JPH08181610A - High speed high accuracy a/d converter - Google Patents

Abstract

PURPOSE: To obtain stable accuracy at a high speed by providing a continuous temperature correction section between an error amplifier receiving a signal from a temperature sensor and an adder. CONSTITUTION: A temperature sensor 12 is placed in the vicinity of a high speed high accuracy A/D converter section 10 fluctuated sensibly with respect to a temperature change and gives a temperature signal to an A/D converter 14, from which the signal is converted into a digital signal and fed to an address input terminal of memories 16, 18 as an address signal. The conversion section 10 is formed by providing a continuous temperature correction section 10 between an A/D converter 60 and an adder section 62. Then the conversion section 10 receives an analog input voltage and applies A/D conversion to the signal and adds very small temperature correction to the signal and provides an output of code data with high accuracy. In this very small correction, an error caused in an offset adder 22 and a memory 16 and a temperature drift in the error amplifier 56 and the A/D converter 60 and the D/A converter 54 are corrected. Furthermore, equivalent gain fluctuation of the error amplifier 56 and the converters 54, 60 caused by a very small temperature change in the multiplier 24 and the memory 28 is corrected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-speed, high-resolution, high-precision AD converter that is stable by correcting the error effect of the AD conversion code due to temperature change.

[0002]

2. Description of the Related Art Since a high speed and high resolution AD converter is not commercially available, a circuit is composed of two low resolution high speed AD converters to realize a high resolution high speed AD converter equivalently. are doing. As an example of the prior art, there is an example of an AD converter having a sampling rate of several MHz and 18-bit resolution. This will be described with reference to FIGS. 5 and 6.

As shown in FIG. 5, this circuit includes a reference signal source 40, changeover switches 42 and 43, a reference digital voltmeter 44, a high-speed and high-accuracy AD conversion section 50, a calibration signal 82, and a control section. It is composed of 80 and.

The reference signal source 40 is a highly stable reference voltage signal generation source for supplying analog voltages at a plurality of points for calibrating the high-speed and high-accuracy AD conversion section 50, and this signal is passed through the changeover switch 42. It is supplied to the high-speed and high-precision AD conversion unit 50, receives a control signal from the control unit 80, and outputs a desired voltage. The changeover switch 42 is for switching to the side of the reference signal source 40 when the original analog signal 100 to be measured is measured and at the time of calibration. The changeover switch 43 is a switch for supplying the same voltage signal of the reference signal source 40 to both the high-speed and high-accuracy AD conversion unit 50 and the reference digital voltmeter 44 for measurement.

The calibration signal 82 detects a desired temperature change of the environment temperature of the entire measurement system including other measurement systems, for example, a temperature change of 3 ° C. or more, temporarily suspends the entire measurement system, and then the other measurement system. Along with this, it is a start signal for acquiring and executing temperature correction parameters in order to carry out temperature calibration and bring the accuracy of the entire measurement system into a desired allowable accuracy range.
The measurement of the D conversion unit is temporarily stopped and calibration is performed. The reference digital voltmeter 44 is a voltage measuring device that serves as a reference for measuring a constant voltage of the reference signal source 40 with high accuracy, receives a control signal from the control unit 80, and receives the high-speed high-precision AD conversion unit 50 and a plurality of points. The same analog voltage is measured and is supplied to the control unit 80.

The control unit 80 has a high-speed digital arithmetic function by, for example, a DSP, and receives continuous 18-bit data from the high-speed and high-accuracy AD conversion unit 50 when measuring the analog signal to be measured 100, and linearly receives it. Code data 80out of 18-bit resolution data of high accuracy by reducing the influence of temperature by performing the characteristic correction and offset correction calculation processing.
Is output. Further, the control unit 80 performs calibration when a desired temperature change is caused by the calibration signal 82, acquires a temperature correction parameter, converts it into correction data, and stores it in the internal memory as a temperature correction parameter. That is, the changeover switches 42 and 43 are switched to measure the same analog constant voltage from the reference signal source 40 at a plurality of points, and the code data value of the high-speed and high-accuracy AD conversion unit 50 becomes the value of the reference digital voltmeter 44. A temperature correction parameter that agrees is obtained. That is, the control unit 80 compares the two to obtain the deviation of the high-speed and high-precision AD conversion unit 50, and from this, obtains the offset correction amount and the gain correction amount of the amplifier. As a result, the calibration value for temperature correction is updated. As described above, when the desired temperature difference is exceeded, the measurement is temporarily stopped, the calibration is performed at that temperature, and the measurement is performed while maintaining the high precision AD conversion accuracy.

The high-speed and high-precision AD converter 50 receives the analog signal 100 to be measured, AD-converts it into 18-bit resolution at a sampling rate of a clock frequency of several MHz, and outputs code data 50out. As shown in FIG. 3, the high-speed sample-hold unit 51, the first AD converter 52, the DA converter 54, the error amplifier 56, the second AD converter 60, and the adder 62 are included.

The input analog signal 50in is sampled at each clock by the sample hold unit 51, and the held analog signal 51a is supplied to the first AD converter 52 and one input end of the error amplifier 56. First AD converter 52
Is a high-speed AD converter with 8-bit resolution, for example. As a result, the analog signal 51a is converted into the code data 52d and then supplied to the DA converter 54 and one input terminal of the adder 62. The DA converter 54 uses an accurate DA converter in order to obtain the remaining analog amount of the quantized and converted difference. As a result, DA conversion is performed to convert into an analog signal, and then the analog signal is supplied to the other input end of the error amplifier 56.
In this circuit system, no error is generated by the first AD converter 52. Instead, the conversion accuracy of the DA converter 54 causes an error.

The error amplifier 56 subtracts the analog amount quantized by the first AD converter 52 from the analog signal 51a and amplifies the remaining difference signal by, for example, several tens of times, and outputs the analog signal 56a as a second AD converter. Supply to 60. The second AD converter 60 is for converting the remaining analog signal 56a corresponding to ± 0 to ± 2 LSB converted by the first AD converter 52 into a digital signal. For example, the first AD converter 52 may have 10 bits. A high-speed AD converter with a 12-bit resolution is used in consideration of the code conversion deviation of. The analog signal 56a is received, converted into digital code data 60d, and then supplied to the other input terminal of the adder 62.

The adder 62 has code data 52d obtained by shifting up the weight of the first AD converter 52 by 10 bits,
Add the code data 60d of the second AD converter 60,
Code data 50out having 18-bit resolution is calculated.
The output code data 80out, which is the result of supplying this data to the control unit 80 and performing the correction calculation using both the offset and gain temperature correction parameters in the control unit 80, is the temperature-corrected high-precision AD conversion with 18-bit resolution. Obtained as data.

[0011]

As described above, since the high-speed and high-accuracy AD conversion section 50 is composed of individual analog circuits, it is sensitive to temperature changes and, in some cases, is fixed by the calibration signal 82. In the correction means by calibration for each temperature change interval, an error may occur during this period, and it may not always be possible to maintain a highly accurate AD converter. Therefore, the problem to be solved by the present invention is to provide an independent temperature sensor in addition to the calibration signal 82 and add means for continuously correcting the temperature without stopping the measurement,
It is another object of the present invention to realize a high-speed and high-precision AD converter with stable accuracy.

[0012]

1 and 2 show a first solution according to the present invention. In order to solve the above problems, in the configuration of the present invention, the temperature sensor 12 that detects the temperature of the high-speed and high-accuracy AD conversion circuit unit is provided, and the error amplifier 56 and the adder 62 receive the signal of the temperature sensor 12. A continuous temperature correction unit 20 that continuously corrects the temperature is provided between them. As a result, the analog signal to be measured 100 is received, the high-speed sample hold unit 51, the low-resolution high-speed first AD converter 52, and the DA converter 54 are provided.
The error amplifier 56, the second AD converter 60 having a low resolution and a high speed, and the adder 62 are provided to realize a high speed and high resolution AD conversion circuit with further improved temperature stability.

The continuous temperature correction unit 20 includes an AD converter 14 which receives a temperature signal from the temperature sensor 12, converts it into a digital signal, and supplies an address signal to a first memory 16 and a second memory 18. A first memory 16 is provided, which receives the digital temperature data from the AD converter 14, reads the correction value of the temperature drift, and supplies the correction value to the offset adder 22, and receives the digital temperature data from the AD converter 14. , The temperature correction value of the amplification degree is read out and the multiplier 24
A second memory 18 for supplying to the first memory 16
The offset adder 22 which receives the correction value of the temperature drift from the second AD converter 60 and the code data 20in from the second AD converter 60, corrects the offset deviation and supplies it to one input end of the multiplier 24 And the second memory 1
A temperature correction value of the amplification degree from 8 and the offset adder 22
There is a configuration means for providing the multiplier 24 which receives the code data from the above and multiplies them, normalizes them, and outputs the code data 20out in which the deviation of the amplification degree is corrected.

3 and 4 show a second solution according to the invention. In order to solve the above problems, in the configuration of the present invention, the temperature sensor 12 that detects the temperature of the high-speed and high-precision AD conversion circuit unit is provided, and the error amplifier 56 and the second AD converter 60 are received by receiving the signal of the temperature sensor 12. In the configuration means, a continuous temperature correction unit 21 that continuously corrects the temperature is provided.

The continuous temperature correction unit 21 includes an AD converter 14 which receives a temperature signal from the temperature sensor 12, converts it into a digital signal, and supplies an address signal to the first memory 16 and the second memory 18. A first memory 16 is provided, which receives the digital temperature data from the AD converter 14, reads the correction value of the temperature drift and supplies it to the offset adder 22, and receives the digital temperature data from the AD converter 14. , The temperature correction value of the amplification degree is read out and the multiplier 24
A second memory 18 for supplying to the first memory 16
A DA converter 26 for receiving the signal from the second memory 18 and DA converting into an analog signal and outputting an offset correction signal 26add is provided, and the signal from the second memory 18 is received and DA converted into an analog signal to obtain a gain correction signal. There is a configuration means for providing the DA converter 28 that outputs 28mul.

[0016]

In the first embodiment, the offset adder 22 and the first memory 16 provide the effect of correcting the offset deviation due to the temperature drift of the error amplifier 56, the second AD converter 60, and the DA converter 54. In the first embodiment, the error amplifier 5 is provided by the multiplier 24 and the second memory 18.
6 gain fluctuation, the second AD converter 60 and the DA converter 54
The effect of correcting the influence error of the equivalent gain variation due to the temperature drift of is obtained. In the second embodiment, the error amplifier 56 and the second amplifier 16 are provided by the first memory 16 and the DA converter 26.
The effect of correcting the offset deviation due to the temperature drift of the D converter 60 and the DA converter 54 can be obtained. In the second embodiment, the second AD converter 6 is controlled by the analog gain correction signal 28mul generated by the second memory 18 and the DA converter 28.
By finely adjusting the reference voltage of 0, the effect of correcting the influence error of the gain variation of the error amplifier 56 and the equivalent gain variation due to the temperature drift of the second AD converter 60 and the DA converter 54 can be obtained.

Since the temperature sensor 12 is provided and the high-speed and high-accuracy AD conversion section 10 corrects the temperature of the factor that the output data fluctuates depending on the temperature, the temperature can be corrected even for a minute temperature change and the measurement is stopped. It is possible to realize a high-speed and high-precision AD converter with continuous and stable accuracy.

[0018]

【Example】

(Embodiment 1) In the embodiment of the present invention, a high-speed, high-resolution (18 bits) is provided in which a temperature sensor is provided to continuously perform minute temperature correction
There is an example of the AD converter of. About this,
Will be described with reference to.

This circuit is based on the conventional high-speed and high-accuracy A shown in FIG.
With respect to the circuit configuration of the D conversion unit 50, as shown in FIG.
The continuous temperature correction unit 20 is added between the second AD converter 60 and the adder 62 to configure the high-speed and high-precision AD conversion unit 10. The high-speed and high-accuracy AD conversion unit 10 receives the analog voltage at the input analog signal 50in end, AD-converts it, adds minute temperature correction, and outputs high-precision code data 50out. The continuous temperature correction unit 20 is provided with the temperature sensor 12 and outputs the code data in which the minute temperature is continuously corrected, and the temperature sensor 12 and the AD converter 1 are provided.
4, a first memory 16, a second memory 18, an offset adder 22, and a multiplier 24.

The temperature sensor 12 is installed in the vicinity of the high-speed and high-precision AD converter 10 that sensitively changes with temperature, supplies the temperature signal to the AD converter 14, and converts it into a digital signal, for example. It is supplied to the address input terminals of the first memory 16 and the second memory 18 as an address signal in 0.2 ° C. units.

As the first minute correction, the offset adder 22 and the first memory 16 correct the offset deviation caused by the temperature drift of the error amplifier 56, the second AD converter 60, and the DA converter 54 caused by the minute temperature change. To do. That is, the first memory 16 stores in advance parameters for correcting the offset deviation caused by the temperature change, and the offset correction amount data corresponding to the unit temperature change of 0.2 ° C. is stored in the first memory 16 from the first memory 16. It is read and supplied to one input terminal of the offset adder 22. The second AD is connected to the other input terminal of the offset adder 22.
By supplying the code data 20in from the converter 60 and adding both, the offset deviation caused by the temperature change is corrected and output to the multiplier 24.

As the second minute correction, the multiplier 24 and the second memory 18 correct the equivalent gain fluctuation of the error amplifier 56, the DA converter 54 and the second AD converter 60 caused by the minute temperature change. That is, the second memory 18 stores in advance a parameter for correcting the gain deviation caused by the temperature change, and the gain correction amount data corresponding to the unit temperature change is read from the second memory 18 to be multiplied. 24 to one input terminal. Then, the signal from the offset adder 22 is supplied to the other input terminal of the multiplier 24, and both are multiplied and normalized to obtain the code data 20out in which the gain deviation caused by the temperature change is corrected. Output. The temperature characteristics of the parameters stored in the first memory 16 and the second memory 18 are measured in advance, and the corresponding correction data values are stored in the respective memories.

(Embodiment 2) The embodiment of the present invention is an example of a high-speed high-resolution AD converter which is provided with a temperature sensor and corrects a minute temperature by an analog correction method. about this,
This will be described with reference to FIGS. 3 and 4. This circuit, as shown in FIG. 3, applies an analog offset correction signal 26add to the error amplifier 56 to perform offset correction with respect to the circuit configuration of the first embodiment shown in FIG. 1, and also the reference of the second AD converter. The high-speed and high-accuracy AD conversion unit 11 that continuously performs the minute temperature correction by changing the voltage and performing the gain correction is configured.

The continuous temperature correction unit 21 receives the signal from the temperature sensor 12 and continuously corrects the minute temperature by an analog offset correction signal 26add and an analog gain correction signal 2.
It outputs 8 mul, and the temperature sensor 12 and AD
A converter 14, a first memory 16, a second memory 18,
It is composed of DA converters 26 and 28. The correction of the first offset is based on the correction amount data for correcting the offset deviation caused by the temperature change from the first memory 16.
After being read from the memory 16 and supplied to the DA converter 26 to be converted into the analog offset correction signal 26add, this is supplied to one input end of the error amplifier 56. As a result, the offset-corrected analog signal is supplied to the second AD converter 60.

For the second gain correction, the correction amount data for correcting the gain deviation caused by the temperature change is read from the second memory 18. This is supplied to the DA converter 28, and the analog gain correction signal 28 is supplied.
After conversion into mul, the gain adjustment is equivalently realized by finely adjusting the reference voltage of the second AD converter 60. As a result, the gain-corrected code data is output from the second AD converter 60. With these corrections, as in the first embodiment, the code data 50out in which the offset or the gain shift caused by the minute temperature change is corrected is corrected.
Is output.

The offset adder 22, the multiplier 24, and the adder 62 for performing the digital calculation in the above embodiment may be constituted by a circuit or a high speed arithmetic processing device such as a DSP.

[0027]

Since the present invention is configured as described above, it has the following effects. In the first embodiment, the offset adder 22 and the first memory 1
6, the error amplifier 56, the second AD converter 60, the DA
The effect of correcting the offset deviation due to the temperature drift of the converter 54 can be obtained. In the first embodiment, the multiplier 24
With the second memory 18, the effect of correcting the influence error of the gain variation of the error amplifier 56 or the equivalent gain variation due to the temperature drift of the second AD converter 60 or the DA converter 54 can be obtained.

In the second embodiment, the first memory 16 and the DA
By the converter 26, the error amplifier 56 and the second AD converter 6
It is possible to obtain the effect of correcting the offset deviation due to the temperature drift of 0 or the DA converter 54. In the second embodiment, by finely adjusting the reference voltage of the second AD converter 60 by the analog gain correction signal 28mul from the second memory 18 and the DA converter 28, the gain variation of the error amplifier 56 and the second AD converter 60 and DA converter 40 can be adjusted. The effect of correcting the influence error of the equivalent gain variation due to the temperature drift of the converter 54 is obtained.

As a whole, the temperature sensor 12 is provided,
The high-speed and high-accuracy AD converter 10 corrects the temperature of the factor that the output data fluctuates depending on the temperature, so that the temperature can be corrected even for a minute temperature change, and the measurement can be performed continuously without any interruption. A / D converter can be realized.

[0030]

[Brief description of drawings]

FIG. 1 is a high-speed and high-precision AD conversion unit 1 according to a first embodiment of the present invention.
It is a circuit block diagram of 0.

FIG. 2 is a circuit configuration diagram of a continuous temperature correction unit 20 according to the first embodiment of the present invention.

FIG. 3 is a high-speed and high-precision AD conversion unit 1 according to a second embodiment of the present invention.
2 is a circuit configuration diagram of FIG.

FIG. 4 is a circuit configuration diagram of a continuous temperature correction unit 21 according to a second embodiment of the present invention.

FIG. 5 is a circuit configuration diagram of a conventional measurement system including a calibration system that performs high-speed and high-precision AD conversion of the analog signal under measurement 100.

FIG. 6 is a circuit configuration diagram of a conventional high-speed and high-precision AD conversion unit 50.

[Explanation of symbols]

10, 50, 11 High-speed and high-accuracy AD converter 12 Temperature sensor 14 AD converter 16 First memory 18 Second memory 20, 21 Continuous temperature corrector 20in, 20out, 80out, 50out, 52d, 60d
Code data 22 Offset adder 24 Multiplier 26add Analog offset correction signal 26, 54, 28 DA converter 28mul Analog gain correction signal 40 Reference signal source 42, 43 Changeover switch 44 Reference digital voltmeter 50in Input analog signal 51 Sample hold section 51a , 56a Analog signal 52 First AD converter 56 Error amplifier 60 Second AD converter 62 Adder 80 Control unit 82 Calibration signal 100 Measured analog signal

Claims (4)

[Claims] 1. A high-speed sample and hold section (51), a first AD converter (52) having a low resolution and a high speed, and a DA converter (54) upon receiving an analog signal (100) to be measured.
And the error amplifier (56) and the low resolution high speed second A
A high-speed, high-resolution AD conversion circuit having a D converter (60) and an adder (62) is provided with a temperature sensor (12) for detecting the temperature of the high-speed and high-precision AD conversion circuit section. A continuous temperature correction unit (20) that receives a signal from the temperature sensor (12) and continuously corrects the temperature between the error amplifier (56) and the adder (62) is provided, and the above is provided. High-speed and high-accuracy AD converter. 2. The continuous temperature correction unit (20) according to claim 1.
Receives the temperature signal from the temperature sensor (12), converts it into a digital signal, and converts it into a first memory (16) and a second memory (1
An AD converter (14) for supplying an address signal to 8) is provided, the digital temperature data from the AD converter (14) is received, the correction value of the temperature drift is read from the first memory (16) and offset. A first memory (16) for supplying to the adder (22) is provided, receives the digital temperature data from the AD converter (14), reads the temperature correction value of the amplification degree from the second memory (18) and performs multiplication. A second memory (18) for supplying to the device (24) is provided, and the correction value of the temperature drift from the first memory (16) and the code data (20 from the second AD converter (60) are provided.
in), the two are added to correct the offset deviation, and an offset adder (22) for supplying to one input end of the multiplier (24) is provided to amplify from the second memory (18). Temperature correction value of
A multiplier (24) is provided which receives the code data from the offset adder (22), multiplies both of them, and normalizes the code data to output code data (20out) in which the deviation of the amplification degree is corrected. A high-speed and high-precision AD converter that is characterized by 3. A high-speed sample-hold section (51), a first AD converter (52) having a low resolution and a high speed, and a DA converter (54) receiving an analog signal to be measured (100).
And the error amplifier (56) and the low resolution high speed second A
A high-speed, high-resolution AD conversion circuit having a D converter (60) and an adder (62) is provided with a temperature sensor (12) for detecting the temperature of the high-speed and high-precision AD conversion circuit section, Upon receiving the signal from the sensor (12), the error amplifier (5
6) and the second AD converter (60) are provided with a continuous temperature correction unit (21) for continuously performing temperature correction, and the high-speed and high-precision AD conversion device is provided with the above. 4. The continuous temperature correction unit (21) according to claim 3.
Receives the temperature signal from the temperature sensor (12), converts it into a digital signal, and converts it into a first memory (16) and a second memory (1
An AD converter (14) for supplying an address signal to 8) is provided, the digital temperature data from the AD converter (14) is received, the correction value of the temperature drift is read from the first memory (16) and offset. A first memory (16) for supplying to the adder (22) is provided, receives the digital temperature data from the AD converter (14), reads the temperature correction value of the amplification degree from the second memory (18) and performs multiplication. A DA converter (which is provided with a second memory (18) for supplying to the device (24), receives the signal from the first memory (16), DA-converts it into an analog signal, and outputs an offset correction signal (26add) ( 26) is provided, and a DA converter (28) that receives the signal from the second memory (18) and DA-converts it into an analog signal and outputs a gain correction signal (28mul) is provided. Special And the high-speed high-precision AD converter.