Modulation method and modulator of 3-level RF-PWM

Abstract

The application discloses a 3-level RF-PWM modulation method and a modulator, and relates to the technical field of wireless communication. According to an input digital baseband signal, a normalized digital baseband signal is obtained, two DSM modulation signals are obtained through DSM respectively, an amplitude signal and a phase signal of the input are obtained by using an amplitude-phase extraction algorithm, the amplitude signal and the phase signal are used to complete mapping in a preset amplitude-phase mapping table according to a specific search strategy with the minimum Euclidean distance as a condition, a complex signal composed of pre-stored 3-level pulse signal amplitude-phase information is obtained, then the corresponding relationship between the amplitude-phase information of the input signal and pulse width and pulse position is used to search for an output pulse sequence corresponding to the complex signal in a 3-level pulse mapping table, and finally the required 3-level radio frequency pulse width modulation signal is obtained by serial splicing, so that the problem that system real-time is limited by time resolution can be solved.

Description

Technical Field

[0001] This invention relates to the field of wireless communication technology, and in particular to a 3-level RF-PWM modulation method and modulator. Background Technology

[0002] To ensure that wireless communication terminals continue to evolve in terms of miniaturization, digitization, low power consumption, and reconfigurability while remaining compatible with more diverse functions and communication standards, the transmitter, as a crucial component of the wireless communication system, must address the high demands and challenges faced by wireless communication terminals in terms of efficiency and configurability. Traditional analog transmitters have long suffered from performance limitations and poor RF reconfigurability. However, thanks to the rapid development of digital processing and microelectronics technologies, all-digital transmitter (ADTx) technology has advanced rapidly over the past decade, offering the unique advantage of reconfigurability and meeting the design requirements of low power consumption and high efficiency.

[0003] The ADTx mainly consists of a Direct Digital Radio Frequency Modulator (DDRFM), a Switch-Mode Power Amplifier (SMPA), and a tuning filter, performing up-conversion and RF power amplification in the digital domain. Since the SMPA operates in pulse mode, to compensate for its strong nonlinearity, the DDRFM needs to convert the digital baseband signal into a suitable digital RF pulse signal for pulse amplification using a specific pulse coding algorithm while performing digital up-conversion. However, this pulse signal contains a significant amount of quantization noise in addition to the required RF signal. Therefore, the DDRFM also needs to convert the in-band noise into out-of-band unwanted transmit components and filter them out using a tuning filter to achieve a high output signal-to-noise ratio and spectral purity.

[0004] The most commonly used pulse coding methods in DDRFM are delta-sigma modulation (DSM) and pulse width modulation (PWM). DSM can transfer in-band noise to out-of-band through noise shaping, resulting in a high in-band signal-to-noise ratio. However, its disadvantages include a relatively complex implementation structure and low coding efficiency (CE). In contrast, the radio frequency pulse width modulation (RF-PWM) scheme based on conventional PWM has a simple structure, high CE, and its noise is mainly manifested as high-order harmonics, resulting in high spectral purity. It is considered one of the most suitable pulse coding methods for application in ADTx.

[0005] Because RF-PWM encodes the amplitude and phase of the input baseband signal based on the pulse width and position, it requires extremely high time resolution, placing high demands on sampling and implementation processes. Furthermore, increasing the number of quantization levels in the pulse encoding can improve the emission response (CE) and reduce higher harmonic amplitudes to some extent, but it increases system complexity. To reduce system implementation difficulty and generate PWM signals flexibly and efficiently, mapping-based PWM methods, such as Mapped Pulse Width Modulation (MPWM), have gradually emerged in recent years. MPWM utilizes the correspondence between input modulation information and output pulse waveforms, achieving direct output of the PWM waveform through a mapping lookup table. Based on the noise shaping characteristics of DSM, Reference 1 (Markert D, YuX, Heimpel H, et al. An All-Digital, Single-Bit RF Transmitter for Massive MIMO[J]. IEEE Trans.CircuitsSyst.I,Reg.Papers,2017,64(3):696-704) proposed a 2-level DSM-MPWM method, which realizes noise shaping and mapping in the baseband and restricts the state of the output pulse. It effectively reduces the implementation complexity under high time resolution, but may also affect the selection of the optimal solution. Moreover, the CE is low due to the 2-level output. To improve the flexibility of carrier frequency agility, reference 2 (Yang J, Yang SY, Chen Z H, et al. An Agile LUT-Based All-Digital Transmitter[J].IEEE Trans.Circuits Syst.I,Reg.Papers,2020,67(12):5550-5560) proposes a 2-level intermediate frequency MPWM scheme, which is mapped to the intermediate frequency. By changing the contents of the lookup table (LUT), carrier frequency agility can be achieved without affecting the system circuit. At the same time, it considers the pulse state of all cases and ensures the selection of the optimal solution. However, as the time resolution increases, the size of the LUT increases exponentially, which will greatly increase the mapping lookup time and affect the real-time performance of the system. Moreover, the problem of low CE has not been improved.Reference 3 (Yang SY, Yang J, Zhao J, et al. Clean Bandwidth Improvement of MPWM Encoding Method for RF All-Digital Transmitter[J].IEEE Trans.Circuits Syst.II,Express Briefs,2021,68(7):2404-2408) expands the modulation bandwidth by optimizing the mapping strategy based on Reference 2, effectively reducing the requirements of the output filter, and improves CE by using 3 and 5 level outputs. However, the problem that the system's real-time performance is limited by the time resolution has not been solved. Summary of the Invention

[0006] To address the aforementioned problems in the existing technology, this invention provides a 3-level RF-PWM modulation method and modulator.

[0007] To achieve the above objectives, the present invention provides the following solution:

[0008] A modulation method for 3-level RF-PWM, comprising:

[0009] The normalized digital baseband signal is obtained from the digital baseband signal; the expression for the normalized digital baseband signal is: In the formula, I n and Q n All are digital baseband signals, and I is the digital baseband signal I. n The normalized digital baseband signal, Q is the digital baseband signal Q. n Normalized digital baseband signal;

[0010] The normalized digital baseband signal is incrementally summed and modulated to obtain the DSM modulated signal; the expression for the DSM modulated signal is: In the formula, ρ is the amplitude signal, θ is the phase signal, and x is the phase signal. i x is the DSM modulated signal of the normalized digital baseband signal I. q For the DSM modulated signal of the normalized digital baseband signal Q, arctan() is the inverse trigonometric function;

[0011] An amplitude and phase extraction algorithm is used to obtain the amplitude and phase signals based on the DSM modulated signal;

[0012] According to a specific search strategy, the amplitude signal and the phase signal are mapped in the preset amplitude-phase mapping table with the condition of minimum Euclidean distance, and the complex signal composed of the amplitude and phase information of the 3-level pulse signal stored in the amplitude-phase mapping table is obtained.

[0013] Based on the one-to-one correspondence between the preset amplitude-phase mapping table and the 3-level pulse mapping table, the output pulse sequence corresponding to the complex signal is found in the 3-level pulse mapping table;

[0014] The output pulse sequence is serially spliced ​​to obtain a 3-level radio frequency pulse width modulation signal.

[0015] Optionally, the length of any pulse sequence in the 3-level pulse mapping table is N, and each pulse period has only one continuous positive pulse.

[0016] Optionally, the 3-level pulse mapping table is [p1,…,p i ,…,p K ];

[0017] Where, p i =[p1,…,p j ,…,p N ], p j The values ​​are 1, 0, or -1, and the positions of 1 or -1 must be consecutive and the widths of positive and negative pulses must be the same, i = 1, 2, ..., K, j = 1, 2, ..., N;

[0018] The amplitude-phase mapping table is a 3-level pulse mapping table p i The corresponding combination of amplitude and phase information.

[0019] Optionally, the amplitude-phase mapping table is [q1,…,q i ,…,q K ];

[0020] in,

[0021] In the formula, q i The amplitude and phase information at time i (ρ) p_i ,θ p_i ) combination, ρ p_i For the amplitude information at time i, θ p_i For the phase information at time i, T c For the pulse period, p w_i Let be the pulse width at time i, A be the modulator gain, and j represent the imaginary part.

[0022] Optionally, it also includes:

[0023] The optimization configuration of modulation and mapping parameters specifically involves: aligning the input point (ρ, θ) with the output point (ρ...). p_i ,θ p_i Matching within the complex space; input point (ρ, θ) and output point (ρ) p_i ,θ p_i The mapping error ε ifor:

[0024]

[0025] In the formula, ρ represents amplitude information and θ represents phase information.

[0026] A 3-level RF-PWM modulator is applied to the modulation method provided above; the modulator includes:

[0027] The first input terminal is used to input the digital baseband signal I. n ;

[0028] The second input terminal is used to input the digital baseband signal Q. n ;

[0029] The baseband signal modulation unit is connected to the first input terminal and the second input terminal respectively, and is used to modulate the digital baseband signal I. n and digital baseband signal Q n Normalized digital baseband signals I and Q are obtained respectively, and are used to perform incremental summation modulation on the normalized digital baseband signals I and Q respectively to obtain the DSM modulated signal x. i and DSM modulated signal x q ;

[0030] The amplitude and phase extraction unit, connected to the baseband signal modulation unit, is used to employ an amplitude and phase extraction algorithm based on the DSM modulated signal x. i and DSM modulated signal x q The amplitude signal ρ and the phase signal θ are obtained;

[0031] The mapping pulse width modulation unit, connected to the amplitude and phase extraction unit, is used to map the amplitude signal and phase signal in a preset amplitude and phase mapping table according to a specific search strategy, with the minimum Euclidean distance as the condition, to obtain a complex signal q composed of the amplitude and phase information of a 3-level pulse signal pre-stored in the amplitude and phase mapping table. k It is used to find the output pulse sequence p corresponding to the complex signal in the 3-level pulse mapping table according to the one-to-one correspondence between the preset amplitude-phase mapping table and the 3-level pulse mapping table. k ;

[0032] The pulse generation unit, connected to the mapped pulse width modulation unit, is used to receive the output pulse sequence p at various times. k And used to generate the output pulse sequence p at each time point. k Serial splicing into a 3-level radio frequency pulse width modulation signal S 3L ;

[0033] The output terminal is connected to the pulse generation unit and is used to output the 3-level radio frequency pulse width modulation signal S.3L .

[0034] Optionally, the baseband signal modulation unit includes:

[0035] The normalization module is connected to the first input terminal and the second input terminal respectively, and is used to normalize the digital baseband signal I. n and digital baseband signal Q n The normalized digital baseband signal I and the normalized digital baseband signal Q are obtained respectively;

[0036] The DSM module, connected to the normalization module, is used to perform incremental summation modulation on the normalized digital baseband signal I and the normalized digital baseband signal Q to obtain the DSM modulated signal x. i and DSM modulated signal x q .

[0037] Optionally, the baseband signal modulation unit is provided with an amplitude correction value and a number of DSM quantization levels;

[0038] Both the amplitude correction value and the DSM quantization level number are used to match the normalized digital baseband signal with the preset amplitude-phase mapping table.

[0039] Optionally, the amplitude and phase extraction unit employs the CORDIC algorithm based on the DSM modulated signal x. i and DSM modulated signal x q The amplitude signal ρ and the phase signal θ are obtained;

[0040] in,

[0041] In the formula, arctan() is the inverse trigonometric function.

[0042] Optionally, the mapped pulse width modulation unit includes:

[0043] An amplitude-phase indexing module, connected to the amplitude-phase extraction unit, is used to perform amplitude indexing on the amplitude signal ρ and phase indexing on the phase signal θ.

[0044] The amplitude-phase mapping module, connected to the amplitude-phase indexing module, is used to map the received amplitude signal ρ (indexed by amplitude) and the phase signal θ (indexed by phase) in a preset amplitude-phase mapping table according to a specific search strategy, with the condition of minimizing the Euclidean distance. This results in a complex signal q composed of the amplitude and phase information of a pre-stored 3-level pulse signal in the amplitude-phase mapping table. k ;

[0045] A 3-level pulse mapping module, connected to the amplitude-phase mapping module, is used to find the output pulse sequence p corresponding to the complex signal in the 3-level pulse mapping table according to the one-to-one correspondence between the preset amplitude-phase mapping table and the 3-level pulse mapping table. k .

[0046] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0047] This invention obtains a normalized digital baseband signal from the input digital baseband signal, which is then processed by a DSM to obtain two DSM modulated signals. An amplitude and phase extraction algorithm is used to obtain the input amplitude and phase signals. Based on a specific search strategy, the amplitude and phase signals are mapped in a preset amplitude-phase mapping table with the minimum Euclidean distance as the condition to obtain a complex signal composed of pre-stored 3-level pulse signal amplitude and phase information. Then, based on the correspondence between the amplitude and phase information of the input signal and the pulse width and pulse position, the corresponding output pulse sequence of the complex signal is found in the 3-level pulse mapping table. Finally, the signals are serially spliced ​​to form the required 3-level RF pulse width modulation signal, which can solve the problem that the system's real-time performance is limited by time resolution. Attached Figure Description

[0048] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0049] Figure 1 This is a schematic diagram of the generation of a 3-level radio frequency pulse width modulation signal provided in an embodiment of the present invention;

[0050] Figure 2 This is a schematic diagram of modulation and mapping parameters provided in an embodiment of the present invention;

[0051] Figure 3 This is a schematic diagram illustrating the influence of modulation and mapping parameters provided in this embodiment of the invention on the mapping space of a preset amplitude-phase mapping table;

[0052] Figure 4 A flowchart illustrating the optimized search strategy provided in an embodiment of the present invention;

[0053] Figure 5 A logical schematic diagram of the optimized search strategy provided in an embodiment of the present invention;

[0054] Figure 6 This is a schematic diagram of the structure of a 3-level radio frequency pulse width modulator provided in an embodiment of the present invention.

[0055] Symbol explanation:

[0056] 11-Baseband signal modulation unit, 111-Normalization module, 112-First incremental summation modulator, 113-Second incremental summation modulator, 12-Amplitude and phase extraction unit, 13-Mapped pulse width modulation unit, 131-Amplitude index, 132-Phase index, 133-Amplitude and phase mapping module, 134-3-Level pulse mapping module, 14-Pulse generation unit. Detailed Implementation

[0057] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0058] The purpose of this invention is to provide a 3-level RF-PWM modulation method and modulator, which can solve the problem that the real-time performance of the system is limited by the time resolution.

[0059] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0060] In one embodiment of the present invention, based on the input digital baseband signal I n Q n The normalized digital baseband signals I and Q are obtained, and then passed through a DSM to obtain two DSM modulated signals x. i x q An amplitude and phase extraction algorithm is used to obtain the input amplitude signal ρ and phase signal θ. Based on a specific search strategy, the amplitude and phase signals ρ and θ are mapped in a preset amplitude-phase mapping table Q, using the minimum Euclidean distance as the condition. This yields a complex signal q composed of the amplitude and phase information of a 3-level pulse signal pre-stored in the preset amplitude-phase mapping table Q. k Then, based on the correspondence between the amplitude and phase information of the input signal and the pulse width and pulse position, q is obtained by looking up the value in the 3-level pulse mapping table P. k The corresponding output pulse sequence p k Finally, the signals are serially spliced ​​together to form the required 3-level RF pulse width modulation signal S. 3L .

[0061] In one embodiment of the present invention, the following steps are included:

[0062] Step 1: Input digital baseband signal I n Q n Normalize and convert to normalized digital baseband I and Q, and satisfy the relationship shown in formula (1).

[0063]

[0064] Step 2: Convert the normalized digital baseband signals I and Q into DSM modulated signals x using a DSM converter. i x q .

[0065] Step 3: Use the amplitude and phase extraction algorithm to extract the DSM modulated signal x i x q It is decomposed into the input amplitude signal ρ and phase signal θ, and satisfies the relationship shown in formula (2).

[0066]

[0067] Step 4: Based on the input amplitude signal ρ and phase signal θ, find the complex signal q composed of the amplitude and phase information of the 3-level pulse signals pre-stored in the preset amplitude-phase mapping table Q, with the condition of minimizing the Euclidean distance. k .

[0068] Step 5: Based on the one-to-one correspondence between the 3-level pulse mapping table P and the preset amplitude-phase mapping table Q, find the complex signal q in the 3-level pulse mapping table P. k The corresponding output pulse sequence p k .

[0069] Step 6: Output pulse sequence p corresponding to the amplitude and phase of the input signal at each moment. k Serial splicing yields the final required 3-level RF pulse width modulation signal S. 3L .

[0070] In one embodiment of the present invention, the length of any pulse sequence in the 3-level pulse mapping table P is N, and each pulse period T c If there is only one continuous positive pulse, then the pulse width p of any pulse sequence is... w The maximum value is N / 2, and the pulse position is p. p There are N possibilities, meaning the pulse sequence has a total of K = N. 2 / 2+1 types.

[0071] In one embodiment of the present invention, the 3-level pulse mapping table P represents all possible combinations of 3-level output pulse sequences [p1,…,p1]. i ,…,p K And p i =[p1,…,p j ,…,p N ], p jThe value is 1, 0, or -1, and the positions of 1 or -1 must be consecutive, with the width of the positive and negative pulses being the same. The amplitude-phase mapping table Q is a 3-level pulse mapping table P containing all p... i The corresponding amplitude and phase information (ρ) p_i ,θ p_i The combination of [q1,…,q) i ,…,q K ].

[0072] In one embodiment of the present invention, there is a relationship between the 3-level pulse mapping table P and the amplitude-phase mapping table Q as follows: Figure 1 The one-to-one correspondence shown indicates that the pulse sequence can be derived from the pulse width p. w and pulse position p p It indicates. q i The corresponding pulse sequence amplitude ρ p_i Phase θ p_i With p i The corresponding pulse width p w_i Pulse position p p_i and pulse period T c The following relationship exists:

[0073]

[0074] In one embodiment of the present invention, the optimization scheme is achieved by... Figure 2 By optimizing the modulation and mapping parameters shown, it is possible to... Figure 3 The mapping input point (ρ, θ) and output point (ρ) shown are... p_i ,θ p_i To minimize mapping error, the mapping error ε between input and output points is minimized by matching as closely as possible within the complex space. i The calculation is as follows:

[0075]

[0076] Figure 2 and Figure 3 a c1 and a c2 These are the amplitude correction values ​​for the normalized digital baseband I and Q signals and the DSM modulated signal, respectively. q N represents the number of DSM quantization levels, where N is p. i The sequence length.

[0077] In one embodiment of the present invention, the mapping lookup strategy employs, as follows: Figure 4 The nearest point search method shown here establishes an amplitude and phase information index table and pre-screens possible mapped output points, such as... Figure 5 As shown, the conventional traversal search can be simplified to a search and comparison of two possible mapping output points. Figure 4LUT(Q) is the established amplitude and phase information index table.

[0078] like Figure 6 As shown, in one embodiment of the present invention, a 3-level radio frequency pulse width modulator has two signal input terminals and one signal output terminal, and mainly includes: a baseband signal modulation unit 11, an amplitude and phase extraction unit 12, a mapped pulse width modulation unit 13, and a pulse generation unit 14.

[0079] The baseband signal modulation unit 11 has two input terminals and two output terminals. The two input terminals are the first signal input terminal and the second signal input terminal of the radio frequency pulse width modulator, respectively. The baseband signal modulation unit 11 is used to receive the input digital baseband signal I. n Q n After normalization and DSM processing, it is converted into a DSM modulated signal x. i x q DSM modulated signal x i x q The signals are output from the first and second output terminals of the baseband signal modulation unit 11, respectively.

[0080] The amplitude and phase extraction unit 12 has two input terminals and two output terminals. The first and second input terminals are coupled to the two output terminals of the baseband signal modulation unit 11, respectively, for receiving the normalized DSM modulated signal x. i x q The amplitude signal ρ and phase signal θ are converted into input signals and output by the first and second output terminals of the amplitude and phase extraction unit 12, respectively.

[0081] The mapped pulse width modulation unit 13 has two input terminals and one output terminal. Its first and second input terminals are coupled to the two output terminals of the amplitude and phase extraction unit 12, respectively, to receive the amplitude signal ρ and the phase signal θ, and generate and output the pulse sequence p through a specific mapping search strategy. k .

[0082] The pulse generation unit 14 has one input terminal and one output terminal. The input terminal is coupled to the output terminal of the mapped pulse width modulation unit 13, and is used to receive the output pulse sequence p corresponding to the amplitude and phase of the input signal at various times. k The output pulse sequence p at each time point k Serial splicing generates and outputs a 3-level radio frequency pulse width modulation signal S 3L The pulse generation unit 14 can be a pulse generator.

[0083] In one embodiment of the present invention, the baseband signal modulation unit 11 includes a normalization module 111 and a DSM module.

[0084] The normalization module 111 has two input terminals and two output terminals. The two input terminals are the first and second signal input terminals of the RF pulse width modulator, respectively, used to receive the input digital baseband signal I. n Q n To satisfy formula (1), after normalization, the results are output by the two output terminals of the normalization module 111.

[0085] The DSM module has two input terminals and two output terminals, including a first incremental summation modulator 112 and a second incremental summation modulator 113. Each incremental summation modulator has the same structure and one input terminal and one output terminal. The input terminals of the first and second incremental summation modulators are coupled to the two output terminals of the normalization module 111, respectively, for receiving normalized digital baseband signals I and Q. The two incremental summation modulators convert signals I and Q into DSM modulated signals x after DSM processing. i x q Each of these is output from its corresponding output terminal.

[0086] In one embodiment of the present invention, the baseband signal modulation unit 11 can be configured by setting an amplitude correction value and a DSM quantization level number l. q This ensures that the normalized input signal matches the amplitude-phase mapping table as closely as possible, thereby minimizing the mapping error.

[0087] In one embodiment of the present invention, the amplitude and phase extraction unit 12 adopts the CORDIC algorithm, and the output signal result satisfies formula (2).

[0088] In one embodiment of the present invention, the mapping pulse width modulation unit 13 includes: an amplitude-phase indexing module, an amplitude-phase mapping module 133, and a 3-level pulse mapping module 134.

[0089] The amplitude and phase indexing module has two input terminals and two output terminals, including amplitude index 131 and phase index 132. Each of amplitude index 131 and phase index 132 has one input terminal and one output terminal. The input terminals of amplitude index 131 and phase index 132 are coupled to the first and second output terminals of the amplitude and phase extraction unit 12, respectively, to receive the amplitude and phase information of the input signal, and output it after passing through amplitude index 131 and phase index 132.

[0090] The amplitude-phase mapping module 133 has two input terminals and one output terminal. The first and second input terminals are coupled to the output terminals of amplitude index 131 and phase index 132, respectively, and are used to receive the amplitude and phase information index values ​​of the input signal, directly look them up in the preset amplitude-phase mapping table Q, and convert them into a complex signal q composed of the amplitude and phase information of a 3-level pulse signal. k .

[0091] The input terminal of the 3-level pulse mapping module 134 is coupled to the output terminal of the amplitude-phase mapping module 133. According to formula (3), based on the correspondence between the amplitude-phase information of the input pulse sequence and the pulse width and pulse position information, the preset pulse sequence p is output. k .

[0092] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0093] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A modulation method for 3-level RF-PWM, characterized in that, include: The normalized digital baseband signal is obtained from the digital baseband signal; The expression for the normalized digital baseband signal is: In the formula, I n and Q n All are digital baseband signals, and I is the digital baseband signal I. n The normalized digital baseband signal, Q is the digital baseband signal Q. n Normalized digital baseband signal; The normalized digital baseband signal is subjected to incremental summation modulation to obtain a DSM modulated signal; The expression for the DSM modulated signal is: In the formula, ρ For amplitude signals, θ It is a phase signal. x i The DSM modulated signal of the normalized digital baseband signal I. x q For the DSM modulated signal of the normalized digital baseband signal Q, arctan() is the inverse trigonometric function; An amplitude and phase extraction algorithm is used to obtain the amplitude and phase signals based on the DSM modulated signal; The nearest neighbor search method is used to map the amplitude signal and the phase signal in the preset amplitude-phase mapping table with the minimum Euclidean distance as the condition, and obtain the complex signal composed of the amplitude and phase information of the 3-level pulse signal stored in the amplitude-phase mapping table. Based on the one-to-one correspondence between the preset amplitude-phase mapping table and the 3-level pulse mapping table, the output pulse sequence corresponding to the complex signal is found in the 3-level pulse mapping table; The output pulse sequence is serially spliced ​​to obtain a 3-level radio frequency pulse width modulation signal.

2. The modulation method of 3-level RF-PWM according to claim 1, characterized in that, The length of any pulse sequence in the 3-level pulse mapping table is: N Furthermore, each pulse cycle contains only one continuous positive pulse.

3. The modulation method of 3-level RF-PWM according to claim 1, characterized in that, The 3-level pulse mapping table is [p1,…,p...]. i ,…,p K ]; Where, p i =[ p 1,…, p j ,…, p N ], p j The value can be 1, 0, or -1, and the positions of 1 or -1 must be consecutive and the width of the positive and negative pulses must be the same. i =1,2,..., K,j =1,2,..., N ; The amplitude-phase mapping table is a pulse sequence p in a 3-level pulse mapping table. i The corresponding combination of amplitude and phase information.

4. The modulation method of 3-level RF-PWM according to claim 3, characterized in that, The amplitude-phase mapping table is [ q 1,…, q i ,…, q K ]; in, ; In the formula, q i For the first i Amplitude and phase information at time (time) ρ p_i , θ p_i ) combination, ρ p_i For the first i Amplitude information at any given time θ p_i For the first i Phase information at any moment, T c For pulse period, p w_i For the first i Pulse width at time, A Let j represent the modulator gain, and j represent the imaginary part.

5. The modulation method of 3-level RF-PWM according to claim 4, characterized in that, Also includes: Optimization of modulation and mapping parameters, specifically: adjusting the input point ( ρ , θ ) and output point ( ρ p_i , θ p_i Matching within the complex space; input point ( ρ , θ ) and output point ( ρ p_i , θ p_i Mapping error ε i for: ； In the formula, ρ For amplitude information, θ This is phase information.

6. A 3-level RF-PWM modulator, characterized in that, The modulator is applied to the modulation method as described in any one of claims 1-5; the modulator comprises: The first input terminal is used to input the digital baseband signal I. n ; The second input terminal is used to input the digital baseband signal Q. n ; The baseband signal modulation unit is connected to the first input terminal and the second input terminal respectively, and is used to modulate the digital baseband signal I. n and digital baseband signal Q n Normalized digital baseband signals I and Q are obtained respectively, and are used to perform incremental summation modulation on the normalized digital baseband signals I and Q respectively to obtain DSM modulated signals. x i and DSM modulated signal x q ; The amplitude and phase extraction unit, connected to the baseband signal modulation unit, is used to apply an amplitude and phase extraction algorithm based on the DSM modulated signal. x i and DSM modulated signal x q Obtain the amplitude signal ρ and phase signal θ ; The mapping pulse width modulation unit, connected to the amplitude and phase extraction unit, is used to map the amplitude signal and phase signal in a preset amplitude and phase mapping table using a nearest neighbor search method, with the minimum Euclidean distance as the condition, to obtain a complex signal composed of the amplitude and phase information of the three-level pulse signal pre-stored in the amplitude and phase mapping table. q k It is used to find the output pulse sequence p corresponding to the complex signal in the 3-level pulse mapping table according to the one-to-one correspondence between the preset amplitude-phase mapping table and the 3-level pulse mapping table. k ; The pulse generation unit, connected to the mapped pulse width modulation unit, is used to receive the output pulse sequence p at various times. k And used to generate the output pulse sequence p at each time point. k Serial splicing into 3-level radio frequency pulse width modulation signals S 3L ; The output terminal is connected to the pulse generation unit and is used to output the 3-level radio frequency pulse width modulation signal. S 3L .

7. The 3-level RF-PWM modulator according to claim 6, characterized in that, The baseband signal modulation unit includes: The normalization module is connected to the first input terminal and the second input terminal respectively, and is used to normalize the digital baseband signal I. n and digital baseband signal Q n The normalized digital baseband signal I and the normalized digital baseband signal Q are obtained respectively; The DSM module, connected to the normalization module, is used to perform incremental summation modulation on the normalized digital baseband signal I and the normalized digital baseband signal Q to obtain the DSM modulated signal. x i and DSM modulated signal x q .

8. The 3-level RF-PWM modulator according to claim 6, characterized in that, The baseband signal modulation unit is equipped with an amplitude correction value and a DSM quantization level number. Both the amplitude correction value and the DSM quantization level number are used to match the normalized digital baseband signal with the preset amplitude-phase mapping table.

9. The 3-level RF-PWM modulator according to claim 6, characterized in that, The amplitude and phase extraction unit uses the CORDIC algorithm based on the DSM modulation signal. x i and DSM modulated signal x q Obtain the amplitude signal ρ and phase signal θ ; in, ; In the formula, arctan() is an inverse trigonometric function.

10. The 3-level RF-PWM modulator according to claim 6, characterized in that, The mapped pulse width modulation unit includes: The amplitude-phase indexing module, connected to the amplitude-phase extraction unit, is used to analyze the amplitude signal. ρ Perform amplitude indexing on the phase signal θ Perform phase indexing; The amplitude-phase mapping module, connected to the amplitude-phase indexing module, is used to receive the amplitude signal indexed by the amplitude index by employing a nearest neighbor search method in a preset amplitude-phase mapping table, with the minimum Euclidean distance as the condition. ρ and the phase signal with phase index θ The mapping yields a complex signal composed of the amplitude and phase information of a 3-level pulse signal pre-stored in the amplitude and phase mapping table. q k ; A 3-level pulse mapping module, connected to the amplitude-phase mapping module, is used to find the output pulse sequence p corresponding to the complex signal in the 3-level pulse mapping table according to the one-to-one correspondence between the preset amplitude-phase mapping table and the 3-level pulse mapping table. k .

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