CN115833840A - Method and device for realizing high-resolution digital-to-analog conversion - Google Patents
Method and device for realizing high-resolution digital-to-analog conversion Download PDFInfo
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Abstract
The application provides a method for realizing high-resolution digital-to-analog conversion, which comprises the following steps: receiving a digital signal; adding at least two groups of current-based analog signals generated by digital-to-analog conversion of the digital signals to generate a synthesized analog signal for output; performing voltage conversion on the synthesized analog signal to generate a high-resolution analog signal based on voltage; and low-pass filtering the high-resolution analog signal, and filtering high-frequency noise to obtain an expected analog signal. According to the method, the analog-to-digital conversion is combined through the multi-level operation, and then filtering and denoising are performed, so that the resolution ratio of the analog signal is increased, the cost of the high-resolution digital-to-analog conversion product is reduced, and meanwhile, the precision is improved and the noise is reduced.
Description
Technical Field
The present invention relates to the field of digital-to-analog conversion, and in particular, to a method and an apparatus for implementing high resolution digital-to-analog conversion.
Background
The information we contact in daily life is simulated, for example: images, sounds, etc., such signals being intuitive to feel and understand. However, a computer can only operate and process information in the form of binary digits, and the communication method in the field of industrial automation is often a binary digital signal. In some device control processes, it is necessary to convert a digital signal into an analog voltage or current signal before an effective control signal can be obtained. The process in which a Digital signal is converted to an Analog signal is called Digital to Analog (d/a) conversion.
The digital-to-analog converter is just a bridge between a digital signal and an analog signal, so that the digital system and an external analog system can well exchange information, and the quality of the digital-to-analog converter depends on the high resolution and high precision of the digital-to-analog conversion. In some application scenarios with high resolution requirements, a digital-to-analog converter with 16 bits or more is often required, however, a high-resolution digital-to-analog conversion chip in the market is expensive, and a high-order digital-to-analog conversion chip is often used in a specific situation, and is not ideal in terms of precision, noise and the like, and the effective bit of the high-order digital-to-analog conversion chip often cannot reach the designed order.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provide a method for realizing high-resolution digital-to-analog conversion. The application also relates to a device for realizing high-resolution digital-to-analog conversion.
The application provides a method for realizing high-resolution digital-to-analog conversion, which comprises the following steps:
receiving a digital signal;
adding at least two groups of current-based analog signals generated by digital-to-analog conversion of the digital signals to generate a synthesized analog signal for output;
performing voltage conversion on the synthesized analog signal to generate a high-resolution analog signal based on voltage;
and low-pass filtering the high-resolution analog signal, and filtering high-frequency noise to obtain an expected analog signal.
Optionally, the digital-to-analog conversion includes:
setting a secondary reference voltage of the digital-to-analog conversion;
and setting a synchronous clock of the digital-to-analog conversion.
Optionally, the secondary reference voltage is generated by a reference voltage, and the reference voltage and the secondary reference voltage satisfy the following expression:
V REF_1 ＝V REF ，k＝1
wherein, the V REF_1 Represents the first secondary reference voltage, said V REF Representing the reference voltage, K representing the number of sub-reference voltages, equal to the number of digital-to-analog conversions, R 0 Representing a resistance connected to the input of the first operational amplifier, said R a Representing the resistance of the inverting input of the first operational amplifier, for grounding, said R f Representing a feedback resistance connecting the inverting input and the output of the first operational amplifier, said i = k-2.
Optionally, the synchronous clock provides a 1MHz clock source, and is divided into at least two clocks with the same frequency and the same initial phase.
Optionally, the generating the voltage-based high-resolution analog signal includes the following expression:
V OUT1 ＝R c ×I OUT1
wherein, the I OUT1 Is an input signal, i.e. a current signal, said V OUT1 Is an output signal, i.e. a voltage signal, said R c Is the feedback resistance value of the second operational amplifier.
Optionally, the low-pass filtering and the filtering of the high-frequency noise are implemented by the following circuits:
the filter operational amplifier is grounded through a first capacitor at the same input end, grounded through a fourth resistor at the inverting input end, and connected between the first resistor and the second resistor through a second capacitor at the output end, and connected to the inverting input end through a third resistor at the output end.
Optionally, the low-pass filtering and the high-frequency noise filtering are implemented by using a digital wave recorder.
The application also provides a device for realizing high-resolution digital-to-analog conversion, which comprises the following components in sequential connection: the device comprises a microcontroller module, a digital-to-analog conversion module, a voltage conversion module and a low-pass filtering module;
the microcontroller module is used for receiving the digital signals and controlling the transmission of the data signals;
the digital-to-analog conversion module is used for adding at least two groups of analog signals of the digital signals through digital-to-analog conversion and outputting high-resolution analog signals;
the voltage conversion module is used for performing voltage conversion on the synthesized analog signal to generate a high-resolution analog signal based on voltage;
the low-pass filtering module is used for low-pass filtering the high-resolution analog signal and filtering high-frequency noise to obtain an expected analog signal.
Optionally, the microcontroller is a control chip for implementing data transmission, and transmits the digital signal to be converted to the digital-to-analog conversion module for control.
Optionally, the microcontroller module further includes: a reference voltage unit, a clock synchronization unit;
the reference voltage unit, the clock synchronization unit and the voltage conversion module are connected with the microcontroller module, and the voltage conversion module is connected with the low-pass filtering module.
The application has the advantages and beneficial effects that:
the application provides a method for realizing high-resolution digital-to-analog conversion, which comprises the following steps: receiving a digital signal; adding at least two groups of current-based analog signals generated by digital-to-analog conversion of the digital signals to generate a synthesized analog signal for output; performing voltage conversion on the synthesized analog signal to generate a high-resolution analog signal based on voltage; and low-pass filtering the high-resolution analog signal, and filtering high-frequency noise to obtain an expected analog signal. According to the method, the analog-to-digital conversion is combined through the multi-level operation, and then filtering and denoising are performed, so that the resolution ratio of the analog signal is increased, the cost of the high-resolution digital-to-analog conversion product is reduced, and meanwhile, the precision is improved and the noise is reduced.
Drawings
Fig. 1 is a schematic diagram of a process for implementing high resolution digital-to-analog conversion in the present application.
Fig. 2 is a schematic diagram of a digital-to-analog conversion reference voltage circuit in the present application.
Fig. 3 is a schematic diagram of a voltage conversion circuit according to the present application.
Fig. 4 is a schematic diagram of a low pass filter circuit in the present application.
Fig. 5 is a schematic diagram of a clock synchronization unit in the present application.
Fig. 6 is a schematic structural diagram of an apparatus for implementing high resolution digital-to-analog conversion according to the present application.
Fig. 7 is a schematic circuit diagram of two digital-to-analog conversions for achieving high resolution in the present application.
Detailed Description
The present invention is further described below in conjunction with the following figures and specific examples so that those skilled in the art may better understand the present invention and practice it.
The following is an example of a specific implementation process provided for explaining the technical solutions to be protected in the present application in detail, but the present application may also be implemented in other ways than those described herein, and a person skilled in the art may implement the present application by using different technical means under the guidance of the idea of the present application, so that the present application is not limited by the following specific embodiments.
The application provides a method for realizing high-resolution digital-to-analog conversion, which comprises the following steps: receiving a digital signal; adding at least two groups of current-based analog signals generated by digital-to-analog conversion of the digital signals to generate a synthesized analog signal for output; performing voltage conversion on the synthesized analog signal to generate a high-resolution analog signal based on voltage; and low-pass filtering the high-resolution analog signal, and filtering high-frequency noise to obtain an expected analog signal. The method and the device convert and combine digital-to-analog conversion according to the conversion degree, and then filter and denoise. The method and the device increase the resolution ratio of the analog signal, reduce the cost of a high-resolution digital-to-analog conversion product, improve the precision and reduce the noise.
Fig. 1 is a schematic diagram of a process for implementing high resolution digital-to-analog conversion in the present application.
Referring to fig. 1, S101 receives a digital signal.
The digital signal refers to a binary signal, and can be transmitted in various ways, such as a network cable, an optical fiber, and the like. In the control process of some devices, after the transmitted digital signals are converted into analog voltage or current signals, effective control signals can be obtained, and accurate control is realized.
The method mainly functions to convert the received digital signal into a high-resolution analog signal.
Referring to fig. 1, S102 adds at least two sets of current-based analog signals generated by digital-to-analog conversion of the digital signals to generate a synthesized analog signal for output.
The addition is to perform a plurality of independent digital-to-analog conversions on the digital signal, and add each digital-to-analog conversion result to improve the resolution. Specifically, a reference voltage is set, and high-resolution digital-to-analog conversion operation is completed by changing the reference voltage.
Fig. 2 is a schematic diagram of a digital-to-analog conversion reference voltage circuit in the present application.
Referring to fig. 2, the digital-to-analog conversion is at least two groups, that is, at least two digital-to-analog conversion chips are used for realizing the digital-to-analog conversion. The digital-to-analog conversion is actually realized by a first operational amplifier circuit in which R is used 0 Representing a resistance connected to the input of the first operational amplifier, said R a Representing the resistance of the inverting input of the first operational amplifier, for grounding, said R f Representing a feedback resistance connecting the inverting input and the output of the first operational amplifier. Between each of the operational amplifiers, a resistor R can be passed 1 ～R k-2 Connected and grounded.
In the present application, the reference voltage is a main reference voltage, and the operational amplifier is used for scaling down to generate a sub-reference voltage for digital-to-analog conversion. Without loss of generality, the main reference voltage generates k sub-reference voltages, which are provided for k digital-to-analog conversion. Wherein the main reference voltage is V REF The reference voltage supplied to the D/A conversion is V REF_K The following relationship is satisfied:
V REF_1 ＝V REF ，k＝1 (1)
to make the circuit structure simpler, let R f ＝R a The following formula is obtained:
can deduce the change of the resistance R 0 、R 1 The reference voltage module provides reference voltages of different digital-to-analog converters of the digital-to-analog conversion module to change the output reference voltageThe low-bit digital-to-analog converter performs high-resolution digital-to-analog conversion, wherein the output voltage V of the digital-to-analog converter with n-bit resolution OUT And input data D n The relationship is as follows:
the input data may again be represented as D = D 0 +2D 1 +…+2 n-1 D n-1 Then, obtaining:
if there are k m-bit digital-to-analog converter combinations to realize n-bit high resolution digital-to-analog conversion, where n = km (k ≧ 2), then:
the expression is the output voltage expression of k combinations of the m-bit digital-to-analog converters, which is the same as the output voltage expression of the n-bit digital-to-analog converter, and proves that the high-resolution n-bit digital-to-analog conversion can be completed by using k m-bit analog-to-digital conversion chips by adjusting the proportion of the reference voltage. The reference voltage of the kth digital-to-analog converter satisfies the following equation:
the formula (8) and the formula (2) are combined to obtain:
in the following, two digital-to-analog conversion chips are taken as an example to explain the technical solution.
Fig. 7 is a schematic circuit diagram of two digital-to-analog conversions for achieving high resolution in the present application.
Referring to fig. 7, the present application adopts two digital-to-analog conversion chips with the types of DAC1210, and simultaneously sets: the input data is a 12-bit binary number, and the resolution is 12 bits. The current establishing time is 1 mus, the power supply voltage is + 5V- +15V, single power supply is adopted for power supply, and the reference voltage V is REF The range is-10V- +10V.
Further, k represents the number of the digital-to-analog conversion chips, m represents the resolution of the input data, and n represents the resolution of the output data.
Based on the above setting, k =2,m =12,n =24, and is substituted into the following expression:
the above equation (10) can be regarded as the sum of the outputs of the two 12-bit digital-to-analog converters, which shows that 24-bit digital-to-analog conversion can be realized by the two 12-bit digital-to-analog conversion chips DAC1210, and the reference voltages of the two digital-to-analog converters can be obtained from equation (7):
the resistance R is obtained from the formula (8) 0 、R 1 The relationship of (1):
in summary, it is determined that R is in the reference voltage unit 0 ＝40.95KΩ，R 1 ＝100Ω，R 1 ＝R 1 ＝10KΩ。
Meanwhile, the clock synchronization is set to divide the clock source of 1MHz from the power divider into two completely same clocks to be sent to the two DAC1210 chips, so as to ensure the digital-to-analog conversion synchronization of the two digital-to-analog converters and reduce the error caused by the asynchronous conversion, as shown in fig. 5.
Referring to fig. 1, S103 performs voltage conversion on the synthesized analog signal to generate a high-resolution analog signal based on voltage.
In the present application, the digital-to-analog conversion outputs a current signal I OUT1 Is converted into a voltage analog signal V after passing through the second operational amplifier OUT1 。
Fig. 3 is a schematic diagram of a voltage conversion circuit according to the present application.
Referring to fig. 3, the second operational amplifier includes: feedback resistor R c The reverse input end of the operational amplifier is connected with I of a digital-to-analog converter for digital-to-analog conversion OUT1 The non-inverting input end of the second operational amplifier is grounded, and the output end of the operational amplifier passes through a feedback resistor R c The inverting input terminal is connected. Its input signal I OUT1 Output signal I OUT1 Satisfies the following relation:
V OUT1 ＝R c *I OUT1 (13)
the kth digital-to-analog converter outputs a current signal of I OUTk The input and the output of the operational amplifier satisfy the following relation:
in this embodiment, the DAC1210 is of a current output type, and outputs the current I from two digital-to-analog converters OUT1 ，I OUT2 And adding the voltage signals according to the kirchhoff current law and inputting the added voltage signals to a voltage conversion module. The voltage conversion module amplifies and converts the input current into a voltage signal in proportion, and the voltage conversion module feeds back a resistor R c Can be selected according to actual requirements, in the embodiment, R c =1K Ω. From equation (14) we can derive:
V OUT ＝1000(I OUT1 +I OUT2 ) (15)
referring to fig. 1, S104 performs low-pass filtering on the high-resolution analog signal to filter high-frequency noise, so as to obtain a desired analog signal.
Converted analog voltage signal V OUT The noise exists in the analog signal, filtering is needed, and high-frequency noise is filtered through a low-pass filter to obtain a high-precision analog signal.
In the embodiment, an improved second-order Butterworth low-pass filter is adopted, the device parameters can be adjusted correspondingly according to actual requirements without loss of generality, and in the embodiment, the parameters of the low-pass filter are set to have the cutoff frequency of 500Hz at the position of 3dB and meet the requirement that the attenuation of the low-pass filter is not less than 35dB at the position of 1 KHz. A device parameter determination process is as follows:
fig. 4 is a schematic diagram of a low pass filter circuit in the present application.
Referring to FIG. 3, the filter for filtering the analog signal output by the voltage conversion to remove the high frequency noise thereof includes an operational amplifier and a resistor R L1 Resistance R L2 Resistance R L3 Resistance R L4 Capacitor C 1 Capacitor C 2 . Wherein the input signal passes through a resistor R L1 Resistance R L2 Is connected with the non-inverting input end of an operational amplifier, and the non-inverting input end of the operational amplifier is connected with the inverting input end of the operational amplifier through a capacitor C 2 Grounded, with the inverting input terminal passing through R L4 Grounding, the output end of the operational amplifier passes through a capacitor C 1 Is connected to a resistor R L1 And a resistor R L2 The output end of the operational amplifier is connected with the output end of the operational amplifier through a resistor R L3 Is connected to the inverting input terminal. The transfer function is expressed as:
the cut-off frequency and the device parameters satisfy the following formula:
resistance R L1 And a resistor R L2 Satisfies the following formula:
specifically, in the present embodiment, C is set 1 ＝C 2 ＝0.1μf，R L1 ＝R L2 And =1K Ω, as can be seen from equations (17) and (18).
R L2 ＝1.4142 2 R L1 ＝1.4142 2 ×2250＝4501Ω
After determining each device parameter, the input signal is input to the improved second order butterworth low pass filter and the filtered signal is output.
The present application further provides a device for implementing high resolution digital-to-analog conversion, the digital-to-analog conversion device comprising: a microcontroller module 601, a digital-to-analog conversion module 602, a voltage conversion module 603 and a low pass filter module 604.
As shown in fig. 6, the apparatus includes a microprocessor module 601, a digital-to-analog conversion module 602, a reference voltage unit 6011, a clock synchronization unit 6012, a voltage conversion module 603, and a low pass filter module 604. The microprocessor module 601 transfers the input digital signal to the digital-to-analog conversion module 602, the reference voltage unit 6011 is configured to provide reference voltages of different digital-to-analog converters of the digital-to-analog conversion module, and complete high resolution digital-to-analog conversion operation by changing the reference voltage, and the clock synchronization unit 6012 is connected to the digital-to-analog conversion module 602 to maintain clock synchronization, so as to ensure simultaneous digital-to-analog conversion and simultaneous output. The output analog signal is processed by the voltage conversion module 603 and the low-pass filter module 604 to obtain a high-resolution analog signal.
The above description is only for the purpose of fully illustrating the preferred embodiments of the present invention, and the scope of the present invention is not limited thereto. The equivalent substitution or change made by the technical personnel in the technical field on the basis of the invention is all within the protection scope of the invention. The protection scope of the invention is subject to the claims.
Claims (10)
1. A method for implementing high resolution digital to analog conversion, comprising:
receiving a digital signal;
adding at least two groups of digital signals, performing digital-to-analog conversion through a digital-to-analog conversion module to obtain analog signals based on current, and generating synthetic analog signals for output;
performing voltage conversion on the synthesized analog signal to obtain a high-resolution analog signal based on voltage;
and sequentially carrying out low-pass filtering and high-frequency noise filtering on the high-resolution analog signal to obtain an expected analog signal.
2. The method of claim 1, wherein before adding at least two sets of the digital signals and performing digital-to-analog conversion by the digital-to-analog conversion module to obtain the current-based analog signal, the method further comprises:
setting a sub-reference voltage of the digital-to-analog conversion of each digital-to-analog conversion module;
and setting the synchronous clock of the digital-to-analog conversion of each digital-to-analog conversion module.
3. The method of claim 2, wherein the sub-reference voltage is generated from a reference voltage, and the reference voltage and the sub-reference voltage satisfy the following expression:
V REF_1 ＝V REF ，k＝1
wherein, the V REF_1 Represents the first secondary reference voltage, said V REF Representing the reference voltage, K representing the number of sub-reference voltages, equal to the number of digital-to-analog conversions, R 0 Showing and connectingA resistance into an input terminal of the first operational amplifier, R a Representing the resistance of the inverting input of the first operational amplifier, for grounding, said R f Representing a feedback resistance connecting the inverting input and the output of the first operational amplifier, said i = k-2.
4. The method of claim 2, wherein the synchronous clock provides a 1MHz clock source and is divided into at least two clocks of the same frequency and the same initial phase.
5. The method of claim 1, wherein generating a voltage-based high resolution analog signal comprises the following expression:
V OUT1 ＝R c ×I OUT1
wherein, the I OUT1 Is an input signal, i.e. a current signal, said V OUT1 Is an output signal, i.e. a voltage signal, said R c Is the feedback resistance value of the second operational amplifier.
6. The method of claim 1, wherein the low-pass filtering and filtering high-frequency noise is performed by:
the filter operational amplifier is grounded through a first capacitor at the same input end, grounded through a fourth resistor at the opposite input end, and connected between the first resistor and the second resistor through a second capacitor at the output end, and connected to the opposite input end through a third resistor at the output end.
7. The method of claim 6, wherein the low pass filtering and the filtering of the high frequency noise are performed using a digital recorder.
8. An apparatus for implementing high resolution digital-to-analog conversion, comprising, connected in sequence: the device comprises a microcontroller module, a digital-to-analog conversion module, a voltage conversion module and a low-pass filtering module;
the microcontroller module is used for receiving digital signals;
the digital-to-analog conversion module is used for receiving the data signals sent by the microcontroller module, adding at least two groups of analog signals of the digital signals through digital-to-analog conversion and outputting high-resolution analog signals;
the voltage conversion module is used for performing voltage conversion on the synthesized analog signal to generate a high-resolution analog signal based on voltage;
and the low-pass filtering module is used for sequentially carrying out low-pass filtering and high-frequency noise filtering on the high-resolution analog signal so as to obtain an expected analog signal.
9. The apparatus according to claim 8, wherein the microcontroller is configured to transmit the digital signal to be converted to the digital-to-analog conversion module and perform control.
10. The apparatus for implementing high resolution digital to analog conversion of claim 8, wherein the microcontroller module further comprises: a reference voltage unit, a clock synchronization unit;
the reference voltage unit, the clock synchronization unit and the voltage conversion module are connected with the microcontroller module, and the voltage conversion module is connected with the low-pass filtering module.
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