Digital-to-analog converter and digital-to-analog conversion circuit thereof

Abstract

A digital-to-analog conversion circuit disclosed by the present invention comprises a digital-to-analog conversion module having a first reference end, a second reference end and an analog output end, the first reference end being used for being connected with a first reference voltage, the second reference end being used for being connected with a second reference voltage, and the analog output end being used for being connected with the analog output end. The digital-to-analog conversion module is used for converting an input digital code value into an analog voltage signal of an analog output end, and the analog voltage signal changes in a first voltage range; the voltage adjusting module is connected between the analog output end of the digital-to-analog conversion module and the first reference end and / or the second reference end, and the voltage adjusting module is used for adjusting the equivalent output impedance and the common-mode voltage of the digital-to-analog conversion module so as to adjust the upper limit value and / or the lower limit value of the first voltage range. Therefore, the output precision can be ensured while the first voltage range of the analog voltage signal is adjusted.

Description

Technical Field

[0001] The present invention relates to the technical field of integrated circuits, and in particular to a digital-to-analog converter and a digital-to-analog conversion circuit thereof. Background Art

[0002] In current-output DACs, precise control and regulation of the output current is critical. Figure 1 FIG. 1 shows a schematic diagram of a digital-to-analog converter according to the prior art. Figure 1 The digital-to-analog converter 100 is a current output type digital-to-analog converter, including a digital-to-analog conversion circuit 110, operational amplifiers A1-A2, resistors R1-R3, and transistors M1-M2. The digital-to-analog conversion circuit 110 is used to convert the input digital code value into an analog voltage signal V DAC , operational amplifier A1, transistor M1 and resistor R1 are used to convert the analog voltage signal V DAC The operational amplifier A2, the transistor M2, and the resistors R2 and R3 are used to amplify the first current to obtain an output current Iout. The output current Iout is expressed as:

[0003] There are generally two methods for adjusting the output range of the output current Iout in the prior art. One is to replace the resistor R2 with an adjustable resistor, and change the ratio of the resistor R2 to the resistor R3 by changing the resistance value of the resistor R2, so as to achieve the purpose of changing the output range (only the upper limit value) of the output current Iout. The other is to use an R-2R ladder resistor network architecture as the digital-to-analog conversion circuit 110, and change the output range of the output current Iout by changing the voltage values ​​of its two reference voltages. Both methods will reduce the output accuracy of the digital-to-analog converter 100 and increase the chip area.

[0004] Therefore, a new digital-to-analog converter is needed to solve the above problems. Summary of the invention

[0005] In view of the above problems, an object of the present invention is to provide a digital-to-analog converter and a digital-to-analog conversion circuit thereof, so as to ensure output accuracy while adjusting the first voltage range of an analog voltage signal.

[0006] According to one aspect of the present invention, there is provided a digital-to-analog conversion circuit, comprising a digital-to-analog conversion module having a first reference terminal, a second reference terminal and an analog output terminal, wherein the first reference terminal is used to be connected to a first reference voltage, the second reference terminal is used to be connected to a second reference voltage, the digital-to-analog conversion module is used to convert an input digital code value into an analog voltage signal of the analog output terminal, wherein the analog voltage signal varies within a first voltage range; and a voltage adjustment module connected between the analog output terminal of the digital-to-analog conversion module and the first reference terminal and / or the second reference terminal, the voltage adjustment module is used to adjust the equivalent output impedance and common-mode voltage of the digital-to-analog conversion module to adjust the upper limit value and / or lower limit value of the first voltage range.

[0007] Optionally, the digital-to-analog conversion module is an R-2R ladder resistor network architecture, and the digital-to-analog conversion module includes multiple first resistors, multiple second resistors and a third resistor, the multiple first resistors are connected in series on the main resistor path between the analog output end and the first end of the third resistor, the second end of the third resistor is connected to the second reference voltage, and except for the last second resistor, each of the second resistors is located on the resistor branch between adjacent first resistors, and the last second resistor is located on the resistor branch between the third resistor and the first resistor.

[0008] Optionally, a voltage value of the first reference voltage is greater than a voltage value of the second reference voltage.

[0009] Optionally, the voltage adjustment module includes a first adjustment resistor, and the first adjustment resistor is connected between the analog output terminal and the first reference terminal or the second reference terminal.

[0010] Optionally, the voltage adjustment module also includes a second adjustment resistor, wherein, when the first adjustment resistor is connected to the first reference end, the second adjustment resistor is connected between the analog output end and the second reference end; when the first adjustment resistor is connected to the second reference end, the second adjustment resistor is connected between the analog output end and the first reference end.

[0011] Optionally, both the first adjusting resistor and the second adjusting resistor are adjustable resistors.

[0012] Optionally, the first regulating resistor and the second regulating resistor each include a plurality of regulating branches connected in parallel, and each of the regulating branches includes a fourth resistor and a third switch connected in series.

[0013] Optionally, each of the resistance branches further includes a first switch and a second switch, wherein the first switch is connected between the second end of the second resistor in the resistance branch in which it is located and the second reference end, and the second switch is connected between the second end of the second resistor in the resistance branch in which it is located and the first reference end, and one of the first switch and the second switch is selectively turned on according to the digital code corresponding to the resistance branch in which it is located.

[0014] Optionally, the on-resistance of the third switch is proportional to the on-resistance of the first switch or the second switch.

[0015] According to another aspect of the present invention, there is provided a digital-to-analog converter, comprising the digital-to-analog conversion circuit as described above; and a voltage-to-current conversion circuit for converting the analog voltage signal into an output current.

[0016] The digital-to-analog conversion circuit provided by the present invention comprises a digital-to-analog conversion module and a voltage adjustment module, wherein the digital-to-analog conversion module has a first reference terminal, a second reference terminal and an analog output terminal, wherein the first reference terminal is used to be connected to a first reference voltage, and the second reference terminal is used to be connected to a second reference voltage, and the digital-to-analog conversion module is used to convert an input digital code value into an analog voltage signal of the analog output terminal, wherein the analog voltage signal varies within a first voltage range; the voltage adjustment module is connected between the analog output terminal of the digital-to-analog conversion module and the first reference terminal and / or the second reference terminal, and the voltage adjustment module is used to adjust the equivalent output impedance and common-mode voltage of the digital-to-analog conversion module to adjust the upper limit value and / or the lower limit value of the first voltage range, so that the adjustment of the first voltage range of the analog voltage signal does not affect the output accuracy of the digital-to-analog conversion circuit, and basically does not increase the area of ​​the digital-to-analog conversion circuit.

[0017] Furthermore, the digital-to-analog converter provided in the embodiment of the present invention includes the digital-to-analog conversion circuit and the voltage-to-current conversion circuit described above. The voltage-to-current conversion circuit converts the second analog voltage into an output current. The digital-to-analog converter adjusts the output range of its output current by adjusting the first voltage range of the analog voltage signal of the digital-to-analog conversion circuit. The adjustment basically does not affect the output accuracy of the digital-to-analog converter and basically does not increase the area of ​​the digital-to-analog converter. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The above and other objects, features and advantages of the present invention will become more apparent through the following description of the embodiments of the present invention with reference to the accompanying drawings, in which:

[0019] Figure 1 A schematic structural diagram of a digital-to-analog converter according to the prior art is shown;

[0020] Figure 2 Shows Figure 1 A circuit diagram of a digital-to-analog conversion circuit in;

[0021] Figure 3 A schematic structural diagram of a digital-to-analog converter is shown;

[0022] Figure 4 Shows Figure 3 The circuit diagram of the adjustable resistor in FIG.

[0023] Figure 5 A schematic diagram of the structure of a digital-to-analog converter according to an embodiment of the present invention is shown;

[0024] Figure 6 A schematic structural diagram of a digital-to-analog conversion circuit according to an embodiment of the present invention is shown;

[0025] Figure 7 A circuit diagram of a digital-to-analog conversion circuit according to an embodiment of the present invention is shown;

[0026] Figure 8 A circuit diagram of adjusting resistance according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0027] Various embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. In each of the accompanying drawings, the same elements or modules are represented by the same or similar reference numerals. For the sake of clarity, the various parts in the accompanying drawings are not drawn to scale.

[0028] It should be understood that in the following description, a "circuit" may include a single or multiple combined hardware circuits, programmable circuits, state machine circuits, and / or elements capable of storing instructions executed by programmable circuits. When an element or circuit is said to be "connected to" another element or an element or circuit is said to be "connected between" two nodes, it may be directly coupled or connected to another element or there may be an intermediate element, and the connection between the elements may be physical, logical, or a combination thereof. Conversely, when an element is said to be "directly coupled to" or "directly connected to" another element, it means that there is no intermediate element between the two.

[0029] At the same time, certain words are used in this patent specification and claims to refer to specific components. It should be understood by those skilled in the art that hardware manufacturers may use different terms to refer to the same component. This patent specification and claims do not use differences in names as a way to distinguish components, but rather use differences in components' functions as the criteria for distinction.

[0030] In addition, it should be noted that, in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or equipment. In the absence of more restrictions, the elements defined by the statement "comprise one..." do not exclude the existence of other identical elements in the process, method, article or equipment including the elements.

[0031] Figure 2 Shows Figure 1 The circuit diagram of the digital-to-analog conversion circuit in . Figure 2 The digital-to-analog conversion circuit 110 adopts an R-2R ladder resistor network architecture, which includes a plurality of first resistors (the resistors marked as R in the figure) connected in series, and a plurality of second resistors (the resistors marked as 2R in the figure), wherein the last second resistor is connected to the first end of the last first resistor and the reference voltage V REFN The first ends of the first to the second-to-last second resistors are respectively connected to the first ends of the first to the last first resistors, and the second ends of the first to the second-to-last second resistors are selectively connected to the reference voltage V through the switch S according to the input digital code value. REFP Or the reference voltage V REFN , the second end of the first resistor provides an analog voltage V DAC .

[0032] The analog voltage V provided by the digital-to-analog conversion circuit 110 DAC The output range is (V EEFP ,V REFN ), by adjusting the reference voltage V EEFP and reference voltage V REFN The voltage value can change the range of the output current Iout (including the upper limit and the lower limit). However, since the switch S is usually implemented by a MOS tube, there is impedance when the switch S is turned on. Therefore, during the calibration process of the digital-to-analog converter 100, it is necessary to eliminate the influence of the impedance on the output current Iout. EEFP and reference voltage V REFN When the voltage value of V changes, the on-resistance of the MOS tube will change, making the original correction invalid and reducing the accuracy of the digital-to-analog converter 100. In order to improve the accuracy of the digital-to-analog converter 100, it is necessary to adjust the reference voltage V for different reference voltages. EEFP and reference voltage VREFN Performing calibration and storing the calibration code not only wastes time but also increases the chip area of ​​the digital-to-analog converter 100 .

[0033] Figure 3 A schematic diagram of the structure of a digital-to-analog converter is shown. Figure 3 The structure of the digital-to-analog converter 200 is basically the same as that of the digital-to-analog converter 100, except that the resistor R2 of the digital-to-analog converter 200 is an adjustable resistor. By adjusting the resistance value of the resistor R2, the ratio of the resistor R2 to R3 can be changed, thereby adjusting the output range (only the upper limit value) of the output current Iout.

[0034] Among them, the resistor R2 is used as follows Figure 4 The circuit shown in the embodiment includes a plurality of parallel-connected regulating branches, each of which includes a resistor and a switch connected in series, and the resistance of the resistor R2 is adjustable by controlling the number of switches that are turned on. Due to the presence of the switch, the resistor R2 will also have non-ideal impedance, which will change with temperature or aging. In order not to introduce gain error, the impedance of the switch needs to be as small as possible to ensure that the influence of the impedance on the output current Iout is minimized, but the low-impedance switch generally increases the area of ​​the chip. Secondly, in order to maintain the symmetry and matching of the circuit and reduce the influence of non-ideal factors on the accuracy of the output current Iout, when the resistance of the adjustable resistor R2 changes, a proportionally increased switch is usually required to be introduced on the output path of the resistor R3 for matching. Since the resistance of the adjustable resistor R2 is usually in the order of kΩ, and the ratio to the resistor R3 may reach a hundred times, this matching requirement not only increases the complexity of the design, but also may lead to a substantial increase in the area occupied by the circuit, resulting in a waste of resources. In addition, when the circuit structure is applied to a high-voltage environment, higher requirements are placed on the withstand voltage performance of the switch component. In order to meet the needs of high-voltage applications, specialized high-voltage devices must be used to build switches, which further increases the cost and difficulty of design. More importantly, although the above solution can effectively adjust the output range swing (i.e., the upper limit value) of the output current Iout, it cannot directly change the zero point offset (i.e., the lower limit value) of the output current Iout. In applications that require precise control of the current zero point, this limitation is obviously disadvantageous.

[0035] In summary, no matter whether the reference voltage V EEFP and reference voltage V REFN There are certain limitations in changing the output range of the output current Iout by adjusting the voltage value of the output current Iout or by adjusting the ratio of the resistors R2 and R3. Based on this, the present invention provides a new digital-to-analog converter to solve the above problems.

[0036] Figure 5A structural schematic diagram of a digital-to-analog converter according to an embodiment of the present invention is shown.

[0037] See also Figure 5 The digital-to-analog converter 300 includes a digital-to-analog conversion circuit 310 and a voltage-to-current conversion circuit 320. The digital-to-analog conversion circuit 310 is used to convert the input digital code value code into an analog voltage signal V DAC The voltage-to-current conversion circuit 320 is used to convert the analog voltage signal V DAC Converted into output current Iout.

[0038] Specifically, the digital-to-analog conversion circuit 310 includes a digital-to-analog conversion module 311 and a voltage adjustment module 312. The digital-to-analog conversion module 311 is used to convert the input digital code value code into an analog voltage signal V DAC , where the analog voltage signal V DAC The voltage adjustment module 312 is used to adjust the equivalent output impedance and common mode voltage of the digital-to-analog conversion module 311 to adjust the upper limit value of the first voltage range (ie, the analog voltage signal V DAC swing) and / or lower limit (i.e. analog voltage signal V DAC zero offset).

[0039] The voltage-to-current conversion circuit 320 includes operational amplifiers A1-A2, resistors R1-R3, and transistors M1-M2. The operational amplifier A1, transistor M1, and resistor R1 are used to convert the analog voltage V DAC The operational amplifier A2, the transistor M2, and the resistors R2 and R3 are used to amplify the first current to obtain the output current Iout.

[0040] The output current Iout can be expressed as:

[0041]

[0042] Figure 6 A structural schematic diagram of a digital-to-analog conversion circuit according to an embodiment of the present invention is shown.

[0043] See also Figure 6 The digital-to-analog conversion module 311 has a first reference terminal, a second reference terminal and an analog output terminal. The first reference terminal is connected to a reference voltage V REFP Connect the second reference terminal to the reference voltage V REFN The analog output terminal provides an analog voltage signal V DAC The voltage adjustment module 312 is connected between the analog output terminal of the digital-to-analog conversion module 311 and the first reference terminal and the second reference terminal.

[0044] The voltage adjustment module 312 includes adjustment resistors RN and RP. The adjustment resistor RN is connected to the analog output terminal of the digital-to-analog conversion module 311 and the reference voltage V REFN The adjusting resistor RP is connected between the analog output terminal of the digital-to-analog conversion module 311 and the reference voltage V REFP Among them, the reference voltage V REFP The voltage value is greater than the reference voltage V REFN Voltage value.

[0045] Optionally, in other embodiments of the present invention, the voltage adjustment module 312 may also only include an adjustment resistor RP or an adjustment resistor RN.

[0046] Figure 7 A circuit diagram of a digital-to-analog conversion circuit according to an embodiment of the present invention is shown.

[0047] See also Figure 7 The digital-to-analog conversion module 311 is an R-2R ladder resistor network architecture. The digital-to-analog conversion module 311 includes a plurality of second resistors R21-R2N, a plurality of first resistors R11-R1N, and a third resistor R20. The plurality of first resistors R11-R1N are connected in series on the main resistor path between the analog output terminal and the first end of the third resistor R20. The second end of the third resistor R20 is connected to the reference voltage V REFN Except for the last second resistor R2N, multiple second resistors R21-R2(N-1) are located on the resistor branch between adjacent first resistors, and the last second resistor R2N is located on the resistor branch between the third resistor R20 and the first resistor R1N. The second end (i.e., the end not connected to the first resistor) of each second resistor R2i (i∈[1,N) is selectively connected to the reference voltage V REFN Or the reference voltage V REFP The end of the first resistor R11 that is not connected to the first resistor R12 serves as the analog output end.

[0048] In addition, each resistor branch further includes a first switch Sia and a second switch Sib. The first switch Sia is connected between the second end of the second resistor R2i of the corresponding resistor branch and the reference voltage V REFN The second switch Sib is connected between the second end of the second resistor R2i of its corresponding resistor branch and the reference voltage V REFP The first switch Sia and the second switch Sib are selectively turned on according to the digital code corresponding to the resistor branch in which they are located, so that the second end of the second resistor R2i is selectively connected to the reference voltage V REFN Or the reference voltage V REFPThe digital code value code input to the digital-to-analog conversion module 311 includes multiple digital codes, and the multiple digital codes correspond to multiple resistance branches one by one. Specifically, the highest digital code corresponds to the resistance branch where the second resistor R21 is located, and the lowest digital code corresponds to the resistance branch where the second resistor R2N is located.

[0049] Optionally, the resistance of each second resistor R2i is twice the resistance of each first resistor R1i.

[0050] Optionally, the resistance of each first resistor R1i is much greater than the resistance of the resistors R1 - R3 .

[0051] Analog voltage signal V DAC It can be expressed as:

[0052] V DAC =V REFN +(V REFP -V REFN )*R M / RP+[(V REFP -V REFN )*code / 2 N ]*

[0053] (R M / R2i) where R M represents the resistance value of the regulating resistor RN, the regulating resistor RP and one of the second resistors R2i connected in parallel, and code represents the digital code value input to the digital-to-analog conversion module 311.

[0054] The above formula can be deduced:

[0055] Analog voltage signal V DAC The lower limit voltage is V REFN +(V REFP -V REFN )*R M / RP, the upper limit voltage is V REFN +[(V REFP -V REFN )*code / 2 N ]*(R M / R2i). Therefore, by adjusting the resistance values ​​of the adjusting resistors RP and RN, the analog voltage signal V DAC The first voltage range is adjusted.

[0056] Furthermore, the regulating resistor RP and the regulating resistor RN are adjustable resistors.

[0057] Optionally, by adjusting the value of the adjustment resistor RN, the analog voltage signal V DACThe upper limit value of the first voltage range is adjusted, thereby adjusting the gain (upper limit value) of the output range of the output current Iout.

[0058] Optionally, by adjusting the value of the adjustment resistor RP, the analog voltage signal V DAC The lower limit value of the first voltage range is adjusted, thereby adjusting the zero point offset (lower limit value) of the output range of the output current Iout.

[0059] Optionally, by changing the resistance values ​​of the adjusting resistor RN and the adjusting resistor RP at the same time, the analog voltage signal V DAC The upper limit value and the lower limit value of the first voltage range are adjusted, so that the gain and the zero offset of the output range of the output current Iout can be adjusted.

[0060] Figure 8 A circuit diagram of adjusting resistance according to an embodiment of the present invention is shown.

[0061] See also Figure 8 , the regulating resistor RP / RN is formed by connecting a plurality of regulating branches in parallel, each regulating branch includes a fourth resistor R3j (j∈[0,m) and a third switch S1j connected in series, and the size of the third switch S1j matches the size of the first switch Sia and the second switch Sib. Specifically, the size of the third switch S1j is set in proportion to the size of the first switch Sia or the second switch Sib, so that the on-resistance of the third switch S1j is proportional to the on-resistance of the first switch Sia or the second switch Sib.

[0062] With reference voltage V REFN =0V, reference voltage V REFP =5V, resistor R1 = 10kΩ, R2 / R3 = 40 as an example:

[0063] When the resistance values ​​of the regulating resistors RN and RP are ∞ (ie, the switches S1j in the regulating resistors RN and RP are both disconnected), the output range of the output current Iout is 0-20 mA.

[0064] When the resistance value of the regulating resistor RP is ∞ and the resistance value of the regulating resistor RN is 8 times that of the first resistor R1i, the output range of the output current Iout is 0-16 mA.

[0065] When the resistance of the regulating resistor RP is 8 times that of the first resistor R1i and the resistance of the regulating resistor RN is ∞, the output range of the output current Iout is 4-20 mA.

[0066] It is understandable that although the embodiment of the present invention uses the adjustment resistor RP / RN as Figure 8The structure shown is used as an example for explanation, but the adjustment resistors RP / RN may also be implemented by using any adjustable resistor structure in the prior art.

[0067] The digital-to-analog conversion circuit provided by an embodiment of the present invention includes a digital-to-analog conversion module and a voltage adjustment module, wherein the digital-to-analog conversion module has a first reference terminal, a second reference terminal and an analog output terminal, wherein the first reference terminal is used to connect to a first reference voltage, and the second reference terminal is used to connect to a second reference voltage, and the digital-to-analog conversion module is used to convert an input digital code value into an analog voltage signal of the analog output terminal, wherein the analog voltage signal varies within a first voltage range; the voltage adjustment module is connected between the analog output terminal of the digital-to-analog conversion module and the first reference terminal and / or the second reference terminal, and the voltage adjustment module is used to adjust the equivalent output impedance and common-mode voltage of the digital-to-analog conversion module to adjust the upper limit value and / or lower limit value of the first voltage range, so that the adjustment of the first voltage range of the analog voltage signal does not affect the output accuracy of the digital-to-analog conversion circuit, and basically does not increase the area of ​​the digital-to-analog conversion circuit.

[0068] Furthermore, the digital-to-analog converter provided in the embodiment of the present invention includes the digital-to-analog conversion circuit and the voltage-to-current conversion circuit described above. The voltage-to-current conversion circuit converts the second analog voltage into an output current. The digital-to-analog converter adjusts the output range of its output current by adjusting the first voltage range of the analog voltage signal of the digital-to-analog conversion circuit. The adjustment basically does not affect the output accuracy of the digital-to-analog converter and basically does not increase the area of ​​the digital-to-analog converter.

[0069] According to the embodiments of the present invention, as described above, these embodiments do not describe all the details in detail, nor do they limit the invention to specific embodiments. Obviously, many modifications and changes can be made based on the above description. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can make good use of the present invention and the modified use based on the present invention. The scope of protection of the present invention shall be based on the scope defined by the claims of the present invention and their equivalents.

Claims

1. A digital-to-analog conversion circuit, include: a digital-to-analog conversion module, comprising a first reference terminal, a second reference terminal and an analog output terminal, wherein the first reference terminal is used to be connected to a first reference voltage, the second reference terminal is used to be connected to a second reference voltage, and the digital-to-analog conversion module is used to convert an input digital code value into an analog voltage signal at the analog output terminal, wherein the analog voltage signal varies within a first voltage range; and A voltage adjustment module is connected between the analog output terminal of the digital-to-analog conversion module and the first reference terminal and / or the second reference terminal, and the voltage adjustment module is used to adjust the equivalent output impedance and common mode voltage of the digital-to-analog conversion module to adjust the upper limit value and / or lower limit value of the first voltage range.

2. The digital-to-analog conversion circuit according to claim 1, in, The digital-to-analog conversion module is an R-2R ladder resistor network architecture, and includes a plurality of first resistors, a plurality of second resistors, and a third resistor. The plurality of first resistors are connected in series on a resistor main path between the analog output terminal and the first end of the third resistor, and the second end of the third resistor is connected to the second reference voltage. Except for the last second resistor, each of the second resistors is located on a resistor branch between adjacent first resistors, and the last second resistor is located on a resistor branch between the third resistor and the first resistor.

3. The digital-to-analog conversion circuit according to claim 2, in, A voltage value of the first reference voltage is greater than a voltage value of the second reference voltage.

4. The digital-to-analog conversion circuit according to claim 3, in, The voltage adjustment module includes a first adjustment resistor, and the first adjustment resistor is connected between the analog output terminal and the first reference terminal or the second reference terminal.

5. The digital-to-analog conversion circuit according to claim 4, in, The voltage adjustment module also includes a second adjustment resistor, wherein: When the first regulating resistor is connected to the first reference terminal, the second regulating resistor is connected between the analog output terminal and the second reference terminal; When the first regulating resistor is connected to the second reference terminal, the second regulating resistor is connected between the analog output terminal and the first reference terminal.

6. The digital-to-analog conversion circuit according to claim 5, in, The first adjusting resistor and the second adjusting resistor are both adjustable resistors.

7. The digital-to-analog conversion circuit according to claim 6, in, The first regulating resistor and the second regulating resistor both include: A plurality of regulating branches are connected in parallel, each of the regulating branches comprises a fourth resistor and a third switch connected in series.

8. The digital-to-analog conversion circuit according to claim 7, in, Each of the resistance branches also includes a first switch and a second switch, wherein the first switch is connected between the second end of the second resistor in the resistance branch where it is located and the second reference end, and the second switch is connected between the second end of the second resistor in the resistance branch where it is located and the first reference end, and one of the first switch and the second switch is selectively turned on according to the digital code corresponding to the resistance branch where it is located.

9. The digital-to-analog conversion circuit according to claim 8, in, The on-resistance of the third switch is proportional to the on-resistance of the first switch or the second switch.

10. A digital-to-analog converter, include: The digital-to-analog conversion circuit according to any one of claims 1 to 9; as well as The voltage-to-current conversion circuit is used to convert the analog voltage signal into an output current.

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