An ADC correction circuit

Abstract

The present invention relates to the field of ADC detection technology, and specifically discloses an ADC correction circuit, comprising a chopper switch, an ADC, a chopper controller, a correction multiplier, a correction adder, and a gain error correction module. The chopper switch receives a voltage signal to be detected at its first input end, a second input end thereof is connected to a first output end of the chopper controller, and an output end thereof is connected to an input end of the ADC. The input end of the chopper controller is connected to an output end of the ADC, and a second output end of the chopper controller is connected to a first input end of the correction adder. The correction multiplier receives raw voltage quantization data at its first input end, and a gain error correction coefficient output by a gain error correction module at its second input end. The correction multiplier and the correction adder correct the gain error and offset error of the raw voltage quantization data to output corrected voltage quantization data. The present invention can correct offset error and gain error in a battery voltage measurement process.

Description

Technical Field

[0001] The present invention relates to the field of ADC detection technology, and more particularly to an ADC correction circuit. Background Art

[0002] Sensing the world is a crucial role for analog-to-digital converters (ADCs). Digital systems often use ADCs to convert external analog signals into processable digital signals. These signals are then processed using the powerful data processing capabilities of digital circuits to achieve the desired functionality. ADC accuracy significantly impacts digital system performance; higher conversion accuracy translates to better system performance. In electric vehicle battery management systems (BMS), various battery states need to be monitored, necessitating high-precision ADCs for precise measurement.

[0003] The ADC is a high-precision data conversion device. However, in actual use, it is easily affected by the external environment and often fails to achieve the ADC's specified accuracy. This loss of accuracy can significantly impact the performance of the entire system, so error correction is necessary for the ADC's output.

[0004] The static indicators of ADC design, that is, the error types, can be roughly divided into the following four categories: offset error, gain error, differential nonlinearity and integral nonlinearity. Among them, offset error and gain error are the main aspects affected by the external environment, while differential nonlinearity and integral nonlinearity errors often depend on the structure and process of the ADC. Moreover, the correction principles of offset error and gain error are relatively simple, require fewer resources, and are suitable for chip-level correction; while differential nonlinearity and integral nonlinearity errors are related to the ADC structure, so they are not easy to correct and require the use of polynomial approximation, table lookup method, etc., which have high area cost and are not universal, and are not suitable for chip-level correction. The present invention mainly studies the correction of offset and gain errors caused by the external environment. Summary of the Invention

[0005] In order to address the deficiencies in the prior art, the present invention provides an ADC correction circuit that can correct gain error and offset error in the ADC sampling channel based on multiplication and addition operations, with significant effect, simple structure and easy implementation.

[0006] As a first aspect of the present invention, there is provided an ADC correction circuit, the ADC correction circuit comprising a chopper switch, an ADC, a chopper controller, a correction multiplier, a correction adder and a gain error correction module;

[0007] The first input end of the chopper switch is used to input a voltage signal to be detected, the second input end of the chopper switch is connected to the first output end of the chopper controller, the output end of the chopper switch is connected to the input end of the ADC, and the chopper switch is used to control the direction of the voltage signal to be detected;

[0008] The input end of the chopping controller is connected to the quantized data output end of the ADC, the second output end of the chopping controller is connected to the first input end of the correction adder, and the chopping controller is used to output the offset error correction coefficient to the correction adder;

[0009] The first input end of the correction multiplier is used to input the original voltage quantization data of the ADC; the second input end of the correction multiplier is connected to the gain error correction module, and is used to obtain the gain error correction coefficient output by the gain error correction module; the output end of the correction multiplier is connected to the second input end of the correction adder;

[0010] The correction multiplier and the correction adder are used to correct the gain error and the offset error of the original voltage quantization data, and the output end of the correction adder outputs the corrected voltage quantization data.

[0011] Furthermore, the gain error correction module includes a memory, a selector, a coefficient adder, a coefficient multiplier and an interpolator;

[0012] The first output end of the memory is connected to the input end of the interpolator and the selection signal input end of the selector respectively, the second output end of the memory is connected to the first data input end of the selector, the third output end of the memory is connected to the second data input end of the selector, and the fourth output end of the memory is connected to the first input end of the coefficient adder. The memory is used to store temperature coefficients and the current external environment temperature value; wherein the temperature coefficients include room temperature coefficients, high temperature coefficients, and low temperature coefficients;

[0013] The output end of the selector is connected to the first input end of the coefficient multiplier, and the selector is used to select the high temperature coefficient or the low temperature coefficient according to the current external environment temperature value;

[0014] The output end of the interpolator is connected to the second input end of the coefficient multiplier, and the interpolator is used to obtain the temperature proportional coefficient according to the current external ambient temperature value. The output end of the coefficient multiplier is connected to the second input end of the coefficient adder, and the third input end of the coefficient adder inputs a fixed value 1. The output end of the coefficient adder is connected to the second input end of the correction multiplier, and the coefficient adder is used to calculate the gain error correction coefficient.

[0015] Furthermore, the calculation formula of the gain error correction coefficient gain_coeff is as follows:

[0016] gain-coeff=1+gain-room+K(T)×gain-hot / cold

[0017] Where gain_room is the room temperature coefficient, K(T) is the temperature proportional coefficient, gain_hot is the high temperature coefficient, and gain_cold is the low temperature coefficient.

[0018] Furthermore, the calculation formula of the corrected voltage quantization data cali_data is as follows:

[0019] cali-data=(src-data×gain-coeff)+off-coeff

[0020] Wherein, src_data is the original voltage quantization data of the ADC, gain_coeff is the gain error correction coefficient, and off_coeff is the offset error correction coefficient.

[0021] Furthermore, the chopping controller is used to obtain the original voltage quantization data src_data of the ADC. Assuming that the original voltage quantization data src_data currently sampled and output by the ADC is V2, and the original voltage quantization data src_data previously sampled and output is V1, the chopping controller obtains the offset error correction coefficient by calculating the difference between the current original voltage quantization data V2 and the previous original voltage quantization data V1.

[0022] Furthermore, the temperature proportionality coefficient K(T) is a decimal within 1, wherein,

[0023] The closer the current external environment temperature value T is to the set high temperature coefficient gain_hot or the low temperature coefficient gain_cold, the larger the temperature proportional coefficient K(T);

[0024] When the current external environment temperature value T is the set room temperature coefficient gain_room, the temperature proportional coefficient K(T) is 0.

[0025] Furthermore, the voltage signal to be detected at the first input end of the chopper switch is a differential signal, and the chopper controller is used to control the chopper switch to alternately output the differential signal.

[0026] Furthermore, the operands of the correction multiplier and the correction adder are both fixed-point numbers.

[0027] Furthermore, the operands of the coefficient adder and the coefficient multiplier are both fixed-point numbers.

[0028] Furthermore, the interpolator obtains the temperature proportional coefficient according to the current external environment temperature value using a linear interpolation method.

[0029] The ADC correction circuit provided by the present invention has the following advantages: a gain error correction coefficient is obtained by using an interpolator and a temperature-dependent gain coefficient in a memory, an offset error correction coefficient is obtained by using a chopping mechanism, and then the gain error and offset error in the ADC sampling channel are corrected according to multiplication and addition operations. The circuit has significant effects, a simple structure, and is easy to implement. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present invention, but do not constitute a limitation of the present invention.

[0031] Figure 1 This is a structural block diagram of the ADC correction circuit provided by the present invention. DETAILED DESCRIPTION

[0032] To further illustrate the technical means and effectiveness of the present invention in achieving its intended purpose, the following, in conjunction with the accompanying drawings and preferred embodiments, describes in detail the specific implementation, structure, features, and effectiveness of the ADC correction circuit proposed in accordance with the present invention. It should be understood that the described embodiments are only a subset of the present invention, not all of it. All other embodiments derived by persons of ordinary skill in the art based on the present embodiments without inventive effort are intended to fall within the scope of protection of the present invention.

[0033] It should be noted that the terms "first," "second," and the like in the specification and claims of the present invention and the accompanying drawings are used to distinguish similar objects and are not necessarily used to describe a particular order or precedence. It should be understood that the terms used in this manner are interchangeable where appropriate for the embodiments of the present invention described herein. In addition, the terms "including," "having," and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus comprising a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to these processes, methods, products, or apparatuses.

[0034] In the context of this invention, it should be noted that the terms "installed," "connected," and "connected" should be interpreted broadly, unless otherwise specified. For example, a connection can be a fixed connection, a connection via a specific interface, or an indirect connection via an intermediary. Those skilled in the art will understand the specific meanings of these terms in this invention on a case-by-case basis.

[0035] In this embodiment, an ADC correction circuit is provided, such as Figure 1 As shown, the ADC correction circuit 10 includes a chopping switch 20, an ADC 30, a chopping controller 40, a correction multiplier 50, a correction adder 60 and a gain error correction module;

[0036] The first input terminal of the chopper switch 20 is used to input the voltage signal to be detected, the second input terminal of the chopper switch 20 is connected to the first output terminal of the chopper controller 40, the output terminal of the chopper switch 20 is connected to the input terminal of the ADC 30, and the chopper switch 20 is used to control the direction of the voltage signal to be detected;

[0037] The input end of the chopping controller 40 is connected to the quantized data output end of the ADC 30, the second output end of the chopping controller 40 is connected to the first input end of the correction adder 60, and the chopping controller 40 is used to output the offset error correction coefficient to the correction adder 60;

[0038] The first input terminal of the correction multiplier 50 is used to input the original voltage quantization data src_data of the ADC; the second input terminal of the correction multiplier 50 is connected to the gain error correction module to obtain the gain error correction coefficient output by the gain error correction module; the output terminal of the correction multiplier 50 is connected to the second input terminal of the correction adder 60;

[0039] The correction multiplier 50 and the correction adder 60 are used to correct the gain error and the offset error of the original voltage quantization data. The output end of the correction adder 60 outputs the corrected voltage quantization data cali_data.

[0040] Preferably, the gain error correction module includes a memory 70, a selector 80, a coefficient adder 90, a coefficient multiplier 100 and an interpolator 110;

[0041] The first output terminal of the memory 70 is connected to the input terminal of the interpolator 110 and the selection signal input terminal of the selector 80 respectively, the second output terminal of the memory 70 is connected to the first data input terminal of the selector 80, the third output terminal of the memory 70 is connected to the second data input terminal of the selector 80, and the fourth output terminal of the memory 70 is connected to the first input terminal of the coefficient adder 90. The memory 70 is used to store a temperature coefficient and a current ambient temperature value Temperature (hereinafter referred to as T); wherein the temperature coefficient includes a room temperature coefficient, a high temperature coefficient, and a low temperature coefficient;

[0042] The output end of the selector 80 is connected to the first input end of the coefficient multiplier 100, and the selector 80 is used to select the high temperature coefficient or the low temperature coefficient according to the current external environment temperature value T;

[0043] The output end of the interpolator 110 is connected to the second input end of the coefficient multiplier 100. The interpolator 110 is used to obtain the temperature proportional coefficient K(T) according to the current external ambient temperature value. The output end of the coefficient multiplier 100 is connected to the second input end of the coefficient adder 90. The third input end of the coefficient adder 90 inputs a fixed value 1. The output end of the coefficient adder 90 is connected to the second input end of the correction multiplier 50. The coefficient adder 90 is used to calculate the gain error correction coefficient gain_coeff.

[0044] Specifically, the selector 80 is a data selector.

[0045] Specifically, the temperature coefficient in the memory 70 is related to the ADC temperature and is obtained through actual testing of the ADC; the current external environment temperature value in the memory is the output value of the temperature sensor or the temperature value written by the MCU.

[0046] Preferably, the calculation formula of the gain error correction coefficient gain_coeff is as follows:

[0047] gain-coeff=1+gain-room+K(T)×gain-hot / cold (1)

[0048] Where gain_room is the room temperature coefficient, K(T) is the temperature proportional coefficient, gain_hot is the high temperature coefficient, and gain_cold is the low temperature coefficient.

[0049] Preferably, the calculation formula of the corrected voltage quantization data cali_data is as follows:

[0050] cali-data=(src-data×gain-coeff)+off-coeff (2)

[0051] Wherein, src_data is the original voltage quantization data of the ADC, gain_coeff is the gain error correction coefficient, and off_coeff is the offset error correction coefficient.

[0052] The ADC correction circuit provided by the present invention obtains a gain error correction coefficient gain_coeff by interpolating the temperature-dependent gain coefficient in the memory 70, as shown in formula (1). It obtains an offset error correction coefficient off_coeff by a chopping mechanism. The gain error and offset error in the ADC sampling channel are then corrected by multiplication and addition operations, as shown in formula (2). cali_data is the final corrected output. The present invention has a significant correction effect, a simple structure, and is easy to implement.

[0053] Preferably, the chopping controller 40 is used to obtain the original voltage quantization data src_data of the ADC. Assuming that the original voltage quantization data src_data currently sampled and output by the ADC30 is V2, and the original voltage quantization data src_data previously sampled and output is V1, the chopping controller 40 obtains the offset error correction coefficient off_coeff by calculating the difference between the current original voltage quantization data V2 and the previous original voltage quantization data V1.

[0054] Preferably, the temperature proportionality coefficient K(T) is a decimal within 1, wherein,

[0055] The closer the current external environment temperature value T is to the set high temperature coefficient gain_hot or the low temperature coefficient gain_cold, the larger the temperature proportional coefficient K(T);

[0056] When the current external environment temperature value T is the set room temperature coefficient gain_room, the temperature proportional coefficient K(T) is 0.

[0057] Preferably, the voltage signal to be detected at the first input end of the chopping switch 20 is a differential signal, and the chopping controller 40 is used to control the chopping switch 20 to alternately output the differential signal. The chopping switch 20 alternately transmits the voltage Vin and the reverse of Vin to the input of the ADC30, and the ADC30 outputs the original voltage quantization data src_data. Assuming that the src_data output by the ADC after two consecutive samplings are V1 and V2 respectively, then V1 = +Vin+offset and V2 = -Vin+offset; generally, the data src_data sampled and output by the ADC is affected by the external environment and its own circuit and has deviations, so a correction circuit is used to adjust these deviations to obtain the corrected data cali_data.

[0058] Preferably, the chopping controller 40 is the control core of the ADC correction circuit, controls the sampling channel and the chopping switch, and obtains the offset error correction coefficient off_coeff according to the ADC quantization data (V1 and V2); the chopping controller 40 obtains the offset error coefficient off_coeff = (V1 + V2) / 2 by calculating the difference between the current sampling (V2) and the previous sampling (V1).

[0059] It should be noted that the chopper switch 20 is a switch that cooperates with the chopper controller 40 to realize the chopping function. Its function is to exchange the direction of the input. Assuming that the input is +vin and -vin from top to bottom, the switch control signal is 0 and the output is directly output; if it is 1, the output is exchanged and the output is -vin and +vin.

[0060] Preferably, the operands of the correction multiplier 50 and the correction adder 60 are both fixed-point numbers.

[0061] Preferably, the operands of the coefficient adder 90 and the coefficient multiplier 100 are both fixed-point numbers.

[0062] Preferably, the interpolator 110 obtains the temperature proportional coefficient according to the current external environment temperature value using a linear interpolation method.

[0063] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as a preferred embodiment, it is not intended to limit the present invention. Any technician familiar with the present profession can make slight changes or modifications to equivalent embodiments using the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. An ADC correction circuit, characterized in that: The ADC correction circuit (10) comprises a chopping switch (20), an ADC (30), a chopping controller (40), a correction multiplier (50), a correction adder (60), and a gain error correction module; The first input end of the chopping switch (20) is used to input a voltage signal to be detected, the second input end of the chopping switch (20) is connected to the first output end of the chopping controller (40), the output end of the chopping switch (20) is connected to the input end of the ADC (30), and the chopping switch (20) is used to control the direction of the voltage signal to be detected; The input end of the chopping controller (40) is connected to the quantized data output end of the ADC (30), the second output end of the chopping controller (40) is connected to the first input end of the correction adder (60), and the chopping controller (40) is used to output the offset error correction coefficient to the correction adder (60); The first input end of the correction multiplier (50) is used to input the original voltage quantization data of the ADC; the second input end of the correction multiplier (50) is connected to the gain error correction module, and is used to obtain the gain error correction coefficient output by the gain error correction module; the output end of the correction multiplier (50) is connected to the second input end of the correction adder (60); The correction multiplier (50) and the correction adder (60) are used to correct the gain error and offset error of the original voltage quantization data, and the output end of the correction adder (60) outputs the corrected voltage quantization data; The gain error correction module includes a memory (70), a selector (80), a coefficient adder (90), a coefficient multiplier (100), and an interpolator (110); The first output end of the memory (70) is connected to the input end of the interpolator (110) and the selection signal input end of the selector (80), respectively; the second output end of the memory (70) is connected to the first data input end of the selector (80); the third output end of the memory (70) is connected to the second data input end of the selector (80); the fourth output end of the memory (70) is connected to the first input end of the coefficient adder (90); the memory (70) is used to store a temperature coefficient and a current external environment temperature value; wherein the temperature coefficient includes a room temperature coefficient, a high temperature coefficient, and a low temperature coefficient; The output end of the selector (80) is connected to the first input end of the coefficient multiplier (100), and the selector (80) is used to select the high temperature coefficient or the low temperature coefficient according to the current external environment temperature value; The output end of the interpolator (110) is connected to the second input end of the coefficient multiplier (100), and the interpolator (110) is used to obtain a temperature proportional coefficient according to the current external environment temperature value. The output end of the coefficient multiplier (100) is connected to the second input end of the coefficient adder (90), and the third input end of the coefficient adder (90) inputs a fixed value 1. The output end of the coefficient adder (90) is connected to the second input end of the correction multiplier (50), and the coefficient adder (90) is used to calculate the gain error correction coefficient. Wherein, the voltage signal to be detected at the first input end of the chopping switch (20) is a differential signal.

2. An ADC correction circuit according to claim 1, characterized in that, The calculation formula of the gain error correction coefficient gain_coeff is as follows: , Where gain_room is the room temperature coefficient, K(T) is the temperature proportional coefficient, gain_hot is the high temperature coefficient, and gain_cold is the low temperature coefficient.

3. An ADC correction circuit according to claim 2, characterized in that: The calculation formula of the corrected voltage quantization data cali_data is as follows: , Wherein, src_data is the original voltage quantization data of the ADC, gain_coeff is the gain error correction coefficient, and off_coeff is the offset error correction coefficient.

4. The ADC correction circuit according to claim 3, wherein: The chopping controller (40) is used to obtain the original voltage quantization data src_data of the ADC, the original voltage quantization data src_data currently sampled and output by the ADC (30) is V2, and the original voltage quantization data src_data previously sampled and output is V1, and the chopping controller (40) obtains the offset error correction coefficient by calculating the difference between the current original voltage quantization data V2 and the previous original voltage quantization data V1.

5. The ADC correction circuit according to claim 2, wherein: The temperature proportionality coefficient K(T) is less than or equal to 1, wherein, The closer the current external environment temperature value T is to the set high temperature coefficient gain_hot or the low temperature coefficient gain_cold, the larger the temperature proportional coefficient K(T); When the current external environment temperature value T is the set room temperature coefficient gain_room, the temperature proportional coefficient K(T) is 0.

6. The ADC correction circuit according to claim 1, wherein: The chopping controller (40) is used to control the chopping switch (20) to alternately output the differential signal.

7. The ADC correction circuit according to claim 1, wherein: The operands of the correction multiplier (50) and the correction adder (60) are both fixed-point numbers.

8. The ADC correction circuit according to claim 1, wherein: The operands of the coefficient adder (90) and the coefficient multiplier (100) are both fixed-point numbers.

9. The ADC correction circuit according to claim 1, wherein: The interpolator (110) uses a linear interpolation method to obtain the temperature proportional coefficient according to the current external environment temperature value.

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