A pulse distortion correction method for multi-level phase-shifted all-digital transmitter
Through the multi-level phase-shifted all-digital transmitter pulse distortion correction method, the pulse waveform distortion in the all-digital transmitter is corrected, solving the problems of delay mismatch and harmonic distortion that are difficult to handle with traditional methods, and improving the linear performance and quality of the signal.
Patent Information
- Application Number
- CN202411777294.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-05
- Publication Date
- 2025-09-23
- Estimated Expiration
- 2044-12-05
AI Technical Summary
When traditional all-digital transmitters process high-bandwidth, high-peak-to-average ratio signals, the pulse signals are prone to waveform distortion, resulting in delay mismatch errors and deterioration of harmonic performance, which are difficult to be effectively corrected by existing linearization methods.
A multi-level phase-shifted all-digital transmitter pulse distortion correction method is adopted. The total delay error and phase-shift control word are calculated by the digital signal processing unit. Combined with the delay preprocessing unit and the clock compensation unit, the delay and duty cycle errors of the pulse waveform are corrected to generate a corrected carrier signal.
It realizes adaptive correction of pulse waveform distortion, improves the linear performance and signal quality of ADTx, and reduces harmonic distortion and delay error.
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Figure CN119696965B_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of all-digital transmitters, and in particular to a method for correcting pulse distortion of a multi-level phase-shifted all-digital transmitter. Background Art
[0002] With the rapid growth in demand for communications services, the widespread use of complex modulation schemes, and the continuous increase in signal rates and bandwidths, the demand for multi-mode and multi-band hardware operation is increasing. Green communications, exemplified by low power consumption, have become the development trend and goal of wireless communication technology. For the transmitter, the need to process signals with larger bandwidths and higher peak-to-average ratios, as well as requirements for greater reconfigurability and compatibility, places tremendous pressure on the design and implementation of traditional transmitters. Meanwhile, the all-digital transmitter (ADTx), a revolutionary technology, differs from traditional transmitter systems in both its structure and mechanism. It offers technical advantages such as high efficiency, high linearity, and flexible reconfigurability and programmability, and is expected to play a key role in future wireless communication systems.
[0003] In recent years, ADTx technology has developed rapidly, with the emergence of various technical architectures, including orthogonal ADTx, polarization ADTx, and outphasing ADTx. Among them, outphasing ADTx solutions based on radio frequency pulse width modulation (RF-PWM) combined with digital delay lines (DDL) offer significant advantages in terms of system complexity, time resolution, and processing power consumption. However, pulse signals can suffer from waveform distortion. The main reason is that due to device non-idealities, the rise and fall times of the pulse signal significantly increase after passing through circuits such as digital delay lines and switching amplifiers, resulting in changes in the duty cycle of the pulse waveform. Furthermore, due to the differences in distortion between multiple pulse signals, the signals can become out of sync, introducing delay mismatch errors. Pulse waveform distortion can impact ADTx performance in the following ways: Since the performance of the RF-PWM algorithm is directly related to the width and position of the pulse signal, duty cycle errors can degrade harmonic performance, generating additional even-order harmonics and increasing filtering difficulties. Delay mismatch errors can also cause severe nonlinear distortion of in-band signals. However, traditional linearization methods such as digital pre-distortion (DPD) are difficult to directly apply to correct these distortion phenomena. Summary of the Invention
[0004] The purpose of this application is to provide a method for correcting pulse distortion of a multi-level phase-shifted all-digital transmitter, which can realize adaptive correction processing of pulse waveform distortion and improve the linear performance of ADTx.
[0005] To achieve the above objectives, this application provides the following solutions:
[0006] The present application provides a method for correcting pulse distortion of a multi-level phase-shifted all-digital transmitter. The method is applied to a multi-level phase-shifted all-digital transmitter pulse distortion correction system. The multi-level phase-shifted all-digital transmitter pulse distortion correction system includes: a digital signal processing unit, a time delay preprocessing unit, a clock compensation unit, a phase modulation unit, and a digital power amplifier; the method includes:
[0007] Determine a relationship between a total delay error and a phase shift control word; the total delay error includes a delay error of a digital delay line circuit in a phase modulation unit and a delay error of a digital power amplifier; the phase shift control word is calculated by a digital signal processing unit using an RF-PWM algorithm based on a baseband signal;
[0008] Determine the integer multiple error relationship between the total delay error and the phase shift control word based on the relationship between the total delay error and the phase shift control word;
[0009] Calculate the preprocessing phase shift control word according to the integer multiple error relationship between the total delay error and the phase shift control word;
[0010] Calculating a compensation control word based on a total duty cycle variation error and a preprocessed phase shift control word; the total duty cycle variation error includes a duty cycle variation error of a digital delay line circuit in a phase modulation unit and a duty cycle variation error of a digital power amplifier;
[0011] Controlling the delay of the carrier signal according to the compensation control word to obtain a carrier signal with a duty cycle variation error;
[0012] generating a correction carrier signal based on the carrier signal with a duty cycle variation error;
[0013] The correction carrier signal is delayed according to the pre-processing phase-shift control word, and the output signal is amplified and synthesized.
[0014] According to the specific embodiments provided in this application, this application has the following technical effects:
[0015] The present application provides a method for correcting pulse distortion of a multi-level phase-shifted all-digital transmitter. The method calculates a pre-processed phase-shift control word based on the integer multiple error relationship between the total delay error and the phase-shift control word, thereby correcting the delay error caused by pulse waveform distortion; calculates a compensation control word based on the pre-processed phase-shift control word, and determines a correction carrier signal based on the compensation control word, thereby compensating for the pulse waveform distortion error caused by the digital delay line circuit and the digital power amplifier in the phase modulation unit. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.
[0017] Figure 1 The diagram is a schematic diagram of the architecture of a five-level phase-shifted all-digital transmitter based on DDL;
[0018] Figure 2 A schematic structural diagram of a multi-level phase-shifted all-digital transmitter pulse distortion correction system provided in one embodiment of the present application;
[0019] Figure 3 This is a schematic diagram of the detailed functional modules of the clock compensation unit;
[0020] Figure 4 A flowchart of a method for correcting pulse distortion in a multi-level phase-shifted all-digital transmitter according to an embodiment of the present application;
[0021] Figure 5 A schematic diagram of pulse waveforms at various stages in a clock compensation unit provided in an embodiment of the present application. DETAILED DESCRIPTION
[0022] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.
[0023] Figure 1 This is a schematic diagram of the architecture of a five-level phase-shifted, all-digital transmitter based on DDL. It comprises three functional units. The signal processing unit calculates four phase-shift control words based on the input baseband signal using an RF-PWM algorithm and sends them to the phase modulation unit. The phase modulation unit, comprised of four DDL circuits, delays the input pulse signal according to the phase-shift control words, thereby modulating and up-converting the baseband signal's amplitude and phase information. A digital power amplifier (DPA) amplifies and synthesizes these signals, outputting a five-level pulse modulated signal. However, in practical circuits, waveform distortion occurs after the pulse signal passes through these units.
[0024] The purpose of this application is to provide a multi-level phase-shifted all-digital transmitter pulse distortion correction method with even-order harmonic elimination function, so as to realize the adaptive correction processing function of pulse waveform distortion and improve the linear performance of the output signal.
[0025] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below with reference to the accompanying drawings and specific implementation methods.
[0026] In an exemplary embodiment, a method for correcting pulse distortion of a multi-level phase-shifted all-digital transmitter is provided. The method is applied to Figure 2 Multi-level phase-shifted all-digital transmitter pulse distortion correction system.
[0027] like Figure 2 As shown in FIG, the pulse distortion correction system of the multi-level phase-shifted all-digital transmitter includes: a digital signal processing unit, a delay pre-processing unit, a clock compensation unit, a phase modulation unit and a digital power amplifier. Figure 3 As shown, the clock compensation unit specifically includes a signal source, a digital delay line circuit and an inverter connected in sequence.
[0028] The carrier signal S with a 50% duty cycle is generated by the signal source sq (t), and input to the DDL circuit in the clock compensation unit to compensate the control word (W CON_i (t)) modulates the phase information to the clock signal to generate an output pulse signal S with duty cycle distortion error DCE (t), a pulse train S with a specific width and compensation characteristics is generated through an inverter CON (t) (i.e., the correction carrier signal).
[0029] The present application decomposes the pulse waveform distortion error of the all-digital transmitter into a delay error and a pulse width error. On the basis of the existing all-digital transmitter architecture, a delay pre-processing unit and a clock compensation unit are added to compensate for the delay error and the pulse width error respectively. First, the delay error caused by the pulse waveform distortion is corrected by the delay pre-processing unit, and the delay error can be offset by adding the corresponding delay error to the delay line control word data of each channel in the phase modulation unit. Then, the clock signal of the DDL circuit in the phase modulation unit is replaced by a two-level signal of a specific width (i.e., a corrected carrier signal) output by the clock compensation unit. The corrected carrier signal output by the clock compensation unit is used as the carrier signal of the DDL circuit in the phase modulation unit, which can compensate for the pulse waveform distortion error caused by the DDL circuit.
[0030] like Figure 4 As shown, the pulse distortion correction method of the multi-level phase-shifted all-digital transmitter includes the following steps:
[0031] S1: Determine the relationship between the total delay error and the phase shift control word; the total delay error includes the delay error of the digital delay line circuit in the phase modulation unit and the delay error of the digital power amplifier; the phase shift control word is calculated by the digital signal processing unit using the RF-PWM algorithm based on the baseband signal.
[0032] In a specific embodiment, step S1 specifically includes:
[0033] S11: measuring the influence of the digital delay line circuit in the phase modulation unit on the pulse waveform distortion, and determining the time delay error of the digital delay line circuit in the phase modulation unit.
[0034] Measure the effect of the components in the DDL circuit on the pulse waveform distortion when the pulse signal passes through the phase modulation unit. The delay error of the DDL is Δδ. ddl (t). Δδ ddl (t) is linearly increasing with the phase shift control word W(t). When W(t) is the largest, Δδ ddl (t) = δ, where δ is the maximum delay error.
[0035] S12: Measure the impact of components in the digital power amplifier on pulse waveform distortion and determine the delay error of the digital power amplifier.
[0036] The actual measurement of the impact of components in the DPA on pulse waveform distortion, the delay error of the DPA is denoted as δ dpa , δ dpa As a constant, the delay error in DPA is converted into the corresponding phase shift control word value W dpa , the delay error δ of DPA dpa The relationship between the phase shift control word W(t) is: dpa =round((δ dpa / δ)W max (t)), W max (t) is the maximum phase shift control word.
[0037] S13: Determine a relationship between the total delay error and the phase shift control word based on the linear relationship between the delay error of the digital delay line circuit in the phase modulation unit and the phase shift control word and the relationship between the delay error of the digital power amplifier and the phase shift control word.
[0038] Establish the relationship between the total delay error Δδ(t) and the phase shift control word:
[0039] Δδ(t)=δ((W(t)+W dpa ) / W max (t)).
[0040] S2: Determine the integer multiple error relationship between the total time delay error and the phase shift control word based on the relationship formula between the total time delay error and the phase shift control word.
[0041] Calculate the integer multiple error (N) relationship between the total time delay error and the phase shift control word:
[0042] When 0 < Δδ(t) < 1, -W dpa <W(t) < W max (t) / δ - W dpa ;
[0043] When 1 < Δδ(t) < 2, W max (t) / δ - W dpa <W(t) < 2W max (t) / δ - W dpa ;
[0044] When 2 < Δδ(t) < 3, 2W max (t) / δ - W dpa <W(t) < 3W max (t) / δ - W dpa ;
[0045]
[0046] When N < Δδ(t) < N + 1, N·W max (t) / δ - W dpa <W(t) < (N + 1)·W max (t) / δ - W dpa .
[0047] S3: Calculate the preprocessed phase shift control word according to the integer multiple error relationship between the total time delay error and the phase shift control word.
[0048] The preprocessed phase shift control word W i ′(t) has the following calculation formula: W i ′(t) = W(t) + N, i ∈ [1, 4], where i is the number of channels of the digital delay line circuit.
[0049] Preprocessing the phase shift control word can achieve the correction of the time delay error caused by pulse waveform distortion in the multi-level RF-PWM all-digital transmitter.
[0050] S4: Calculate the compensation control word according to the total duty cycle change error and the preprocessed phase shift control word; the total duty cycle change error includes the duty cycle change error of the digital delay line circuit and the duty cycle change error of the digital power amplifier in the phase modulation unit.
[0051] In a specific embodiment, the effect of the components in the DPA on the pulse waveform distortion is actually measured, and the duty cycle variation error of the DPA is denoted as τ dpa , τ dpa is a constant.
[0052] Measure the effect of components in the DDL circuit of the phase modulation unit on the pulse waveform distortion, and record the duty cycle variation error of the DDL as Δτ ddl (t), Δτ ddl (t) is linearly increasing with the phase shift control word W(t). When W(t) is the largest, Δτ ddl (t) = τ, where τ is the maximum duty cycle variation error.
[0053] Calculate the total duty cycle variation error Δτ(t) caused by the DDL circuit and DPA of the phase modulation unit: Δτ(t) = Δτ ddl (t)+τ dpa , Δτ(t) and the phase shift control word W(t) are in a linear increasing relationship.
[0054] Calculate the compensation control word W in the clock compensation unit CON_i (t):
[0055] W CON_i (t) = W i (t)+round((Δτ ddl (t)+τ dpa ) / τ)
[0056] The pulse waveform distortion Δτ caused by the DDL circuit in the phase modulation unit ddl (t) The delay error is linearly increasing with the phase shift control word W(t) as mentioned above, so W CON_i (t) = W i ′(t)+round(τ dpa / τ).
[0057] S5: Control the delay of the carrier signal according to the compensation control word to obtain a carrier signal with a duty cycle variation error.
[0058] W CON_i (t) Control the delay of the clock carrier signal in the clock compensation unit to obtain a carrier signal S with a duty cycle variation error DCE_i (t), such as Figure 5 As shown in (a) in .
[0059] S6: Generate a correction carrier signal based on the carrier signal with duty cycle variation error.
[0060] S DCE_i (t) is generated after passing through the inverter in the clock compensation unit and S DCE_i(t) Corrected carrier signal S with opposite distortion CON_i (t), such as Figure 5 As shown in (b) in .
[0061] S7: Delay processing is performed on the correction carrier signal according to the pre-processing phase shift control word, and the output signal is amplified and synthesized.
[0062] S CON_i (t) is used as the input carrier clock of the DDL circuit in the phase modulator. The two are cascaded to produce an ideal two-level signal S i (t), such as Figure 5 As shown in (c) in .
[0063] The clock compensation unit can be used to correct the duty cycle distortion error caused by pulse waveform distortion in a multi-level RF-PWM full digital transmitter.
[0064] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0065] This document uses specific examples to illustrate the principles and implementation methods of this application. The description of the above examples is only intended to help understand the method and core concept of this application. At the same time, for those skilled in the art, based on the concept of this application, there may be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.
Claims
1. A method for correcting pulse distortion of a multi-level phase-shifted all-digital transmitter, characterized in that: The method is applied to a multi-level phase-shifted all-digital transmitter pulse distortion correction system, which includes: a digital signal processing unit, a time delay preprocessing unit, a clock compensation unit, a phase modulation unit and a digital power amplifier; the method includes: Determine a relationship between a total delay error and a phase shift control word; the total delay error includes a delay error of a digital delay line circuit in a phase modulation unit and a delay error of a digital power amplifier; the phase shift control word is calculated by a digital signal processing unit using an RF-PWM algorithm based on a baseband signal; Determine the integer multiple error relationship between the total delay error and the phase shift control word based on the relationship between the total delay error and the phase shift control word; Calculate the preprocessing phase shift control word according to the integer multiple error relationship between the total delay error and the phase shift control word; Calculating a compensation control word based on a total duty cycle variation error and a preprocessed phase shift control word; the total duty cycle variation error includes a duty cycle variation error of a digital delay line circuit in a phase modulation unit and a duty cycle variation error of a digital power amplifier; Controlling the delay of the carrier signal according to the compensation control word to obtain a carrier signal with a duty cycle variation error; generating a correction carrier signal based on the carrier signal with a duty cycle variation error; The correction carrier signal is delayed according to the pre-processing phase-shift control word, and the output signal is amplified and synthesized.
2. The pulse distortion correction method for a multi-level phase-shifted all-digital transmitter according to claim 1, characterized in that: Determine the relationship between the total delay error and the phase shift control word, specifically including: Measure the effect of the digital delay line circuit in the phase modulation unit on the pulse waveform distortion and determine the time delay error of the digital delay line circuit in the phase modulation unit; Measure the impact of components in digital power amplifiers on pulse waveform distortion and determine the delay error of digital power amplifiers; Based on the linear relationship between the delay error of the digital delay line circuit in the phase modulation unit and the phase shift control word and the relationship between the delay error of the digital power amplifier and the phase shift control word, the relationship between the total delay error and the phase shift control word is determined.
3. The pulse distortion correction method for a multi-level phase-shifted all-digital transmitter according to claim 2, characterized in that: The relationship between the delay error of the digital power amplifier and the phase shift control word is: W dpa =round((δ dpa / δ)W max (t)) Among them, W dpa The phase shift control word value converted from the delay error of the digital power amplifier, δ dpa is the delay error of the digital power amplifier, δ is the maximum delay error, W max (t) is the maximum phase shift control word.
4. The pulse distortion correction method for a multi-level phase-shifted all-digital transmitter according to claim 3, characterized in that: The relationship between the total delay error and the phase shift control word is: Δδ(t)=δ((W(t)+W dpa ) / W max (t)) Where Δδ(t) is the total delay error.
5. The pulse distortion correction method for a multi-level phase-shifted all-digital transmitter according to claim 4, characterized in that: The relationship between the total delay error and the integer multiple error between the phase shift control word is as follows: When 0 < Δδ(t) < 1, -W dpa <W(t) < W max (t) / δ - W dpa When 1 < Δδ(t) < 2, W max (t) / δ - W dpa < W(t) < 2W max (t) / δ - W dpa When 2 < Δδ(t) < 3, 2W max (t) / δ - W dpa < W(t) < 3W max (t) / δ - W dpa When N < Δδ(t) < N + 1, N·W max (t) / δ - W dpa <W(t) < (N + 1)·W max (t) / δ - W dpa Where W(t) is the phase shift control word, and N is the integer multiple error.
6. The pulse distortion correction method for a multi-level phase-shifted all-digital transmitter according to claim 5, characterized in that: The calculation formula of the preprocessing phase shift control word is: W i ′(t)=W(t)+N,i∈[1,4] Among them, W i ′(t) is the preprocessing phase shift control word, and i is the number of channels of the digital delay line circuit.
7. The pulse distortion correction method for a multi-level phase-shifted all-digital transmitter according to claim 1, characterized in that: Before calculating the compensation control word according to the total duty cycle variation error and the pre-processed phase shift control word, it also includes: Measure the effect of the digital delay line circuit in the phase modulation unit on the pulse waveform distortion and determine the duty cycle variation error of the digital delay line circuit in the phase modulation unit; Measure the impact of components in digital power amplifiers on pulse waveform distortion and determine the duty cycle variation error of digital power amplifiers; A total duty cycle variation error is calculated based on a duty cycle variation error of a digital delay line circuit in a phase modulation unit and a duty cycle variation error of a digital power amplifier.
8. The pulse distortion correction method for a multi-level phase-shifted all-digital transmitter according to claim 1, characterized in that: The calculation formula of the compensation control word is: W CON_i (t)=W i ′(t)+round(τ dpa / t) Among them, W CON_i (t) is the compensation control word, W i ′(t) is the pre-processing phase shift control word, τ dpa is the duty cycle variation error of the digital delay line circuit in the phase modulation unit, and τ is the maximum duty cycle variation error.