Analog-to-digital converter (ADC) real-time calibration device, control method of ADC real-time calibration device, and electronic device

Abstract

The embodiment of the application discloses an ADC real-time calibration device, a control method and electronic equipment, and relates to the field of power supply circuits. The application generates a stable reference signal through a band gap reference circuit, which significantly optimizes the performance of an ADC (analog-to-digital converter) in a complex environment. In the face of reference voltage instability caused by external factors such as voltage fluctuation and temperature change, the technology can effectively offset the gain error caused thereby, ensuring the accuracy and reliability of the ADC conversion process, thereby greatly improving the accuracy of calibration. In the gap between the normal conversion task of the ADC, the band gap reference signal is seamlessly integrated and converted, and this process does not need to interrupt the continuous work flow of the ADC, realizing efficient use of resources and smooth operation.

Description

TECHNICAL FIELD

[0001] The application relates to the field of power supplies, in particular to an ADC real-time calibration device, a chip and an electronic device. BACKGROUND

[0002] ADC is an abbreviation of Analog-to-Digital Converter, which is mainly used for converting continuous analog signals into digital signals, so that a digital system (such as a central processing unit MCU) can quickly process and analyze the transmitted information. The analog signal refers to information expressed by a continuously changing physical quantity, such as temperature, humidity, pressure, voltage, current and the like. The signal collected by the ADC module is a continuous analog signal (voltage or current) that changes continuously within a certain range, and the conversion result of the ADC module is a discontinuous digital signal (0 / 1 sequence) that often has different degrees of deviation. The most common one is the gain error introduced by the change of the reference voltage, and the bias error introduced by the change of the reference ground.

[0003] In the general sense, the ADC is calibrated by continuously sampling a certain ground signal inside the ADC, and the bias error under the current condition of the ADC is obtained through the conversion result of the reference ground. This method can eliminate the bias error introduced by the reference ground, but cannot eliminate the gain error introduced by the change of the reference signal. Moreover, this method needs to continuously sample the ground signal, and the real-time calibration is poor, and the purpose of real-time calibration during the normal operation of the ADC cannot be achieved. SUMMARY

[0004] The ADC real-time calibration device, the chip and the electronic device provided by the embodiments of the application can reduce power consumption and simplify the circuit structure. The technical solution is as follows:

[0005] In a first aspect, the embodiments of the application provide an ADC real-time calibration device, which comprises:

[0006] a bandgap reference circuit, a first switch circuit, a second switch circuit, an analog-to-digital conversion circuit and a main control circuit, the first switch circuit is provided with a first input end, a second input end, a control end and an output end, the second switch circuit is provided with an input end, a control end, a first output end and a second output end;

[0007] The first switch circuit is provided with a first input end and a second input end, the first input end is connected with an analog signal source, the second input end is connected with the bandgap reference signal, the output end of the first switch circuit is connected with the input end of the analog-to-digital converter, and the control end of the first switch circuit is connected with the main control circuit;

[0008] The reference end of the analog-digital conversion circuit is connected with the reference circuit, the control end of the analog-digital conversion circuit is connected with the master control circuit, the output end of the analog-digital conversion circuit is connected with the input end of the second switch circuit, the first output end of the second switch circuit is connected with the master control circuit, the second output end of the second switch circuit is connected with an external circuit, the calibration end of the analog-digital converter is connected with the master control circuit, and the control end of the second switch circuit is connected with the master control circuit.

[0009] In the calibration operation state, the master control circuit instructs the first switch circuit to conduct between the second input end and the output end through the control end of the first switch circuit, instructs the second switch circuit to conduct between the first input end and the first output end through the control end of the second switch circuit, and instructs the analog-digital conversion circuit to start working through the control end of the analog-digital conversion circuit; the analog-digital conversion circuit converts the band-gap reference signal from the band-gap reference circuit into a conversion result, and the master control circuit calculates a calibration coefficient according to the conversion result and sends the calculated calibration coefficient to the analog-digital conversion circuit through the calibration end, so that the analog-digital conversion circuit updates the currently stored calibration coefficient.

[0010] In the normal operation state, the master control circuit instructs the first switch circuit to conduct between the first input end and the output end through the control end of the first switch circuit, instructs the second switch circuit to conduct between the input end and the second output end through the control end of the second switch circuit, and instructs the analog-digital conversion circuit to start working through the control end of the analog-digital conversion circuit; the analog-digital conversion circuit receives an analog signal from an analog signal source and converts the analog signal into a digital signal by using the currently stored calibration coefficient, and outputs the digital signal to an external circuit for processing.

[0011] In a second aspect, the application provides an electronic device comprising the ADC real-time calibration device.

[0012] In a third aspect, the application provides a control method of an ADC real-time calibration device, which is applied to the ADC real-time calibration device, and the method comprises the following steps.

[0013] In the calibration operation state, the main control circuit instructs the first switch circuit to conduct between the second input end and the output end of the first switch circuit through the control end of the first switch circuit, instructs the second switch circuit to conduct between the first input end and the first output end of the second switch circuit through the control end of the second switch circuit, and instructs the analog-to-digital conversion circuit to start working through the control end of the analog-to-digital conversion circuit; the analog-to-digital conversion circuit performs analog-to-digital conversion on the bandgap reference signal from the bandgap reference circuit to obtain a conversion result, and the main control circuit calculates a calibration coefficient according to the conversion result and sends the calculated calibration coefficient to the analog-to-digital conversion circuit through the calibration end, so that the analog-to-digital conversion circuit updates the currently stored calibration coefficient.

[0014] In the normal operation state, the main control circuit instructs the first switch circuit to conduct between the first input end and the output end of the first switch circuit through the control end of the first switch circuit, instructs the second switch circuit to conduct between the input end and the second output end of the second switch circuit through the control end of the second switch circuit, and instructs the analog-to-digital conversion circuit to start working through the control end of the analog-to-digital conversion circuit; the analog-to-digital conversion circuit receives an analog signal from an analog signal source, and converts the analog signal into a digital signal by using the currently stored calibration coefficient, and outputs the digital signal to an external circuit for processing.

[0015] The technical scheme provided by some embodiments of the present application has at least the following beneficial effects:

[0016] The bandgap reference circuit is used to generate a stable reference signal, which significantly optimizes the performance of the ADC (analog-to-digital converter) in a complex environment. In the face of reference voltage instability caused by external factors such as voltage fluctuation and temperature change, this technology can effectively offset the gain error caused thereby, ensuring the accuracy and reliability of the ADC conversion process, thereby greatly improving the accuracy of calibration. In the gap between the normal conversion task of the ADC, the bandgap reference signal is seamlessly integrated and converted, and this process does not interrupt the continuous workflow of the ADC, realizing efficient use of resources and smooth operation. This non-intrusive calibration strategy enables the real-time gain coefficient to be applied immediately in the subsequent ADC conversion, not only reducing the calibration lag, but also greatly enhancing the real-time response capability of ADC calibration, ensuring the immediacy and accuracy of data conversion, and laying a solid foundation for high-precision data acquisition and processing. BRIEF DESCRIPTION OF DRAWINGS

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention 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 only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a structural diagram of the ADC real-time calibration device provided in the embodiments of this application;

[0019] Figure 2 This is a schematic flowchart of the calibration method of the ADC real-time calibration device provided in the embodiments of this application;

[0020] Figure 3 This is a timing diagram of the calibration process provided in the embodiments of this application. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Please see Figure 1 This invention provides a schematic diagram of the structure of an ADC real-time calibration device according to an embodiment, including: a bandgap reference circuit, a first switching circuit K1, a second switching circuit K2, an analog-to-digital conversion circuit, and a main control circuit. The first switching circuit K1 has a first input terminal, a second input terminal, a control terminal, and an output terminal. The second switching circuit K2 has an input terminal, a control terminal, a first output terminal, and a second output terminal. The first switching circuit K1 selects one of the two input terminals to conduct between the input and output terminals based on the channel switching signal from the control terminal. The second switching circuit K2 selects one of the two output terminals to conduct between the input and output terminals based on the channel switching signal from the control terminal. The bandgap reference circuit is used to generate a bandgap reference signal.

[0023] The connection relationship of the above components: the first input terminal of the first switching circuit K1 is connected to the analog signal source ( Figure 1 (Not shown in the diagram) The analog signal source is used to generate the analog signal to be converted. The second input terminal of the first switching circuit K1 is connected to the bandgap reference circuit. The control terminal of the first switching circuit K1 is connected to the main control circuit. The output terminal of the first switching circuit K1 is connected to the input terminal of the analog-to-digital converter circuit. The reference terminal of the analog-to-digital converter circuit is connected to the reference circuit, which is used to generate the reference signal V. refThe output end of the analog-digital conversion circuit is connected with the input end of the second switch circuit K2, the control end of the analog-digital conversion circuit is connected with the master control circuit, and the calibration end of the mode conversion circuit is connected with the master control circuit. The first output end of the second switch circuit K2 is connected with the master control circuit, and the second output end of the second switch circuit K2 is connected with the external circuit.

[0024] The working principle of the calibration device of the present application comprises: in the calibration running state, the master control circuit sends a channel switching signal to the control end of the first switch circuit K1 to control the conduction between the second input end and the output end of the first switch circuit K1, sends a working indication signal to the control end of the analog-digital conversion circuit to instruct the analog-digital conversion circuit to start working, and sends a channel switching signal to the control end of the second switch circuit K2 to control the conduction between the input end and the first output end of the second switch circuit. In the calibration running state, the bandgap reference signal generated by the bandgap reference circuit, the analog-digital conversion result obtained by the analog-digital conversion circuit according to the bandgap reference signal and the reference signal, the master control circuit calculates the gain coefficient according to the analog-digital conversion result, and updates the locally stored gain coefficient. In this way, the analog-digital conversion circuit in the normal running state carries out analog-digital conversion processing according to the gain coefficient stored in the master control circuit.

[0025] In some embodiments of the present application, the method for calculating the gain coefficient comprises:

[0026] 1. Based on the voltage of the bandgap reference signal and the ideal reference voltage of the reference signal, the ideal conversion result of the bandgap reference signal is obtained.

[0027] Suppose the voltage of the bandgap reference signal is V bandgap , and the ideal reference voltage of the reference signal is V refideal , then the ideal conversion result DataIdeal of the bandgap reference signal is calculated as

[0028] DataIdeal=(V bandgap / V refideal )×DataFull, wherein DataFull is the maximum digital result of the analog-digital conversion, for example: if the resolution is 16 bits, the value is 2^16-1=65535, and if the resolution is 8 bits, the value is 2^8-1=255.

[0029] 2. Based on the ideal conversion result of the bandgap reference signal and the actual conversion result, the actual reference voltage of the analog-digital conversion circuit is obtained.

[0030] Suppose the actual conversion result of the bandgap reference signal is DataActual, then the actual reference voltage V refactual of the analog-digital conversion circuit is calculated as V refactual =V bandgap× (DataFull / DataActual).

[0031] 3. Calculate the gain coefficient based on the actual reference voltage of the analog-digital conversion circuit.

[0032] The gain coefficient Coeff acts on the analog-digital conversion result, and the actual analog-digital conversion result multiplied by Coeff is the ideal analog-digital conversion result. The calculation formula of the gain coefficient Coeff is Coeff = (V bandgap / V refideal ) × (DataFull / DataActual). The processed analog-digital conversion result is the conversion result obtained by the ideal reference voltage.

[0033] For example, assuming that the bit width of the analog-digital conversion circuit ADC is 12 bits, the maximum digital result is 2^12-1 = 4095, the ideal reference voltage is 3V, the actual reference voltage fluctuates from 3V to 2.9V, the voltage of the bandgap reference signal is 1.2V, and the actual conversion result is 1696. The steps are as follows:

[0034] 1. The ideal conversion result DataIdeal of the bandgap reference signal, DataIdeal = (1.2V / 3V) × 4095 = 1638.

[0035] 2. The actual reference voltage V refactual of the analog-digital conversion circuit, V refactual = 1.2V × (4095 / 1696) = 2.897V.

[0036] 3. The gain coefficient Coeff, Coeff = (1.2V / 3V) × (4095 / 1696) = 0.9658

[0037] Finally, the gain coefficient is applied to the actual analog-digital conversion result. Taking the bandgap reference signal as an example, the conversion result after applying the gain coefficient is (1696 × 0.9658 = 1638), which is consistent with the ideal conversion result 1638. Thus, the effect of real-time calibration can be seen. By applying the gain coefficient obtained by calibration, the gain error introduced by the change of the reference voltage is eliminated.

[0038] In some embodiments of the present application, the method for generating a bandgap reference signal by a bandgap reference circuit includes: adding two voltage signals with opposite temperature coefficients in the chip with appropriate weights to finally obtain a bandgap reference signal with zero temperature coefficient. The bandgap reference signal is equivalent to a constant ruler. The change of the reference voltage is measured by the ruler to realize real-time calibration of the gain coefficient.

[0039] In the normal operation state, the main control circuit sends a channel switching signal to the control end of the first switch circuit K1 to control the first input end and the output end of the first switch circuit K1 to conduct, sends a working indication signal to the control end of the analog-digital conversion circuit to control the analog-digital conversion circuit to start working, and sends a channel switching signal to the control end of the second switch circuit K2 to control the input end and the second output end of the second switch circuit K2 to conduct. signal In the normal operation state, the analog-digital conversion circuit receives an analog signal from the analog signal source, the voltage of the analog signal is denoted as V

[0040] In some embodiments of the present application, the main control circuit comprises a channel switching circuit and an operation storage circuit.

[0041] The channel switching circuit is connected with the control end of the first switch circuit, the control end of the second switch circuit, the control end of the analog-digital conversion circuit and the operation storage circuit; and the operation storage circuit is connected with the first output end of the second switch circuit and the calibration end of the analog-digital conversion circuit.

[0042] Referring to Figure 3 , it is a waveform diagram of the ADC real-time calibration provided by the present application, in which ADC_CLK is an ADC clock signal, ADC_CHSEL is an ADC channel switching signal, CONV_STATE is a conversion initiated in the normal operation of the ADC, CALI_STATE is a conversion initiated in the calibration operation of the ADC, CALI_ENABLE is the start and end of the ADC calibration signal, and GAIN_COEFF is a gain coefficient.

[0043] As can be seen from the diagram, before the ADC calibration signal is initiated, the ADC is in the normal operation state, in which the ADC converts an external input signal, and the channel selection corresponds to the external signal 0 / external signal 1; after the ADC calibration signal is initiated, the ADC is in the calibration operation state, in which the ADC converts a bandgap reference signal, and the channel selection corresponds to the reference signal; after the calibration signal ends, the gain coefficient is updated, and the new gain coefficient is immediately applied to the next ADC conversion.

[0044] The ADC real-time calibration circuit of the present application has the following technical effects.

[0045] High-precision calibration: the stable bandgap reference signal is used as a calibration reference, which effectively eliminates the reference voltage changes caused by environmental factors such as voltage fluctuation and temperature change, thereby significantly improving the precision of the ADC conversion and reducing the gain error.

[0046] Real-time calibration capability: By intelligently controlling the switching circuit, calibration operations are seamlessly performed during the gaps of normal ADC operation, ensuring that the calibration process does not affect the continuous work of the ADC, while updating the calibration coefficients in real time and applying them to the next conversion, greatly improving the real-time performance and dynamic response capability of the calibration.

[0047] Flexibility and scalability: The master control circuit comprehensively controls the first and second switching circuits and the analog-to-digital conversion circuit, enabling the entire system to flexibly adjust the working mode according to actual needs, easily integrated into a wider range of electronic systems, and supporting future functional expansion.

[0048] Efficient resource utilization: Fast switching between calibration and normal operation modes without additional calibration cycles or interrupting the normal conversion process of the ADC improves the overall work efficiency and resource utilization of the system.

[0049] Simplified design complexity: Through integrated hardware design and intelligent control logic, the complex process of traditional ADC calibration is simplified, reducing design difficulty and cost, and improving product reliability and market competitiveness.

[0050] The electronic device provided by the embodiments of the present application includes but is not limited to communication devices, terminal devices, computer devices, etc. In addition to the ADC real-time calibration device described above, the electronic device can also include a housing for accommodating various components, a display screen, an input device (such as a keyboard, a mouse, or a touch screen), etc.

[0051] The above-described embodiments do not constitute a limitation on the scope of protection of the technical solutions. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the above-described embodiments shall be included in the scope of protection of the technical solutions.

Claims

1. An ADC real-time calibration apparatus, characterized by, The application relates to a bandgap reference circuit, a first switch circuit, a second switch circuit, an analog-digital conversion circuit and a main control circuit, wherein the first switch circuit is provided with a first input end, a second input end, a control end and an output end, and the second switch circuit is provided with an input end, a control end, a first output end and a second output end. The first switch circuit is provided with the first input end and the second input end, the first input end is connected with an analog signal source, the second input end is connected with the bandgap reference circuit, the output end of the first switch circuit is connected with the input end of the analog-digital conversion circuit, and the control end of the first switch circuit is connected with the main control circuit. The reference end of the analog-digital conversion circuit is connected with a reference circuit, the control end of the analog-digital conversion circuit is connected with the main control circuit, the output end of the analog-digital conversion circuit is connected with the input end of the second switch circuit, the first output end of the second switch circuit is connected with the main control circuit, the second output end of the second switch circuit is connected with an external circuit, the calibration end of the analog-digital conversion circuit is connected with the main control circuit, and the control end of the second switch circuit is connected with the main control circuit. In a calibration operation state, the main control circuit indicates that the second input end and the output end of the first switch circuit are conducted through the control end of the first switch circuit, indicates that the first input end and the first output end of the second switch circuit are conducted through the control end of the second switch circuit, and indicates that the analog-digital conversion circuit starts to work through the control end of the analog-digital conversion circuit. The analog-digital conversion circuit converts a bandgap reference signal from the bandgap reference circuit into a conversion result, the main control circuit calculates a calibration coefficient according to the conversion result, and sends the calculated calibration coefficient to the analog-digital conversion circuit through the calibration end, so that the analog-digital conversion circuit updates a currently stored calibration coefficient. In a normal operation state, the main control circuit indicates that the first input end and the output end of the first switch circuit are conducted through the control end of the first switch circuit, indicates that the input end and the second output end of the second switch circuit are conducted through the control end of the second switch circuit, and indicates that the analog-digital conversion circuit starts to work through the control end of the analog-digital conversion circuit. The analog-digital conversion circuit receives an analog signal from the analog signal source, converts the analog signal into a digital signal by using the currently stored calibration coefficient, and outputs the digital signal to the external circuit for processing. The bandgap reference circuit is a bandgap reference circuit in which two voltages with opposite temperature coefficients are added with suitable weights to obtain a reference voltage with zero temperature coefficient.

2. The apparatus of claim 1, wherein, The main control circuit calculates the calibration coefficient according to the conversion result, and the calculation includes the following steps:

3. The apparatus of claim 1 or 2, wherein, The main control circuit comprises a channel switching circuit and an operation and storage circuit. Compute ideal conversion result: DataIdeal = (V bandgap / V refideal ) × DataFull; V bandgap is the voltage of the bandgap reference signal, V refideal is the ideal reference voltage, and DataFull is the maximum digital result of the analog-to-digital conversion; Computing actual reference voltage V refactual = V bandgap × (DataFull / DataActual); DataActual is the actual conversion result of the bandgap reference signal; Compute gain coefficient: Coeff = (V bandgap / V refideal ) x (DataFull / DataActual).

4. The apparatus of claim 1, wherein, The channel switching circuit is connected with the control end of the first switch circuit, the control end of the second switch circuit, the control end of the analog-digital conversion circuit and the operation and storage circuit, and the operation and storage circuit is connected with the first output end of the second switch circuit and the calibration end of the analog-digital conversion circuit. ​ 5. The apparatus of claim 1, wherein, The bandgap reference circuit, the first switch circuit, the second switch circuit, the analog-digital conversion circuit and the main control circuit are arranged in the interior of a chip.

6. An ADC real-time calibration method, characterized in that, The ADC real-time calibration device is applied to any one of claims 1 to 5. In the calibration operation state, the main control circuit instructs the first switch circuit to conduct between the second input end and the output end through the control end of the first switch circuit, instructs the second switch circuit to conduct between the first input end and the first output end through the control end of the second switch circuit, and instructs the analog-digital conversion circuit to start working through the control end of the analog-digital conversion circuit. The analog-digital conversion circuit converts the bandgap reference signal from the bandgap reference circuit into a conversion result, the main control circuit calculates a calibration coefficient according to the conversion result, and sends the calculated calibration coefficient to the analog-digital conversion circuit through the calibration end, so that the analog-digital conversion circuit updates the currently stored calibration coefficient. In the normal operation state, the main control circuit instructs the first switch circuit to conduct between the first input end and the output end through the control end of the first switch circuit, instructs the second switch circuit to conduct between the input end and the second output end through the control end of the second switch circuit, and instructs the analog-digital conversion circuit to start working through the control end of the analog-digital conversion circuit. The analog-digital conversion circuit receives an analog signal from an analog signal source, converts the analog signal into a digital signal by using the currently stored calibration coefficient, and outputs the digital signal to an external circuit for processing.

7. An electronic device, comprising: The ADC real-time calibration device comprises any one of claims 1 to 3.

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