Transmitting device and signal predistortion method thereof

Abstract

A signal predistortion method is applied to a transmitting device, wherein the transmitting device comprises a signal processing circuit, a transmitting chain, and a power amplifier, and the power amplifier is used to amplify a radio frequency input signal output by the transmitting chain to generate a radio frequency output signal. The signal predistortion method comprises: performing, by the signal processing circuit, a first signal processing operation on a baseband signal to generate an in-band predistortion output; performing, by the signal processing circuit, a second signal processing operation on the in-band predistortion output to generate an out-band predistortion output; and generating, by the signal processing circuit, a full-band predistortion signal according to the in-band predistortion output and the out-band predistortion output to the transmitting chain, so that the transmitting chain generates the radio frequency input signal according to the full-band predistortion signal.

Description

Technical Field

[0001] This disclosure relates to an electronic device, and more particularly to a transmitting device and a method for signal predistortion thereof. Background Technology

[0002] To compensate for energy loss during transmission, existing wireless transmission devices typically use radio frequency (RF) power amplifiers to pre-amplify the signal. Because RF power amplifiers are non-linear components, signals amplified by these amplifiers are prone to in-band distortion and out-of-band component growth (e.g., intermodulation products), leading to interference in adjacent channels. To address these issues, most current methods utilize digital predistortion techniques to compensate for the signal before it is input to the power amplifier.

[0003] However, as signal transmission bandwidth increases, in addition to the aforementioned problems, power amplifiers also introduce memory effects. Due to these memory effects, the compensation amount may differ at different frequencies, requiring transmission devices to expend enormous computational resources to perform complex predistortion processing. Furthermore, the transmission device needs to calculate parameters suitable for this predistortion processing, and the calculation process is prone to numerical convergence instability, resulting in the inability to effectively eliminate out-of-band components. Summary of the Invention

[0004] The embodiments of this disclosure are signal predistortion methods. The signal predistortion method is applicable to a transmitting device, which includes a signal processing circuit, a transmitting chain, and a power amplifier. The power amplifier amplifies the radio frequency input signal output from the transmitting chain to generate a radio frequency output signal. The signal predistortion method includes: performing a first signal processing operation on a baseband signal through the signal processing circuit to generate an in-band predistortion output; performing a second signal processing operation on the in-band predistortion output through the signal processing circuit to generate an out-of-band predistortion output; and generating a full-band predistortion signal from the in-band predistortion output and the out-of-band predistortion output to the transmitting chain through the signal processing circuit, so that the transmitting chain generates the radio frequency input signal based on the full-band predistortion signal.

[0005] Another embodiment of this disclosure is a transmitting device. The transmitting device includes a signal processing circuit, a transmit chain, and a power amplifier. The signal processing circuit includes an in-band predistortion circuit, an out-of-band predistortion circuit, and a first operational circuit. The in-band predistortion circuit performs a first signal processing operation on the baseband signal to generate an in-band predistortion output. The out-of-band predistortion circuit performs a second signal processing operation on the in-band predistortion output to generate an out-of-band predistortion output. The first operational circuit generates a full-band predistortion signal based on the in-band predistortion output and the out-of-band predistortion output. The transmit chain generates a radio frequency (RF) input signal based on the full-band predistortion signal. The power amplifier amplifies the RF input signal to generate an RF output signal.

[0006] In summary, by performing predistortion processing on in-band and out-of-band signals separately, the transmitting device of this disclosure has the advantage of reducing the computational dimensionality of digital predistortion. Furthermore, by generating in-band and out-of-band predistortion parameter sets separately, the transmitting device of this disclosure has the advantages of reducing computational complexity and improving the stability of numerical convergence. Attached Figure Description

[0007] Figure 1 This is a block diagram illustrating a launching device according to some embodiments of the present disclosure.

[0008] Figure 2 This is a block diagram illustrating a signal processing circuit according to some embodiments of the present disclosure.

[0009] Figure 3 A block diagram illustrating a firing chain according to some embodiments of the present disclosure.

[0010] Figure 4 This is a flowchart illustrating a signal predistortion method according to some embodiments of the present disclosure.

[0011] Figure 5 This is a block diagram illustrating a signal processing circuit according to some embodiments of the present disclosure.

[0012] Figure 6 This is a schematic diagram illustrating the generation of an in-band predistortion parameter set according to some embodiments of the present disclosure.

[0013] Figure 7 A block diagram illustrating a feedback path according to some embodiments of this disclosure.

[0014] Figure 8 This is a schematic diagram illustrating the generation of out-of-band predistortion parameter sets according to some embodiments of the present disclosure.

[0015] Figure 9This is a flowchart illustrating a signal predistortion method according to some embodiments of the present disclosure.

[0016] Figure 10 This is a schematic diagram of the spectrum of some signals illustrated according to some embodiments of the present disclosure. Detailed Implementation

[0017] The embodiments are described in detail below with reference to the accompanying drawings. However, the specific embodiments described are only for explaining this case and are not intended to limit this case. The description of the structural operations is not intended to limit their execution order. Any structure that is recombined from components and produces an apparatus with equivalent function is within the scope of this disclosure.

[0018] Unless otherwise specified, the terms used throughout the specification and claims generally have their ordinary meaning in the context of the art, the disclosure, and the specific content.

[0019] The terms "coupled" or "connected" as used in this article can refer to two or more components making direct physical or electrical contact with each other, or making indirect physical or electrical contact with each other, or to two or more components operating or moving with each other.

[0020] Please see Figure 1 , Figure 1 This is a block diagram illustrating a transmitting device 100 according to some embodiments of the present disclosure. In some embodiments, the transmitting device 100 includes a signal processing circuit 10, a transmitting chain 20, a power amplifier 30, and an antenna 40.

[0021] like Figure 1 As shown, signal processing circuit 10 receives baseband signal x1(t) and performs signal processing operations on baseband signal x1(t) to generate a full-band predistorted signal z(t) to transmitter chain 20. The input and output terminals of transmitter chain 20 are coupled to signal processing circuit 10 and power amplifier 30, respectively. Transmitter chain 20 generates RF input signal w(t) based on the full-band predistorted signal z(t) and sends it to power amplifier 30. The input and output terminals of power amplifier 30 are coupled to transmitter chain 20 and antenna 40, respectively. Power amplifier 30 amplifies RF input signal w(t) to generate RF output signal y(t) to antenna 40 for information transmission. It should be understood that "t" represents time.

[0022] The following will be paired Figure 2 Detailed description of signal processing circuit 10. Please refer to [link / reference]. Figure 2 , Figure 2This is a block diagram illustrating a signal processing circuit 10 according to some embodiments of the present disclosure. In some embodiments, the signal processing circuit 10 includes an in-band predistortion circuit 11, an out-of-band predistortion circuit 13, and a first operational circuit 15. The in-band predistortion circuit 11 receives a baseband signal x1(t) and performs a first signal processing operation on the baseband signal x1(t) to generate an in-band predistortion output x2(t). The input and output terminals of the out-of-band predistortion circuit 13 are coupled to the in-band predistortion circuit 11 and the first operational circuit 15, respectively, and the out-of-band predistortion circuit 13 performs a second signal processing operation on the in-band predistortion output x2(t) to generate an out-of-band predistortion output x3(t). The first operational circuit 15 is coupled to the output terminal of the in-band predistortion circuit 11 and the output terminal of the out-of-band predistortion circuit 13 to receive the in-band predistortion output x2(t) and the out-of-band predistortion output x3(t), and to generate a full-band predistortion signal z(t) based on the in-band predistortion output x2(t) and the out-of-band predistortion output x3(t).

[0023] In some embodiments, such as Figure 2 As shown, the in-band predistortion circuit 11 includes an in-band predistorter 110 and a first filter 112. The in-band predistorter 110 is used to perform in-band predistortion processing on the baseband signal x1(t) according to the in-band predistortion parameter set Pib to generate a first predistortion output pd1(t). The first filter 112 is coupled to the output of the in-band predistorter 110 and is used to perform a first filtering process on the first predistortion output pd1(t) to generate an in-band predistortion output x2(t).

[0024] Specifically, the in-band predistorter 110 is mainly used to compensate for in-band distortion caused by the nonlinear characteristics of the power amplifier 30, and the in-band predistortion processing can be implemented by applying an algorithm using an indirect learning architecture and the least square method. The first predistortion output pd1(t) includes at least one first in-band predistortion compensation term and at least one first out-of-band predistortion compensation term to compensate for in-band distortion and out-of-band components increased due to the nonlinear characteristics of the power amplifier 30, respectively. The first in-band predistortion compensation term in the first predistortion output pd1(t) can effectively compensate for in-band distortion. However, the first out-of-band predistortion compensation term in the first predistortion output pd1(t) is prone to errors due to poor numerical convergence, resulting in the inability to effectively eliminate out-of-band components. Accordingly, the signal processing circuit 10 of this disclosure uses a first filter 112 to filter out the first out-of-band predistortion compensation term in the first predistortion output pd1(t) to generate an in-band predistortion output x2(t). The first filter 112 can be implemented by a low-pass filter, and the first filtering process can be a low-pass filtering process. It is worth noting that the in-band predistortion output x2(t) can effectively compensate for in-band distortion, so that the signal output by the power amplifier 30 can have a better error vector magnitude within the band.

[0025] In some embodiments, such as Figure 2 As shown, the out-of-band predistortion circuit 13 includes an out-of-band predistorter 130 and a second filter 132. The out-of-band predistorter 130 performs out-of-band predistortion processing on the in-band predistortion output x2(t) according to the out-of-band predistortion parameter set Pob to generate a second predistortion output pd2(t). The second filter 132 is coupled to the output of the out-of-band predistorter 130 and performs a second filtering process on the second predistortion output pd2(t) to generate an out-of-band predistortion output x3(t).

[0026] Specifically, the out-of-band predistorter 130 is mainly used to compensate for out-of-band distortion (e.g., increased out-of-band components) caused by the nonlinear characteristics of the power amplifier 30, and the out-of-band predistortion processing can be implemented by an algorithm. Similar to the first predistortion output pd1(t), the second predistortion output pd2(t) also includes at least one second in-band predistortion compensation term and at least one second out-of-band predistortion compensation term. The second out-of-band predistortion compensation term in the second predistortion output pd2(t) can effectively eliminate out-of-band components. However, the second in-band predistortion compensation term in the second predistortion output pd2(t) is essentially a term modified from the first in-band predistortion compensation term in the first predistortion output pd1(t), therefore it cannot effectively eliminate in-band distortion. Accordingly, the signal processing circuit 10 of this disclosure uses the second filter 132 to filter out the second in-band predistortion compensation term in the second predistortion output pd2(t) to generate the out-of-band predistortion output x3(t), wherein the second filter 132 can be implemented by a high-pass filter, and the second filtering process can be a high-pass filtering process.

[0027] In some embodiments, such as Figure 2 As shown, the signal processing circuit 10 uses the first arithmetic circuit 15 to perform signal synthesis processing on the in-band predistortion output x2(t) and the out-of-band predistortion output x3(t) to generate a full-band predistortion signal z(t). As explained above, the full-band predistortion signal z(t) includes a first in-band predistortion compensation term in the first predistortion output pd1(t) and a second out-of-band predistortion compensation term in the second predistortion output pd2(t), thus effectively compensating for both in-band and out-of-band distortion.

[0028] The following will be paired Figure 3 Detailed explanation of launch chain 20. Please refer to [link / reference]. Figure 3 , Figure 3This is a block diagram illustrating a transmit chain 20 according to some embodiments of the present disclosure. In some embodiments, the transmit chain 20 includes a digital-to-analog converter 21, an output filter 23, a local oscillator 25, and a mixer 27. The digital-to-analog converter 21 receives a full-band predistorted signal z(t) and performs a digital-to-analog conversion operation on the full-band predistorted signal z(t) to convert the full-band predistorted signal z(t) from digital form to analog form. The output filter 23 filters the analog full-band predistorted signal z(t). The local oscillator 25 and the mixer 27 modulate the full-band predistorted signal z(t) output from the output filter 23 to generate an RF input signal w(t) to the power amplifier 30. It is worth noting that the RF input signal w(t) generated based on the full-band predistortion signal z(t) can effectively compensate for the in-band and out-of-band distortion caused by the nonlinear characteristics of the power amplifier 30, so that the power amplifier 30 can generate a good RF output signal y(t) to the antenna 40.

[0029] Please see Figure 4 , Figure 4 The present disclosure describes a signal predistortion method 200 illustrated in some embodiments thereof. The signal predistortion method 200 may be derived from, for example... Figure 1 or Figure 2 The signal processing circuit 10 shown performs to generate a signal capable of compensating for in-band and out-of-band distortion caused by the nonlinear characteristics of the power amplifier 30. In some embodiments, such as Figure 4 As shown, the signal predistortion method 200 includes steps S201 to S203. For convenience and clarity, the following will be accompanied by... Figure 2 Detailed explanation of signal predistortion method 200.

[0030] In step S201, the signal processing circuit 10 performs a first signal processing operation on the baseband signal x1(t) using the in-band predistortion circuit 11 to generate an in-band predistortion output x2(t). It should be understood that the first signal processing operation includes in-band predistortion processing performed by the in-band predistorter 110 and a first filtering processing performed by the first filter 112. The descriptions of the in-band predistortion processing and the first filtering processing are the same as or similar to those in the aforementioned embodiments, and therefore will not be repeated here.

[0031] In step S202, the signal processing circuit 10 performs a second signal processing operation on the in-band predistortion output x2(t) using the out-of-band predistortion circuit 13 to generate an out-of-band predistortion output x3(t). It should be understood that the second signal processing operation includes out-of-band predistortion processing performed by the out-of-band predistorter 130 and a second filtering processing performed by the second filter 132. The descriptions of the out-of-band predistortion processing and the second filtering processing are the same as or similar to those in the aforementioned embodiments, and therefore will not be repeated here.

[0032] In step S203, the signal processing circuit 10 generates a full-band predistortion signal z(t) based on the in-band predistortion output x2(t) and the out-of-band predistortion output x3(t) using the first arithmetic circuit 15. The operation of generating the full-band predistortion signal z(t) is the same as or similar to that in the previous embodiment, and therefore will not be described in detail here.

[0033] In the foregoing embodiments, as Figure 2 As shown, the in-band predistortion parameter set Pib and the out-of-band predistortion parameter set Pob can be pre-stored in the memory (e.g., RAM) of the transmitting device 100, and the signal processing circuit 10 can access the in-band predistortion parameter set Pib and the out-of-band predistortion parameter set Pob from the memory only when performing relevant operations. However, this disclosure is not limited thereto. For example, in some embodiments, the signal processing circuit 10 is also used to generate the in-band predistortion parameter set Pib and the out-of-band predistortion parameter set Pob.

[0034] The following will be paired Figure 5 This section details the operations for generating the in-band predistortion parameter set Pib and the out-of-band predistortion parameter set Pob. Please refer to [link to documentation]. Figure 5 , Figure 5 This is a block diagram illustrating a signal processing circuit 10' according to some embodiments of the present disclosure. Compared to Figure 2 The signal processing circuit 10 shown is... Figure 5 The signal processing circuit 10' further includes an in-band predistortion correction circuit 17 and an out-of-band predistortion correction circuit 19. In some embodiments, the signal processing circuit 10' is used to generate an in-band predistortion parameter set Pib by means of the in-band predistortion correction circuit 17, and to generate an out-of-band predistortion parameter set Pob by means of the out-of-band predistortion correction circuit 19. Figure 5 In the signal processing circuit 10', with Figure 2 The same components as those in the signal processing circuit 10 are represented by the same symbols, and their descriptions are omitted.

[0035] The following will be paired Figure 6 This section details the operation of generating the in-band predistortion parameter set Pib using the in-band predistortion correction circuit 17. Please refer to [link / reference needed]. Figure 6 , Figure 6 This is a schematic diagram illustrating the generation of an in-band predistortion parameter set Pib according to some embodiments of this disclosure. In some embodiments, such as Figure 6As shown, to generate the in-band predistortion parameter set Pib, the signal processing circuit 10 inputs the baseband signal x1(t) to the transmitter chain 20. The transmitter chain 20 generates a first input signal w1(t) based on the baseband signal x1(t). For example, the transmitter chain 20 sequentially performs digital-to-analog conversion, filtering, and modulation operations on the baseband signal x1(t) to generate the first input signal w1(t). The power amplifier 30 amplifies the first input signal w1(t) to generate a first output signal y1(t).

[0036] In some embodiments, such as Figure 6 As shown, the transmitting device 100 also includes a feedback path 50, the input and output of which are coupled to the power amplifier 30 and the in-band predistortion correction circuit 17, respectively. The feedback path 50 is used to generate a first feedback signal z1(t) based on the first output signal y1(t). The following will be paired with... Figure 7 Detailed explanation of feedback path 50. Please refer to [link / reference]. Figure 7 , Figure 7 This is a block diagram illustrating a feedback path 50 according to some embodiments of the present disclosure. In some embodiments, the feedback path 50 includes an attenuator 51, a local oscillator 53, a mixer 55, a feedback filter 57, and an analog-to-digital converter 59. The attenuator 51 receives and attenuates a first output signal y1(t). The attenuated first output signal y1(t) is demodulated by the local oscillator 53 and the mixer 55, filtered by the feedback filter 57, and converted from analog to digital form by the analog-to-digital converter 59 to generate a first feedback signal z1(t). It should be understood that the local oscillator 53 in the feedback path 50 and the local oscillator 25 in the transmit chain 20 may be the same component.

[0037] In some embodiments, such as Figure 6 As shown, the in-band predistortion correction circuit 17 is used to determine the in-band predistortion parameter set Pib based on the baseband signal x1(t) and the first feedback signal z1(t). Specifically, the in-band predistortion correction circuit 17 includes an in-band predistortion parameter training unit 170 and a second arithmetic circuit 172. The in-band predistortion parameter training unit 170 is used to generate a first reference signal x1'(t) based on the first feedback signal z1(t) and the first reference parameter set P1. In some embodiments, the relationship between the first reference signal x1'(t), the first reference parameter set P1, and the first feedback signal z1(t) can be expressed by the following equation (1):

[0038] x1′(t)=a0z1(t)+a1z1(t)|z1(t)| 2 +a2z1(t)|z1(t)| 4 …(1),

[0039] Among them, a0, a1 and a2 are multiple parameters included in the first reference parameter set P1.

[0040] Generally, it is desirable for the first reference signal x1'(t) to be the same as the baseband signal x1(t) to optimize the in-band predistortion processing performed by the in-band predistorter 110. Accordingly, the second operational circuit 172 generates a first adjustment signal e1(t) to the in-band predistortion parameter training unit 170 based on the difference between the first reference signal x1'(t) and the baseband signal x1(t). The in-band predistortion parameter training unit 170 is also used to modify the first reference parameter set P1 according to the first adjustment signal e1(t) so that the first reference signal x1'(t) approximates the baseband signal x1(t). For example, the smaller the difference between the first reference signal x1'(t) and the baseband signal x1(t), the smaller the first adjustment signal e1(t). The in-band predistortion parameter training unit 170 can continuously modify the first reference parameter set P1 by the least squares method until the first adjustment signal e1(t) is minimized (e.g., approaches 0). After multiple corrections, the in-band predistortion parameter training unit 170 can use the first reference parameter set P1, which makes the first reference signal x1'(t) approximately equal to the baseband signal x1(t), as the in-band predistortion parameter set Pib, and provide the in-band predistortion parameter set Pib to the in-band predistorter 110.

[0041] The following will be paired Figure 8 This section details the operation of generating the out-of-band predistortion parameter set Pob using the out-of-band predistortion correction circuit 19. Please refer to [link / reference needed]. Figure 8 , Figure 8 This is a schematic diagram illustrating the generation of an out-of-band predistortion parameter set Pob according to some embodiments of the present disclosure. In some embodiments, such as Figure 8 As shown, to generate the out-of-band predistortion parameter set Pob, the signal processing circuit 10 inputs the in-band predistortion output x2(t) to the transmitter chain 20. The transmitter chain 20 generates a second input signal w2(t) based on the in-band predistortion output x2(t). For example, the transmitter chain 20 sequentially performs digital-to-analog conversion, filtering, and modulation operations on the in-band predistortion output x2(t) to generate the second input signal w2(t). The power amplifier 30 amplifies the second input signal w2(t) to generate a second output signal y2(t).

[0042] In some embodiments, such as Figure 8 As shown, the input and output terminals of the feedback path 50 are coupled to the power amplifier 30 and the out-of-band predistortion correction circuit 19, respectively, and the feedback path 50 is used to generate a second feedback signal z2(t) based on the second output signal y2(t). The operation of the feedback path 50 in generating the second feedback signal z2(t) is the same as or similar to that in the previous embodiment, and therefore will not be described in detail here.

[0043] In some embodiments, such as Figure 8 As shown, the out-of-band predistortion correction circuit 19 is used to determine the out-of-band predistortion parameter set Pob based on the in-band predistortion output x2(t) and the second feedback signal z2(t). Specifically, the out-of-band predistortion correction circuit 19 includes multiple third filters 190A-190B, an out-of-band predistortion parameter training unit 192, and a third operational circuit 194. The out-of-band predistortion parameter training unit 192 is used to generate a second reference signal z2'(t) based on the in-band predistortion output x2(t) and the second reference parameter set P2. In some embodiments, the relationship between the second reference signal z2'(t), the second reference parameter set P2, and the in-band predistortion output x2(t) can be expressed by the following equation (2):

[0044] z2′(t)=b0x2(t)+b1x2(t)|x2(t)| 2 +b2x2(t)|x2(t)| 4 …(2),

[0045] Among them, b0, b1 and b2 are multiple parameters included in the second reference parameter set P2.

[0046] The third filters 190A to 190B are used to perform third filtering on the second feedback signal z2(t) and the second reference signal z2'(t) to generate the filtered second feedback signal TF{z2(t)} and the filtered second reference signal TF{z2'(t)}. The third filters 190A to 190B can be implemented by high-pass filters, and the third filtering can be high-pass filtering.

[0047] Generally, it is desirable to minimize the sum of the filtered second feedback signal TF{z2(t)} and the filtered second reference signal TF{z2'(t)} to optimize the out-of-band predistortion processing performed by the out-of-band predistorter 130. Accordingly, the third operational circuit 194 generates a second adjustment signal e2(t) to the out-of-band predistortion parameter training unit 192 based on the sum of the filtered second feedback signal TF{z2(t)} and the filtered second reference signal TF{z2'(t)}. The out-of-band predistortion parameter training unit 192 corrects the second reference parameter set P2 based on the second adjustment signal e2(t) to minimize the second adjustment signal e2(t) (e.g., approaching 0). For example, the out-of-band predistortion parameter training unit 192 can generate a cost function (e.g., J = ...) based on the second adjustment signal e2(t). e2 H e2 Where J is the cost function, and e2The second adjustment signal e2(t) is in matrix form, and the cost function is minimized using the least square method, the Newton-Raphson method, or the least mean square method to continuously modify the second reference parameter set P2. After multiple modifications, the out-of-band predistortion parameter training unit 192 can use the second reference parameter set P2 that minimizes the second adjustment signal e2(t) as the out-of-band predistortion parameter set Pob, and provide the out-of-band predistortion parameter set Pob to the out-of-band predistorter 130.

[0048] Generally, the out-of-band components in the output signal of power amplifier 30, which increase due to the nonlinear characteristics of power amplifier 30, vary depending on the quality of the input signal of power amplifier 30 within the band. It is worth noting that the signal processing circuit 10' of this disclosure utilizes the in-band components (i.e., the in-band predistortion output x2(t)) in the full-band predistortion signal z(t) subsequently transmitted through transmit chain 20 and power amplifier 30 to generate the out-of-band predistortion parameter set Pob. Therefore, the out-of-band predistortion processing performed by out-of-band predistorter 130 based on the out-of-band predistortion parameter set Pob can effectively eliminate out-of-band components.

[0049] In the foregoing embodiments, the out-of-band predistortion correction circuit 19 uses third filters 190A and 190B to filter out in-band components in the signal, because the out-of-band predistortion correction circuit 19 primarily generates the out-of-band predistortion parameter set Pob based on the out-of-band components in the observed signal. However, this disclosure is not limited thereto. In some embodiments, the out-of-band predistortion correction circuit 19 omits the third filters 190A and 190B. It should be understood that even without the third filters 190A and 190B, the out-of-band predistortion correction circuit 19 can still generate the out-of-band predistortion parameter set Pob based on the out-of-band components in the observed signal.

[0050] Please see Figure 9 , Figure 9 The flowchart illustrates a signal predistortion method 300 according to some embodiments of the present disclosure. The signal predistortion method 300 may be derived from, for example... Figure 5 The signal processing circuit 10' shown is executed. In some embodiments, such as Figure 9 As shown, the signal predistortion method 300 includes steps S301 to S304. In step S301, the signal processing circuit 10' generates an in-band predistortion parameter set Pib and an out-of-band predistortion parameter set Pob. The operation of generating the in-band predistortion parameter set Pib and the out-of-band predistortion parameter set Pob is the same as or similar to that in the previous embodiment, and therefore will not be described again here. In addition, steps S302 to S304 are similar to... Figure 4 The steps S201 to S203 are the same or similar, so they will not be described in detail here.

[0051] It should be understood that the signal processing circuit 10' does not necessarily execute step S301 every time the transmitting device 100 needs to transmit information. In some embodiments, the signal processing circuit 10' may execute step S301 only when the transmitting device 100 is first powered on or first connected.

[0052] Please see Figure 10 , Figure 10 This is a schematic diagram of the spectrum of some signals illustrated according to some embodiments of this disclosure. For example... Figure 10 As shown, curve A represents the spectrum of the baseband signal x1(t). Curve B represents the spectrum of the signal amplified by power amplifier 30 without pre-distortion processing. Curve C represents the spectrum of the signal amplified by power amplifier 30 after in-band and out-of-band pre-distortion processing by signal processing circuit 10, where curve C includes curve C1 (in-band, Bin) and curves C2A and C2B (out-of-band, Bout). Figure 10 It can be seen that, compared with the curve B without pre-distortion processing, the curve C processed by the signal processing circuit 10 has good signal quality in the in-band Bin, and the curve C processed by the signal processing circuit 10 has lower energy in the out-of-band Bout.

[0053] In the foregoing embodiments, when generating a full-band predistorted signal z(t), the signal processing circuit 10 first performs in-band predistortion processing through the in-band predistorter 110, and then performs out-of-band predistortion processing through the out-of-band predistorter 130. However, this disclosure is not limited thereto. In some embodiments, the signal processing circuit 10 may first perform out-of-band predistortion processing through the out-of-band predistorter 130, and then perform in-band predistortion processing through the in-band predistorter 110, to generate a full-band predistorted signal z(t).

[0054] In the foregoing embodiments, the signal processing circuit and its included circuits may be implemented by one or more central processing units (CPUs), application-specific integrated circuits (ASICs), microprocessors, system-on-a-chip (SoCs), or other suitable processing units.

[0055] As can be seen from the above embodiments of the present disclosure, by performing predistortion processing on in-band and out-of-band signals respectively, the transmitting device 100 of the present disclosure has the advantage of reducing the computational dimension of digital predistortion. Furthermore, by generating in-band and out-of-band predistortion parameter sets respectively, the transmitting device 100 of the present disclosure has the advantage of reducing computational complexity and improving the stability of numerical convergence.

[0056] Although the present disclosure has been described above with reference to embodiments, it is not intended to limit the present disclosure. Those skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present disclosure. Therefore, the scope of protection of the present disclosure shall be determined by the scope defined in the appended claims.

[0057] Explanation of reference numerals in the attached figures:

[0058] 10,10': Signal processing circuit

[0059] 11: In-band predistortion circuit

[0060] 13: Out-of-band predistortion circuit

[0061] 15: First operational circuit

[0062] 17: In-band pre-distortion correction circuit

[0063] 19: Out-of-band pre-distortion correction circuit

[0064] 20: Launch Chain

[0065] 21: Digital-to-Analog Converter

[0066] 23: Output filter

[0067] 25,53: Local Oscillator

[0068] 27,55: Mixer

[0069] 30: Power Amplifier

[0070] 40: Antenna

[0071] 50: Feedback Path

[0072] 51: Attenuator

[0073] 57: Feedback Filter

[0074] 59: Analog-to-digital converter

[0075] 100: Launching device

[0076] 110: With in-line predistorter

[0077] 112: First Filter

[0078] 130: Out-of-band predistorter

[0079] 132: Second Filter

[0080] 170: In-band predistortion parameter training unit

[0081] 172: Second Operational Circuit

[0082] 190A, 190B: Third Filter

[0083] 192: Out-of-band predistortion parameter training unit

[0084] 194: Third Operational Circuit

[0085] 200, 300: Signal predistortion method

[0086] P1: First reference parameter set

[0087] P2: Second reference parameter set

[0088] Pib: In-band predistortion parameter set

[0089] Pob: Out-of-band predistortion parameter set

[0090] x1(t): Baseband signal

[0091] x2(t): Output with in-band predistortion

[0092] x3(t): Out-of-band predistortion output

[0093] x1'(t): First reference signal

[0094] pd1(t): First predistortion output

[0095] pd2(t): Second predistortion output

[0096] z(t): Full-band predistortion signal

[0097] z1(t): First feedback signal

[0098] z2(t): Second feedback signal

[0099] z2'(t): Second reference signal

[0100] w(t): Radio frequency input signal

[0101] w1(t): First input signal

[0102] w2(t): Second input signal

[0103] y(t): Radio frequency output signal

[0104] y1(t): First output signal

[0105] y2(t): Second output signal

[0106] e1(t): First adjustment signal

[0107] e2(t): Second adjustment signal

[0108] TF{z2(t)}: The filtered second feedback signal

[0109] TF{z2'(t)}: The filtered second reference signal

[0110] S201~S203, S301~S304: Steps

[0111] A, B, C, C1, C2A, C2B: Curve

[0112] Bin: In-band

[0113] Bout: outside the band

Claims

1. A signal predistortion method, applicable to a transmitting device, wherein the transmitting device includes a signal processing circuit, a transmitting chain, and a power amplifier, the power amplifier being used to amplify the radio frequency input signal output from the transmitting chain to generate a radio frequency output signal, and the signal predistortion method comprising: The signal processing circuit performs a first signal processing operation on the baseband signal to generate an in-band predistortion output. The signal processing circuit performs a second signal processing operation on the in-band predistortion output to generate an out-of-band predistortion output. as well as The signal processing circuit generates a full-band predistortion signal based on the in-band predistortion output and the out-of-band predistortion output, which is then sent to the transmitter chain so that the transmitter chain generates the radio frequency input signal based on the full-band predistortion signal.

2. The signal predistortion method as described in claim 1, wherein the first signal processing operation includes: The baseband signal is subjected to in-band predistortion processing based on the in-band predistortion parameter set to generate the first predistortion output; as well as The first predistorted output is subjected to a first filtering process to generate the in-band predistorted output, wherein the first filtering process is a low-pass filtering process.

3. The signal predistortion method as described in claim 2, wherein the signal predistortion method further includes: The signal processing circuit generates the in-band predistortion parameter set. The transmitting device also includes a feedback path, and the generation of the in-band predistortion parameter set includes: The baseband signal is input to the transmitter chain, wherein the transmitter chain generates a first input signal based on the baseband signal, the power amplifier amplifies the first input signal to generate a first output signal, and the feedback path generates a first feedback signal based on the first output signal. as well as The in-band predistortion parameter set is determined based on the baseband signal and the first feedback signal.

4. The signal predistortion method as described in claim 1, wherein the second signal processing operation includes: The in-band predistortion output is processed by out-of-band predistortion based on the out-of-band predistortion parameter set to generate a second predistortion output; as well as The second predistorted output is subjected to a second filtering process to generate the out-of-band predistorted output, wherein the second filtering process is a high-pass filtering process.

5. The signal predistortion method as described in claim 4, wherein the signal predistortion method further comprises: The out-of-band predistortion parameter set is generated through this signal processing circuit; The transmitting device also includes a feedback path, and the generation of the out-of-band predistortion parameter set includes: The in-band predistortion output is input to the transmitter chain, wherein the transmitter chain generates a second input signal based on the in-band predistortion output, the power amplifier amplifies the second input signal to generate a second output signal, and the feedback path generates a second feedback signal based on the second output signal. as well as The out-of-band predistortion parameter set is determined based on the in-band predistortion output and the second feedback signal.

6. A launching device, comprising: Signal processing circuit, including: The in-band predistortion circuit is used to perform the first signal processing operation on the baseband signal to generate the in-band predistortion output; An out-of-band predistortion circuit is used to perform a second signal processing operation on the in-band predistortion output to generate an out-of-band predistortion output; and The first operational circuit is used to generate a full-band predistortion signal based on the in-band predistortion output and the out-of-band predistortion output. The transmitter chain is used to generate an RF input signal based on the full-band predistortion signal; and A power amplifier is used to amplify the RF input signal to generate an RF output signal.

7. The transmitting apparatus of claim 6, wherein the in-band predistortion circuit comprises: An in-band predistorter is used to perform in-band predistortion processing on the baseband signal according to an in-band predistortion parameter set to generate a first predistortion output; as well as A first filter is used to perform a first filtering process on the first predistortion output to generate the in-band predistortion output, wherein the first filtering process is a low-pass filtering process.

8. The transmitting apparatus of claim 7, wherein the signal processing circuit further includes an in-band predistortion correction circuit, and the signal processing circuit is configured to generate the in-band predistortion parameter set through the in-band predistortion correction circuit; The launching device also includes a feedback path; The transmitter chain is used to generate a first input signal based on the baseband signal, the power amplifier is used to amplify the first input signal to generate a first output signal, and the feedback path is used to generate a first feedback signal based on the first output signal. The in-band predistortion correction circuit is used to determine the in-band predistortion parameter set based on the baseband signal and the first feedback signal.

9. The transmitting apparatus of claim 6, wherein the out-of-band predistortion circuit comprises: An out-of-band predistorter is used to perform out-of-band predistortion processing on the in-band predistortion output according to the out-of-band predistortion parameter set to generate a second predistortion output; as well as A second filter is used to perform a second filtering process on the second predistortion output to generate the out-of-band predistortion output, wherein the second filtering process is a high-pass filtering process.

10. The transmitting apparatus of claim 9, wherein the signal processing circuit further includes an out-of-band predistortion correction circuit, and the signal processing circuit is configured to generate the out-of-band predistortion parameter set through the out-of-band predistortion correction circuit; The launching device also includes a feedback path; The transmitter chain is used to generate a second input signal based on the in-band predistortion output, the power amplifier amplifies the second input signal to generate a second output signal, and the feedback path generates a second feedback signal based on the second output signal. The out-of-band predistortion correction circuit is used to determine the out-of-band predistortion parameter set based on the in-band predistortion output and the second feedback signal.

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