Digital-to-analog conversion circuit and method, and communication device

Abstract

Provided in the present application are a digital-to-analog conversion circuit and method, and a communication device. The digital-to-analog conversion circuit comprises a DPD, a first DAC, a second DAC, and an ADC. The second DAC and the ADC may be used as feedback channels for controlling the DPD to perform pre-distortion compensation for the first DAC, so as to improve the linearity of the digital-to-analog conversion circuit.

Description

A digital-to-analog conversion circuit, method, and communication device

[0001] This application claims priority to Chinese Patent Application No. 202411457797.8, filed on October 17, 2024, entitled "A Digital-to-Analog Conversion Circuit, Method and Communication Device", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of communications, and more particularly to a digital-to-analog conversion circuit, method, and communication device. Background Technology

[0003] In communication systems, digital-to-analog converters (DACs) play a crucial role. To improve the performance of communication equipment, DACs often need to possess both high linearity and high dynamic range. For example, when the linearity of a DAC is poor, the nonlinear signal generated by the DAC (the signal generated by intermodulation) is strong, which can affect the electrical signals in other nearby frequency bands, thus impairing the performance of the communication equipment. However, achieving high linearity in DACs is a problem that urgently needs to be solved. Summary of the Invention

[0004] This application provides a digital-to-analog converter (DAC), a method, and a communication device. The DAC includes a digital-to-analog converter (DPD), a first DAC, a second DAC, and an ADC. The second DAC and ADC can serve as feedback channels to control the DPD to perform pre-distortion compensation on the first DAC, thereby improving the linearity of the DAC.

[0005] In a first aspect, a digital-to-analog converter circuit is provided, comprising: a digital predistorter (DPD), a first digital-to-analog converter (DAC), and a coupler, wherein a first input port of the DPD is used to input a digital signal to be processed, the output port of the DPD is coupled to the input port of the first DAC, and the output port of the first DAC is coupled to the input port of the coupler; a second DAC and a first combiner, wherein the input port of the second DAC is used to input the digital signal to be processed, the first input port of the first combiner is coupled to the coupling port of the coupler, and the second input port of the first combiner is coupled to the output port of the second DAC; an analog-to-digital converter (ADC) and a digital decoder, wherein the input port of the ADC is coupled to the output port of the first combiner, the output port of the ADC is coupled to the first input port of the digital decoder, the second input port of the digital decoder is used to input the digital signal to be processed, and the output port of the digital decoder is coupled to the second input port of the DPD.

[0006] According to embodiments of this application, the DPD, the first DAC, and the coupler can form the main channel in the digital-to-analog converter circuit, used to process the input digital signal to be processed and convert it into a processed analog signal. The second DAC, the first combiner, the ADC, and the digital solver can form a feedback channel to improve the transmission characteristics of the main channel, such as linearity.

[0007] The digital signal to be processed undergoes digital predistortion followed by a first digital-to-analog converter (DAC) to generate a first analog signal. The digital signal to be processed then undergoes a second DAC to generate a second analog signal. The second and third analog signals are combined and then converted to digital signals via an analog-to-digital converter (ADC) to generate a first digital signal. The third analog signal is generated by coupling the first analog signal. The digital signal to be processed and the first digital signal undergo digital computation to generate a second digital signal. The second digital signal is used to adjust the compensation of the digital signal to be processed during digital predistortion.

[0008] It should be understood that after the second and third analog signals are combined, they can cancel each other out (linear cancellation). The combined analog signal can be understood as consisting only of the nonlinear analog signal. Since the analog signal input to the ADC only includes the nonlinear part generated by the main channel, the linearity requirement of the ADC is reduced, making it easier to implement in engineering. In one embodiment, the ADC can be used to implement other transmission characteristics of the digital-to-analog conversion circuit, such as dynamic range (which can be simply understood as signal-to-noise ratio).

[0009] In conjunction with the first aspect, in some implementations of the first aspect, the digital-to-analog converter circuit further includes: an amplifier; wherein the input port of the amplifier is coupled to the output port of the first combiner, and the output port of the amplifier is coupled to the input port of the ADC.

[0010] According to an embodiment of this application, the second analog signal and the third analog signal are combined, amplified, and then converted from analog to digital to generate the aforementioned first digital signal. The power of the analog signal after combining the second and third analog signals is relatively low, and the power of the amplifier can be used to amplify the analog signal for subsequent processing.

[0011] In conjunction with the first aspect, in some implementations of the first aspect, the digital-to-analog converter circuit further includes: a first signal conditioner; wherein the input port of the first signal conditioner is used to input the digital signal to be processed, and the output port of the first signal conditioner is coupled to the input port of the second DAC.

[0012] According to an embodiment of this application, the digital signal to be processed is subjected to signal conditioning and then converted into the second analog signal by a second digital-to-analog converter. The digital signal to be processed can be adjusted by a first signal conditioner, for example, by adjusting the amplitude, frequency, and time delay, so that the linear components in the second and third analog signals can be canceled out more completely.

[0013] In conjunction with the first aspect, in some implementations of the first aspect, the digital-to-analog converter circuit further includes: a code pattern converter; wherein, the input port of the code pattern converter is used to input the digital signal to be processed, and the output port of the code pattern converter is coupled to the first input port of the DPD, or, the input port of the code pattern converter is coupled to the output port of the DPD, and the output port of the code pattern converter is coupled to the input port of the first DAC.

[0014] According to an embodiment of this application, the code converter can be located before the first input port of the DPD. The digital signal to be processed undergoes code conversion, digital predistortion, and a first digital-to-analog conversion to generate the aforementioned first analog signal. Alternatively, the code converter can be located after the output port of the DPD. The digital signal to be processed undergoes digital predistortion, code conversion, and a first digital-to-analog conversion to generate the aforementioned first analog signal.

[0015] In conjunction with the first aspect, in some implementations of the first aspect, the digital-to-analog converter circuit further includes: a noise generator, a second combiner, and a quantizer; wherein, the first input port of the second combiner is used to input the digital signal to be processed, the second input port of the second combiner is coupled to the output port of the noise generator, the output port of the second combiner is coupled to the input port of the quantizer, and the output port of the quantizer is coupled to the input port of the second DAC.

[0016] According to an embodiment of this application, the digital signal to be processed is combined with noise, quantized, and then converted to a second analog signal via a second digital-to-analog converter to generate the aforementioned second analog signal. The digital signal generated after combining the digital signal to be processed with noise may not be periodic. When a non-periodic digital signal is quantized, the resulting error is not related to the original signal and does not affect the cancellation performed by the subsequent first combiner, thus reducing the nonlinearity generated by the quantizer. The quantizer can be used to reduce the bit width of the digital signal to improve the linearity of the second analog signal after processing by the second DAC.

[0017] In conjunction with the first aspect, in some implementations of the first aspect, the linearity of the second DAC is greater than that of the first DAC; the dynamic range of the second DAC is smaller than that of the first DAC; and / or, the bit width of the second DAC is smaller than that of the first DAC.

[0018] According to embodiments of this application, a second DAC can be used to improve the linearity of the first DAC. Therefore, when the second DAC has better linearity, the linear components in the second and third analog signals cancel each other out more completely, resulting in better linearity of the digital-to-analog converter circuit. Generally, when a DAC has a small dynamic range, its linearity is easier to improve. Generally, the more bits the DAC processes in a digital signal, the worse its linearity.

[0019] Secondly, a digital-to-analog conversion method is provided, comprising: digitally predistorting a digital signal to be processed and then performing a first digital-to-analog conversion to generate a first analog signal; the digital signal to be processed and then performing a second digital-to-analog conversion to generate a second analog signal; combining the second analog signal and a third analog signal and then performing an analog-to-digital conversion to generate a first digital signal, wherein the third analog signal is generated by coupling the first analog signal; and performing digital computation on the digital signal to be processed and the first digital signal to generate a second digital signal, wherein the second digital signal is used to adjust the compensation of the digital signal to be processed in the digital predistortion.

[0020] In conjunction with the second aspect, in some implementations of the second aspect, the second analog signal and the third analog signal are combined and then converted to a first digital signal by analog-to-digital conversion, including: the second analog signal and the third analog signal are combined, amplified, and then converted to a first digital signal by analog-to-digital conversion.

[0021] In conjunction with the second aspect, in some implementations of the second aspect, the digital signal to be processed is converted into a second analog signal by a second digital-to-analog converter, including: the digital signal to be processed is conditioned and then converted into the second analog signal by a second digital-to-analog converter.

[0022] In conjunction with the second aspect, in some implementations of the second aspect, the digital signal to be processed undergoes digital predistortion followed by a first digital-to-analog conversion to generate a first analog signal, including: the digital signal to be processed undergoes code pattern conversion followed by digital predistortion and then undergoes a first digital-to-analog conversion to generate the first analog signal, or the digital signal to be processed undergoes digital predistortion followed by code pattern conversion and then undergoes a first digital-to-analog conversion to generate the first analog signal.

[0023] In conjunction with the second aspect, in some implementations of the second aspect, the digital signal to be processed is converted into a second analog signal by a second digital-to-analog converter, including: the digital signal to be processed is combined with noise, quantized, and then converted into the second analog signal by a second digital-to-analog converter.

[0024] Thirdly, a digital-to-analog converter circuit is provided, comprising: a first digital-to-analog converter (DAC), a first combiner, and a coupler, wherein the input port of the first DAC is used to input a digital signal to be processed, the output port of the first DAC is coupled to the first input port of the first combiner, and the output port of the first combiner is coupled to the input port of the coupler; a digital predistorter (DPD) and a second DAC, wherein the first input port of the DPD is coupled to the digital signal to be processed, the output port of the DPD is coupled to the input port of the second DAC, and the output port of the second DAC is coupled to the second input port of the first combiner; a third DAC and a second combiner, wherein the input port of the third DAC is used to input the digital signal to be processed, the first input port of the second combiner is coupled to the coupling port of the coupler, and the second input port of the second combiner is coupled to the output port of the third DAC; an analog-to-digital converter (ADC) and a digital decoder, wherein the input port of the ADC is coupled to the output port of the second combiner, the output port of the ADC is coupled to the first input port of the digital decoder, the second input port of the digital decoder is used to input the digital signal to be processed, and the output port of the digital decoder is coupled to the second input port of the DPD.

[0025] In conjunction with the third aspect, in some implementations of the third aspect, the digital-to-analog converter circuit further includes: a first signal conditioner; wherein the input port of the first signal conditioner is used to input the digital signal to be processed, and the output port of the first signal conditioner is coupled to the input port of the first DAC.

[0026] In conjunction with the third aspect, in some implementations of the third aspect, the digital-to-analog converter circuit further includes: a second signal conditioner; wherein the input port of the second signal conditioner is used to input the digital signal to be processed, and the output port of the second signal conditioner is coupled to the input port of the third DAC.

[0027] In conjunction with the third aspect, in some implementations of the third aspect, the digital-to-analog conversion circuit further includes an amplifier; wherein the input port of the amplifier is coupled to the output port of the second combiner, and the output port of the amplifier is coupled to the input port of the ADC.

[0028] In conjunction with the third aspect, in some implementations of the third aspect, the digital-to-analog converter circuit further includes: a code converter; wherein, the input port of the code converter is used to input the digital signal to be processed, and the output port of the code converter is coupled to the first input port of the DPD, or, the input port of the code converter is coupled to the output port of the DPD, and the output port of the code converter is coupled to the input port of the second DAC.

[0029] In conjunction with the third aspect, in some implementations of the third aspect, the digital-to-analog converter circuit further includes: a noise generator, a third combiner, and a quantizer; wherein, the first input port of the third combiner is used to input the digital signal to be processed, the second input port of the third combiner is coupled to the output port of the noise generator, the output port of the third combiner is coupled to the input port of the quantizer, and the output port of the quantizer is coupled to the input port of the third DAC.

[0030] In conjunction with the third aspect, in some implementations of the third aspect, the linearity of the third DAC is greater than the linearity of the first DAC and / or the linearity of the second DAC; the dynamic range of the third DAC is smaller than the dynamic range of the first DAC and / or the dynamic range of the second DAC; and / or, the bit width of the third DAC is smaller than the bit width of the first DAC and / or the bit width of the second DAC.

[0031] Fourthly, a digital-to-analog conversion method is provided, comprising: a digital signal to be processed undergoing a first digital-to-analog conversion to generate a first analog signal; the digital signal to be processed undergoing digital predistortion and then undergoing a second digital-to-analog conversion to generate a second analog signal; the first analog signal and the second analog signal are combined to generate a third analog signal; the digital signal to be processed undergoing a third digital-to-analog conversion to generate a fourth analog signal; the fourth analog signal and the fifth analog signal are combined and then undergoing an analog-to-digital conversion to generate a first digital signal; the fifth analog signal is generated by coupling the third analog signal; the digital signal to be processed and the first digital signal undergo digital computation to generate a second digital signal, the second digital signal being used to adjust the compensation of the digital signal to be processed in digital predistortion.

[0032] In conjunction with the fourth aspect, in some implementations of the fourth aspect, the digital signal to be processed is converted into a first analog signal by a first digital-to-analog converter, including: the digital signal to be processed is subjected to a first signal conditioning and then converted into the first analog signal by a first digital-to-analog converter.

[0033] In conjunction with the fourth aspect, in some implementations of the fourth aspect, the digital signal to be processed is converted into a fourth analog signal by a third digital-to-analog converter, including: the digital signal to be processed is subjected to a second signal conditioning and then converted into the fourth analog signal by a third digital-to-analog converter.

[0034] In conjunction with the fourth aspect, in some implementations of the fourth aspect, the fourth analog signal and the fifth analog signal are combined and then converted to a first digital signal by analog-to-digital conversion, including: the fourth analog signal and the fifth analog signal are combined, amplified, and then converted to a first digital signal by analog-to-digital conversion.

[0035] In conjunction with the fourth aspect, in some implementations of the fourth aspect, the digital signal to be processed undergoes digital predistortion and then undergoes a second digital-to-analog conversion to generate a second analog signal, including: the digital signal to be processed undergoes digital predistortion after code conversion and then undergoes a second digital-to-analog conversion to generate the second analog signal, or the digital signal to be processed undergoes digital predistortion and then undergoes code conversion and then undergoes a second digital-to-analog conversion to generate the second analog signal.

[0036] In conjunction with the fourth aspect, in some implementations of the fourth aspect, the digital signal to be processed is converted into a fourth analog signal by a third digital-to-analog converter, including: the digital signal to be processed is combined with noise, quantized, and then converted into the fourth analog signal by a third digital-to-analog converter.

[0037] Fifthly, a communication device is provided, the communication device comprising any of the digital-to-analog conversion circuits described in the first aspect and the third aspect. Attached Figure Description

[0038] Figure 1 is a schematic diagram of a digital-to-analog converter circuit 100 provided in an embodiment of this application.

[0039] Figure 2 is a schematic diagram of a digital-to-analog converter circuit 100 provided in an embodiment of this application.

[0040] Figure 3 is a schematic diagram of a digital-to-analog converter circuit 100 provided in an embodiment of this application.

[0041] Figure 4 is a schematic diagram of a digital-to-analog converter circuit 100 provided in an embodiment of this application.

[0042] Figure 5 is a schematic diagram of a digital-to-analog converter circuit 200 provided in an embodiment of this application.

[0043] Figure 6 is a schematic diagram of a digital-to-analog converter circuit 200 provided in an embodiment of this application.

[0044] Figure 7 is a schematic diagram of a digital-to-analog converter circuit 200 provided in an embodiment of this application. Detailed Implementation

[0045] The following explains the terminology that may appear in the embodiments of this application.

[0046] It should be understood that the term "and / or" used in this document is merely a description of the same field in the related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, and B alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0047] The phrase "within the range" used in this application, unless otherwise specified, includes both endpoints of the range by default. For example, in the range of 1 to 5, it includes the values ​​1 and 5.

[0048] Coupling can be understood as direct coupling and / or indirect coupling. "Coupled connection" can be understood as a direct coupling connection and / or indirect coupling connection. Direct coupling can also be called "electrical connection," which can be understood as physical contact and electrical conduction between components; it can also be understood as the form of connection between different components in a circuit structure through physical lines that can transmit electrical signals, such as copper foil or wires on a printed circuit board (PCB). "Indirect coupling" can be understood as electrical conduction between two conductors through a gap / non-contact method. In one embodiment, indirect coupling can also be called capacitive coupling, for example, signal transmission is achieved by forming an equivalent capacitance through coupling between the gaps between two conductive parts.

[0049] Components / devices: including at least one of lumped components / devices and distributed components / devices.

[0050] Lumped components / devices: This refers to all components whose size is much smaller than the wavelength relative to the circuit's operating frequency. For signals, the characteristics of these components remain constant regardless of frequency. Lumped components / devices can include lumped capacitors, lumped inductors, etc.

[0051] Distributed elements / devices: Unlike lumped elements, when a signal passes through an element, the characteristics of each point within the element will vary depending on the signal. Therefore, the element as a whole cannot be considered a single entity with fixed characteristics, and should be called a distributed element. Distributed elements / devices can include distributed capacitance, distributed inductance, etc.

[0052] Capacitance: can be understood as lumped capacitance and / or distributed capacitance. Lumped capacitance includes capacitive components, such as capacitor elements; distributed capacitance (or distributed capacitance) includes the equivalent capacitance formed by two conductive components separated by a certain gap.

[0053] Inductance: can be understood as lumped inductance and / or distributed inductance. Lumped inductance includes inductive components, such as inductive elements; distributed inductance (or distributed inductance) includes the equivalent inductance formed through a conductive element of a certain length, such as the equivalent inductance formed by a conductor due to bending or rotation.

[0054] Linearity and Nonlinearity: In electrical engineering, linearity and nonlinearity refer to the relationship between voltage and current in a circuit. Linearity means that the components in the circuit satisfy a linear relationship, that is, there is a linear proportional relationship between input and output; while nonlinearity means that the components in the circuit do not satisfy a linear relationship, that is, the relationship between input and output is not linear.

[0055] In linear circuits, the relationship between voltage and current can be represented by the mathematical equation y = kx + b, where k is a proportionality constant, x is the input, and y is the output. This relationship satisfies the superposition principle, meaning that the superposition of multiple signals equals the sum of the outputs of each signal acting alone.

[0056] In contrast, the relationship between voltage and current in nonlinear circuits typically exhibits a polynomial relationship of higher than one order.

[0057] Digital predistortion (DPD): A component used in signal processing techniques to compensate for nonlinear distortion during processing. By introducing a predistorter before processing the electrical signal, whose nonlinear characteristics are opposite to those of the processing signal, overall linearization is achieved.

[0058] Signal-to-noise ratio (SNR) is the ratio of the strength of the received useful signal to the strength of the received interference signal (noise and interference).

[0059] The technical solutions in this application will now be described with reference to the accompanying drawings.

[0060] In communication systems, DACs play a crucial role. To improve the performance of communication equipment, DACs often need to possess both high linearity and large dynamic range. For example, when the linearity of a DAC is poor, the nonlinear signal generated by the DAC (the signal generated by intermodulation) is strong, which can affect the electrical signals of other nearby frequency bands, thus impairing the performance of the communication equipment.

[0061] Figure 1 is a schematic diagram of a digital-to-analog converter circuit 100 provided in an embodiment of this application.

[0062] It should be understood that the digital-to-analog conversion circuits described in the embodiments of this application can all be applied to communication devices that require digital-to-analog conversion. For example, the communication device can be a base station, etc., and for the sake of brevity, they will not be described in detail here.

[0063] As shown in Figure 1, a feedback channel is introduced into the digital-to-analog converter circuit to improve the linearity of the DAC output signal. The feedback channel can include an analog-to-digital converter (ADC) and a digital calibrator. The digital calibrator can determine the nonlinear changes between the electrical signals at the DAC input port and the output port, thereby controlling the DPD to perform pre-distortion compensation on the input DAC signal to improve the linearity of the DAC output signal.

[0064] In the feedback channel, the analog signal needs to be converted into a digital signal, and the electrical signal processed by the ADC also introduces nonlinear effects. Therefore, to improve the linearity of the electrical signal output by the DAC, the ADC in the feedback channel also needs to have high linearity. However, achieving a high-linearity ADC is more difficult than achieving a high-linearity DAC, and directly compensating for the linearity of the DAC with a high-linearity ADC is often not feasible in engineering.

[0065] This application provides a digital-to-analog converter (DAC), a method, and a communication device. The DAC includes a digital-to-analog converter (DPD), a first DAC, a second DAC, and an ADC. The second DAC and ADC can serve as feedback channels to control the DPD to perform pre-distortion compensation on the first DAC, thereby improving the linearity of the DAC.

[0066] Figure 2 is a schematic diagram of a digital-to-analog converter circuit 100 provided in an embodiment of this application.

[0067] As shown in Figure 2, the digital-to-analog converter circuit 100 includes a DPD 121, a first DAC 122, a coupler 123, a second DAC 131, a first combiner 132, an ADC 141, and a digital solver 142.

[0068] The first input port of DPD121 is coupled to the digital signal to be processed. The first input port of DPD121 is used to input the digital signal to be processed. The output port of DPD121 is coupled to the input port of the first DAC122, and the output port of the first DAC122 is coupled to the input port of coupler 123.

[0069] The input port of the second DAC 131 is coupled to the digital signal to be processed. The input port of the second DAC 131 is used to input the digital signal to be processed. The first input port of the first combiner 132 is coupled to the coupling port of the coupler 123. The second input port of the first combiner 132 is coupled to the output port of the second DAC 131.

[0070] The input port of ADC141 is coupled to the output port of the first combiner 132. The output port of ADC141 is coupled to the first input port of digital solver 142. The second input port of digital solver 142 is coupled to the digital signal to be processed. The second input port of digital solver 142 is used to input the digital signal to be processed. The output port of digital solver 142 is coupled to the second input port of DPD121.

[0071] According to an embodiment of this application, DPD121, first DAC122, and coupler123 can form the main channel in digital-to-analog converter circuit 100, used to process the input digital signal to be processed and convert it into a processed analog signal. Second DAC131, first combiner 132, ADC141, and digital solver 142 can form a feedback channel to improve the transmission characteristics of the main channel, such as linearity.

[0072] The digital signal to be processed can be understood as a digital signal that needs to be processed by the digital-to-analog converter circuit 100. For example, the digital signal to be processed can be a digital signal transmitted to the first input port of the DPD121. The digital signal to be processed can be a digital signal generated by other components in the communication device, and this embodiment does not limit this.

[0073] It should be understood that the phrase "input port for inputting digital signal to be processed" in the embodiments of this application can be understood as the input port being used to input an unprocessed digital signal to be processed (for example, no other components are provided between the input port and the port of the external circuit), or it can also be understood as the input port being used to input a partially processed digital signal to be processed (for example, other components are provided between the input port and the port of the external circuit, and the digital signal to be processed can be input into the input port after undergoing other processing (for example, filtering, code transformation, etc.)).

[0074] The digital signal to be processed is digitally predistorted and then converted into a first analog signal by a first digital-to-analog converter. In one embodiment, the digital signal to be processed is sequentially passed through a DPD121 and a first DAC122 to generate the aforementioned first analog signal.

[0075] The digital signal to be processed is converted into a second analog signal by a second digital-to-analog converter. In one embodiment, the digital signal to be processed is converted into the second analog signal by a second DAC131.

[0076] The second and third analog signals are combined and then converted to a first digital signal via an analog-to-digital converter. The third analog signal is generated by coupling the first analog signal. In one embodiment, the second and third analog signals pass through a first combiner 132 and an ADC 141 to generate the first digital signal. The first analog signal passes through a coupler 123 to generate the third analog signal.

[0077] The digital signal to be processed and the first digital signal are digitally processed to generate a second digital signal. The second digital signal is used to adjust the compensation of the digital signal to be processed in digital predistortion. In one embodiment, the digital signal to be processed and the first digital signal are processed by a digital processor 142 to generate the aforementioned second digital signal. The second digital signal can be used to indicate the nonlinearity of the first DAC 122 (or, it can also be understood as the nonlinearity of the main channel). The DPD 121 can adjust the predistortion compensation of the first DAC 122 according to the second digital signal to improve the transmission characteristics of the digital-to-analog converter 100, such as linearity.

[0078] It should be understood that after the second and third analog signals are combined, they can cancel each other out (linear cancellation). The combined analog signal can be understood as including only the nonlinear analog signal. Since the analog signal input to ADC141 only includes the nonlinear part generated by the main channel, the linearity requirement of ADC141 is reduced, making it easier to implement in engineering. In one embodiment, ADC141 can be used to implement other transmission characteristics of the digital-to-analog converter circuit 100, such as dynamic range (which can be simply understood as signal-to-noise ratio).

[0079] In one embodiment, the linearity of the second DAC131 is greater than that of the first DAC122.

[0080] It should be understood that the second DAC131 can be used to improve the linearity of the first DAC122. Therefore, when the second DAC131 has better linearity, the linear components in the second and third analog signals cancel out more completely, and the digital-to-analog converter circuit 100 has better linearity.

[0081] In one embodiment, the dynamic range of the second DAC131 is smaller than that of the first DAC122.

[0082] It should be understood that, under normal circumstances, when a DAC has a small dynamic range, the linearity of the DAC is easier to improve.

[0083] In one embodiment, the bit width of the second DAC131 is smaller than the bit width of the first DAC122.

[0084] It should be understood that, generally speaking, the more bits the digital signal encoded by the DAC has, the worse the linearity of the DAC becomes.

[0085] In one embodiment, the digital-to-analog converter circuit 100 may further include an amplifier 143, as shown in FIG3. The input port of the amplifier 143 is coupled to the output port of the first combiner 132. The output port of the amplifier 143 is coupled to the input port of the ADC 141.

[0086] It should be understood that the second and third analog signals are combined, amplified, and then converted from analog to digital to generate the first digital signal mentioned above. The power of the analog signal after combining the second and third analog signals is relatively low, and this analog signal can be amplified by the power of amplifier 143 for subsequent processing.

[0087] For the sake of brevity, the analog-to-digital converter circuit 100 shown in Figure 3 is only illustrated with a single amplifier 143. In actual production or design, the analog-to-digital converter circuit 100 may include more amplifiers. For the sake of brevity, these will not be described in detail.

[0088] In one embodiment, amplifier 143 may be a Class A amplifier, such as a low noise amplifier (LNA), a variable gain amplifier (VGA), etc.

[0089] In one embodiment, the digital-to-analog converter circuit 100 may further include a first signal conditioner 133, as shown in FIG3. The input port of the first signal conditioner 133 is coupled to the digital signal to be processed. The input port of the first signal conditioner 133 is used to input the digital signal to be processed. The output port of the first signal conditioner 133 is coupled to the input port of the second DAC 131.

[0090] It should be understood that the digital signal to be processed undergoes signal conditioning and then a second digital-to-analog conversion to generate the aforementioned second analog signal. The digital signal to be processed can be adjusted by the first signal conditioner 133, for example, by adjusting the amplitude, frequency, and time delay, so that the linear components in the second and third analog signals can be canceled out more completely.

[0091] For the sake of brevity, in the digital-to-analog converter circuit 100 shown in Figure 3, only the example of the first signal conditioner 133 being located before the input port of the second DAC 131 is used for explanation. In actual production or design, the first signal conditioner 133 can also be located in other positions, such as before the first input port of the DPD 121. The digital-to-analog converter circuit 100 can also include multiple signal conditioners. For the sake of brevity, they will not be described in detail.

[0092] In one embodiment, the first signal conditioner 133 may be a digital filter or a delay unit.

[0093] In one embodiment, the digital-to-analog converter circuit 100 may further include a code converter 124, as shown in FIG3. The code converter 124 can be used to adjust the bit width of the digital signal input to the first DAC 122 to adapt to the first DAC 122.

[0094] In one embodiment, the input port of the code converter 124 is coupled to the digital signal to be processed. The input port of the code converter 124 is used to input the digital signal to be processed. The output port of the code converter 124 is coupled to the first input port of the DPD 121.

[0095] In one embodiment, the input port of the code converter 124 is coupled to the output port of the DPD 121. The output port of the code converter 124 is coupled to the input port of the first DAC 122.

[0096] It should be understood that the code converter 124 can be located before the first input port of the DPD 121. The digital signal to be processed undergoes code conversion, digital predistortion, and a first digital-to-analog conversion to generate the aforementioned first analog signal. Alternatively, the code converter 124 can be located after the output port of the DPD 121. The digital signal to be processed undergoes digital predistortion, code conversion, and a first digital-to-analog conversion to generate the aforementioned first analog signal.

[0097] For the sake of brevity, this embodiment of the application only uses the example of the code converter 124 being located before the input port of the first DAC 122. In actual production or design, the digital-to-analog converter circuit 100 may also include multiple code converters. For the sake of brevity, they will not be described in detail.

[0098] In the digital-to-analog converter circuit 100 shown in Figure 3, only the amplifier 143, the first signal conditioner 133, and the code converter 124 are shown. In actual production or design, the digital-to-analog converter circuit 100 may also include other components, such as capacitors and inductors. For the sake of brevity, they will not be described in detail.

[0099] In one embodiment, the digital-to-analog converter circuit 100 may further include a second combiner 134, a noise generator 135, and a quantizer 136, as shown in FIG4.

[0100] The first input port of the second combiner 134 is coupled to the digital signal to be processed. The first input port of the second combiner 134 is used to input the digital signal to be processed. The second input port of the second combiner 134 is coupled to the output port of the noise generator 135. The output port of the second combiner 134 is coupled to the input port of the quantizer 136. The output port of the quantizer 136 is coupled to the input port of the second DAC 131.

[0101] It should be understood that the digital signal to be processed is combined with noise, quantized, and then converted to the second analog signal via a second digital-to-analog converter. The digital signal generated after combining the digital signal to be processed with noise may not be periodic. When a non-periodic digital signal is quantized, the resulting error is not related to the original signal and does not affect the cancellation performed by the first combiner 132, thus reducing the nonlinearity generated by the quantizer 136. The quantizer 136 can be used to reduce the bit width of the digital signal to improve the linearity of the second analog signal processed by the second DAC 131.

[0102] In the digital-to-analog converter circuit 100 shown in Figure 4, only one method for improving the linearity of the second DAC 131 is illustrated. In actual production or design, other technical solutions can also be used to improve the linearity of the second DAC 131, such as power back-off, reducing the bit width, reducing the signal-to-noise ratio, or dynamic matching, etc. For the sake of brevity, these will not be elaborated on further.

[0103] In one embodiment, the output port of coupler 123 can be coupled to an antenna in a communication device. In another embodiment, the output port of coupler 123 can be coupled to a radio frequency circuit in a communication device to process the analog signal output from the output port of coupler 123, for example, by up-conversion.

[0104] It should be understood that the digital-to-analog converter circuit 100 shown in Figures 2 to 4 includes only one main channel. In actual production or design, the digital-to-analog converter circuit 100 may include multiple main channels, with multiple main channels sharing a single feedback channel. This feedback channel can improve the linearity of multiple main channels. Under this technical solution, the layout space for multiple main channels is smaller, making it easier to implement in the increasingly limited internal space of communication equipment. For the sake of brevity, further details will not be provided.

[0105] Figure 5 is a schematic diagram of a digital-to-analog converter circuit 200 provided in an embodiment of this application.

[0106] As shown in Figure 5, the digital-to-analog converter circuit 200 includes a first DAC 211, a first combiner 212, a coupler 213, a DPD 221, a second DAC 222, a third DAC 231, a second combiner 232, an ADC 241, and a digital solver 242.

[0107] The input port of the first DAC 211 is coupled to the digital signal to be processed. The input port of the first DAC 211 is used to input the digital signal to be processed. The output port of the first DAC 211 is coupled to the first input port of the first combiner 212. The output port of the first combiner 212 is coupled to the input port of the coupler 123.

[0108] The first input port of DPD221 is coupled to the digital signal to be processed. The first input port of DPD221 is used to input the digital signal to be processed. The output port of DPD221 is coupled to the input port of the second DAC222. The output port of the second DAC222 is coupled to the second input port of the first combiner 212.

[0109] The input port of the third DAC231 is coupled to the digital signal to be processed. The input port of the third DAC231 is used to input the digital signal to be processed. The first input port of the second combiner 232 is coupled to the coupling port of the coupler 213. The second input port of the second combiner 232 is coupled to the output port of the third DAC231.

[0110] The input port of ADC241 is coupled to the output port of the second combiner 232. The output port of ADC241 is coupled to the first input port of digital solver 242. The second input port of digital solver 242 is coupled to the digital signal to be processed. The second input port of digital solver 242 is used to input the digital signal to be processed. The output port of digital solver 242 is coupled to the second input port of DPD221.

[0111] According to an embodiment of this application, the first DAC 211, the first combiner 212, the coupler 213, the DPD 221, and the second DAC 222 can form the main channel in the digital-to-analog converter circuit 200, used to process the input digital signal to be processed and convert it into a processed analog signal. The second DAC 222, the third DAC 231, the second combiner 232, the ADC 241, and the digital decoder 242 can form a feedback channel to improve the transmission characteristics of the main channel, such as linearity.

[0112] The digital signal to be processed can be understood as a digital signal that needs to be processed by the digital-to-analog converter circuit 200. For example, the digital signal to be processed can be a digital signal transmitted to the first input port of DPD221. The digital signal to be processed can be a digital signal generated by other components in the communication device, and this embodiment of the application does not limit this.

[0113] The digital signal to be processed is converted into a first analog signal by a first digital-to-analog converter. In one embodiment, the digital signal to be processed is converted into the first analog signal by a first DAC211.

[0114] The digital signal to be processed is digitally predistorted and then converted into a second analog signal by a second digital-to-analog converter. In one embodiment, the digital signal to be processed is sequentially passed through a DPD221 and a second DAC222 to generate the aforementioned second analog signal.

[0115] The first analog signal and the second analog signal are combined to generate a third analog signal. In one embodiment, the first analog signal and the second analog signal pass through the first combiner 212 to generate the aforementioned third analog signal. The DPD 221 can perform pre-distortion compensation on the second DAC 222, so that the aforementioned second analog signal generated at the output port of the second DAC 222 includes only the nonlinear portion. After the first analog signal and the second analog signal are combined through the first combiner 212, the nonlinear portion can be canceled out.

[0116] The digital signal to be processed is converted into a fourth analog signal by a third digital-to-analog converter. In one embodiment, the digital signal to be processed is converted into the fourth analog signal by a third DAC231.

[0117] The fourth and fifth analog signals are combined and then converted to a first digital signal via analog-to-digital conversion. The fifth analog signal is generated by coupling the third analog signal. In one embodiment, the fourth and fifth analog signals pass through a second combiner 232 and an ADC 241 to generate the first digital signal. The third analog signal passes through a coupler 213 to generate the fifth analog signal.

[0118] The digital signal to be processed and the first digital signal are digitally processed to generate a second digital signal. The second digital signal is used to adjust the compensation of the digital signal to be processed in digital predistortion. In one embodiment, the digital signal to be processed and the first digital signal are processed by a digital processor 242 to generate the aforementioned second digital signal. The second digital signal can be used to indicate the nonlinearity of the second DAC 222 (or, it can also be understood as the nonlinearity of the main channel). The DPD 221 can adjust the predistortion compensation of the second DAC 222 according to the second digital signal, so that after the first analog signal and the second analog signal are canceled out, the third analog signal at the output port of the first combiner 212 has better linearity.

[0119] It should be understood that after the fourth and fifth analog signals are combined, they can cancel each other out (linear cancellation). The combined analog signal can be understood as including only the nonlinear analog signal. Since the analog signal input to ADC241 only includes the nonlinear part generated by the main channel, the linearity requirement of ADC241 is reduced, making it easier to implement in engineering. In one embodiment, ADC241 can be used to implement other transmission characteristics of the digital-to-analog converter circuit 200, such as dynamic range (which can be simply understood as signal-to-noise ratio).

[0120] In one embodiment, the linearity of the third DAC231 is greater than the linearity of the second DAC222 and / or the linearity of the first DAC211.

[0121] It should be understood that the third DAC231 can be used to improve the linearity of the main channel. Therefore, when the third DAC231 has better linearity, the linear components in the fourth and fifth analog signals cancel out more completely, and the digital-to-analog converter circuit 100 has better linearity.

[0122] In one embodiment, the dynamic range of the third DAC231 is smaller than the dynamic range of the second DAC222 and / or the dynamic range of the first DAC211.

[0123] It should be understood that, under normal circumstances, when a DAC has a small dynamic range, the linearity of the DAC is easier to improve.

[0124] In one embodiment, the bit width of the third DAC231 is smaller than the bit width of the second DAC222 and / or the bit width of the first DAC211.

[0125] It should be understood that, generally speaking, the more bits the digital signal encoded by the DAC has, the worse the linearity of the DAC becomes.

[0126] In one embodiment, the digital-to-analog converter circuit 200 may further include an amplifier 243, as shown in FIG6. The input port of the amplifier 243 is coupled to the output port of the second combiner 232. The output port of the amplifier 243 is coupled to the input port of the ADC 241.

[0127] It should be understood that the fourth and fifth analog signals are combined, amplified, and then converted from analog to digital to generate the aforementioned first digital signal. The power of the analog signal after combining the fourth and fifth analog signals is relatively low, and this analog signal can be amplified by the power of amplifier 243 for subsequent processing.

[0128] In one embodiment, amplifier 243 may be a Class A amplifier, such as a low noise amplifier (LNA), a variable gain amplifier (VGA), etc.

[0129] For the sake of brevity, the analog-to-digital converter circuit 200 shown in Figure 6 will only be described with the amplifier 243 as an example. In actual production or design, the analog-to-digital converter circuit 200 may include more amplifiers. For the sake of brevity, they will not be described in detail.

[0130] In one embodiment, the digital-to-analog converter circuit 200 may further include a first signal conditioner 214, as shown in FIG6. The input port of the first signal conditioner 214 is coupled to the digital signal to be processed. The input port of the first signal conditioner 214 is used to input the digital signal to be processed. The output port of the first signal conditioner 214 is coupled to the input port of the first DAC 211.

[0131] In one embodiment, the digital-to-analog converter circuit 200 may further include a second signal conditioner 233, as shown in FIG6. The input port of the second signal conditioner 233 is coupled to the digital signal to be processed. The input port of the second signal conditioner 233 is used to input the digital signal to be processed. The output port of the second signal conditioner 233 is coupled to the input port of the third DAC 231.

[0132] It should be understood that the digital signal to be processed, after signal conditioning, can generate the aforementioned second and fourth analog signals through a first digital-to-analog converter and a second digital-to-analog converter, respectively. The digital signal to be processed can be adjusted by a signal conditioner, for example, by adjusting the amplitude, frequency, and time delay, so that the cancellation of analog signals during the combining process is more complete.

[0133] For the sake of brevity, the analog-to-digital converter circuit 200 shown in Figure 6 will only use the first signal conditioner 214 and the second signal conditioner 233 as examples. In actual production or design, the analog-to-digital converter circuit 200 may also include multiple signal conditioners. For the sake of brevity, they will not be described in detail.

[0134] In one embodiment, the first signal conditioner 214 may be a digital filter or a delay unit.

[0135] In one embodiment, the second signal conditioner 233 may be a digital filter or a delay unit.

[0136] In one embodiment, the digital-to-analog converter 200 may further include a code converter 223, as shown in FIG6. The code converter 223 can be used to adjust the bit width of the digital signal input to the second DAC 222 to adapt to the second DAC 222.

[0137] In one embodiment, the input port of the code converter 223 is coupled to the digital signal to be processed. The input port of the code converter 223 is used to input the digital signal to be processed. The output port of the code converter 223 is coupled to the first input port of the DPD 221.

[0138] In one embodiment, the input port of the code converter 223 is coupled to the output port of the DPD 221. The output port of the code converter 223 is coupled to the input port of the second DAC 222.

[0139] It should be understood that the code converter 223 can be located before the first input port of the DPD221. After code conversion, the digital signal to be processed undergoes digital predistortion and a second digital-to-analog conversion to generate the aforementioned second analog signal. Alternatively, the code converter 223 can be located after the output port of the DPD221. After digital predistortion, the digital signal to be processed undergoes code conversion and a second digital-to-analog conversion to generate the aforementioned second analog signal.

[0140] For the sake of brevity, this embodiment of the application only takes the example of the code converter 223 being located after the output port of the second DAC 222. In actual production or design, the digital-to-analog conversion circuit 200 may also include multiple code converters. For the sake of brevity, they will not be described in detail.

[0141] In the digital-to-analog converter circuit 200 shown in Figure 6, only the amplifier 243, the first signal conditioner 214, the second signal conditioner 233, and the code converter 223 are shown. In actual production or design, the digital-to-analog converter circuit 200 may also include other components, such as capacitors and inductors. For the sake of brevity, they will not be described in detail.

[0142] In one embodiment, the digital-to-analog converter circuit 200 may further include a third combiner 234, a noise generator 235, and a quantizer 236, as shown in FIG7.

[0143] The first input port of the third combiner 234 is coupled to the digital signal to be processed. The first input port of the third combiner 234 is used to input the digital signal to be processed. The second input port of the third combiner 234 is coupled to the output port of the noise generator 235. The output port of the third combiner 234 is coupled to the input port of the quantizer 236. The output port of the quantizer 236 is coupled to the input port of the third DAC 231.

[0144] It should be understood that the digital signal to be processed is combined with noise, quantized, and then converted to the fourth analog signal via a third digital-to-analog converter. The digital signal generated after combining the digital signal to be processed with noise may not be periodic. When a non-periodic digital signal is quantized, the resulting error is not related to the original signal and does not affect the cancellation performed by the subsequent second combiner 232, thus reducing the nonlinearity generated by the quantizer 236. The quantizer 236 can be used to reduce the bit width of the digital signal to improve the linearity of the fourth analog signal after processing by the third DAC 231.

[0145] The digital-to-analog converter circuit 200 shown in Figure 7 illustrates only one way to improve the linearity of the third DAC 231. In actual production or design, other technical solutions can also be used to improve the linearity of the third DAC 231, such as power back-off, reducing bit width, reducing signal-to-noise ratio, or dynamic matching, etc. For the sake of brevity, these will not be elaborated on further.

[0146] In one embodiment, the output port of coupler 213 can be coupled to an antenna in a communication device. In another embodiment, the output port of coupler 213 can be coupled to a radio frequency circuit in a communication device to process the analog signal output from the output port of coupler 213, for example, by up-conversion.

[0147] It should be understood that the digital-to-analog converter circuit 200 shown in Figures 5 to 7 includes only one main channel. In actual production or design, the digital-to-analog converter circuit 200 may include multiple main channels, with multiple main channels sharing a single feedback channel. This feedback channel can improve the linearity of multiple main channels. Under this technical solution, the layout space for multiple main channels is smaller, making it easier to implement in the increasingly limited internal space of communication equipment. For the sake of brevity, further details will not be provided.

[0148] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A digital-to-analog conversion circuit, characterized by comprising: include: The system comprises a digital predistorter (DPD), a first digital-to-analog converter (DAC), and a coupler. The first input port of the DPD is used to input the digital signal to be processed, and the output port of the DPD is coupled to the input port of the first DAC. The output port of the first DAC is coupled to the input port of the coupler. The second DAC and the first combiner are described. The input port of the second DAC is used to input the digital signal to be processed. The first input port of the first combiner is coupled to the coupling port of the coupler. The second input port of the first combiner is coupled to the output port of the second DAC. The analog-to-digital converter (ADC) and the digital solver are provided. The input port of the ADC is coupled to the output port of the first combiner, the output port of the ADC is coupled to the first input port of the digital solver, the second input port of the digital solver is used to input the digital signal to be processed, and the output port of the digital solver is coupled to the second input port of the DPD.

2. The digital-to-analog conversion circuit of claim 1, wherein, The digital-to-analog converter circuit also includes: Amplifier; The input port of the amplifier is coupled to the output port of the first combiner, and the output port of the amplifier is coupled to the input port of the ADC.

3. The digital-to-analog conversion circuit according to claim 1 or 2, characterized in that, The digital-to-analog converter circuit also includes: First signal conditioner; The input port of the first signal conditioner is used to input the digital signal to be processed, and the output port of the first signal conditioner is coupled to the input port of the second DAC.

4. The digital-to-analog conversion circuit according to any one of claims 1 to 3, characterized in that, The digital-to-analog converter circuit also includes: Code converter; The input port of the code converter is used to input the digital signal to be processed, and the output port of the code converter is coupled to the first input port of the DPD, or... The input port of the code converter is coupled to the output port of the DPD, and the output port of the code converter is coupled to the input port of the first DAC.

5. The digital-to-analog conversion circuit according to any one of claims 1 to 4, characterized in that, The digital-to-analog converter circuit also includes: Noise generator, second combiner, and quantizer; The first input port of the second combiner is used to input the digital signal to be processed, the second input port of the second combiner is coupled to the output port of the noise generator, the output port of the second combiner is coupled to the input port of the quantizer, and the output port of the quantizer is coupled to the input port of the second DAC.

6. The digital-to-analog converter circuit according to any one of claims 1 to 5, characterized in that, The linearity of the second DAC is greater than that of the first DAC; The dynamic range of the second DAC is smaller than that of the first DAC, and / or the bit width of the second DAC is smaller than that of the first DAC.

7. A method of digital-to-analog conversion, characterized by, include: The digital signal to be processed undergoes digital predistortion and is then converted into a first analog signal via a first digital-to-analog converter. The digital signal to be processed is converted into a second analog signal through a second digital-to-analog converter; The second analog signal and the third analog signal are combined and then converted from analog to digital to generate a first digital signal. The third analog signal is generated by coupling the first analog signal. The digital signal to be processed and the first digital signal are digitally processed to generate a second digital signal, which is used to adjust the compensation of the digital signal to be processed in digital predistortion.

8. The method of claim 7, wherein, The second and third analog signals are combined and then converted by analog-to-digital converters to generate a first digital signal, including: The second analog signal and the third analog signal are combined, amplified, and then converted from analog to digital to generate the first digital signal.

9. The method according to claim 7 or 8, characterized in that, The digital signal to be processed is converted into a second analog signal through a second digital-to-analog converter, including: The digital signal to be processed is conditioned and then converted into the second analog signal by a second digital-to-analog converter.

10. The method according to any one of claims 7 to 9, characterized in that, The digital signal to be processed, after digital predistortion, undergoes a first digital-to-analog conversion to generate a first analog signal, including: The digital signal to be processed undergoes digital predistortion after code conversion and is then converted to analog signal via a first digital-to-analog converter to generate the first analog signal, or... The digital signal to be processed is digitally predistorted, then undergoes code conversion and is converted into the first analog signal through a first digital-to-analog conversion.

11. The method according to any one of claims 7 to 10, characterized in that, The digital signal to be processed is converted into a second analog signal through a second digital-to-analog converter, including: The digital signal to be processed is combined with noise, quantized, and then converted into the second analog signal by a second digital-to-analog converter.

12. A digital-to-analog conversion circuit, characterized by comprising: include: The system comprises a first digital-to-analog converter (DAC), a first combiner, and a coupler. The input port of the first DAC is used to input the digital signal to be processed. The output port of the first DAC is coupled to the first input port of the first combiner, and the output port of the first combiner is coupled to the input port of the coupler. The digital predistorter (DPD) and the second DAC are provided. The first input port of the DPD is coupled to the digital signal to be processed, the output port of the DPD is coupled to the input port of the second DAC, and the output port of the second DAC is coupled to the second input port of the first combiner. A third DAC and a second combiner, wherein the input port of the third DAC is used to input the digital signal to be processed, the first input port of the second combiner is coupled to the coupling port of the coupler, and the second input port of the second combiner is coupled to the output port of the third DAC; The analog-to-digital converter (ADC) and the digital solver are provided. The input port of the ADC is coupled to the output port of the second combiner, the output port of the ADC is coupled to the first input port of the digital solver, the second input port of the digital solver is used to input the digital signal to be processed, and the output port of the digital solver is coupled to the second input port of the DPD.

13. The digital-to-analog conversion circuit of claim 12, wherein, The digital-to-analog converter circuit also includes: First signal conditioner; The input port of the first signal conditioner is used to input the digital signal to be processed, and the output port of the first signal conditioner is coupled to the input port of the first DAC.

14. The digital-to-analog conversion circuit of claim 12 or 13, wherein, The digital-to-analog converter circuit also includes: Second signal conditioner; The input port of the second signal conditioner is used to input the digital signal to be processed, and the output port of the second signal conditioner is coupled to the input port of the third DAC.

15. The digital-to-analog conversion circuit according to any one of claims 12 to 14, characterized in that, The digital-to-analog converter circuit also includes: Amplifier; The input port of the amplifier is coupled to the output port of the second combiner, and the output port of the amplifier is coupled to the input port of the ADC.

16. The digital-to-analog conversion circuit of any one of claims 12 to 15, wherein, The digital-to-analog converter circuit also includes: Code converter; The input port of the code converter is used to input the digital signal to be processed, and the output port of the code converter is coupled to the first input port of the DPD, or... The input port of the code converter is coupled to the output port of the DPD, and the output port of the code converter is coupled to the input port of the second DAC.

17. The digital-to-analog conversion circuit of any one of claims 12 to 16, wherein, The digital-to-analog converter circuit also includes: Noise generator, third combiner, and quantizer; The first input port of the third combiner is used to input the digital signal to be processed. The second input port of the third combiner is coupled to the output port of the noise generator. The output port of the third combiner is coupled to the input port of the quantizer. The output port of the quantizer is coupled to the input port of the third DAC.

18. The digital-to-analog converter circuit according to any one of claims 12 to 17, characterized in that, The linearity of the third DAC is greater than the linearity of the first DAC and / or the linearity of the second DAC; The dynamic range of the third DAC is smaller than the dynamic range of the first DAC and / or the dynamic range of the second DAC, and / or, The bit width of the third DAC is smaller than the bit width of the first DAC and / or the bit width of the second DAC.

19. A method of digital-to-analog conversion, characterized by, include: The digital signal to be processed is converted into a first analog signal through a first digital-to-analog converter; The digital signal to be processed is digitally predistorted and then converted into a second analog signal by a second digital-to-analog converter. The first analog signal and the second analog signal are combined to generate a third analog signal. The digital signal to be processed is converted into a fourth analog signal through a third digital-to-analog converter. The fourth and fifth analog signals are combined and then converted from analog to digital to generate a first digital signal. The fifth analog signal is generated by coupling the third analog signal. The digital signal to be processed and the first digital signal are digitally processed to generate a second digital signal, which is used to adjust the compensation of the digital signal to be processed in digital predistortion.

20. The method of claim 19, wherein, The digital signal to be processed is converted into a first analog signal through a first digital-to-analog converter, including: The digital signal to be processed is subjected to a first signal adjustment and then undergoes a first digital-to-analog conversion to generate the first analog signal.

21. The method of claim 19 or 20, wherein, The digital signal to be processed is converted into a fourth analog signal through a third digital-to-analog converter, including: The digital signal to be processed undergoes a second signal conditioning process followed by a third digital-to-analog conversion to generate the fourth analog signal.

22. The method of any one of claims 19-21, wherein, The fourth and fifth analog signals are combined and then converted from analog to digital to generate a first digital signal, including: The fourth and fifth analog signals are combined, amplified, and then converted from analog to digital to generate the first digital signal.

23. The method of any one of claims 19-22, wherein, The digital signal to be processed, after digital predistortion, undergoes a second digital-to-analog conversion to generate a second analog signal, including: The digital signal to be processed undergoes digital predistortion after code conversion and is then converted to analog signal via a second digital-to-analog conversion to generate the second analog signal, or... The digital signal to be processed is digitally predistorted, then undergoes code conversion and a second digital-to-analog conversion to generate the second analog signal.

24. The method according to any one of claims 19 to 23, characterized in that, The digital signal to be processed is converted into a fourth analog signal through a third digital-to-analog converter, including: The digital signal to be processed is combined with noise, quantized, and then converted into the fourth analog signal by a third digital-to-analog converter.

25. A communications device, characterized by The communication device includes the digital-to-analog conversion circuit as claimed in claims 1 to 6, and as claimed in any one of claims 12 to 18.

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