CN117527494A - Transmitting device and signal predistortion method thereof - Google Patents

Abstract

A signal predistortion method is suitable for 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 for amplifying a radio frequency input signal output by the transmitting chain to generate a radio frequency output signal. The signal predistortion method comprises the following steps: performing a first signal processing operation on the baseband signal by means of a signal processing circuit to produce an in-band predistortion output; performing a second signal processing operation on the in-band predistortion output by the signal processing circuit to produce an out-of-band predistortion output; and generating, by the signal processing circuit, a full-band predistortion signal to the transmit chain in accordance with the in-band predistortion output and the out-of-band predistortion output, such that the transmit chain generates a radio frequency input signal in accordance with the full-band predistortion signal.

Description

Transmitting device and signal predistortion method thereof

Technical Field

The present disclosure relates to an electronic device, and more particularly, to a transmitting device and a signal predistortion method thereof.

Background

To compensate for the energy loss during transmission, conventional wireless transmission devices typically use rf power amplifiers to pre-amplify the signal. Because the radio frequency power amplifier is a nonlinear component, the signal amplified by the power amplifier is prone to in-band (in-band) distortion and out-of-band (out-of-band) component growth problems, such as intermodulation products (intermodulation product), causing adjacent channels to be disturbed. In view of the above, most of today, digital predistortion (digital predistortion) is used to compensate the signal before the signal is input to the power amplifier.

However, as the signal transmission bandwidth increases, the power amplifier introduces a memory effect in addition to the aforementioned problems. The compensation amount of the signal under different frequencies may be different due to the influence of the memory effect, so that the transmission device needs to spend huge operation resources to perform complex predistortion processing. In addition, the transmission device needs to calculate the parameters suitable for the predistortion processing, and the problem of unstable numerical convergence is easy to occur in the process of calculating the parameters, so that the out-of-band component cannot be effectively eliminated.

Disclosure of Invention

An embodiment of the present disclosure is a signal predistortion method. The signal predistortion method is suitable for 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 for amplifying a radio frequency input signal output by the transmitting chain to generate a radio frequency output signal. The signal predistortion method comprises the following steps: performing a first signal processing operation on the baseband signal by the signal processing circuit to produce an in-band predistortion output; performing a second signal processing operation on the in-band predistortion output by the signal processing circuit to produce an out-of-band predistortion output; and generating, by the signal processing circuit, a full-band predistortion signal to the transmit chain in accordance with the in-band predistortion output and the out-of-band predistortion output, such that the transmit chain generates the radio frequency input signal in accordance with the full-band predistortion signal.

Another embodiment of the present disclosure is a transmitting device. The transmitting device comprises a signal processing circuit, a transmitting chain and a power amplifier. The signal processing circuit includes an in-band predistortion circuit, an out-of-band predistortion circuit, and a first arithmetic circuit. The in-band predistortion circuit is configured to perform a first signal processing operation on the baseband signal to produce an in-band predistortion output. The out-of-band predistortion circuit is configured to perform a second signal processing operation on the in-band predistortion output to produce an out-of-band predistortion output. The first operation circuit is used for generating a full-band predistortion signal according to the in-band predistortion output and the out-of-band predistortion output. The transmitting chain is used for generating a radio frequency input signal according to the full-band predistortion signal. The power amplifier is used for amplifying the radio frequency input signal to generate a radio frequency output signal.

In summary, the transmitting device of the present disclosure has the advantage of reducing the operation dimension of digital predistortion by performing predistortion processing on an in-band signal and an out-of-band signal, respectively. In addition, by generating the in-band predistortion parameter set and the out-of-band predistortion parameter set separately, the transmitting device of the disclosure has the advantages of reducing the operation complexity and improving the stability of numerical convergence.

Drawings

Fig. 1 is a block diagram of a transmitting device according to some embodiments of the present disclosure.

Fig. 2 is a block diagram of a signal processing circuit according to some embodiments of the present disclosure.

Fig. 3 is a block diagram of a transmit chain according to some embodiments of the present disclosure.

Fig. 4 is a flow chart of a signal predistortion method according to some embodiments of the present disclosure.

Fig. 5 is a block diagram of a signal processing circuit according to some embodiments of the present disclosure.

Fig. 6 is a schematic diagram illustrating the generation of an in-band predistortion parameter set, in accordance with some embodiments of the present disclosure.

Fig. 7 is a block diagram of a feedback path according to some embodiments of the present disclosure.

Fig. 8 is a schematic diagram illustrating the generation of out-of-band predistortion parameter sets in accordance with some embodiments of the present disclosure.

Fig. 9 is a flow chart of a signal predistortion method according to some embodiments of the present disclosure.

Fig. 10 is a schematic spectrum diagram of some signals according to some embodiments of the present disclosure.

Detailed Description

The following detailed description of the embodiments is provided in connection with the accompanying drawings, but the embodiments are merely for the purpose of illustrating the disclosure and are not intended to limit the order of execution of the operations of the structures, and any device with equivalent performance resulting from the re-combination of the components is intended to be encompassed by the present disclosure.

The term "as used throughout the specification and claims" is used in its ordinary sense in the art, throughout the disclosure and in the specific text, unless otherwise indicated.

As used herein, "coupled" or "connected" may mean that two or more elements are in direct physical or electrical contact with each other, or in indirect physical or electrical contact with each other, and may also mean that two or more elements are in operation or action with each other.

Referring to fig. 1, fig. 1 is a block diagram of 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 transmit chain 20, a power amplifier 30, and an antenna 40.

As shown in fig. 1, the signal processing circuit 10 is configured to receive the baseband signal x1 (t) and perform a signal processing operation on the baseband signal x1 (t) to generate a full-band predistortion signal z (t) to the transmit chain 20. The input and output terminals of the transmit chain 20 are coupled to the signal processing circuit 10 and the power amplifier 30, respectively, and the transmit chain 20 is configured to generate a radio frequency input signal w (t) to the power amplifier 30 according to the full-band predistortion signal z (t). The input and output terminals of the power amplifier 30 are coupled to the transmitting chain 20 and the antenna 40, respectively, and the power amplifier 30 is configured to amplify the rf input signal w (t) to generate the rf output signal y (t) to the antenna 40 for transmitting information. It should be understood that "t" is used to denote time.

The signal processing circuit 10 will be described in detail with reference to fig. 2. Referring to fig. 2, fig. 2 is a block diagram of 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 operation circuit 15. The in-band predistortion circuit 11 is configured to receive the baseband signal x1 (t) and perform a first signal processing operation on the baseband signal x1 (t) to generate an in-band predistortion output x2 (t). The input and output ends of the out-of-band predistortion circuit 13 are coupled to the in-band predistortion circuit 11 and the first operation circuit 15, respectively, and the out-of-band predistortion circuit 13 is configured to perform 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 operation 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, and is configured to receive the in-band predistortion output x2 (t) and the out-of-band predistortion output x3 (t) and generate the full-band predistortion signal z (t) according to the in-band predistortion output x2 (t) and the out-of-band predistortion output x3 (t).

In some embodiments, as shown in fig. 2, the in-band predistortion circuit 11 includes an in-band predistorter 110 and a first filter 112. The in-band predistorter 110 is configured 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 configured to perform a first filtering process on the first predistortion output pd1 (t) to generate an in-band predistortion output x2 (t).

Specifically, the in-band predistorter 110 is mainly used to compensate in-band (in-band) distortion due to the nonlinear characteristics of the power amplifier 30, and the in-band predistortion process can be implemented by an algorithm applying the techniques of the indirect learning architecture (indirect learning architecture) and the least squares method (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 (out-of-band) components growing 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) may 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 incorrect problems due to poor numerical convergence, resulting in an inability to effectively cancel out-of-band components. Accordingly, the signal processing circuit 10 of the present disclosure utilizes the first filter 112 to filter out the first out-of-band predistortion compensation term in the first predistortion output pd1 (t) to generate the in-band predistortion output x2 (t), wherein the first filter 112 may be implemented by a low pass filter and the first filtering process may be a low pass filtering process. Notably, the in-band predistortion output x2 (t) is effective to compensate for in-band distortion such that the signal output by the power amplifier 30 has a better error vector magnitude (error vector magnitude) in-band.

In some embodiments, as shown in FIG. 2, 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 is configured to perform 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 is configured to perform a second filtering process on the second predistortion output pd2 (t) to generate an out-of-band predistortion output x3 (t).

Specifically, the out-of-band predistorter 130 is primarily used to compensate for out-of-band distortion (e.g., an increased out-of-band component) due to the nonlinear characteristics of the power amplifier 30, and the out-of-band predistortion process may be implemented by an algorithm. Similar to the first predistortion output pd1 (t), the second predistortion output pd2 (t) also comprises 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) may effectively cancel the out-of-band component. In addition, the second in-band predistortion compensation term in the second predistortion output pd2 (t) is equivalent to a term changed from the first in-band predistortion compensation term in the first predistortion output pd1 (t), and thus it cannot effectively cancel in-band distortion. Accordingly, the signal processing circuit 10 of the present disclosure utilizes 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 may be implemented by a high pass filter and the second filtering process may be a high pass filtering process.

In some embodiments, as shown in fig. 2, the signal processing circuit 10 performs signal synthesis processing on the in-band predistortion output x2 (t) and the out-of-band predistortion output x3 (t) by the first operation circuit 15 to generate a full-band predistortion signal z (t). As is apparent from the above description, the full-band predistortion signal z (t) includes the first in-band predistortion compensation term in the first predistortion output pd1 (t) and the second out-of-band predistortion compensation term in the second predistortion output pd2 (t), and thus both in-band distortion and out-of-band distortion can be effectively compensated.

The transmit chain 20 will be described in detail below in conjunction with fig. 3. Referring to fig. 3, fig. 3 is a block diagram of a transmit chain 20 according to some embodiments of the present disclosure. In some embodiments, 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 is configured to receive the full-band predistortion signal z (t) and perform a digital-to-analog conversion operation on the full-band predistortion signal z (t) to convert the full-band predistortion signal z (t) from a digital form to an analog form. The output filter 23 is used for filtering the full-band predistortion signal z (t) in analog form. The local oscillator 25 and the mixer 27 are used for modulating the full-band predistortion signal z (t) output from the output filter 23 to generate a radio frequency input signal w (t) to the power amplifier 30. It should be noted that the rf input signal w (t) generated according to the full-band predistortion signal z (t) can effectively compensate for the in-band distortion and the out-of-band distortion caused by the nonlinear characteristic of the power amplifier 30, so that the power amplifier 30 generates a good rf output signal y (t) to the antenna 40.

Referring to fig. 4, fig. 4 depicts a signal predistortion method 200 according to some embodiments of the present disclosure. The signal predistortion method 200 may be performed by the signal processing circuit 10 as shown in fig. 1 or fig. 2 to generate a signal capable of compensating for in-band distortion and out-of-band distortion due to the nonlinear characteristics of the power amplifier 30. In some embodiments, as shown in fig. 4, the signal predistortion method 200 includes steps S201 to S203. For convenience and clarity, the signal predistortion method 200 will be described in detail below with reference to fig. 2.

In step S201, the signal processing circuit 10 performs a first signal processing operation on the baseband signal x1 (t) by the in-band predistortion circuit 11 to generate an in-band predistortion output x2 (t). It should be appreciated that the first signal processing operation includes an in-band predistortion process by the in-band predistorter 110 and a first filtering process by the first filter 112. The description of the in-band predistortion process and the first filtering process is the same as or similar to the previous embodiments, and thus is not repeated here.

In step S202, the signal processing circuit 10 performs a second signal processing operation on the in-band predistortion output x2 (t) by the out-of-band predistortion circuit 13 to generate an out-of-band predistortion output x3 (t). It should be appreciated that the second signal processing operation includes an out-of-band predistortion process by the out-of-band predistorter 130 and a second filtering process by the second filter 132. The out-of-band predistortion process and the second filtering process are the same as or similar to those of the previous embodiments, and are not described here.

In step S203, the signal processing circuit 10 generates a full-band predistortion signal z (t) according to the in-band predistortion output x2 (t) and the out-of-band predistortion output x3 (t) by the first operation circuit 15. The operation of generating the full-band predistortion signal z (t) is the same as or similar to the previous embodiment, and will not be described here.

In the foregoing embodiment, as shown in fig. 2, the in-band predistortion parameter set Pib and the out-of-band predistortion parameter set Pob may be pre-stored in a memory (e.g., a memory) of the transmitting device 100, and the signal processing circuit 10 may access the in-band predistortion parameter set Pib and the out-of-band predistortion parameter set Pob from the memory when performing the correlation operation. However, the present disclosure is not limited thereto. For example, in some embodiments, the signal processing circuit 10 is also configured to generate the in-band predistortion parameter set Pib and the 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 described in detail below with reference to fig. 5. Referring to fig. 5, fig. 5 is a block diagram of a signal processing circuit 10' according to some embodiments of the present disclosure. In comparison with the signal processing circuit 10 shown in fig. 2, the signal processing circuit 10' of fig. 5 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 configured to generate the in-band predistortion parameter set Pib by the in-band predistortion correction circuit 17 and to generate the out-of-band predistortion parameter set Pob by the out-of-band predistortion correction circuit 19. In the signal processing circuit 10' of fig. 5, the same components as those of the signal processing circuit 10 of fig. 2 are denoted by the same symbols, and the description thereof is omitted.

The operation of generating the in-band predistortion parameter set Pib by the in-band predistortion correction circuit 17 will be described in detail below with reference to fig. 6. Referring to fig. 6, fig. 6 is a schematic diagram illustrating generation of an in-band predistortion parameter set Pib according to some embodiments of the present disclosure. In some embodiments, as shown in fig. 6, to generate the in-band predistortion parameter set Pib, the signal processing circuit 10 inputs the baseband signal x1 (t) into the transmit chain 20. The transmit chain 20 generates a first input signal w1 (t) from the baseband signal x1 (t). For example, the transmit 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).

In some embodiments, as shown in fig. 6, the transmitting device 100 further includes a feedback path 50, wherein an input end and an output end of the feedback path 50 are coupled to the power amplifier 30 and the in-band predistortion correction circuit 17, respectively, and the feedback path 50 is configured to generate a first feedback signal z1 (t) according to the first output signal y1 (t). Feedback path 50 will be described in detail below in conjunction with fig. 7. Referring to fig. 7, fig. 7 is a block diagram of a feedback path 50 according to some embodiments of the present disclosure. In some embodiments, feedback path 50 includes attenuator 51, local oscillator 53, mixer 55, feedback filter 57, and analog-to-digital converter 59. The attenuator 51 is configured to receive the first output signal y1 (t) and attenuate the 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 form to digital form by the analog-to-digital converter 59 to generate the first feedback signal z1 (t). It should be appreciated that the local oscillator 53 in the feedback path 50 may be the same component as the local oscillator 25 in the transmit chain 20.

In some embodiments, as shown in fig. 6, the in-band predistortion correction circuit 17 is configured to determine the in-band predistortion parameter set Pib according to 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 configured to generate a first reference signal x1' (t) according to 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 represented by the following formula (1):

x1′(t)＝a ₀ z1(t)+a ₁ z1(t)|z1(t)| ² +a ₂ z1(t)|z1(t)| ⁴ …(1)，

wherein a is ₀ 、a ₁ A ₂ A plurality of parameters included for the first reference parameter set P1.

In general, it may be desirable that the first reference signal x1' (t) be the same as the baseband signal x1 (t) to optimize the in-band predistortion process performed by the in-band predistorter 110. Accordingly, the second operation circuit 172 is configured to generate the 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 further configured 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 may continuously modify the first reference parameter set P1 by a 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 may set the first reference parameter set P1, which makes the first reference signal x1' (t) be approximately 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.

The operation of generating the out-of-band predistortion parameter set Pob by the out-of-band predistortion correction circuit 19 will be described in detail below in conjunction with fig. 8. Referring to fig. 8, fig. 8 is a schematic diagram illustrating the generation of an out-of-band predistortion parameter set Pob in accordance with some embodiments of the present disclosure. In some embodiments, as shown in fig. 8, to generate the out-of-band predistortion parameter set Pob, the signal processing circuit 10 inputs an in-band predistortion output x2 (t) into the transmit chain 20. The transmit chain 20 generates a second input signal w2 (t) from the in-band predistortion output x2 (t). For example, the transmit chain 20 sequentially performs digital-to-analog conversion operations, filtering processing, 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).

In some embodiments, as shown in fig. 8, the input and the output 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 configured to generate the second feedback signal z2 (t) according to the second output signal y2 (t). The operation of the feedback path 50 to generate the second feedback signal z2 (t) is the same as or similar to the previous embodiment, and will not be described here.

In some embodiments, as shown in fig. 8, the out-of-band predistortion correction circuit 19 is configured 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 a plurality of third filters 190A to 190B, an out-of-band predistortion parameter training unit 192 and a third arithmetic circuit 194. The out-of-band predistortion parameter training unit 192 is configured to generate a second reference signal z2' (t) according to 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 formula (2):

z2′(t)＝b ₀ x2(t)+b ₁ x2(t)|x2(t)| ² +b ₂ x2(t)|x2(t)| ⁴ …(2)，

wherein b ₀ 、b ₁ B ₂ A plurality of parameters included for the second reference parameter set P2.

The third filters 190A-190B are configured to perform a third filtering process on the second feedback signal z2 (t) and the second reference signal z2 '(t) to generate a filtered second feedback signal TF { z2 (t) } and a filtered second reference signal TF { z2' (t) }, respectively, wherein the third filters 190A-190B may be implemented as high-pass filters, and the third filtering process may be a high-pass filtering process.

In general, it may be desirable that the sum of the filtered second feedback signal TF { z2 (t) } and the filtered second reference signal TF { z2' (t) } be smaller to optimize the out-of-band predistortion process by the out-of-band predistorter 130. Accordingly, the third operation circuit 194 is configured to generate the second adjustment signal e2 (t) to the out-of-band predistortion parameter training unit 192 according to 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 is configured to modify the second reference parameter set P2 according to 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 may generate a cost function (e.g., J=from the second adjustment signal e2 (t)e2 ^H e2Wherein J is a cost function, ane2The second adjustment signal e2 (t) in matrix form) and the cost function is minimized using the least squares method, newton-Raphson method (Newton-Raphson method), or the least squares method (least mean square method) to continuously modify the second reference parameter set P2. After a plurality of corrections, the out-of-band predistortion parameter training unit 192 may take the second reference parameter set P2 minimizing 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.

In general, the out-of-band component of the output signal of the power amplifier 30 that grows due to the non-linear nature of the power amplifier 30 may vary depending on the in-band quality of the input signal of the power amplifier 30. Notably, the signal processing circuit 10' of the present disclosure utilizes the intra-band components (i.e., in-band predistortion output x2 (t)) in the full-band predistortion signal z (t) that will subsequently pass through the transmit chain 20 and the power amplifier 30 to produce the out-of-band predistortion parameter set Pob. Thus, the out-of-band predistorter 130 performs out-of-band predistortion processing according to the out-of-band predistortion parameter set Pob to effectively cancel out-of-band components.

In the foregoing embodiment, the out-of-band predistortion correction circuit 19 uses the third filters 190A and 190B to filter out the in-band components in the signal, because the out-of-band predistortion correction circuit 19 generates the out-of-band predistortion parameter set Pob based mainly on the out-of-band components in the observation signal. However, the present disclosure is not limited thereto. In some embodiments, out-of-band predistortion correction circuit 19 omits third filters 190A and 190B. It should be appreciated that even without the third filters 190A and 190B, the out-of-band predistortion correction circuit 19 may still generate the out-of-band predistortion parameter set Pob from out-of-band components in the observation signal.

Referring to fig. 9, fig. 9 is a flow chart of a signal predistortion method 300 according to some embodiments of the present disclosure. The signal predistortion method 300 may be performed by the signal processing circuit 10' as shown in fig. 5. In some embodiments, as shown in fig. 9, 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 the previous embodiment, and will not be described here. In addition, steps S302-S304 are the same as or similar to steps S201-S203 of FIG. 4, and are not described herein.

It should be understood that the signal processing circuit 10' does not necessarily perform step S301 every time the transmitting apparatus 100 is to transmit information. In some embodiments, the signal processing circuit 10' may perform step S301 only when the transmitting device 100 is turned on or connected.

Referring to fig. 10, fig. 10 is a schematic spectrum diagram of some signals according to some embodiments of the present disclosure. As shown in fig. 10, a curve a represents the spectrum of the baseband signal x1 (t). Curve B represents the spectrum of the signal that has not been predistorted and then amplified by power amplifier 30. Curve C represents the spectrum of the signal after in-band and out-of-band predistortion processing by the signal processing circuit 10 and then amplified by the power amplifier 30, where curve C includes curve C1 for in-band Bin and curves C2A and C2B for out-of-band Bout. As can be seen from fig. 10, the curve C processed by the signal processing circuit 10 has a good signal quality in the in-band Bin, and the curve C processed by the signal processing circuit 10 has a lower energy in the out-band Bout, compared to the curve B without the predistortion processing.

In the foregoing embodiment, when generating the full-band predistortion signal z (t), the signal processing circuit 10 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, the disclosure is not limited thereto. In some embodiments, the signal processing circuit 10 may perform the out-of-band predistortion processing through the out-of-band predistorter 130, and then perform the in-band predistortion processing through the in-band predistorter 110 to generate the full-band predistortion signal z (t).

In the foregoing embodiments, the signal processing circuit and the circuits included therein may be implemented by one or more Central Processing Units (CPUs), application Specific Integrated Circuits (ASICs), microprocessors, system on a chip (SoC), or other suitable processing units.

As can be seen from the above embodiments of the present disclosure, the transmitting device 100 of the present disclosure has the advantage of reducing the operation dimension of digital predistortion by performing predistortion processing on an in-band signal and an out-of-band signal, respectively. In addition, the transmitting device 100 of the present disclosure has advantages of reducing the complexity of operation and improving the stability of numerical convergence by generating the in-band predistortion parameter set and the out-of-band predistortion parameter set respectively.

Although the present disclosure has been described with reference to the embodiments, it should be understood that the invention is not limited thereto, but may be variously changed and modified by those skilled in the art without departing from the spirit and scope of the present disclosure, and thus the scope of the present disclosure is defined by the appended claims.

Reference numerals illustrate:

10,10' signal processing circuit

11 in-band predistortion circuit

13 out-of-band predistortion circuit

15 first arithmetic circuit

17 in-band predistortion correction circuit

Out-of-band predistortion correction circuit

20 transmit chain

21 digital-to-analog converter

23 output filter

25,53 local oscillator

27,55 Mixer

30 Power Amplifier

40 antenna

50 feedback path

51 attenuator

57 feedback end filter

59 analog-to-digital converter

100 transmitting device

110 in-band predistorter

112 first filter

130 out-of-band predistorter

132 second filter

170 in-band predistortion parameter training unit

172 second arithmetic circuit

190A,190B third filter

192 out-of-band predistortion parameter training unit

194 third arithmetic circuit

200,300 signal predistortion method

P1 first reference parameter set

P2:

pib in-band predistortion parameter set

Pob out-of-band predistortion parameter set

x1 (t) baseband signal

x2 (t) in-band predistortion output

x3 (t) out-of-band predistortion output

x1' (t) first reference signal

pd1 (t) first predistortion output

pd2 (t) second predistortion output

z (t) full band predistortion signal

z1 (t) first feedback signal

z2 (t) second feedback signal

z2' (t) second reference signal

w (t) radio frequency input signal

w1 (t) first input signal

w2 (t) second input signal

y (t) radio frequency output signal

y1 (t) first output signal

y2 (t) a second output signal

e1 (t) first adjustment signal

e2 (t) second adjustment signal

TF { z2 (t) } filtered second feedback signal

TF { z2' (t) } filtered second reference signal

S201 to S203, S301 to S304

Curves of A, B, C, C1, C2A, C2B

Bin in-band

Bout out of band

Claims (10)

1. A signal predistortion method for a transmitting device, wherein the transmitting device comprises a signal processing circuit, a transmitting chain and a power amplifier for amplifying a radio frequency input signal output by the transmitting chain to generate a radio frequency output signal, and the signal predistortion method comprises:

performing a first signal processing operation on the baseband signal by the signal processing circuit to produce an in-band predistortion output;

performing a second signal processing operation on the in-band predistortion output by the signal processing circuit to produce an out-of-band predistortion output; and

and generating a full-band predistortion signal to the transmitting chain according to the in-band predistortion output and the out-of-band predistortion output by the signal processing circuit, so that the transmitting chain generates the radio frequency input signal according to the full-band predistortion signal.

2. A signal pre-distortion method as set forth in claim 1, wherein the first signal processing operation comprises:

performing in-band predistortion processing on the baseband signal according to an in-band predistortion parameter set to generate a first predistortion output; and

the first predistortion output is subjected to a first filtering process to produce the in-band predistortion output, wherein the first filtering process is a low pass filtering process.

3. A signal predistortion method as claimed in claim 2, wherein the signal predistortion method further comprises:

generating, by the signal processing circuit, the in-band predistortion parameter set;

wherein the transmitting means further comprises a feedback path and generating the set of in-band predistortion parameters comprises:

inputting the baseband signal into the transmitting chain, wherein the transmitting chain generates a first input signal according to 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 according to the first output signal; and

the set of in-band predistortion parameters is determined based on the baseband signal and the first feedback signal.

4. A signal pre-distortion method as set forth in claim 1, wherein the second signal processing operation comprises:

performing 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; and

and performing 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.

5. A signal predistortion method as set out in claim 4, wherein the signal predistortion method further comprises:

generating, by the signal processing circuit, the out-of-band predistortion parameter set;

wherein the transmitting means further comprises a feedback path and generating the out-of-band predistortion parameter set comprises:

inputting the in-band predistortion output into the transmit chain, wherein the transmit chain generates a second input signal in accordance with 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 in accordance with the second output signal; and

the out-of-band predistortion parameter set is determined based on the in-band predistortion output and the second feedback signal.

6. A transmitting device, comprising:

a signal processing circuit comprising:

an in-band predistortion circuit for performing a first signal processing operation on the baseband signal to produce an in-band predistortion output;

an out-of-band predistortion circuit for performing a second signal processing operation on the in-band predistortion output to produce an out-of-band predistortion output; and

a first operation circuit for generating a full band predistortion signal based on the in-band predistortion output and the out-of-band predistortion output;

a transmitting chain for generating a radio frequency input signal according to the full band predistortion signal; and

the power amplifier is used for amplifying the radio frequency input signal to generate a radio frequency output signal.

7. The transmitting device of claim 6, wherein the in-band predistortion circuit comprises:

an in-band predistorter for performing in-band predistortion processing on the baseband signal according to an in-band predistortion parameter set to produce a first predistortion output; and

a first filter for performing 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 device of claim 7, wherein the signal processing circuit further comprises an in-band predistortion correction circuit and the signal processing circuit is configured to generate the in-band predistortion parameter set by the in-band predistortion correction circuit;

wherein the transmitting means further comprises a feedback path;

the power amplifier is used for amplifying the first input signal to generate a first output signal, and the feedback path is used for generating a first feedback signal according to the first output signal;

the in-band predistortion correction circuit is used for determining the in-band predistortion parameter set according to the baseband signal and the first feedback signal.

9. The transmitting device of claim 6, wherein the out-of-band predistortion circuit comprises:

an out-of-band predistorter for performing out-of-band predistortion processing on the in-band predistortion output in accordance with an out-of-band predistortion parameter set to produce a second predistortion output; and

and a second filter for performing 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 device of claim 9, wherein the signal processing circuit further comprises an out-of-band predistortion correction circuit and the signal processing circuit is configured to generate the set of out-of-band predistortion parameters by the out-of-band predistortion correction circuit;

wherein the transmitting means further comprises a feedback path;

the transmitting chain is used for generating a second input signal according to 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 according to the second output signal;

the out-of-band predistortion correction circuit is used for determining the out-of-band predistortion parameter set according to the in-band predistortion output and the second feedback signal.