Digital-to-analog conversion circuit and control chip

Abstract

The invention relates to the technical field of integrated circuits, and provides a digital-to-analog conversion circuit and a control chip. The circuit comprises a digital decoder, a nonlinear digital-to-analog converter and a linear digital-to-analog converter, the digital decoder is used for decoding the first M bits of the N-bit digital code and outputting a decoding result; the nonlinear digital-to-analog converter is connected with the linear digital-to-analog converter, and the nonlinear digital-to-analog converter is used for processing a voltage range formed by the received first input voltage and second input voltage according to a decoding result and outputting corresponding voltages respectively; the linear digital-to-analog converter receives the last N-M digital codes of the N digital codes, quantizes a voltage range formed by voltages received by the two input ends of the linear digital-to-analog converter according to the last N-M digital codes of the N digital codes, and outputs a reference voltage. According to the digital-to-analog conversion circuit provided by the embodiment of the invention, the consumption of parts and the layout area of the digital-to-analog conversion circuit can be reduced.

Description

Technical Field

[0001] The present application relates to the field of integrated circuit technology, and in particular to a digital-to-analog conversion circuit and a control chip. Background Art

[0002] Currently, the generation of a sinusoidal reference signal usually relies on a digital-to-analog conversion circuit. In related art, the design of a digital-to-analog conversion circuit can use a nonlinear digital-to-analog converter to achieve the generation of a sinusoidal reference signal.

[0003] However, if only a nonlinear digital-to-analog converter is used to generate a sinusoidal reference signal, when the digital circuit provides a large number of digital code bits to the digital-to-analog conversion circuit, the nonlinear digital-to-analog converter needs to design a large number of resistors, resulting in a large consumption of layout area by components and the digital-to-analog conversion circuit. Summary of the Invention

[0004] The present application aims to solve at least one of the technical problems existing in the related art. To this end, the present application proposes a digital-to-analog conversion circuit that can reduce the amount of layout area consumed by components and the digital-to-analog conversion circuit.

[0005] The digital-to-analog conversion circuit according to the first embodiment of the present application includes: a digital decoder, a nonlinear digital-to-analog converter, and a linear digital-to-analog converter; The digital decoder is used to decode the first M bits of the N-bit digital code and output the decoding result; The first output terminal of the nonlinear digital-to-analog converter is connected to the first input terminal of the linear digital-to-analog converter, and the second output terminal of the nonlinear digital-to-analog converter is connected to the second input terminal of the linear digital-to-analog converter. The nonlinear digital-to-analog converter is used to process a voltage range consisting of the received first input voltage and the second input voltage according to the decoding result, and output corresponding voltages through the first output terminal and the second output terminal of the nonlinear digital-to-analog converter respectively; The linear digital-to-analog converter receives the last NM bits of the N-bit digital code, quantizes a voltage range consisting of voltages received by the first input terminal and the second input terminal of the linear digital-to-analog converter respectively according to the last NM bits of the N-bit digital code, and outputs a reference voltage; Among them, M≥1, N>M.

[0006] A digital-to-analog conversion circuit is provided, comprising a digital decoder, a nonlinear digital-to-analog converter, and a linear digital-to-analog converter; the digital decoder is used to decode the first M bits of an N-bit digital code and output a decoding result; a first output end of the nonlinear digital-to-analog converter is connected to a first input end of the linear digital-to-analog converter, and a second output end of the nonlinear digital-to-analog converter is connected to a second input end of the linear digital-to-analog converter; the nonlinear digital-to-analog converter is used to process a voltage range consisting of a received first input voltage and a second input voltage based on the decoding result, and output corresponding voltages through the first output end and the second output end respectively; the linear digital-to-analog converter receives the last NM bits of the N-bit digital code, quantizes the voltage range consisting of the voltages received at the first input end and the second input end respectively based on the last NM bits of the N-bit digital code, and outputs a reference voltage. Therefore, by using high-bit digital codes to drive nonlinear digital-to-analog converters and low-bit digital codes to drive linear digital-to-analog converters, piecewise linear fitting and quantization of sinusoidal signals can be achieved within the digital-to-analog conversion circuit. There is no need to process the complete digital code through a nonlinear digital-to-analog converter, thereby reducing the consumption of components and digital-to-analog conversion circuits on the layout area while achieving the generation of sinusoidal variation reference signals.

[0007] According to one embodiment of the present application, a multi-channel analog buffer unit is further included, and the nonlinear digital-to-analog converter is connected to the linear digital-to-analog converter through the analog buffer unit; The first output terminal of the nonlinear digital-to-analog converter is connected to the first input terminal of the analog buffer unit, and the second output terminal of the nonlinear digital-to-analog converter is connected to the second input terminal of the analog buffer unit; The first output terminal of the analog buffer unit is connected to the first input terminal of the linear digital-to-analog converter, and the second output terminal of the analog buffer unit is connected to the second input terminal of the linear digital-to-analog converter; The first input terminal and the first output terminal of the analog buffer unit correspond to the same channel, and the second input terminal and the second output terminal of the analog buffer unit correspond to the same channel; The analog buffer unit is used to convert the voltage output by the nonlinear digital-to-analog converter and output the converted voltage to the linear digital-to-analog converter.

[0008] According to one embodiment of the present application, the analog buffer unit includes a first analog buffer and a second analog buffer; The first output terminal of the nonlinear digital-to-analog converter is connected to the first input terminal of the linear digital-to-analog converter through the first analog buffer, and the second output terminal of the nonlinear digital-to-analog converter is connected to the second input terminal of the linear digital-to-analog converter through the second analog buffer; The first analog buffer and the second buffer are used to convert the voltage output by the nonlinear digital-to-analog converter and output the converted voltage to the linear digital-to-analog converter.

[0009] According to one embodiment of the present application, the first analog buffer or the second analog buffer includes a first MOS transistor, a second MOS transistor, a third MOS transistor, a fourth MOS transistor, a fifth MOS transistor, a sixth MOS transistor, a seventh MOS transistor and a capacitor; The current input end of the first MOS transistor and the current input end of the fourth MOS transistor are connected to a power supply, the control end of the first MOS transistor and the control end of the fourth MOS transistor are connected to a bias voltage, and the current output end of the first MOS transistor is connected to the current input end of the second MOS transistor and the current input end of the third MOS transistor; The control end of the second MOS transistor is connected to the current output end of the fourth MOS transistor and one end of the capacitor to be connected to the linear digital-to-analog converter, and the current output end of the second MOS transistor is connected to the current input end of the fifth MOS transistor, the control end of the fifth MOS transistor, and the control end of the sixth MOS transistor; The control end of the third MOS transistor is connected to the nonlinear digital-to-analog converter, and the current output end of the third MOS transistor is connected to the current input end of the sixth MOS transistor, the control end of the seventh MOS transistor, and the other end of the capacitor; The current output end of the fifth MOS transistor, the current output end of the sixth MOS transistor, and the current output end of the seventh MOS transistor are grounded.

[0010] According to one embodiment of the present application, a digital buffer is further included; The digital buffer is used to receive the last NM bits of the N-bit digital code and output the code to the linear digital-to-analog converter.

[0011] According to one embodiment of the present application, the nonlinear digital-to-analog converter includes: a resistor string formed by alternately connecting a plurality of first resistor units and a plurality of second resistor units in series, wherein one end of the resistor string is an input end of the nonlinear digital-to-analog converter for receiving the first input voltage, one end of the resistor string is an input end of the nonlinear digital-to-analog converter for receiving the second input voltage, and two ends of the resistor string are respectively a first end of one of the first resistor units and a second end of another of the first resistor units; a plurality of first switch units, wherein a first end of each of the first switch units is connected in parallel to a first output end of the nonlinear digital-to-analog converter, and a second end of one of the switch units is connected to a first end of one of the first resistor units; A plurality of second switch units, wherein a first end of each second switch unit is connected in parallel to the second output end of the nonlinear digital-to-analog converter, and a second end of one of the switch units is connected to the second end of one of the first resistor units.

[0012] According to an embodiment of the present application, the resistance values ​​of the first resistance units are different from each other, and the resistance values ​​of the second resistance units are the same.

[0013] According to one embodiment of the present application, the linear digital-to-analog converter is a digital-to-analog converter with an R-2R structure.

[0014] The control chip according to the second embodiment of the present application includes the digital-to-analog conversion circuit as described in any of the above embodiments.

[0015] According to the second aspect of the present application, the electric device includes a stepper motor and a control chip as described in the second aspect; the control chip is connected to the stepper motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments of the present application. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0017] Figure 1 Schematic diagram for realizing sinusoidal reference voltage digitally; Figure 2 Schematic diagram of realizing sinusoidal reference voltage in analog mode; Figure 3 A first structural diagram of a digital-to-analog conversion circuit provided in an embodiment of the present application; Figure 4 A schematic diagram of the structure of a nonlinear digital-to-analog converter provided in an embodiment of the present application; Figure 5 A schematic diagram of the structure of a linear digital-to-analog converter provided in an embodiment of the present application; Figure 6 A second structural diagram of the digital-to-analog conversion circuit provided in an embodiment of the present application; Figure 7 A third structural diagram of the digital-to-analog conversion circuit provided in an embodiment of the present application; Figure 8 A schematic diagram of the structure of an analog buffer provided in an embodiment of the present application; Figure 9 A fourth structural diagram of the digital-to-analog conversion circuit provided in an embodiment of the present application; Figure 10Schematic diagram of the sinusoidal reference voltage output by the digital-to-analog conversion circuit provided in an embodiment of the present application.

[0018] Some of the accompanying drawings in the specific implementation manner are as follows: 10 - digital decoder; 20 - non-linear digital-to-analog converter; 30 - linear digital-to-analog converter; 40 - analog buffer unit; 50 - first analog buffer; 60 - second analog buffer; 70 - digital buffer. DETAILED DESCRIPTION

[0019] To make the objectives, technical solutions, and advantages of this application more clear, the technical solutions in this application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of this application.

[0020] In the description of the embodiments of this application, unless otherwise expressly specified or limited, technical terms such as "connected" and "connection" should be understood in a broad sense. For example, they may refer to direct electrical connection or connection, indirect electrical connection or connection through an intermediate medium, internal communication between two components, or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the embodiments of this application based on specific circumstances.

[0021] Below, the digital-to-analog conversion circuit and control chip provided in the embodiments of the present application will be introduced and explained in detail through several specific embodiments.

[0022] The control chip used to drive a stepper motor converts the stepping step into a sinusoidal current. Therefore, to ensure proper operation of the motor, an accurate sinusoidal reference signal, such as a sinusoidal reference voltage, must be generated within the control chip.

[0023] Currently, the generation of sinusoidal reference signals usually relies on digital-to-analog conversion circuits. The design of the digital-to-analog conversion circuit can be to use a linear digital-to-analog converter as the digital-to-analog conversion circuit to achieve the generation of sinusoidal reference signals in a digital manner. This method requires first processing through a digital circuit, using digital logic, clocks, counters, registers and other digital circuits to realize a digital code that steps according to the sine law, and then input the digital code into the linear digital-to-analog converter to generate a sinusoidal reference signal, such as Figure 1 However, this approach requires complex logic design and consumes more registers and storage units.

[0024] To this end, in related technologies, a nonlinear digital-to-analog converter can also be used as a digital-to-analog conversion circuit to achieve the generation of a sinusoidal reference signal in an analog manner. This method only requires the digital circuit to generate a linearly varying digital code, and then send the digital code to the nonlinear digital-to-analog converter so that its output presents a sinusoidal variation, such as Figure 2 This approach can simplify digital circuit design, but nonlinear DACs typically require resistors. When the digital circuit provides a large number of digital code bits to the DAC, the nonlinear DAC requires a large number of resistors, resulting in a large consumption of layout area for components and the DAC circuit.

[0025] To this end, in one embodiment, a digital-to-analog conversion circuit is provided. Figure 3 As shown, a digital-to-analog conversion circuit provided in this embodiment includes: a digital decoder 10, a nonlinear digital-to-analog converter 20, and a linear digital-to-analog converter 30. The digital decoder 10 is used to decode the first M bits of an N-bit digital code and output a decoding result. The first output terminal of the nonlinear digital-to-analog converter 20 is connected to the first input terminal of the linear digital-to-analog converter 30, and the second output terminal of the nonlinear digital-to-analog converter 20 is connected to the second input terminal of the linear digital-to-analog converter 30. The nonlinear digital-to-analog converter 20 is used to process a voltage range consisting of a received first input voltage and a second input voltage based on the decoding result, and output corresponding voltages through the first output terminal and the second output terminal of the nonlinear digital-to-analog converter 20, respectively. The linear digital-to-analog converter 30 receives the last NM bits of the N-bit digital code, and quantizes the voltage range consisting of the voltages received at the first input terminal and the second input terminal of the linear digital-to-analog converter 30 based on the last NM bits of the N-bit digital code, and outputs a reference voltage. Wherein, M≥1, N>M.

[0026] The core function of the digital decoder 10 is to convert the encoded input signal into a specific output signal. For example, the digital decoder 10 can be a binary decoder including several digital inverters and NAND gates to convert n-bit binary input into 2^n independent outputs.

[0027] In some embodiments, the output of digital decoder 10 is connected to the digital code input of nonlinear digital-to-analog converter 20. The input of digital decoder 10 receives the first M binary bits of an N-bit digital code output by the digital circuit. Digital decoder 10 is configured to decode the first M binary bits of the N-bit digital code, generating a 2^M-bit output code as the decoding result. For example, decoding the first M bits of an N-bit digital code generates a 2^M-bit thermometer code, which is then output to nonlinear digital-to-analog converter 20.

[0028] The nonlinear digital-to-analog converter 20 is a digital-to-analog converter in which the relationship between the output analog signal and the input digital code is nonlinear. It can be a 2^M-bit nonlinear digital-to-analog converter. The first output of the nonlinear digital-to-analog converter 20 is connected to the first input of the linear digital-to-analog converter 30. This connection can be direct or indirect. For example, a filter or buffer can be connected in series between the first output of the nonlinear digital-to-analog converter 20 and the first input of the linear digital-to-analog converter 30. Similarly, the second output of the nonlinear digital-to-analog converter 20 is connected to the second input of the linear digital-to-analog converter 30. This connection can be direct or indirect.

[0029] The first input terminal and the second output terminal of the nonlinear digital-to-analog converter 20 can respectively receive a first input voltage V REF and the second input voltage V SS , which is used to convert the voltage V REF and V SS The voltage range formed is divided into 2^M voltage intervals of unequal lengths. The corresponding analog voltage interval V is selected according to the decoding result received from the digital decoder 10, such as the 2^M-bit thermometer code. s1 -V s2 Then, the analog voltage V is outputted through the first output terminal of the nonlinear digital-to-analog converter 20. s1 , and outputs an analog voltage V through the second output terminal of the nonlinear digital-to-analog converter 20 s2 .

[0030] The linear DAC 30 is a device that converts digital signals into analog signals. Its output analog voltage (or current) is linearly related to the input digital code. It can be an NM-bit linear DAC. The digital code input terminal of the linear DAC 30 receives the last NM bits of the N-bit digital code. Based on the last NM bits of the digital code, the linear DAC 30 quantizes the voltage range consisting of the voltages received at the first input terminal and the second input terminal of the linear DAC 30, and ultimately outputs a reference voltage V SINE If the first input terminal of the linear DAC 30 is directly electrically connected to the first output terminal of the nonlinear DAC 20, and the second input terminal of the linear DAC 30 is directly electrically connected to the second output terminal of the nonlinear DAC 20, then the linear DAC 30 receives the analog voltage V through its first input terminal. s1 , receives the analog voltage V through its second input terminals2 , and according to the received NM-digit digital code, the analog voltage interval V s1 -V s2 Quantize and finally output the reference voltage V SINE .

[0031] As a possible implementation, the nonlinear digital-to-analog converter 20 may be an 8-bit nonlinear digital-to-analog converter, and the linear digital-to-analog converter 30 may be a 5-bit linear digital-to-analog converter. The digital decoder 10 is used to receive the high-order 3-bit digital code in the 8-bit digital code and convert it into an 8-bit thermometer code and output it to the 8-bit nonlinear digital-to-analog converter. The 8-bit nonlinear digital-to-analog converter is used to receive the first input voltage V through its first input terminal and the second output terminal respectively. REF and the second input voltage V SS and the first input voltage V REF To the second input voltage V SS Voltage range V REF -V SS It is divided into eight voltage intervals of unequal lengths. The corresponding interval is selected according to the received thermometer code, and the analog voltage V is output. s1 and the analog voltage V s2 The digital code receiving end of the 5-bit linear DAC is used to receive the last 5 bits of the same 8-bit digital code. The 5-bit linear DAC is used to quantize the voltage range composed of the analog voltages received at the first input end and the second input end of the 5-bit linear DAC according to the received last 5 bits of the digital code, and finally output a reference voltage V SINE .

[0032] A digital-to-analog conversion circuit is provided, comprising: a digital decoder, a nonlinear digital-to-analog converter, and a linear digital-to-analog converter; the digital decoder is used to decode the first M bits of an N-bit digital code and output a decoding result; a first output end of the nonlinear digital-to-analog converter is connected to a first input end of the linear digital-to-analog converter, and a second output end of the nonlinear digital-to-analog converter is connected to a second input end of the linear digital-to-analog converter; the nonlinear digital-to-analog converter is used to process a voltage range consisting of a received first input voltage and a second input voltage based on the decoding result, and output corresponding voltages through the first output end and the second output end respectively; the linear digital-to-analog converter receives the last NM bits of the N-bit digital code, quantizes the voltage range consisting of the voltages received at the first input end and the second input end respectively based on the last NM bits of the N-bit digital code, and outputs a reference voltage. Therefore, by using high-bit digital codes to drive nonlinear digital-to-analog converters and low-bit digital codes to drive linear digital-to-analog converters, piecewise linear fitting and quantization of sinusoidal signals can be achieved within the digital-to-analog conversion circuit. There is no need to process the complete digital code through a nonlinear digital-to-analog converter, thereby reducing the consumption of components and digital-to-analog conversion circuits on the layout area while achieving the generation of sinusoidal variation reference signals.

[0033] In some embodiments, as Figure 4 As shown, the nonlinear digital-to-analog converter 20 includes: a resistor string formed by alternately connecting a plurality of first resistor units and a plurality of second resistor units in series, wherein one end of the resistor string is an input end of the nonlinear digital-to-analog converter 20 for receiving the first input voltage, one end of the resistor string is an input end of the nonlinear digital-to-analog converter 20 for receiving the second input voltage, and two ends of the resistor string are respectively a first end of one of the first resistor units and a second end of another of the first resistor units; a plurality of first switch units, wherein a first end of each of the first switch units is connected in parallel to the first output end of the nonlinear digital-to-analog converter 20, and a second end of one of the switch units is connected to the first end of one of the first resistor units; A plurality of second switch units, wherein the first end of each of the first switch units is connected in parallel to the second output end of the nonlinear digital-to-analog converter 20 , and the second end of one of the switch units is connected to the second end of one of the first resistor units.

[0034] The first resistor unit includes at least one resistor, which may be a single resistor or multiple resistors connected in series, in parallel, or in series and parallel. Similarly, the second resistor unit may be a single resistor or multiple resistors connected in series, in parallel, or in series and parallel.

[0035] The number of first and second resistor units is determined by the number of bits of the nonlinear DAC 20. If the nonlinear DAC 20 needs to be an n-bit nonlinear DAC 20, the number of first and second resistor units is n and n-1.

[0036] Exemplarily, the nonlinear digital-to-analog converter 20 is an 8-bit nonlinear digital-to-analog converter, which includes R S1 -R S8 There are 8 first resistance units in total, and R INT1 -R INT7 7 second resistance units. The first resistance unit and the second resistance unit are alternately connected in series, that is, the first resistance unit R Si With the first resistance unit R S（i+1） A second resistance unit R is connected in series between INTi , thus forming a resistor string. Figure 4 As shown, the first resistance unit R S1 With the first resistance unit R S2 A second resistance unit R is connected in series between INT1 , and so on.

[0037] The first resistor in the resistor string is the first resistor unit R S1 The last resistor in the resistor string is the first resistor unit R S8 , the first resistance unit R S1 The first end of the nonlinear digital-to-analog converter 20 receives the second input voltage V SS The input terminal of the first resistor unit R S8 The second end of the nonlinear digital-to-analog converter 20 receives the first input voltage V REF For example, the first resistor unit R S1 The first end of the first resistor unit R S8 The second end is connected to the first input voltage, that is, the analog voltage V REF .

[0038] In some embodiments, the first switch unit S na and the second switch unit S nb The number of is the same as the number of bits of the nonlinear digital-to-analog converter 20. Exemplarily, the nonlinear digital-to-analog converter 20 is an 8-bit nonlinear digital-to-analog converter, which also includes S 1a -S 8a A total of 8 first switch units, and S 1b -S 8b There are 8 second switch units in total.

[0039] Each first switch unit S 1a -S 8aThe first end of the nonlinear digital-to-analog converter 20 is connected in parallel to the first output end thereof for outputting an analog voltage V s1 , each second switch unit S 1b -S 8b The first end is connected in parallel to the second output end of the nonlinear digital-to-analog converter 20 to output an analog voltage V s2 .

[0040] The first switch unit S ia The second end of the first resistor unit R Si The first end of the second switch unit S ib The second end of the first resistor unit R Si The second end of the Figure 4 As shown, the first switch unit S 1a The second end of the first resistor unit R S1 The first end of the second switch unit S 1b The second end of the first resistor unit R S1 and so on.

[0041] The first switch unit and the second switch unit connected to the two ends of the same first resistor unit are the same switch group. 1a The second end of the first resistor unit R S1 The first end of the second switch unit S 1b The second end of the first resistor unit R S1 The second end of the first switch unit S 1a and the second switch unit S 1b For the same switch group.

[0042] To ensure the nonlinearity of the output of the nonlinear DAC 20 , in some embodiments, the resistance values ​​of the first resistor units are different from each other, and the resistance values ​​of the second resistor units are the same.

[0043] Specifically, the second input voltage V is connected to the resistor string. SS The first resistor unit is connected to the first input voltage V REF In the direction of the first resistance unit, the resistance of each first resistance unit decreases in sequence. Figure 4 As shown, the resistor string includes 8 first resistor units R S1 -R S8 , the first resistor is the first resistor unit R S1 The last resistor in the resistor string is the first resistor unit R S8 , the first resistance unit R Si The resistance value of the first resistance unit R S（i+1）Since the resistance values ​​of the first resistance units are different from each other and the resistance values ​​of the second resistance units are the same, it is possible to ensure that the output of the nonlinear digital-to-analog converter 20 becomes nonlinear.

[0044] The specific resistance values ​​of each first resistor unit and each second resistor unit can be set according to actual conditions. For example, the first resistor units and each second resistor unit with corresponding resistance values ​​can be selected based on the piecewise linear fitting result of the sine function.

[0045] For example, taking the nonlinear digital-to-analog converter 20 as an 8-bit nonlinear digital-to-analog converter, when the digital decoder 10 decodes the first 3 bits of the 8-bit digital code and outputs an 8-bit thermometer code to the 8-bit nonlinear digital-to-analog converter, the first switch unit and the second switch unit can select a corresponding voltage range based on the input thermometer code, so as to select a switch group from each first switch unit and each second switch unit to close according to the voltage range, thereby outputting an analog voltage V through the first output terminal. S1 , and outputs an analog voltage V through the first output terminal S2 Specifically: ,

[0046] Wherein, n represents the first switch unit S na and the second switch unit S nb The nth switch group is formed.

[0047] In some embodiments, the linear DAC 30 may be an R-2R DAC.

[0048] For example, Figure 5 As shown, the linear digital-to-analog converter 30 is an n-bit linear digital-to-analog converter 30, which includes n single-unit resistance resistors R X1 to R Xn The series resistor string formed in series is n+2 resistors with twice the resistance value R Y1 to R Y（n+2） , and n+1 selection switches T S1 to T S（n+1） Among them, the resistor R X1 One end is connected to the first and second resistors R with twice the resistance Y1 and R Y2 The other end is connected to a third resistor R with twice the resistance Y3 The second to last unit resistance resistor R X2 to R Xn With similar connection relationship: the nth (n>1) unit resistance resistor R Xn One end is connected to the n+1th resistor R with twice the resistance Y（n+1）The other end is connected to the n+2th resistor R with twice the resistance Y（n+2） The last unit resistance resistor R in the series resistor string Xn The other end is connected to the output end of the output reference voltage VSINE.

[0049] The first resistor R has twice the resistance Y1 One end is connected to the second input terminal of the linear digital-to-analog converter 30, and the other end is connected to the resistor R X1 and a second resistor R with twice the resistance Y2 Connected; the second to n+2 resistors with twice the resistance R Y2 to R Y（n+2） Similar connection relationship: the nth resistor R with twice the resistance Yn One end is connected to the n-1th unit resistance resistor R X（n-1） The other end is connected to the n-1 selection switch T S（n-1） The last double unit resistor R Y（n+2） One end of the selector switch is connected to the output end of the output reference voltage VSINE. The normally closed contact of each selector switch is connected in parallel to the first input end of the linear digital-to-analog converter 30, and the normally open contact of each selector switch is connected in parallel to the second input end of the linear digital-to-analog converter 30.

[0050] In order to further improve the accuracy of the sinusoidal reference signal output by the digital-to-analog conversion circuit, in some embodiments, Figure 6 As shown, the digital-to-analog conversion circuit further includes a multi-channel analog buffer unit 40, and the nonlinear digital-to-analog converter 20 is connected to the linear digital-to-analog converter 30 through the analog buffer unit 40; The first output terminal of the nonlinear digital-to-analog converter 20 is connected to the first input terminal of the analog buffer unit 40, and the second output terminal of the nonlinear digital-to-analog converter 20 is connected to the second input terminal of the analog buffer unit 40; The first output terminal of the analog buffer unit 40 is connected to the first input terminal of the linear digital-to-analog converter 30 , and the second output terminal of the analog buffer unit 40 is connected to the second input terminal of the linear digital-to-analog converter 30 ; The first input terminal and the first output terminal of the analog buffer unit 40 correspond to the same channel, and the second input terminal and the second output terminal of the analog buffer unit 40 correspond to the same channel; The analog buffer unit 40 is used to convert the voltage output by the nonlinear D / A converter 20 and output the converted voltage to the linear D / A converter 30 .

[0051] In some embodiments, the analog buffer unit 40 may be a dual-channel analog buffer, primarily used for impedance matching, signal isolation, and driving capability enhancement. Its function is to improve the driving capability of the signal and reduce the impact of the load on the source signal without changing the signal amplitude.

[0052] Since the first input terminal and the first output terminal of the analog buffer unit 40 correspond to the same channel, and the second input terminal and the second output terminal correspond to the same channel, the analog buffer unit 40 can receive the analog voltage V outputted by the first output terminal of the nonlinear digital-to-analog converter 20 through the first input terminal. s1 and convert the analog voltage V s1 Convert to analog voltage V UP The first input terminal of the linear DAC 30 receives the analog voltage V outputted from the second output terminal of the nonlinear DAC 20 through the second input terminal of the linear DAC 30. s2 and convert the analog voltage V s2 Convert to analog voltage V DOWN Output to the second input terminal of the linear digital-to-analog converter 30, so that the linear digital-to-analog converter 30 converts the analog voltage V UP and the analog voltage V DOWN The analog voltage range V UP -V DOWN Quantize and finally output the reference voltage V SINE .

[0053] Since an analog buffer unit is provided between the nonlinear digital-to-analog converter 20 and the linear digital-to-analog converter 30, the nonlinear digital-to-analog converter 20 and the linear digital-to-analog converter 30 can be physically isolated by the analog buffer unit 40, thereby reducing the influence of the resistance value in the nonlinear digital-to-analog converter 20 on the output voltage of the linear digital-to-analog converter 30 and improving the accuracy of the sinusoidal reference signal output by the digital-to-analog conversion circuit.

[0054] In some embodiments, as Figure 7 As shown, the analog buffer unit 40 includes a first analog buffer 50 and a second analog buffer 60; The first output terminal of the nonlinear digital-to-analog converter 20 is connected to the first input terminal of the linear digital-to-analog converter 30 through the first analog buffer 50, and the second output terminal of the nonlinear digital-to-analog converter 20 is connected to the second input terminal of the linear digital-to-analog converter 30 through the second analog buffer 60; The first analog buffer 50 and the second buffer are used to convert the voltage output by the nonlinear D / A converter 20 and output the converted voltage to the linear D / A converter 30 .

[0055] In some embodiments, the first analog buffer 50 and the second analog buffer 60 can be identical. Analog buffers can be voltage followers or unity-gain amplifiers, primarily used for impedance matching, signal isolation, and enhanced drive capability. Their purpose is to improve signal drive capability and reduce the impact of load on the source signal without changing the signal amplitude.

[0056] The first output of the nonlinear digital-to-analog converter 20 is indirectly electrically connected to the first input of the linear digital-to-analog converter 30 via a first analog buffer 50, and the second output of the nonlinear digital-to-analog converter 20 is indirectly electrically connected to the second input of the linear digital-to-analog converter 30 via a second analog buffer 60. Specifically, the first output of the nonlinear digital-to-analog converter 20 is connected to the input of the first analog buffer 50, and the output of the first analog buffer 50 is connected to the first input of the linear digital-to-analog converter 30; the second output of the nonlinear digital-to-analog converter 20 is connected to the input of the second analog buffer 60, and the output of the second analog buffer 60 is connected to the second input of the linear digital-to-analog converter 30.

[0057] The first analog buffer 50 is used to convert the analog voltage V outputted from the first output terminal of the nonlinear digital-to-analog converter 20 into s1 Convert to analog voltage V UP The second analog buffer 60 is used to output the analog voltage V outputted from the second output terminal of the nonlinear digital-to-analog converter 20 to the first input terminal of the linear digital-to-analog converter 30. s2 Convert to analog voltage V DOWN Output to the second input terminal of the linear digital-to-analog converter 30, so that the linear digital-to-analog converter 30 converts the analog voltage V UP and the analog voltage V DOWN The analog voltage range V UP -V DOWN Quantize and finally output the reference voltage V SINE .

[0058] Since the first analog buffer 50 and the second analog buffer 60 are provided between the nonlinear digital-to-analog converter 20 and the linear digital-to-analog converter 30, the nonlinear digital-to-analog converter 20 and the linear digital-to-analog converter 30 can be physically isolated by the first analog buffer 50 and the second analog buffer 60, thereby reducing the influence of the resistance value in the nonlinear digital-to-analog converter 20 on the output voltage of the linear digital-to-analog converter 30 and improving the accuracy of the sinusoidal reference signal output by the digital-to-analog conversion circuit.

[0059] In some embodiments, the first analog buffer 50 and the second analog buffer 60 are the same analog buffer. The analog buffer may be composed of an operational amplifier with a two-stage amplification structure. For example, Figure 8 As shown, the first analog buffer 50 or the second analog buffer 60 includes: A first MOS transistor M1, a second MOS transistor M2, a third MOS transistor M3, a fourth MOS transistor M4, a fifth MOS transistor M5, a sixth MOS transistor M6, a seventh MOS transistor M7 and a capacitor C; a current input end of the first MOS transistor M1 and a current input end of the fourth MOS transistor M4 are connected to a power supply, a control end of the first MOS transistor M1 and a control end of the fourth MOS transistor M4 are connected to a bias voltage, a current output end of the first MOS transistor M1 is connected to a current input end of the second MOS transistor M2 and a current input end of the third MOS transistor M3; a control end of the second MOS transistor M2 is connected to a current output end of the fourth MOS transistor M4 and a capacitor C. One end is connected to the linear digital-to-analog converter 30, a current output end of the second MOS transistor M2 is connected to the current input end of the fifth MOS transistor M5, the control end of the fifth MOS transistor M5, and the control end of the sixth MOS transistor M6; the control end of the third MOS transistor M3 is connected to the nonlinear digital-to-analog converter 20, a current output end of the third MOS transistor M3 is connected to the current input end of the sixth MOS transistor M6, the control end of the seventh MOS transistor M7, and the other end of the capacitor C; the current output end of the fifth MOS transistor M5, the current output end of the sixth MOS transistor M6, and the current output end of the seventh MOS transistor M7 are grounded.

[0060] Any of the first to seventh MOS transistors may be a PMOS transistor or an NMOS transistor. The PMOS transistor has a gate as its control terminal, a source as its current input terminal, and a drain as its current output terminal; the NMOS transistor has a gate as its control terminal, a drain as its current input terminal, and a source as its current output terminal.

[0061] For example, Figure 8As shown, the first MOS transistor M1 , the second MOS transistor M2 , the third MOS transistor M3 and the fourth MOS transistor M4 are PMOS transistors, and the fifth MOS transistor M5 , the sixth MOS transistor M6 and the seventh MOS transistor M7 are NMOS transistors. The source of the first MOS transistor M1 and the source of the fourth MOS transistor M4 are connected to the power supply VDD, the gate of the first MOS transistor M1 and the gate of the fourth MOS transistor M4 are connected to the bias voltage PB, the drain of the first MOS transistor M1 is connected to the source of the second MOS transistor M2 and the source of the third MOS transistor M3; the gate of the second MOS transistor M2 is connected to the drain of the fourth MOS transistor M4 and one end of the capacitor C to be connected to the first input terminal or the second input terminal of the linear digital-to-analog converter 30, the drain of the second MOS transistor M2 is connected to the drain of the fifth MOS transistor M5, the gate of the fifth MOS transistor M5, and the gate of the sixth MOS transistor M6; the gate of the third MOS transistor M3 is connected to the first output terminal or the second output terminal of the nonlinear digital-to-analog converter 20, the drain of the third MOS transistor M3 is connected to the drain of the sixth MOS transistor M6, the gate of the seventh MOS transistor M7, and the other end of the capacitor C; the source of the fifth MOS transistor M5, the source of the sixth MOS transistor M6, and the source of the seventh MOS transistor M7 are grounded.

[0062] Because the first analog buffer 50 and the second analog buffer 60 are composed of two-stage operational amplifiers, the high input impedance of MOS transistor-type operational amplifiers effectively shields the influence of the output impedance of the preceding stage. Furthermore, their unity-gain closed-loop amplification configuration accurately transmits the output voltage of the nonlinear digital-to-analog converter 20 to the subsequent stage, thereby improving the accuracy of the analog voltage received by the linear digital-to-analog converter 30 and, in turn, further enhancing the precision of the reference voltage output by the linear digital-to-analog converter 30.

[0063] In order to further improve the accuracy of the sinusoidal reference signal output by the digital-to-analog conversion circuit, in some embodiments, Figure 9 As shown, the digital-to-analog conversion circuit further includes: a digital buffer 70 ; the digital buffer 70 is used to receive the last NM bits of the N-bit digital code and output it to the linear digital-to-analog converter 30 .

[0064] In some embodiments, digital buffer 70 is a basic logic gate circuit whose core function is to enhance the driving capability and improve signal quality of digital signals while maintaining the logic state unchanged. It is primarily used for signal shaping, driving capability enhancement, and logic isolation. The output of digital buffer 70 is connected to the digital code input of linear digital-to-analog converter 30. Digital buffer 70 is configured to receive the last NM bits of an N-bit digital code through its input and output the received last NM bits of the digital code to linear digital-to-analog converter 30.

[0065] As a possible implementation, digital buffer 70 includes multiple digital inverters connected in series. Exemplarily, if linear DAC 30 is a 5-bit linear DAC, digital buffer 70 includes an even number of digital inverters connected in series, configured to receive the last 5 bits of an 8-bit digital code and send them to the 5-bit linear DAC.

[0066] By receiving the last NM bits of the N-bit digital code through the digital buffer 70 and outputting it to the linear digital-to-analog converter 30, the signal quality of the last NM bits of the digital code received by the linear digital-to-analog converter 30 can be improved, thereby improving the accuracy of the sinusoidal reference signal output by the digital-to-analog conversion circuit.

[0067] In order to make the purpose, technical solutions and advantages of this application clearer, the technical solutions in this application will be described clearly and completely below. In some embodiments, Figure 9 As shown, the digital-to-analog conversion circuit includes: The digital decoder 10 , the non-linear digital-to-analog converter 20 , the linear digital-to-analog converter 30 , the first analog buffer 50 , the second analog buffer 60 and the digital buffer 70 .

[0068] The output terminal of the digital decoder 10 is connected to the digital code input terminal of the nonlinear digital-to-analog converter 20. The input terminal of the digital decoder 10 is used to receive the first M bits of the binary digital code of the N-bit digital code output by the digital circuit. The first input terminal of the nonlinear digital-to-analog converter 20 is used to receive the first input voltage V REF The second input terminal of the nonlinear digital-to-analog converter 20 is used to receive the second input voltage V SS The first output terminal of the nonlinear digital-to-analog converter 20 is connected to the input terminal of the first analog buffer 50, and the second output terminal of the nonlinear digital-to-analog converter 20 is connected to the input terminal of the second analog buffer 60. The output terminal of the first analog buffer 50 is connected to the first input terminal of the linear digital-to-analog converter 30, and the output terminal of the second analog buffer 60 is connected to the second input terminal of the linear digital-to-analog converter 30. The digital code input terminal of the linear digital-to-analog converter 30 is connected to the output terminal of the digital buffer 70, and the output terminal of the linear digital-to-analog converter 30 is used to output the reference voltage V SINE The input end of the digital buffer 70 is used to receive the last NM bits of the N-bit digital code output by the digital circuit. The nonlinear DAC 20 is a 2^M-bit nonlinear DAC, and the linear DAC 30 is an NM-bit linear DAC. M≥1, N>M.

[0069] The digital decoder 10 is used to decode the first M bits of the binary digital code of the N-bit digital code, and obtain a 2^M-bit output code as a decoding result for output.

[0070] The nonlinear digital-to-analog converter 20 is used to convert the received first input voltage V REF and the second input voltage V SS The voltage range formed is divided into 2^M voltage intervals of unequal lengths. The corresponding interval is selected according to the decoding result output by the digital decoder 10, and the analog voltage V is output through the first output terminal. S1 , and outputs an analog voltage V through the second output terminal S2 .

[0071] The first analog buffer 50 is used to receive the analog voltage V S1 , convert it into an analog voltage V UP Output to the linear digital-to-analog converter 30; the second analog buffer 60 is used to receive the analog voltage V S2 , convert it into an analog voltage V DOWN Output to the linear digital-to-analog converter 30.

[0072] The digital buffer 70 is configured to output the received last NM bits of the digital code to the linear D / A converter 30 .

[0073] The linear digital-to-analog converter 30 is used to convert the analog voltage V UP and the analog voltage V DOWN The analog voltage range formed is V UP -V DOWN Quantize and finally output the reference voltage V SINE .

[0074] For example, the final output reference voltage V SINE Ke Ru Figure 10 shown.

[0075] On the other hand, an embodiment of the present application further provides a control chip, comprising a digital-to-analog conversion circuit as provided in any of the above embodiments.

[0076] Another embodiment of the present application provides an electric device comprising a stepper motor and the control chip provided in the above embodiment; the control chip is connected to the stepper motor. The electric device can be a power device with a stepper motor, such as a new energy vehicle, or an electronic device with a stepper motor.

[0077] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units. That is, they may be located in one place or distributed across multiple network units. Some or all of the modules may be selected based on actual needs to achieve the objectives of the present embodiment. Persons of ordinary skill in the art will be able to understand and implement the present invention without inventive effort.

[0078] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A digital-to-analog conversion circuit, characterized in that: include: Digital decoders, nonlinear digital-to-analog converters, and linear digital-to-analog converters; The digital decoder is used to decode the first M bits of the N-bit digital code and output the decoding result; The first output terminal of the nonlinear digital-to-analog converter is connected to the first input terminal of the linear digital-to-analog converter, and the second output terminal of the nonlinear digital-to-analog converter is connected to the second input terminal of the linear digital-to-analog converter. The nonlinear digital-to-analog converter is used to process a voltage range consisting of the received first input voltage and the second input voltage according to the decoding result, and output corresponding voltages through the first output terminal and the second output terminal of the nonlinear digital-to-analog converter respectively; The linear digital-to-analog converter receives the last NM bits of the N-bit digital code, quantizes a voltage range consisting of voltages received by the first input terminal and the second input terminal of the linear digital-to-analog converter respectively according to the last NM bits of the N-bit digital code, and outputs a reference voltage; Among them, M≥1, N>M.

2. The digital-to-analog conversion circuit according to claim 1, wherein: It also includes a multi-channel analog buffer unit, and the nonlinear digital-to-analog converter is connected to the linear digital-to-analog converter through the analog buffer unit; The first output terminal of the nonlinear digital-to-analog converter is connected to the first input terminal of the analog buffer unit, and the second output terminal of the nonlinear digital-to-analog converter is connected to the second input terminal of the analog buffer unit; The first output terminal of the analog buffer unit is connected to the first input terminal of the linear digital-to-analog converter, and the second output terminal of the analog buffer unit is connected to the second input terminal of the linear digital-to-analog converter; The first input terminal and the first output terminal of the analog buffer unit correspond to the same channel, and the second input terminal and the second output terminal of the analog buffer unit correspond to the same channel; The analog buffer unit is used to convert the voltage output by the nonlinear digital-to-analog converter and output the converted voltage to the linear digital-to-analog converter.

3. The digital-to-analog conversion circuit according to claim 1, wherein: The analog buffer unit includes a first analog buffer and a second analog buffer; The first output terminal of the nonlinear digital-to-analog converter is connected to the first input terminal of the linear digital-to-analog converter through the first analog buffer, and the second output terminal of the nonlinear digital-to-analog converter is connected to the second input terminal of the linear digital-to-analog converter through the second analog buffer; The first analog buffer and the second buffer are used to convert the voltage output by the nonlinear digital-to-analog converter and output the converted voltage to the linear digital-to-analog converter.

4. The digital-to-analog conversion circuit according to claim 3, wherein: The first analog buffer or the second analog buffer includes a first MOS transistor, a second MOS transistor, a third MOS transistor, a fourth MOS transistor, a fifth MOS transistor, a sixth MOS transistor, a seventh MOS transistor and a capacitor; The current input end of the first MOS transistor and the current input end of the fourth MOS transistor are connected to a power supply, the control end of the first MOS transistor and the control end of the fourth MOS transistor are connected to a bias voltage, and the current output end of the first MOS transistor is connected to the current input end of the second MOS transistor and the current input end of the third MOS transistor; The control end of the second MOS transistor is connected to the current output end of the fourth MOS transistor and one end of the capacitor to be connected to the linear digital-to-analog converter, and the current output end of the second MOS transistor is connected to the current input end of the fifth MOS transistor, the control end of the fifth MOS transistor, and the control end of the sixth MOS transistor; The control end of the third MOS transistor is connected to the nonlinear digital-to-analog converter, and the current output end of the third MOS transistor is connected to the current input end of the sixth MOS transistor, the control end of the seventh MOS transistor, and the other end of the capacitor; The current output end of the fifth MOS transistor, the current output end of the sixth MOS transistor, and the current output end of the seventh MOS transistor are grounded.

5. The digital-to-analog conversion circuit according to any one of claims 1 to 4, characterized in that: Also included is a digital buffer; The digital buffer is used to receive the last NM bits of the N-bit digital code and output the code to the linear digital-to-analog converter.

6. The digital-to-analog conversion circuit according to any one of claims 1 to 4, characterized in that: The nonlinear digital-to-analog converter comprises: a resistor string formed by alternately connecting a plurality of first resistor units and a plurality of second resistor units in series, wherein one end of the resistor string is an input end of the nonlinear digital-to-analog converter for receiving the first input voltage, one end of the resistor string is an input end of the nonlinear digital-to-analog converter for receiving the second input voltage, and two ends of the resistor string are respectively a first end of one of the first resistor units and a second end of another of the first resistor units; a plurality of first switch units, wherein a first end of each of the first switch units is connected in parallel to a first output end of the nonlinear digital-to-analog converter, and a second end of one of the switch units is connected to a first end of one of the first resistor units; A plurality of second switch units, wherein a first end of each second switch unit is connected in parallel to the second output end of the nonlinear digital-to-analog converter, and a second end of one of the switch units is connected to the second end of one of the first resistor units.

7. The digital-to-analog conversion circuit according to claim 6, wherein: The resistance values ​​of the first resistance units are different from each other, and the resistance values ​​of the second resistance units are the same.

8. The digital-to-analog conversion circuit according to any one of claims 1 to 4 and 7, characterized in that: The linear digital-to-analog converter is a digital-to-analog converter with an R-2R structure.

9. A control chip, characterized in that: The method comprises the digital-to-analog conversion circuit according to any one of claims 1 to 8.

10. An electric device, characterized in that: It comprises a stepper motor and the control chip as claimed in claim 9; the control chip is connected to the stepper motor.

Images