Current source control circuit and digital to analog conversion circuit for current steering

Abstract

This application relates to the field of electronic circuit technology, and in particular to a current source control circuit and a digital-to-analog converter circuit applied to a current steering system. The control circuit stores the output signal of the adder at the first moment through a storage circuit, and then inputs the output signal of the first moment back into the adder. Then, the signal output by the adder at the second moment is accumulated with the digital signal of the first moment. After converting the digital signals of the second moment and the first moment through two thermometer code decoders, logical operations are performed on the converted first thermometer code and the second thermometer code, taking into account the magnitude of the digital signal at the first moment. The resulting switch control signals for each current source are used to control the operation of the corresponding current source. This avoids the current source controlled by the low-order digital signal having a higher probability of being selected, making the probability of each current source being selected almost equal, thereby reducing the error caused by current source mismatch in the current steering system.

Description

Technical Field

[0001] This application relates to the field of electronic circuit technology, and in particular to a current source control circuit and a digital-to-analog converter circuit applied to a current steering wheel. Background Technology

[0002] Due to their inherent structural characteristics, current-driven circuits are well-suited for high-speed, high-precision circuit systems. In a current-driven DAC (Digital to Analog Converter), the digital input signal controls a corresponding current source, and the sum of the currents from the selected sources yields the DAC's output current. However, due to manufacturing variations in integrated circuits, errors exist between the current sources in a current-driven DAC, causing the output current to deviate from the ideal output current, thus generating nonlinear errors.

[0003] For a typical thermometer-coded current-driven DAC, the deviations of each current source are different, and the probability of each current source being selected is also different. Please refer to [reference needed]. Figure 1 For example, if the input digital signal to be converted is 3, then the selected current sources are 1-3. If the input digital signal is 7 at the next moment, then the selected current sources are 1-7. And if the input digital signal is 6 at the next moment, then the selected current sources are 1-6. It is evident that in existing technology, the probability of a current source controlled by a lower-order digital signal being selected is higher than that controlled by a higher-order digital signal. Therefore, the current source controlled by the lower-order digital signal has a greater impact on DAC performance, and the error of the current source controlled by the lower-order digital signal has a significant impact on the entire circuit. In this case, the error signal is essentially correlated with the input signal, resulting in severe harmonic distortion in the DAC output signal, leading to a larger error during the operation of the digital-to-analog conversion circuit. Summary of the Invention

[0004] This application provides a current source control circuit and a digital-to-analog converter circuit for use in a current steering wheel, in order to solve the technical problem of large errors in the operation of digital-to-analog converter circuits in the prior art.

[0005] On the one hand, this application provides a current source control circuit for a current rudder, including: a storage circuit, an adder, a first thermometer code decoder, a second thermometer code decoder, and multiple logic operation circuits;

[0006] The first input terminal of the adder is used to receive the input digital signal to be transformed. The first output terminal of the adder is connected to the input terminal of the storage circuit, and the output terminal of the storage circuit is connected to the second input terminal of the adder. The storage circuit is used to store the output signal of the adder at a first moment and input the output signal into the adder. The adder is used to sum the output signal at the first moment and the signal to be transformed received at the second moment to obtain the output signal at the second moment.

[0007] The output of the adder is connected to the input of the first thermometer code decoder, the output of the storage circuit is connected to the input of the second thermometer code decoder, and the input of the logic operation circuit is connected to the outputs of the first thermometer code decoder and the second thermometer code decoder, respectively.

[0008] The first thermometer code decoder is used to convert the output signal at the second moment into a first thermometer code, and the second thermometer code decoder is used to convert the output signal at the first moment into a second thermometer code. The logic operation circuit is used to perform logic operations on the first thermometer code and the second thermometer code to obtain the corresponding switch control signal. The switch control signal is used to control the operation of the corresponding current source.

[0009] The current source control circuit for a current steering wheel provided in this application also includes a logic control circuit.

[0010] The input terminal of the logic control circuit is connected to the carry signal terminal of the adder, and the output terminal of the logic control circuit is connected to the control terminal of the logic operation circuit. The logic control circuit is used to generate a corresponding logic control signal based on the carry signal output from the carry signal terminal, so as to control the logic operation circuit to select the corresponding operation logic, thereby obtaining the corresponding switch control signal.

[0011] According to the current source control circuit for a current steering wheel provided in this application, the logic operation circuit includes an XOR gate circuit and a NAND gate circuit.

[0012] The two inputs of the XOR gate are connected to the outputs of the first thermometer code decoder and the second thermometer code decoder, respectively; the two inputs of the XNOR gate are also connected to the outputs of the first thermometer code decoder and the second thermometer code decoder, respectively; the outputs of the XOR gate and the XNOR gate are used to output the switch control signal.

[0013] The output terminal of the logic control circuit is connected to the control terminals of the XOR gate circuit and the XNOR gate circuit respectively. When the carry signal is 0, the logic control circuit controls the XOR gate circuit to work so that the signal output by the XOR gate circuit is the switch control signal; when the carry signal is 1, the logic control circuit controls the XNOR gate circuit to work so that the signal output by the XNOR gate circuit is the switch control signal.

[0014] According to the current source control circuit for a current rudder provided in this application, the logic operation circuit includes an XOR gate circuit and a NOT gate circuit.

[0015] The two inputs of the XOR gate are connected to the outputs of the first thermometer code decoder and the second thermometer code decoder, respectively. The output of the XOR gate is connected to the input of the NOT gate. The output of the NOT gate is used to output the switch control signal.

[0016] The output terminal of the logic control circuit is connected to the control terminal of the NOT gate circuit. When the carry signal is 0, the logic control circuit controls the NOT gate circuit to not work, so that the signal output by the XOR gate circuit is the switch control signal; when the carry signal is 1, the logic control circuit controls the NOT gate circuit to work, so that the signal output by the NOT gate circuit is the switch control signal.

[0017] According to the present application, a current source control circuit for a current steering wheel is provided, wherein the logic operation circuit includes an XOR gate circuit, a NOT gate circuit, and a selector circuit.

[0018] The two inputs of the XOR gate are connected to the outputs of the first thermometer code decoder and the second thermometer code decoder, respectively. One output of the XOR gate is connected to the input of the NOT gate. The other output of the XOR gate and the output of the NOT gate are both connected to the input of the selector circuit. The output of the selector circuit is used to output the switch control signal.

[0019] The output terminal of the logic control circuit is connected to the control terminal of the selector circuit. When the carry signal is 0, the selector circuit selects the signal output by the XOR gate circuit as the switch control signal; when the carry signal is 1, the selector circuit selects the signal output by the NOT gate circuit as the switch control signal.

[0020] According to the present application, a current source control circuit for a current steering wheel is provided, wherein the logic control circuit includes an AND gate circuit;

[0021] One input of the AND gate is connected to the carry signal of the adder, the other end of the AND gate is used to receive the first clock control signal, and the output of the AND gate is the output of the logic control circuit; the first clock control signal is synchronized with the second time.

[0022] According to the current source control circuit for a current rudder provided in this application, the number of logic operation circuits is M;

[0023] The M=2 N N is the maximum number of bits in the input signal to be transformed to the adder.

[0024] According to the current source control circuit for a current rudder provided in this application, the storage circuit is a register;

[0025] The register is provided with a clock signal terminal for receiving a second clock control signal, which is half a cycle later than the first clock control signal.

[0026] According to the current source control circuit for a current rudder provided in this application, the output terminals of the plurality of logic operation circuits are respectively used to connect to the control terminals of the plurality of current sources;

[0027] When the switch control signal output by the logic operation circuit is 1, the corresponding current source works; when the switch control signal output by the logic operation circuit is 0, the corresponding current source stops working.

[0028] On the other hand, this application also provides a digital-to-analog conversion circuit, which includes a current source control circuit applied to a current rudder as described in any of the above.

[0029] The current source control circuit and digital-to-analog converter circuit provided in this application for a current steering system store the output signal of the adder at the first moment through a storage circuit, and then input the output signal of the first moment back into the adder. The signal output by the adder at the second moment is then accumulated with the digital signal from the first moment. After converting the digital signals from the second moment and the first moment through two thermometer code decoders, logical operations are performed on the converted first thermometer code and the second thermometer code, taking into account the magnitude of the digital signal at the first moment. This yields the corresponding switch control signals for each current source, controlling the operation of the corresponding current source. This avoids a higher probability of the current source controlled by the lower-order digital signal being selected, ensuring that the probability of each current source being selected is almost equal, thereby reducing the error caused by current source mismatch in the current steering system. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a schematic diagram illustrating the principle of selecting a current source in a DAC in existing technology;

[0032] Figure 2 This is one of the schematic diagrams of the current source control circuit provided in this application;

[0033] Figure 3 This is one of the schematic diagrams showing the selection of the current source when the current source control circuit provided in this application is working;

[0034] Figure 4 This is the second schematic diagram of the current source control circuit provided in this application;

[0035] Figure 5 This is the second schematic diagram of selecting the current source when the current source control circuit provided in this application is working. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0037] The current source control circuit for a current rudder provided in this embodiment records the digital signal input at the first moment through a register, while an adder accumulates the digital signals input at the first moment and the second moment. Finally, two thermometer code decoders convert the digital signal input at the first moment and the currently accumulated digital signal into thermometer codes, respectively. Logical operations are then performed on the first and second thermometer codes to obtain the corresponding switch control signals to control the opening and closing of the current sources. This makes the probability of each current source being selected tend to be equal, ensuring that the error signal is independent of the input signal, thereby reducing harmonic distortion of the DAC output signal (i.e., analog signal). From a frequency domain perspective, the higher harmonic energy is now evenly distributed across the entire frequency spectrum, and low-pass filtering can then filter out portions outside the signal bandwidth. This ensures that the probability of each current source being selected tends to be equal, thereby improving the DAC's performance.

[0038] In this embodiment, the second moment is later than the first moment. The second moment can be any moment in the current cycle, and the first moment can be any moment in the previous cycle. For example, the second moment is the start moment of the current cycle, and the first moment is the end moment of the previous cycle.

[0039] Example 1:

[0040] This embodiment provides a current source control circuit for a current rudder, such as... Figure 2 The control circuit includes: a storage circuit 10, an adder 11, a first thermometer code decoder 12, a second thermometer code decoder 13, and multiple logic operation circuits 18.

[0041] In this circuit, the first input terminal of adder 11 receives the input digital signal to be converted. The first output terminal Sum of adder 11 is connected to the input terminal of storage circuit 10, and the output terminal of storage circuit 10 is connected to the second input terminal of adder 11. Storage circuit 10 stores the output signal of adder 11 at a first moment and inputs the output signal back into adder 11. Adder 11 sums the output signal at the first moment and the signal to be converted received at the second moment to obtain the output signal at the second moment. Figure 2 For ease of understanding, in this embodiment, the output signal of adder 11 at the first moment is represented as I. start The output signal of adder 11 at the second moment is represented as I. end I start and I end All are binary digital signals.

[0042] The output of adder 11 is connected to the input of first thermometer code decoder 12, the output of storage circuit 10 is connected to the input of second thermometer code decoder 13, and the input of logic operation circuit 18 is connected to the outputs of first thermometer code decoder 12 and second thermometer code decoder 13, respectively. First thermometer code decoder 12 is used to convert the output signal I at the second time step... end The first thermometer code is converted into the second thermometer code. The second thermometer code decoder 13 is used to convert the output signal I at the first moment into the first thermometer code. start The first thermometer code is converted into a second thermometer code. The logic operation circuit is used to perform logic operations on the first thermometer code and the second thermometer code to obtain the corresponding switch control signal. The switch control signal is used to control the opening and closing of the corresponding current source.

[0043] In this embodiment, the current source control circuit first employs the coordinated operation of the storage circuit 10 and the adder 11 to make the output signal I at the second moment... end The output signal I at the first moment was taken into consideration. startThe magnitude of the current source changes after being converted into thermometer code, thus altering the position of the selected current source. Finally, the output signals I at the two moments are combined. end and I start The magnitude of the signal is processed by the logic operation circuit 18 to obtain the switching control signal used to control the operation of the corresponding current source. Using the control circuit provided in this embodiment, the probability of each current source being selected tends to be equal during digital-to-analog conversion, reducing the error caused by current source mismatch in the current rudder, thereby improving the working performance of the current rudder DAC.

[0044] In one embodiment, the current source control circuit further includes a logic control circuit. The input terminal of the logic control circuit is connected to the carry signal terminal Co of the adder 11, and the output terminal of the logic control circuit is connected to the control terminal of the logic operation circuit. The logic control circuit generates a corresponding logic control signal based on the carry signal output from the carry signal terminal, thereby controlling the logic operation circuit to select the corresponding operation logic, and thus obtaining the corresponding switch control signal. The carry signal represents I. end and I start During addition, if there is a carry, the carry signal terminal Co outputs 1; otherwise, the carry signal terminal Co outputs 0. The logic control circuit controls all logic operation circuits to work according to the 1 or 0 output of the carry signal terminal Co, so as to obtain the corresponding switch control signal.

[0045] After testing, based on the control circuit provided in this embodiment, and through experimentation, if I end and I start When the carry signal during addition is 0, an XOR operation is performed on the first thermometer code and the second thermometer code output by the first thermometer code decoder 12 and the second thermometer code decoder 12. The resulting thermometer code corresponds exactly to the state of the corresponding current source. For example, after the XOR operation, the fifth bit of the thermometer code corresponding to the fifth current source is 1, which means that the fifth current source is turned on. The seventh bit of the thermometer code corresponding to the seventh current source is 0, which means that the seventh current source is turned off.

[0046] Based on the above correspondence between the current source and the thermometer code, this embodiment provides the following logic operation circuits.

[0047] In one embodiment, for example, the logic operation circuit 18 includes an XOR gate and a NAND gate. The two inputs of the XOR gate are connected to the outputs of the first thermometer code decoder 12 and the second thermometer code decoder 13, respectively; the two inputs of the NAND gate are also connected to the outputs of the first thermometer code decoder 12 and the second thermometer code decoder 13, respectively; the outputs of the XOR and NAND gates are used to output switch control signals. The outputs of the logic control circuit are connected to the control terminals of the XOR and NAND gates, respectively. For example, when the carry signal is 0, the logic control circuit controls the XOR gate to operate, so that the signal output by the XOR gate is the switch control signal; when the carry signal is 1, the logic control circuit controls the NAND gate to operate, so that the signal output by the NAND gate is the switch control signal. In this embodiment, the XOR gate circuit refers to a circuit that can perform XOR operations. Specifically, the XOR gate circuit includes an XOR gate circuit and a NOT gate circuit. First, the input signal is subjected to an XOR gate operation, and then the result of the XOR gate operation is subjected to a NOT gate operation to achieve the purpose of XOR operation.

[0048] In one embodiment, for example, the logic operation circuit 18 includes an XOR gate circuit and a NOT gate circuit. The two input terminals of the XOR gate circuit are respectively connected to the output terminals of the first thermometer code decoder 12 and the second thermometer code decoder 13. The output terminal of the XOR gate circuit is connected to the input terminal of the NOT gate circuit, and the output terminal of the NOT gate circuit is used to output a switch control signal. The output terminal of the logic control circuit is connected to the control terminal of the NOT gate circuit. When the carry signal is 0, the logic control circuit controls the NOT gate circuit to not work, so that the signal output by the XOR gate circuit is the switch control signal; when the carry signal is 1, the logic control circuit controls the NOT gate circuit to work, so that the signal output by the NOT gate circuit is the switch control signal.

[0049] In one embodiment, such as Figure 2 For example, logic operation circuit 18 includes an XOR gate 14, a NOT gate 15, and a selector circuit 16. The two inputs of the XOR gate 14 are connected to the outputs of the first thermometer code decoder 12 and the second thermometer code decoder 13, respectively. One output of the XOR gate 14 is connected to the input of the NOT gate 15. The other output of the XOR gate and the output of the NOT gate 15 are both connected to the input of the selector circuit 16. The output of the selector circuit 16 is used to output a switch control signal. The output of the logic control circuit is connected to the control terminal of the selector circuit 16. When the carry signal is 0, the selector circuit 16 selects the signal output by the XOR gate 14 as the switch control signal; when the carry signal is 1, the selector circuit 16 selects the signal output by the NOT gate 15 as the switch control signal. For example... Figure 2 In the middle, the output signal I end and Istart After decoding by the first thermometer code decoder 12 and the second thermometer code decoder 123, thermometer codes a0, a1, ... a1 are obtained respectively. M and b0, b1, ... b M , where a M and b M The value is always 0. Finally, the switch control signals obtained after the operation of logic circuit 18 are S0, S1, ... S... M When the carry signal is 0, the selector circuit 16 selects... Figure 2 The signal output from the terminal marked 0 of selector circuit 16 is a switch control signal. When the carry signal is 1, selector circuit 16 selects... Figure 2 The signal output from the terminal marked 1 is a switch control signal.

[0050] In one embodiment, such as Figure 2 The logic control circuit includes an AND gate circuit 17. One input of the AND gate circuit 17 is connected to the carry signal Co of the adder 11, and the other end of the AND gate circuit 17 is used to receive the first clock control signal Clk. The output of the AND gate circuit is the output of the logic control circuit, that is, the output of the AND gate circuit is connected to the control terminal of the selector circuit 16. In this embodiment, the first clock control signal Clk is synchronized with the second time.

[0051] Specifically, in this embodiment, the storage circuit 10 is a register; the register is provided with a clock signal terminal, which is used to receive a second clock control signal Clk′, which is half a cycle later than the first clock control signal. Correspondingly, in this embodiment, the first moment corresponds to the second clock control signal Clk′, and the second moment corresponds to the first clock control signal Clk.

[0052] Generally, the number of logic operation circuits 18 needs to be determined based on the maximum number of bits of the input signal to be transformed. For example, if the number of logic operation circuits is M, then M = 2. N N is the maximum number of bits in the input signal to the adder. The outputs of multiple logic operation circuits 18 are respectively connected to the control terminals of multiple current sources; according to the embodiment provided... Figure 2 In the circuit, when the switch control signal output by the logic operation circuit 18 is 1, the corresponding current source works; when the switch control signal output by the logic operation circuit 18 is 0, the corresponding current source stops working.

[0053] In this embodiment, taking N=2 as an example, the calibration circuit starts working. If the initial input signal to be converted (digital signal) is 01, then signal I... end =01,I start=00, after passing through two thermometer decoders, we get a0=1, a1=0, a2=0, a3=0 and b0=0, b1=0, b2=0, b3=0; corresponding a n With b n After passing through the XOR gate, the output is 1 if the values ​​are the same, and 0 if they are different; and since the carry C of the adder is also present at this time... o =0, the AND gate output of the clock signal Clk is 0. When the clock is high, the outputs of the two selectors are equal to the output of the XOR gate, i.e., S0=1, S1=0, S2=0, S3=0; during this clock cycle, when the clock goes low, the register stores the current signal, i.e., I start =01.

[0054] When the second input digital signal is 10, the input digital signal and the signal stored in the register are added together by the adder to obtain I. end =11, I start Still = 01, I end and I start After passing through two thermometer decoders, we obtain a0=1, a1=1, a2=1, a3=0 and b0=1, b1=0, b2=0, b3=0; corresponding a n With b n After passing through the XOR gate, the output is 1 if the values ​​are the same, and 0 if they are different; and since the carry C of the adder is also present at this time... o =0, and the output of the AND gate of the clock signal Clk is 0. When the clock is high, the output of the two selectors is equal to the output of the XOR gate, that is, S0=0, S1=1, S2=1, S3=0; during this clock cycle, when the clock signal goes low, the register saves the current signal, that is, I start =11. It can be seen that the XOR gate outputs 0 from a0 and b0, which removes the previous digital signal and completes the cyclic selection of the current source.

[0055] When the third input digital signal is 10, the input digital signal and the signal stored in the register are added together by the adder to obtain I. end =01,I start It remains = 11, I end and I start After passing through the thermometer decoder, we obtain a0=1, a1=0, a2=0, a3=0 and b0=1, b1=1, b2=1, b3=0; corresponding a n With b n After passing through the XOR gate, the output is 1 if the values ​​are the same, and 0 if they are different; and due to the carry C of the adder... o=1, and the clock signal Clk is ANDed with the output Clk through an AND gate. When the clock is high, the outputs of the two selectors are opposite to the output of the XOR gate, that is, the output signal of NOT gate 15 is selected, i.e., S0=1, S1=0, S2=0, S3=1; during this clock cycle, when the clock goes low, the register saves the current signal, i.e., I start =01. And so on, the control circuit in this embodiment completes the cyclic selection of current sources, making the probability of each current source being selected tend to be equal, effectively reducing the error caused by current source mismatch in the current-steering DAC. For example, Figure 3 This is a schematic diagram illustrating the selection of the current source based on the input in the circuit of this embodiment. Figure 3 Black fill indicates that the current source is selected and working, while white fill indicates that the current source is not working.

[0056] In this embodiment, based on TSMC's 22nm process and using the DWA calibration scheme proposed in this proposal, a 4-bit input signal DWA circuit was designed. The effect of the output control signal changing with the input signal is as follows: Figure 4 As shown in the figure, the control circuit cyclically selects the current source as the input signal changes. Statistics show that the control circuit provided in this embodiment has 295 gates and a delay time of 3ns, making it highly suitable for high-speed current-driven DACs.

[0057] Example 2:

[0058] Based on the design concept of this application, this embodiment provides a modified solution of the above embodiment one, such as... Figure 4 This embodiment provides a current source control circuit for a current rudder. Figure 4 The pointer register in the middle is equivalent to Figure 2 The register in, at the same time Figure 4 The adder and pointer register together form a control shift circuit. The pointer register stores the digital signal input at the first moment, and the control shift circuit controls the logarithmic shift circuit. The input binary code digital signal is decoded by the thermometer code decoder, and then the logarithmic shift circuit outputs a control signal to complete the sequential selection of the current source. The specific implementation principle and the effect of achieving equal probability selection of the current source are as follows: Figure 5 As shown, Figure 5 When the input signal is 3, current sources 1-3 are selected to operate; when the second input signal is 7, current sources 4-10 are selected to operate; and when the third input signal is 6, current sources 11-15 and current source 1 are selected to operate. Therefore, based on this embodiment... Figure 4 The circuit shown can also achieve cyclic selection of the current source, which can reduce circuit errors to some extent, but the specific construction... Figure 4The circuitry in this device is quite complex, with many gate circuits, resulting in a large circuit area and slow response speed, which limits its application in high-speed current-controlled DACs.

[0059] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. 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 can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0060] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0061] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A current source control circuit applied to a current-driven steering wheel, characterized in that, include: Storage circuit, adder, first thermometer code decoder, second thermometer code decoder, and multiple logic operation circuits; The first input terminal of the adder is used to receive the input digital signal to be converted, the first output terminal of the adder is connected to the input terminal of the storage circuit, and the output terminal of the storage circuit is connected to the second input terminal of the adder. The storage circuit is used to store the output signal of the adder at a first moment and input the output signal into the adder. The adder is used to sum the output signal at the first moment and the signal to be transformed received at the second moment to obtain the output signal at the second moment. The second moment is later than the first moment. The second moment is any moment in the current cycle, and the first moment is any moment in the previous cycle of the current cycle. The output of the adder is connected to the input of the first thermometer code decoder, the output of the storage circuit is connected to the input of the second thermometer code decoder, and the input of the logic operation circuit is connected to the outputs of the first thermometer code decoder and the second thermometer code decoder, respectively. The first thermometer code decoder is used to convert the output signal at the second moment into a first thermometer code, and the second thermometer code decoder is used to convert the output signal at the first moment into a second thermometer code. The logic operation circuit is used to perform logic operations on the first thermometer code and the second thermometer code to obtain the corresponding switch control signal. The switch control signal is used to control the operation of the corresponding current source.

2. The current source control circuit for a current-driven steering wheel according to claim 1, characterized in that, It also includes logic control circuitry; The input terminal of the logic control circuit is connected to the carry signal terminal of the adder, and the output terminal of the logic control circuit is connected to the control terminal of the logic operation circuit. The logic control circuit is used to generate a corresponding logic control signal based on the carry signal output from the carry signal terminal, so as to control the logic operation circuit to select the corresponding operation logic, thereby obtaining the corresponding switch control signal.

3. The current source control circuit applied to a current-driven steering wheel according to claim 2, characterized in that, The logic operation circuit includes an XOR gate circuit and a NAND gate circuit; The two inputs of the XOR gate are connected to the outputs of the first thermometer code decoder and the second thermometer code decoder, respectively; the two inputs of the XNOR gate are also connected to the outputs of the first thermometer code decoder and the second thermometer code decoder, respectively; the outputs of the XOR gate and the XNOR gate are used to output the switch control signal. The output terminal of the logic control circuit is connected to the control terminals of the XOR gate circuit and the XNOR gate circuit respectively. When the carry signal is 0, the logic control circuit controls the XOR gate circuit to work so that the signal output by the XOR gate circuit is the switch control signal; when the carry signal is 1, the logic control circuit controls the XNOR gate circuit to work so that the signal output by the XNOR gate circuit is the switch control signal.

4. The current source control circuit for a current-driven steering wheel according to claim 2, characterized in that, The logic operation circuit includes an XOR gate circuit and a NOT gate circuit; The two inputs of the XOR gate are connected to the outputs of the first thermometer code decoder and the second thermometer code decoder, respectively. The output of the XOR gate is connected to the input of the NOT gate. The output of the NOT gate is used to output the switch control signal. The output terminal of the logic control circuit is connected to the control terminal of the NOT gate circuit. When the carry signal is 0, the logic control circuit controls the NOT gate circuit to not work, so that the signal output by the XOR gate circuit is the switch control signal; when the carry signal is 1, the logic control circuit controls the NOT gate circuit to work, so that the signal output by the NOT gate circuit is the switch control signal.

5. The current source control circuit applied to a current-driven steering wheel according to claim 2, characterized in that, The logic operation circuit includes an XOR gate circuit, a NOT gate circuit, and a selector circuit; The two inputs of the XOR gate are connected to the outputs of the first thermometer code decoder and the second thermometer code decoder, respectively. One output of the XOR gate is connected to the input of the NOT gate. The other output of the XOR gate and the output of the NOT gate are both connected to the input of the selector circuit. The output of the selector circuit is used to output the switch control signal. The output terminal of the logic control circuit is connected to the control terminal of the selector circuit. When the carry signal is 0, the selector circuit selects the signal output by the XOR gate circuit as the switch control signal; when the carry signal is 1, the selector circuit selects the signal output by the NOT gate circuit as the switch control signal.

6. The current source control circuit for a current-driven steering wheel according to any one of claims 2 to 5, characterized in that, The logic control circuit includes an AND gate circuit; One input terminal of the AND gate is connected to the carry signal terminal of the adder, the other terminal of the AND gate is used to receive the first clock control signal, and the output terminal of the AND gate is the output terminal of the logic control circuit. The first clock control signal is synchronized with the second time.

7. The current source control circuit for a current-driven steering wheel according to claim 6, characterized in that, The number of logic operation circuits is M; The M= The N The maximum number of bits in the signal to be transformed input to the adder.

8. The current source control circuit for a current-driven steering wheel according to claim 6, characterized in that, The storage circuit is a register; The register is provided with a clock signal terminal for receiving a second clock control signal, which is half a cycle later than the first clock control signal.

9. The current source control circuit for a current-driven steering wheel according to any one of claims 3-5, characterized in that, The output terminals of the multiple logic operation circuits are respectively used to connect to the control terminals of multiple current sources; When the switch control signal output by the logic operation circuit is 1, the corresponding current source works; when the switch control signal output by the logic operation circuit is 0, the corresponding current source stops working.

10. A digital-to-analog converter circuit, characterized in that, Includes the current source control circuit applied to the current rudder as described in any one of claims 1-9.

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