2. During routine maintenance, use a FLUKE5520A multifunction calibrator to check the temperature sensor's measurement accuracy monthly. If the deviation exceeds ±0.2℃, rewrite the correction parameters through the calibration interface of the constant temperature control unit. When disassembling and repairing, use a temperature-adjustable hot air gun (set to 60-80℃) to heat the heat shrink tubing of the shielded wire connector. After softening, pull out the connector to avoid damaging the internal circuitry with force.

[0042] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the claims.

Claims

1. A local oscillator device for a K-band tracking receiver, characterized in that, include: A frequency synthesis module, comprising a reference source unit, a direct digital synthesizer, a first phase-locked loop unit, and a frequency multiplier unit that are electrically connected in sequence. A temperature compensation module, comprising a temperature sensor, a constant temperature control unit, and a thermoelectric cooler, wherein the temperature sensor is attached to the surface of the voltage-controlled oscillator of the first phase-locked loop unit, and the thermoelectric cooler is disposed below the voltage-controlled oscillator and electrically connected to the constant temperature control unit; An adaptive control module, comprising a microprocessor, a memory, and a digital signal processor, wherein the microprocessor is electrically connected to the reference source unit, the direct digital synthesizer, the first phase-locked loop unit, the temperature sensor, and the constant temperature control unit, respectively. The output of the direct digital synthesizer is electrically connected to the phase detector input of the first phase-locked loop unit via a first bandpass filter. The output of the voltage-controlled oscillator of the first phase-locked loop unit is electrically connected to the input of the frequency multiplier unit via a second bandpass filter. The output of the frequency multiplier unit is connected to a directional coupler. The coupling end of the directional coupler is connected to the phase detector input of the second phase-locked loop unit via a third bandpass filter. The output of the second phase-locked loop unit is electrically connected to the microprocessor.

2. The local oscillator device for a K-band tracking receiver according to claim 1, characterized in that, The reference source unit uses a temperature-controlled crystal oscillator with an output frequency of 100MHz±0.1ppm. The temperature-controlled crystal oscillator is electrically connected to the microprocessor through a power management unit, which uses a low-dropout linear regulator with an output voltage of 3.3V±1%.

3. The local oscillator device for a K-band tracking receiver according to claim 1, characterized in that, The direct digital synthesizer employs a 14-bit phase accumulator and integrates a 16-bit digital-to-analog converter. Its output frequency range is 0-500MHz, and its frequency resolution is 0.01Hz. The direct digital synthesizer is connected to the microprocessor via an SPI bus with a data transmission rate of 10MHz.

4. The local oscillator device for a K-band tracking receiver according to claim 1, characterized in that, The first phase-locked loop unit includes a phase detector, a charge pump, a loop filter, and a voltage-controlled oscillator connected in sequence. The voltage-controlled oscillator uses a GaNHEMT device with an operating frequency range of 8-12 GHz and a tuning voltage range of 0-5 V. The loop filter uses a third-order passive RC filter with a cutoff frequency of 10 kHz.

5. The local oscillator device for a K-band tracking receiver according to claim 1, characterized in that, The frequency multiplier unit includes a frequency multiplier, a driver amplifier, and a power amplifier connected in sequence. The frequency multiplier adopts a balanced Schottky diode frequency multiplier circuit with an input frequency of 8-12GHz and an output frequency of 16-24GHz. The power amplifier adopts a two-stage cascaded structure with an output power of ≥15dBm and a noise figure of ≤3dB.

6. The local oscillator device for a K-band tracking receiver according to claim 1, characterized in that, The temperature sensor is a platinum resistance temperature sensor with a measurement range of -55℃ to +125℃ and an accuracy of ±0.1℃. The constant temperature control unit adopts a PID control circuit with a control accuracy of ±0.05℃. The maximum cooling power of the thermoelectric cooler is 5W.

7. The local oscillator device for a K-band tracking receiver according to claim 1, characterized in that, The microprocessor uses a 32-bit ARM Cortex-M4 core with a working frequency of 168MHz and has a built-in 12-bit ADC and DAC. The digital signal processor uses a floating-point unit with a computing speed of ≥1GFLOPS for real-time calculation of phase noise compensation parameters.

8. The local oscillator device for a K-band tracking receiver according to claim 1, characterized in that, It also includes a shielding shell made of aluminum alloy, with multiple compartments inside. The frequency synthesis module, temperature compensation module and adaptive control module are respectively located in different compartments. Electromagnetic shielding partitions are provided between adjacent compartments. Heat dissipation fins are provided on the outer surface of the shielding shell.

9. The local oscillator device for a K-band tracking receiver according to claim 1, characterized in that, The second phase-locked loop unit adopts a fractional-frequency-division phase-locked loop with a phase detection frequency of 10MHz and an adjustable division ratio of 800-1200. The output signal of the second phase-locked loop unit is sampled by a 16-bit ADC and then transmitted to the microprocessor for closed-loop calibration of the output frequency.

10. The local oscillator device for a K-band tracking receiver according to claim 1, characterized in that, The adaptive control module also includes: A phase noise monitoring unit is used to collect phase noise data of the output signal in real time. The spurious signal suppression unit is used to analyze and suppress spurious components in the output signal; Temperature drift compensation unit is used to adjust the control voltage of the voltage-controlled oscillator in real time based on temperature sensor data; The phase noise monitoring unit is connected to the coupling terminal of the directional coupler via a high-speed comparator, and the spurious suppression unit is electrically connected to the frequency control terminal of the direct digital synthesizer.

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