Broadband digital precision phase locking system and method
By employing fully digital frequency self-detection and tracking technology, the problems of frequency drift and dynamic range variation in the phase-locked loop of the optical frequency comb system are solved, achieving stable phase locking and efficient frequency signal control. This technology is applicable to optical frequency comb systems and other digital phase-locked control systems.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-17
- Publication Date
- 2026-04-17
AI Technical Summary
In existing technologies, optical frequency comb systems suffer from systematic frequency drift that leads to phase-locked loop (PLL) loss of lock-up, and it is difficult to achieve adaptive closed-loop locking of the loop within a large dynamic range of the reference signal frequency.
Employing fully digital frequency self-detection and tracking technology, a coarse estimate of the reference signal frequency is obtained through frequency and phase measurement methods. Frequency conversion and phase control of the reference signal and VCO signal are achieved using mixing, filtering, downsampling, and phase detection. Combined with loop filtering and DAC control, frequency and phase adjustment tracking of the VCO signal is realized.
It achieves stable phase-locking of the optical frequency comb system, has strong anti-interference ability, adapts to high-stability clock frequency signal output in complex environments, and reduces hardware resource requirements and computational complexity.
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Figure CN121887182A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of time and frequency measurement, and more specifically, to a wideband digital precision phase-locked loop system and method. Background Technology
[0002] Optical frequency combs, serving as a bridge between optical and microwave frequencies, enable broadband lossless frequency conversion and characteristic transfer from microwave to optical, optical to optical, and optical to microwave. They are currently the most accurate frequency transfer tools and have significant application value in communication and navigation, precision space ranging, and time and frequency transfer.
[0003] Optical frequency combs are an important application of ultrafast laser technology. Essentially, they detect and lock the frequency of a mode-locked laser. In the frequency domain, a mode-locked laser manifests as a discrete comb structure. The rate of any comb tooth can be characterized by the superposition of the repetition frequency of the mode-locked pulse in the frequency domain and the carrier envelope phase shift frequency. By locking two microwave frequencies to an external reference source, the stability of the entire optical frequency comb can be achieved, thus realizing an effective connection between the microwave frequency and the optical frequency. Detecting and locking the repetition frequency and the carrier envelope phase shift frequency are key to realizing the function of an optical frequency comb. The carrier envelope phase shift frequency-locked loop ensures the high stability of the main laser's output frequency and synchronization with the external reference signal. The stability of the main frequency directly determines the reference accuracy of the entire frequency comb. If the main frequency drifts, all comb tooth frequencies will drift systematically, leading to measurement errors. The repetition frequency-locked loop controls the frequency spacing between the comb teeth to keep it uniform and unaffected by environmental disturbances (such as temperature and mechanical vibration). Uniform comb tooth spacing is a core condition for the frequency comb to function as an "optical ruler." Uneven spacing will prevent accurate demodulation of the target signal's frequency information during spectral analysis. Summary of the Invention
[0004] To overcome at least one deficiency in the prior art, this application provides a wideband digital precision phase-locked loop system and method.
[0005] In a first aspect, a wideband digital precision phase-locked loop system is provided, comprising: a reference signal frequency coarse estimation module, a reference signal frequency precision measurement module, and a precision phase-locked loop tracking module; The reference signal is input to the reference signal frequency coarse estimation module, which uses frequency measurement and phase measurement methods to obtain a coarse estimate of the reference signal frequency. The reference signal frequency precision measurement module includes a second NCO. The coarse estimate of the reference signal frequency is used as the initial frequency value of the second NCO. The second NCO generates two orthogonal signals, which are mixed, filtered, and downsampled with the reference signal, respectively. The phase difference between the reference signal and the output signal of the second NCO is obtained by phase detection. The frequency adjustment value is obtained based on the phase difference. The frequency value of the second NCO is adjusted based on the frequency adjustment value, and the precise measurement value of the reference signal frequency is output. The precision phase-locked tracking module includes a third NCO. The frequency value of the third NCO is determined by comparing the precise frequency measurement value of the reference signal with the center frequency value of the VCO signal. The third NCO generates a sine wave signal, which is mixed with the reference signal, decimated, filtered, and interpolated to obtain the local oscillator signal. The phase difference between the local oscillator signal and the VCO signal is obtained using a phase detection method. The phase difference is filtered and the gain is adjusted. The adjusted signal is converted into an analog quantity to control the VCO to achieve frequency and phase adjustment tracking.
[0006] In one embodiment, the reference signal frequency coarse estimation module includes: an FFT module, a first mixer, a first low-pass filter, a first comb filter, a first arctangent function calculation module, a phase-frequency conversion module, and a first NCO; The reference signal is sampled by the ADC to obtain a digital signal. The FFT module performs FFT on the digital signal to obtain a frequency estimate, which is used as the initial frequency value of the first NCO. The first NCO generates two quadrature signals, which are input to the first mixer to mix the digital signal with the two quadrature signals respectively, resulting in two mixed signals. The two mixed signals are then filtered by a first low-pass filter to remove high-frequency signals, resulting in two low-frequency signals. The two low-frequency signals are then downsampled by a first comb filter, resulting in two downsampled signals. The two downsampled signals are then processed by a first arctangent function calculation module to calculate the first phase difference. The first phase difference is then processed by a phase-frequency conversion module to obtain a first frequency adjustment amount. The first frequency adjustment amount is used to modulate the frequency value of the first NCO to obtain a coarse estimate of the reference signal's frequency.
[0007] In one embodiment, the reference signal frequency precision measurement module includes: a second mixer, a second low-pass filter, a second comb filter, a second arctangent function calculation module, and a first loop filter; The reference signal is sampled by an ADC to obtain a digitized signal, which is then input to a second mixer. Two quadrature signals generated by a second NCO are input to the second mixer to mix the digitized signal with the two quadrature signals respectively, resulting in two mixed signals. The two mixed signals are then filtered by a second low-pass filter to remove high-frequency signals, resulting in two low-frequency signals. The two low-frequency signals are then downsampled by a second comb filter, resulting in two downsampled signals. The two downsampled signals are then processed by a second arctangent function calculation module to calculate the second phase difference. The second phase difference is then processed by a first loop filter to obtain a second frequency modulation amount. The frequency value of the second NCO is modulated using the second frequency modulation amount to obtain a precise measurement value of the reference signal's frequency.
[0008] In one embodiment, the precision phase-locked tracking module includes a third mixer, a decimation filter, a bandpass filter, an interpolation filter, a fourth mixer, a third low-pass filter, a third arctangent function calculation module, a second loop filter, and a DAC. The reference signal is sampled by the ADC to obtain a digital signal, which is then input to the third mixer. The sinusoidal signal generated by the third NCO is input to the third mixer to mix the digital signal with the sinusoidal signal, resulting in a mixed signal. The mixed signal is then passed through a decimation filter, a bandpass filter, and an interpolation filter in sequence to perform downsampling, signal extraction, and sampling rate recovery, respectively, to obtain the local oscillator signal. The VCO signal is sampled by an ADC to obtain two quadrature digital signals. These two quadrature digital signals and the local oscillator signal are input to a fourth mixer to mix the local oscillator signal with the two quadrature digital signals, resulting in two mixed signals. The two mixed signals are then filtered by a third low-pass filter to remove high-frequency signals, resulting in two low-frequency signals. The two low-frequency signals are then processed by a third arctangent function calculation module to calculate the third phase difference. The third phase difference is then processed by a second loop filter to obtain the loop control quantity. The loop control quantity is converted into an analog quantity by a DAC, and the analog quantity is used to control the VCO to achieve frequency and phase adjustment and tracking.
[0009] In one embodiment, the frequency value of the third NCO is determined by comparing a precise frequency measurement of the reference signal with the center frequency value of the VCO signal, using the following formula:
[0010] in, The frequency value of the third NCO. For the precise measurement of the frequency of the reference signal, This is the center frequency value of the VCO signal.
[0011] In one embodiment, the center frequency value of the VCO signal is set according to the nominal frequency of the VCO.
[0012] In one embodiment, the center frequency value of the VCO signal is determined using the following method: After passing through the reference signal frequency coarse estimation module and the reference signal frequency precise measurement module, the VCO signal obtains the precise frequency measurement value, which is the center frequency value of the VCO signal.
[0013] Secondly, a wideband digital precision phase-locked loop (PLL) method is provided, based on the aforementioned wideband digital precision PLL system, comprising: A rough estimate of the frequency of the reference signal is obtained by using frequency and phase measurement methods. The coarse frequency estimate of the reference signal is used as the initial frequency value of the second NCO. The second NCO generates two orthogonal signals, which are mixed, filtered, and downsampled with the reference signal, respectively. The phase difference between the reference signal and the output signal of the second NCO is obtained by phase detection, and the frequency adjustment value is obtained based on the phase difference. The frequency value of the second NCO is adjusted based on the frequency adjustment value, and the precise frequency measurement value of the reference signal is output. The frequency value of the third NCO is determined by comparing the precise frequency measurement value of the reference signal with the center frequency value of the VCO signal. The third NCO generates a sine wave signal, which is mixed with the reference signal, decimated, filtered, and interpolated to obtain the local oscillator signal. The phase difference between the local oscillator signal and the VCO signal is obtained using a phase detection method. The phase difference is filtered and the gain is adjusted. The adjusted signal is converted into an analog quantity to control the VCO to achieve frequency and phase adjustment and tracking.
[0014] Compared with the prior art, this application has the following advantages: This application addresses the phase-locked loop (PLL) lockout phenomenon caused by systematic frequency drift (including factors such as temperature, mechanical vibration, and air pressure) in optical frequency comb systems, and utilizes frequency self-detection and tracking technology to achieve stable loop locking output; at the same time, this method can meet the adaptive closed-loop locking scenario when the reference signal frequency changes within a large dynamic range; this method can not only be implemented entirely in digital engineering, but also has a simplified implementation process, low complexity, small computational load, and low hardware resource requirements. Attached Figure Description
[0015] This application can be better understood by referring to the description given below in conjunction with the accompanying drawings, which, together with the detailed description below, are incorporated in and form part of this specification. In the drawings: Figure 1 A schematic diagram of a broadband digital precision phase-locked loop system is shown. Detailed Implementation
[0016] Exemplary embodiments of the present application will be described below with reference to the accompanying drawings. For clarity and brevity, not all features of the actual embodiments are described in the specification. However, it should be understood that many embodiment-specific decisions can be made in the development of any such actual embodiment to achieve the developer’s specific objectives, and these decisions may vary as the embodiments differ.
[0017] It should also be noted that, in order to avoid obscuring this application with unnecessary details, only the device structure closely related to the solution according to this application is shown in the accompanying drawings, while other details that are not closely related to this application are omitted.
[0018] It should be understood that this application is not limited to the described embodiments by virtue of the following description with reference to the accompanying drawings. In this document, embodiments may be combined with each other, features may be substituted or borrowed between different embodiments, and one or more features may be omitted in one embodiment, where feasible.
[0019] This application provides a wideband digital precision phase-locked loop (PLL) method that solves the problem of PLL lockout caused by systematic frequency drift (including factors such as temperature, mechanical vibration, and air pressure) and the challenge of adaptive closed-loop locking when the reference signal frequency changes over a large dynamic range. This application employs an auxiliary frequency and phase measurement method to achieve high-precision measurement of the reference signal frequency. Then, it compares the relationship between the reference signal frequency and the VCO signal frequency, using mixing, decimation, filtering, and interpolation to achieve frequency conversion between the reference signal and the VCO signal. Finally, it achieves precise control of the VCO signal frequency and phase through same-frequency phase detection, loop filtering, and DAC control. This application considers low complexity, low cost, and full digitalization in the engineering process, possessing feasibility for productization and high integration. It also has universality and can be widely applied to different types of optical frequency comb systems and other digital PLL control systems.
[0020] Figure 1 A schematic diagram of a wideband digital precision phase-locked loop system is shown. See [link / reference] Figure 1 The system includes: a reference signal frequency coarse estimation module, a reference signal frequency precision measurement module, and a precision phase-locked tracking module; the functions of each module are described in detail below.
[0021] The reference signal input frequency coarse estimation module uses frequency and phase measurement methods to obtain a coarse estimate of the reference signal frequency. Here, the reference signal refers to the external reference signal provided to the optical frequency comb. A phase-locked loop (PLL) is used to lock the carrier envelope phase shift frequency and repetition frequency to the external reference signal. The coarse frequency estimation of the reference signal is a rough estimation of the frequency of an unknown reference signal, or an automated measurement and estimation of the frequency when the reference signal frequency changes, achieved using frequency and phase measurement methods. The coarse frequency estimate of the reference signal calculated in this process serves as the initial value of the NCO (Digital Controlled Oscillator) frequency control word during the precise measurement of the reference signal frequency.
[0022] The reference signal frequency precision measurement module includes a second NCO. The coarse estimate of the reference signal frequency is used as the initial frequency value of the second NCO. The second NCO generates two orthogonal signals, which are mixed, filtered, and downsampled with the reference signal, respectively. The phase difference between the reference signal and the output signal of the second NCO is obtained by phase detection. The frequency adjustment value is obtained based on the phase difference. The frequency value of the second NCO is adjusted based on the frequency adjustment value, and the precise measurement value of the reference signal frequency is output.
[0023] The precision phase-locked tracking module includes a third NCO. The frequency value of the third NCO is determined by comparing the precisely measured frequency of the reference signal with the center frequency value of the VCO (voltage-controlled oscillator) signal. The third NCO generates a sinusoidal signal, which is mixed with the reference signal, decimated, filtered, and interpolated to obtain the local oscillator signal. The phase difference between the local oscillator signal and the VCO signal is obtained using a phase detection method. The phase difference is filtered and the gain is adjusted. The adjusted signal is converted into an analog quantity to control the VCO to achieve frequency and phase adjustment tracking. Here, the center frequency value of the VCO signal is not limited to the frequency of the laser output RF signal in the optical frequency comb; it can also be the signal frequency of other controlled devices or apparatuses.
[0024] In one embodiment, the reference signal frequency coarse estimation module includes: an FFT module, a first mixer, a first low-pass filter LPF, a first comb filter CIC, a first arctangent function calculation module, a phase-frequency conversion module, and a first NCO; Reference signal The digitized signal is obtained after sampling by the ADC (Analog-to-Digital Converter). The sampling clock signal of the ADC is The frequency source provides the sampling clock for the ADC. The FFT module processes the digitized signal. Perform an FFT to obtain the frequency estimate. Frequency estimates As the initial frequency value for the first NCO; The first NCO generates two orthogonal signals, namely and Two orthogonal signals are input to the first mixer to realize the digitization of the signal. The signals are mixed with two orthogonal signals to obtain two mixed signals. The two mixed signals are then filtered by a first low-pass filter (LPF) to remove high-frequency signals, resulting in two low-frequency signals. The two low-frequency signals are then downsampled by a first comb filter (CIC) to obtain two downsampled signals. The two downsampled signals are then processed by a first arctangent function calculation module to calculate a first phase difference. The first phase difference is then processed by a phase-frequency conversion module to obtain a first frequency adjustment amount. The first frequency adjustment amount is used to modulate the frequency value of the first NCO. Here, the frequency value of the first NCO is the coarse estimate of the frequency of the output reference signal.
[0025] Here, the phase-frequency conversion module obtains the first phase difference through the differential relationship between phase and frequency. The first frequency adjustment is added to the frequency value of the first NCO to obtain the new frequency value of the first NCO; the frequency value of the first NCO is the coarse estimate of the frequency of the reference signal.
[0026] In one embodiment, the reference signal frequency precision measurement module includes: a second mixer, a second low-pass filter (LPF), a second comb filter (CIC), a second arctangent function calculation module, and a first loop filter; Reference signal The digitized signal is obtained after ADC sampling. The signal is input to the second mixer; the two quadrature signals generated by the second NCO are respectively... and The signal is input to the second mixer to achieve digitalization. The two signals are mixed with two orthogonal signals to obtain two mixed signals. The two mixed signals are then filtered by a second low-pass filter (LPF) to remove high-frequency signals, resulting in two low-frequency signals. The two low-frequency signals are then downsampled by a second comb filter (CIC) to obtain two downsampled signals. The two downsampled signals are then processed by a second arctangent function calculation module to calculate the second phase difference. The second phase difference is then processed by a first loop filter to obtain the second frequency modulation amount. The second frequency modulation amount is used to modulate the frequency value of the second NCO to output a precise frequency measurement value of the reference signal.
[0027] Here, the second frequency adjustment is added to the frequency value of the second NCO to obtain a new frequency value of the second NCO; the frequency value of the second NCO is the precise measurement value of the frequency of the output reference signal.
[0028] In one embodiment, the precision phase-locked tracking module includes a third mixer, a decimation filter, a bandpass filter (BPF), an interpolation filter, a fourth mixer, a third low-pass filter (LPF), a third arctangent function calculation module, a second loop filter, and a DAC (digital-to-analog converter). The reference signal is sampled by the ADC to obtain a digital signal, which is then input to the third mixer. The sinusoidal signal generated by the third NCO is input to the third mixer to mix the digital signal with the sinusoidal signal, resulting in a mixed signal. The mixed signal is then passed through a decimation filter, a bandpass filter (BPF), and an interpolation filter in sequence to perform downsampling, signal extraction, and sampling rate recovery, respectively, to obtain the local oscillator signal. The VCO signal is sampled by the ADC to obtain two quadrature digital signals, where the ADC's sampling clock signal is... The frequency source provides the sampling clock for the ADC. Two quadrature digital signals and the local oscillator signal are input to the fourth mixer, which mixes the local oscillator signal with the two quadrature digital signals respectively, resulting in two mixed signals. The two mixed signals are then filtered by a third low-pass filter to remove high-frequency signals, resulting in two low-frequency signals. The two low-frequency signals are then processed by a third arctangent function calculation module to calculate the third phase difference. The third phase difference is then processed by a second loop filter to obtain the loop control quantity. The loop control quantity is converted into an analog quantity by a DAC, and the analog quantity is used to control the VCO to achieve frequency and phase adjustment and tracking.
[0029] In one embodiment, the frequency value of the third NCO is determined by comparing a precise frequency measurement of the reference signal with the center frequency value of the VCO signal, using the following formula:
[0030] in, The frequency value of the third NCO. For the precise measurement of the frequency of the reference signal, This is the center frequency value of the VCO signal.
[0031] In one embodiment, the center frequency value of the VCO signal is set according to the nominal frequency of the VCO.
[0032] In other embodiments, the center frequency value of the VCO signal is determined using the following method: After passing through the reference signal frequency coarse estimation module and the reference signal frequency precise measurement module, the VCO signal obtains the precise frequency measurement value, which is the center frequency value of the VCO signal.
[0033] This application also provides a broadband digital precision phase-locked loop method, and a broadband digital precision phase-locked loop system based on the above embodiments, comprising: A rough estimate of the frequency of the reference signal is obtained by using frequency and phase measurement methods. The coarse frequency estimate of the reference signal is used as the initial frequency value of the second NCO. The second NCO generates two orthogonal signals, which are mixed, filtered, and downsampled with the reference signal, respectively. The phase difference between the reference signal and the output signal of the second NCO is obtained by phase detection, and the frequency adjustment value is obtained based on the phase difference. The frequency value of the second NCO is adjusted based on the frequency adjustment value, and the precise frequency measurement value of the reference signal is output. The frequency value of the third NCO is determined by comparing the precise frequency measurement value of the reference signal with the center frequency value of the VCO signal. The third NCO generates a sine wave signal, which is mixed with the reference signal, decimated, filtered, and interpolated to obtain the local oscillator signal. The phase difference between the local oscillator signal and the VCO signal is obtained using a phase detection method. The phase difference is filtered and the gain is adjusted. The adjusted signal is converted into an analog quantity to control the VCO to achieve frequency and phase adjustment and tracking.
[0034] In summary, this application employs a fully digital approach to achieve a large dynamic range tracking and locking of the voltage-controlled oscillator (VCO) signal frequency to the reference signal frequency. This phase-locked loop (PLL) method exhibits strong anti-interference capabilities against external interference and frequency drift, and demonstrates strong adaptability and high reliability in providing a highly stable clock frequency signal output under complex environments. The PLL method is implemented entirely digitally, and the algorithm implementation process considers factors such as low cost and low power consumption in engineering, as well as product versatility and software portability.
[0035] The above descriptions are merely various embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.
Claims
1. A broadband digital precision phase-locked loop system, characterized in that, include: The module includes a coarse estimation module for the reference signal frequency, a precise measurement module for the reference signal frequency, and a precise phase-locked tracking module. The reference signal is input to the reference signal frequency coarse estimation module, and the frequency coarse estimate of the reference signal is obtained by using frequency measurement and phase measurement methods; The reference signal frequency precision measurement module includes a second NCO. The coarse estimate of the reference signal frequency is used as the initial frequency value of the second NCO. The second NCO generates two orthogonal signals, which are mixed, filtered, and downsampled with the reference signal, respectively. The phase difference between the reference signal and the output signal of the second NCO is obtained by phase detection. The frequency adjustment value is obtained based on the phase difference. The frequency value of the second NCO is adjusted based on the frequency adjustment value, and the precise frequency measurement value of the reference signal is output. The precision phase-locked tracking module includes a third NCO, which determines the frequency value of the third NCO by comparing the precise frequency measurement value of the reference signal with the center frequency value of the VCO signal. The third NCO generates a sinusoidal signal, which is mixed with the reference signal, decimated, filtered, and interpolated to obtain the local oscillator signal. The phase difference between the local oscillator signal and the VCO signal is obtained using a phase detection method. The phase difference is then filtered and the gain is adjusted. The adjusted signal is converted into an analog quantity to control the VCO to achieve frequency and phase adjustment and tracking.
2. The system as described in claim 1, characterized in that, The reference signal frequency coarse estimation module includes: an FFT module, a first mixer, a first low-pass filter, a first comb filter, a first arctangent function calculation module, a phase-frequency conversion module, and a first NCO; The reference signal is sampled by the ADC to obtain a digital signal. The FFT module performs an FFT on the digital signal to obtain a frequency estimate. The frequency estimate is used as the initial frequency value of the first NCO. The first NCO generates two orthogonal signals, which are input to the first mixer to mix the digitized signal with the two orthogonal signals respectively, resulting in two mixed signals. The two mixed signals are then filtered by the first low-pass filter to remove high-frequency signals, resulting in two low-frequency signals. The two low-frequency signals are then downsampled by the first comb filter, resulting in two downsampled signals. The two downsampled signals are then processed by the first arctangent function calculation module to calculate the first phase difference. The first phase difference is then processed by the phase-frequency conversion module to obtain a first frequency adjustment. The first frequency adjustment is used to modulate the frequency value of the first NCO to obtain a coarse estimate of the reference signal's frequency.
3. The system as described in claim 1, characterized in that, The reference signal frequency precision measurement module includes: a second mixer, a second low-pass filter, a second comb filter, a second arctangent function calculation module, and a first loop filter; The reference signal is sampled by the ADC to obtain a digitized signal, which is then input to the second mixer. Two orthogonal signals generated by the second NCO are input to the second mixer to mix the digitized signal with the two orthogonal signals, resulting in two mixed signals. These two mixed signals are then filtered by the second low-pass filter to remove high-frequency signals, resulting in two low-frequency signals. The two low-frequency signals are then downsampled by the second comb filter, resulting in two downsampled signals. These downsampled signals are then processed by the second arctangent function calculation module to calculate the second phase difference. The second phase difference is then processed by the first loop filter to obtain the second frequency modulation amount. The second frequency modulation amount is used to modulate the frequency value of the second NCO, resulting in a precise measurement of the reference signal's frequency.
4. The system as described in claim 1, characterized in that, The precision phase-locked tracking module includes a third mixer, a decimation filter, a bandpass filter, an interpolation filter, a fourth mixer, a third low-pass filter, a third arctangent function calculation module, a second loop filter, and a DAC; The reference signal is sampled by the ADC to obtain a digital signal, which is then input to the third mixer. The sinusoidal signal generated by the third NCO is input to the third mixer to mix the digital signal with the sinusoidal signal, resulting in a mixed signal. The mixed signal is then passed sequentially through the decimation filter, the bandpass filter, and the interpolation filter to perform downsampling, signal extraction, and sampling rate recovery, respectively, to obtain the local oscillator signal. The VCO signal is sampled by an ADC to obtain two quadrature digital signals. These two quadrature digital signals and the local oscillator signal are input to the fourth mixer to mix the local oscillator signal with the two quadrature digital signals, resulting in two mixed signals. The two mixed signals are then filtered by a third low-pass filter to remove high-frequency signals, resulting in two low-frequency signals. The two low-frequency signals are then processed by a third arctangent function calculation module to calculate a third phase difference. This third phase difference is then processed by a second loop filter to obtain a loop control quantity. The loop control quantity is converted into an analog quantity by a DAC, and this analog quantity is used to control the VCO to achieve frequency and phase adjustment and tracking.
5. The system as described in claim 1, characterized in that, in, The frequency value of the third NCO is determined by comparing the precise frequency measurement of the reference signal with the center frequency value of the VCO signal, using the following formula: in, The frequency value of the third NCO. For the precise measurement of the frequency of the reference signal, This is the center frequency value of the VCO signal.
6. The system as described in claim 1, characterized in that, The center frequency value of the VCO signal is set according to the nominal frequency of the VCO.
7. The system as described in claim 1, characterized in that, The center frequency value of the VCO signal is determined using the following method: After the VCO signal passes through the reference signal frequency coarse estimation module and the reference signal frequency precise measurement module, a precise frequency measurement value is obtained, which is the center frequency value of the VCO signal.
8. A broadband digital precision phase-locked loop method, based on the broadband digital precision phase-locked loop system according to any one of claims 1-7, characterized in that, include: A rough estimate of the frequency of the reference signal is obtained by using frequency and phase measurement methods. The coarse frequency estimate of the reference signal is used as the initial frequency value of the second NCO. The second NCO generates two orthogonal signals, which are mixed, filtered, and downsampled with the reference signal, respectively. The phase difference between the reference signal and the output signal of the second NCO is obtained by phase detection, and the frequency adjustment value is obtained based on the phase difference. The frequency value of the second NCO is adjusted based on the frequency adjustment value, and the precise frequency measurement value of the reference signal is output. The frequency value of the third NCO is determined by comparing the precise frequency measurement value of the reference signal with the center frequency value of the VCO signal. The third NCO generates a sine wave signal, which is mixed with the reference signal, decimated, filtered, and interpolated to obtain the local oscillator signal. The phase difference between the local oscillator signal and the VCO signal is obtained using a phase detection method. The phase difference is filtered and the gain is adjusted. The adjusted signal is converted into an analog quantity to control the VCO to achieve frequency and phase adjustment and tracking.