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CN-122027080-A - Pre-equalization method and system for TI-DAC inherent frequency response degradation based on W-CGLS

CN122027080ACN 122027080 ACN122027080 ACN 122027080ACN-122027080-A

Abstract

A pre-equalization method and a system for TI-DAC inherent frequency response degradation based on W-CGLS belong to the technical field of digital signal processing, and solve the problem that the conventional compensation method can only process a single factor independently and cannot synchronously compensate multiple degradation effects, so that the waveform quality and the effective bandwidth of a system are affected. The method comprises the steps of modeling the inherent frequency response degradation of the TI-DAC to obtain target frequency response of the inherent frequency response degradation compensation of the TI-DAC, designing a pre-equalizer by using a weighted regularized conjugate gradient least square method based on the target frequency response, iteratively solving a pre-equalizer coefficient by introducing a weighted parameter and a regularized parameter through the weighted regularized conjugate gradient least square method to fit the target frequency response, and applying the pre-equalizer to the TI-DAC system to perform pre-equalization processing on an input signal to compensate the passband amplitude-frequency response attenuation and improve the amplitude-frequency response flatness. The invention is suitable for the design scene of the digital-to-analog conversion system.

Inventors

  • PENG YU
  • GU GUANGYU
  • LIU LIANSHENG

Assignees

  • 哈尔滨工业大学

Dates

Publication Date
20260512
Application Date
20251229

Claims (10)

  1. 1. The pre-equalization method for the TI-DAC inherent frequency degradation based on the W-CGLS is characterized by comprising the following steps of: S1, modeling the inherent frequency response degradation of the TI-DAC to obtain a target frequency response of the inherent frequency response degradation compensation of the TI-DAC; s2, designing a pre-equalizer by using a weighted regularized conjugate gradient least square method based on the target frequency response, wherein the weighted regularized conjugate gradient least square method iteratively solves the pre-equalizer coefficient by introducing a weighted parameter and a regularized parameter so as to fit the target frequency response; And S3, applying the pre-equalizer to the TI-DAC system, and performing pre-equalization processing on the input signal to compensate the attenuation of the amplitude-frequency response of the passband and improve the flatness of the amplitude-frequency response.
  2. 2. The pre-equalization method of TI-DAC natural frequency response degradation based on W-CGLS according to claim 1, wherein in S1, the target frequency response of pre-equalization is expressed as: Where T s is the system period and f represents the frequency.
  3. 3. The pre-equalization method of inherent frequency response degradation of TI-DAC based on W-CGLS according to claim 1, wherein the pre-equalizer in S2 is a Type-I FIR filter with linear phase characteristics, whose frequency response is expressed as: Where a 0 ,…,a k is the pre-equalizer coefficient, m= (N-1)/2, where N-1 is the filter order, e -jωM is the phase response, a (e jω ) is the amplitude response function, ω is the digital angular frequency.
  4. 4. The pre-equalization method of W-CGLS based TI-DAC natural frequency response degradation of claim 3 wherein S2 further comprises converting the pre-equalizer design problem into a linear system of equations solution problem, expressed as a least squares problem: C is a cosine base matrix, b is a target frequency response vector, and a is a pre-equalizer coefficient vector.
  5. 5. The pre-equalization method of TI-DAC natural frequency degradation based on W-CGLS of claim 4, wherein said weighted regularized conjugate gradient least square method comprises introducing frequency weighting parameters and regularized parameters into a conjugate gradient least square algorithm, and converting the least square problem into the following form: Where W is a diagonal weight matrix, w=diag (Ww 1 ,Ww 2 ,…,Ww L ), λ >0 is a regular parameter, and I is an identity matrix.
  6. 6. The pre-equalization method of W-CGLS based TI-DAC natural frequency response degradation of claim 5, wherein the iterative process of weighted regularized conjugate gradient least squares comprises: S21, initializing a diagonal weight matrix and a regular parameter, and calculating an initial residual error and an initial searching direction; s22, calculating an iteration step length according to the energy of the current residual error and the searching direction; S23, updating the current estimated solution vector along the searching direction; s24, calculating residual errors according to the current estimated solution vector, and correcting the next iteration direction; s25, calculating a conjugate coefficient according to the residual error obtained in the S24; S26, updating the new searching direction according to the conjugate coefficient; And S27, determining an iteration termination condition according to the given tolerance and the maximum iteration number, obtaining an equalizer coefficient if the condition is met, otherwise, increasing the iteration number, and returning to S22 to continue iteration.
  7. 7. The pre-equalization method of inherent frequency response degradation of TI-DAC based on W-CGLS of claim 1, wherein in S3, the pre-equalization process comprises the steps of dividing an input signal into multiple sub-signals through downsampling after passing through the pre-equalizer, respectively inputting the sub-signals into each sub-channel of the TI-DAC, and finally synthesizing an output signal through a combiner.
  8. 8. A pre-equalization system for TI-DAC natural frequency response degradation based on W-CGLS, characterized in that the system is implemented based on the pre-equalization method for TI-DAC natural frequency response degradation based on W-CGLS according to any one of claims 1-7, the system comprising: The modeling module is used for modeling the inherent frequency response degradation of the TI-DAC to obtain the target frequency response of the inherent frequency response degradation compensation of the TI-DAC; The pre-equalizer design module is used for designing a pre-equalizer by using a weighted regularized conjugate gradient least square method based on the target frequency response, and the weighted regularized conjugate gradient least square method iteratively solves the pre-equalizer coefficient by introducing a weighted parameter and a regularized parameter so as to fit the target frequency response; And the signal and equalization processing module is used for applying the pre-equalizer to the TI-DAC system and carrying out pre-equalization processing on the input signal so as to compensate the attenuation of the amplitude-frequency response of the passband and improve the flatness of the amplitude-frequency response.
  9. 9. A computer device, characterized in that it comprises a memory in which a computer program is stored and a processor which, when running the computer program stored in the memory, performs a pre-equalization method of the W-CGLS based TI-DAC natural frequency response degradation according to any of claims 1-7.
  10. 10. A computer-readable storage medium, characterized in that the computer-readable storage medium is for storing a computer program that performs the pre-equalization method of the W-CGLS-based TI-DAC natural frequency response degradation of any one of claims 1-7.

Description

Pre-equalization method and system for TI-DAC inherent frequency response degradation based on W-CGLS Technical Field The invention belongs to the technical field of digital signal processing, and particularly relates to a signal integrity compensation technology in a high-frequency digital-to-analog converter system. Background The time interleaving DAC (TIME INTERLEAVED DAC, TI-DAC) technology can effectively break through the limitation of single-channel sampling rate by parallel interleaving sampling of the multi-channel DAC, and multiplication of the sampling rate of the system is realized. But due to the inherent frequency response and the characteristics of the interweaving structure of the DAC, the flatness of the amplitude of the pass band is attenuated, so that the waveform quality is reduced. The causes of the inherent frequency response degradation in the TI-DAC mainly include the sinc frequency response attenuation of the ZOH and the amplitude overlap of the NRZ mode in the interleaved structure. The inherent sinc frequency response attenuation exists in a single DAC, so that the amplitude flatness is reduced, and particularly the high-frequency amplitude loss is serious. When the operating frequency is close to the nyquist frequency, the amplitude attenuation is about 3.9dB and spectral nulls occur at integer multiples of the sampling rate. In the time interleaving structure, sampling clock phases of all sub-channels are staggered in sequence, and finally outputs of sub-DACs are added by a combiner. Since each sub-DAC holds the input digital samples for a period of time, for the NRZ mode, the problem of amplitude overlap occurs when the outputs are added, resulting in signal distortion. The compensation method for the inherent frequency response degradation is only calibrated for a single degradation factor currently, and synchronous analysis of the two factors is not carried out. Disclosure of Invention The invention provides a pre-equalization method and a pre-equalization system for TI-DAC natural frequency response degradation based on W-CGLS, which aim to solve the problem that the TI-DAC natural frequency response is uneven due to the natural frequency response degradation, and the existing compensation method can only process a single factor independently and cannot compensate multiple degradation effects synchronously, so that the system waveform quality and the effective bandwidth are affected. In a first aspect, the present invention aims to provide a pre-equalization method for inherent frequency response degradation of a TI-DAC based on W-CGLS, comprising the steps of: S1, modeling the inherent frequency response degradation of the TI-DAC to obtain a target frequency response of the inherent frequency response degradation compensation of the TI-DAC; s2, designing a pre-equalizer by using a weighted regularized conjugate gradient least square method based on the target frequency response, wherein the weighted regularized conjugate gradient least square method iteratively solves the pre-equalizer coefficient by introducing a weighted parameter and a regularized parameter so as to fit the target frequency response; And S3, applying the pre-equalizer to the TI-DAC system, and performing pre-equalization processing on the input signal to compensate the attenuation of the amplitude-frequency response of the passband and improve the flatness of the amplitude-frequency response. Still further, a preferable scheme is provided, wherein in S1, the target frequency response of the pre-equalization is expressed as: Where T s is the system period and f represents the frequency. Still further, a preferred scheme is provided: the pre-equalizer in S2 is a Type-I FIR filter with linear phase characteristics, and the frequency response is expressed as: Where a 0,…,ak is the filter coefficient, m= (N-1)/2, where N-1 is the filter order, e -jωM is the phase response, a (e jω) is the amplitude response function, ω is the angular frequency. Still further, a preferred scheme is provided: the S2 further comprises converting the pre-equalizer design problem into a linear equation set solution problem, expressed as a least squares problem: C is a cosine base matrix, b is a target frequency response vector, and a is a pre-equalizer coefficient vector. Still further, a preferred scheme is provided: The weighted regularized conjugate gradient least square method specifically comprises the steps of introducing frequency weighting parameters and regularization parameters into a conjugate gradient least square algorithm, and converting the least square problem into the following form: Where W is a diagonal weight matrix, w=diag (Ww 1,Ww2,…,WwL), λ >0 is a regular parameter, and I is an identity matrix. Still further, a preferred embodiment is provided, wherein the iterative process of the weighted regularized conjugate gradient least squares method comprises: S21, initializing a diagonal weight matrix and a regula