Classifications

• • H—ELECTRICITY
  • H03—ELECTRONIC CIRCUITRY
  • H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
  • H03M1/00—Analogue/digital conversion; Digital/analogue conversion
  • H03M1/06—Continuously compensating for, or preventing, undesired influence of physical parameters
  • H03M1/0617—Continuously compensating for, or preventing, undesired influence of physical parameters characterised by the use of methods or means not specific to a particular type of detrimental influence
  • H03M1/0626—Continuously compensating for, or preventing, undesired influence of physical parameters characterised by the use of methods or means not specific to a particular type of detrimental influence by filtering
• • H—ELECTRICITY
  • H03—ELECTRONIC CIRCUITRY
  • H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
  • H03M1/00—Analogue/digital conversion; Digital/analogue conversion
  • H03M1/12—Analogue/digital converters
  • H03M1/20—Increasing resolution using an n bit system to obtain n + m bits
  • H03M1/201—Increasing resolution using an n bit system to obtain n + m bits by dithering
• • H—ELECTRICITY
  • H03—ELECTRONIC CIRCUITRY
  • H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
  • H03M1/00—Analogue/digital conversion; Digital/analogue conversion
  • H03M1/002—Provisions or arrangements for saving power, e.g. by allowing a sleep mode, using lower supply voltage for downstream stages, using multiple clock domains or by selectively turning on stages when needed
• • H—ELECTRICITY
  • H03—ELECTRONIC CIRCUITRY
  • H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
  • H03M1/00—Analogue/digital conversion; Digital/analogue conversion
  • H03M1/06—Continuously compensating for, or preventing, undesired influence of physical parameters
  • H03M1/0614—Continuously compensating for, or preventing, undesired influence of physical parameters of harmonic distortion
• • H—ELECTRICITY
  • H03—ELECTRONIC CIRCUITRY
  • H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
  • H03M1/00—Analogue/digital conversion; Digital/analogue conversion
  • H03M1/10—Calibration or testing
  • H03M1/1009—Calibration
• • H—ELECTRICITY
  • H03—ELECTRONIC CIRCUITRY
  • H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
  • H03M1/00—Analogue/digital conversion; Digital/analogue conversion
  • H03M1/12—Analogue/digital converters
  • H03M1/124—Sampling or signal conditioning arrangements specially adapted for A/D converters
• • H—ELECTRICITY
  • H03—ELECTRONIC CIRCUITRY
  • H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
  • H03M1/00—Analogue/digital conversion; Digital/analogue conversion
  • H03M1/12—Analogue/digital converters
  • H03M1/60—Analogue/digital converters with intermediate conversion to frequency of pulses

Definitions

• the invention relates to a device for digitizing an analog signal.
• the device has an analog-to-digital converter with a signal input for the signal.
• the apparatus further includes a distortion signal generator having a distortion signal output, wherein the distortion signal generator is configured to provide a distortion signal at the distortion signal output.
• Generic devices are used in particular to convert analog signals into digital signals, for example to be able to evaluate and further process signals delivered by a sensor by means of electronic data processing in a microcontroller or another control unit.
• the distortion signal generator serves in particular to increase the resolution of the analog-to-digital converter.
• Background of the use of such a Verzerrsignalgenerators is the fact that many analog-to-digital converters have a sampling frequency, which is much faster than necessary for a particular application, but at the same time because of their resolution, ie the minimum distinguishable signal level, but only one allow coarse detection of the signal.
• the resolution is usually specified in bit for analog-to-digital converters.
• analog-to-digital converters also referred to as analog-to-digital converters
• the resolution is often on the order of about 10 bits, where however, in many applications, resolutions of, for example, 13 bits or 14 bits would be desirable.
• the distortion signal generator is therefore used to convert the temporal resolution into a higher sampling accuracy.
• This method is also called dithering.
• noise with a low rms value is added to the signal to be digitized, typically of the order of a few least significant bits, also referred to as Least Significant Bits (LSB).
• Least Significant Bits A therefrom resul ⁇ animal end signal which is then digitized by the analog-to-digital converter fluctuates around the digitized signal to the corresponding value with the instantaneous value of the Verzerrsignals. For example, if the distortion signal has the mean value of zero, the average of many output values of the analog-to-digital converter may correspond to the correct output value of the constant signal to be digitized.
• this average has a higher resolution. In the averaging, in fact, places with a lower significance than 1 LSB arise.
• both the use of a random noise and of a pseudo noise as a distortion signal are available for this purpose.
• random noise it is not necessarily guaranteed that for a group of, for example, fifty consecutive values of noise, the mean will actually be zero.
• Such random noise may be generated, for example, by a random generator based on the observation of a natural phenomenon such as a radioactive decay.
• a pseudo noise a mathematical function is typically used which generates pseudorandom numbers based on an output value. These pseudorandom numbers have defined properties; in particular can be calculated how many must be grouped pseudo-random ⁇ pay, around a mean of zero to to reach. Even if the average of such a group is not zero, the pseudo noises can still be used because the average is known and can be computationally easily compensated.
• random noise also refers in particular to "random dithering”
• pseudo-random numbers also refers to "deterministic dithering”.
• a simply defined signal such as a triangular or sawtooth signal can also be used.
• a zero average is to be achieved, this may be done by including the period of time from which the used values are averaged to an integer number of periods of the corresponding warping signal.
• the implementation of deterministic dithering is typically one
• Distortion signal generator an adder, an analog-to-digital converter and a microcontroller used.
• the adder typically provides for a superimposition of the distortion signal on the analog signal to be digitized, whereupon it is digitized by the analog-to-digital converter and forwarded in digitized form to the microcontroller.
• the microcontroller then forms the mean value over a number of measured values, wherein it uses information of the distortion signal generator.
• Adders are typi cally ⁇ constructed using active components such as operational amplifiers. It has been shown that although the ⁇ -like versions achieve high resolution and for Numerous purposes are suitable, but on the other hand also expensive and expensive to produce.
• the invention relates to a device for digitizing an analog signal.
• the device has an analog-to-digital converter with a signal input for the signal.
• the apparatus further includes a distortion signal generator having a distortion signal output, wherein the distortion signal generator is configured to provide a distortion signal at the distortion signal output.
• the distortion signal output is coupled exclusively to the analog-to-digital converter by means of passive components.
• the invention is based on the recognition that the use of a conventional adder implemented by means of active components, such as operational amplifiers, is not absolutely necessary in order to achieve sufficient accuracy for many applications. Rather satisfy this passive components, in particular resistors (R) and / or Kondensa ⁇ factors (C) and optionally inductors (L).
• the magnitude of the distortion signal is typi ⁇ cally few Least Significant Bits (LSB), for example 1, 2 or 3 LSB.
• the magnitude of the Verzerrsignals is typically much smaller than the large ⁇ xowskiowski of the signal to be digitized, for example, the Verzerrsignal may have a maximum amount which is less than 10% or less than 5% of the maximum amount of the digitized analog signal.
• the Verzerrsignal is preferably deterministic, for example, a three ⁇ ecks- or sawtooth signal or a pseudo-random signal.
• the distortion signal preferably has a mean value of zero, but this is not absolutely necessary since a mean value deviating from zero can be computationally compensated without problems.
• the analog-to-digital converter is preferably synchronized with the distortion signal generator.
• a microcontroller for example, which receives and / or evaluates a signal supplied by the analog-to-digital converter can also be synchronized with the distortion signal generator.
• information about the distortion signal can be transmitted as part of a synchronization.
• the distortion signal output without active components, in particular without Operationsver ⁇ stronger, coupled to the analog-to-digital converter is particularly advantageous reduction of the effort and thus the cost.
• the inventor of the present application has found that sufficient accuracy and quality can nevertheless be achieved for a variety of applications.
• the analog-to-digital converter is part of a microcontroller. This allows direct further processing ⁇ the signals generated by the analog-to-digital converter, in particular an averaging and also a Ver ⁇ application in further calculations. b
• the distortion signal generator is also part of the microcontroller. This allows a particularly advantageous simplification of the structure, since the microcontroller, which contains the analog-to-digital converter, can also generate the distortion signal at the same time.
• the distortion signal generator can be implemented, for example, by means of a digital output of the microcontroller, which the
• Distortion signal output forms Such digital outputs are often present in microcontrollers, for example, to perceive control functions. They are typically switchable via internal registers or counters in a defined manner, whereby the circuit can be controlled by software. This allows a software implementation of the Verzerrsignals by appropriate control of the digital output of the microcontroller.
• the analog-to-digital converter has a differential input, the distortion signal output being coupled to a differential input terminal.
• a differential input is typically an input in which the signal to be digitized is determined by the analog-to-digital converter between a positive signal input and a negative signal input.
• the di ⁇ to gital bede signal can be in particular connected to the positive input signal thereby, whereas the Verzerrsignal output is coupled to the negative input of the analog-to-digital converter log.
• the reverse version is possible.
• the adder provided according to the prior art for generating an overlay can be replaced by the distortion signal output in a simple manner with an input of the Analog-to-digital converter is coupled. This allows a particularly simple, yet equally functional design.
• a voltage divider is connected between the Verzerrsignal-output and a reference potential, preferably ground, wherein the terminal of the differential input is connected to an output of the voltage divider.
• a voltage which is applied to the Verzerrsignalsignal output and which is typically much higher than needed, since it is typically the supply voltage of the microcontroller, can be reduced to a desired, much smaller value. This much smaller voltage is then used to distort the measurement of the analog-to-digital converter.
• a capacitor is preferably further connected, which further preferably bridges at least one resistor of the voltage divider.
• an applied respectively to the terminal of the differential input voltage may be, for example, by means of pulse width modulation is ⁇ provides means of Verzerrsignal output.
• the capacitor is charged, for example, just enough so that it has the desired voltage.
• a symmetrical square-wave voltage is output at the distortion signal output, whereby charge and discharge curves are produced at the capacitor, which typically each follow an exponential function. These can be used like the already mentioned triangular or sawtooth voltages.
• the analog-to-digital converter has a reference input in addition to the signal input.
• the distortion signal output is with the Coupled reference input.
• an immediate coupling of the distortion signal output with the analog-to-digital converter can still be achieved using the reference input, which is typical for analog-digital Converters, in particular in microcontrollers, according to the manufacturer's specification should typically be connected to a terminal of one of the supply voltages, however, as the inventor has recognized, it can also be coupled to the distortion signal output.
• a division operation is typically performed in the analog-to-digital converter with respect to the reference input.
• the Verzerrsignal-output and a reference potential, preferably a positive potential, a voltage divider, wherein the reference input is connected to an output of the voltage divider.
• a reference potential preferably a positive potential
• a voltage divider wherein the reference input is connected to an output of the voltage divider.
• a capacitor is preferably connected, which further preferably bridges at least one resistor of the voltage field.
• Verzerrsignal output and the signal-providing signal terminal to the signal input are ge ⁇ coupled.
• This allows for a superimposition of the at digitali ⁇ -stabilizing signal which is accommodatedge ⁇ up by the signal terminal and the Verzerrsignals.
• the overlay does not take place here as in the two embodiments described above within the analog-to-digital converter, but outside.
• passive components can be used, which saves a considerable amount of effort and costs. Nevertheless, a sufficient quality for most applications is achieved.
• the Verzerrsignal-output is preferably DC coupled to the signal input, wherein the coupling is carried out in particular galvanically.
• the signal terminal is preferably coupled to the signal input AC voltage, and more preferably capacitive.
• Distortion signal output from the signal terminal reached Distortion signal output from the signal terminal reached.
• the embodiment described here is particularly advantageous if the signal present at the signal terminal has a minimum frequency at least with regard to its relevant frequency components, frequency components below this minimum frequency not being relevant. In particular ⁇ sondere the signal should have no relevant DC ⁇ share.
• the reverse embodiment can also be used, ie the distortion signal output can be AC-coupled to the signal input, whereas the signal connection is DC-coupled. This can be advantageous in particular when the signal has a relevant DC component or particularly low frequencies.
• a voltage divider is connected between the Verzerrsignal-output and a reference potential, preferably ground, wherein the signal input is connected to an output of the voltage divider.
• a reference potential preferably ground
• the signal supplied by the analog-to-digital converter carries out signal demodulation, for example in the microcontroller.
• components of AC signals can be identified in an advantageous manner. For this purpose, recourse can be had to known algorithms.
• a resistor of the voltage divider connected between the distortion signal output and the output of the voltage divider is preferably larger than a resistance between the output of the voltage divider and connected to the reference potential. This achieves an advantageous reduction of the signal present at the distortion signal output, which is typically too high for a supply voltage of a microcontroller and thus too large.
• FIG. 2 shows a microcontroller with wiring according to a second embodiment
• FIG. 3 shows a microcontroller with wiring according to a third embodiment.
• Fig. 1 shows a microcontroller yC, which has an integrated analog-to-digital converter ADC. This has a differential input, wherein the differential input has a positive terminal ADC + and a negative terminal ADC-. An applied between the two terminals ADC +, ADC- voltage difference is digitized by the analog-to-digital converter ADC.
• the microcontroller yC has a digital output D, which in the present case serves as a distortion signal output.
• the microcontroller yC thus also serves as a distortion signal generator at the same time.
• the microcontroller software is implemented which ensures that the digital output D pulse width modulated or with a square wave signal at ⁇ at ⁇ can be controlled play in such a manner as already described above, so that a defined Verzerrsignal is generated across the subsequently described circuit , A frequency of a rectangular signal or another signal can be determined in particular by means of software.
• the digital output D is connected via a voltage divider S to ground, the voltage divider S having a first resistor Rl and a second resistor R2.
• the first resistor Rl has a significantly higher resistance than the second resistor R2.
• the signal supplied by the digital output D which can change between ground and a Ver ⁇ supply voltage of the microcontroller yC, on divided down a much smaller value, which in terms of voltage three Least Significant Bits (LSB) of the analog-to-digital converter ADC corresponds here.
• LSB Least Significant Bits
• a capacitor C1 which can be charged by the voltage divider S, is connected via the second resistor R2.
• the capacitor Cl is connected to an output of the voltage divider S, which is located between the two resistors Rl, R2.
• the capacitor C1 When the digital output D assumes a positive potential, the capacitor C1 is charged in this way. When the digital output D assumes a negative potential, the capacitor C1 is discharged.
• the distortion signal may arise as a sequence of different pulse width modulation settings at the digital output D.
• the output of the voltage divider S and the associated terminal of the capacitor Cl is further connected to the negative terminal ADC- of the analog-to-digital converter ADC.
• the signal applied to the positive terminal ADC + is digitized relative to a voltage value adjustable by means of the digital output D. This makes it possible to superimpose a distortion signal which can be adjusted via the digital output D in a manner similar to that which would occur if the distortion signal were superimposed by means of an upstream adder, as is customary in the prior art.
• active components necessary according to the prior art can be dispensed with.
• the microcontroller yC At the positive terminal ADC + is a signal VS, which is to be digitized.
• the microcontroller yC further has a reference terminal Ref, which is connected to a reference voltage VR. This is used internally in the microcontroller yC, but is not relevant for the interconnection according to FIG.
• the microcontroller yC is formed further to a defined signal sequence, in this case in the form of a sawtooth ⁇ signal to generate on the negative terminal ADC.
• the digital output D is driven accordingly, so that the capacitor Cl assumes the necessary voltages. Since the microcontroller yC generates these values itself, it also knows them and can evaluate the signals supplied by the analog-to-digital converter ADC accordingly. In particular, an average value is formed over a plurality of measurements carried out in succession, this mean value being more accurate than the resolution of the analog-to-digital converter ADC.
• the possible sampling frequency of the analog-to-digital converter ADC is considerably higher than would be required for sampling the signal VS.
• a sawtooth signal as a distortion signal is advantageous in many applications. This can be done, for example, by means of a sequence of Pulse width modulation signals are generated at the digital output D.
• Pulse width modulation signals are generated at the digital output D.
• Fig. 2 shows a microcontroller with wiring according to a second embodiment.
• the analog-to-digital converter ADC of the second embodiment has no differential input. It has only one positive terminal ADC +, to which the signal VS to be digitized is connected. Measured is relative to a purely internal negative terminal ADC-, which hard-wired to ground and not ver ⁇ changeable.
• the microcontroller yC has a digital output D as in the first embodiment. This is also coupled to a voltage divider S with two resistors Rl, R2, wherein via the second resistor R2, a capacitor Cl is connected. In contrast to the first exemplary embodiment, however, the voltage divider S is not connected to ground at its end opposite the digital terminal D but to a supply voltage VDD. Basically, it can be used in a very similar way with respect to the first exporting ⁇ approximately example describes a Verzerrsignal be generated.
• the output of the voltage divider S, to which also the capacitor C1 is connected is not connected to the negative terminal ADC, but to the reference terminal.
• connection reference is an input for a used in the analog-digital converter ADC reference potential through which is shared at the positive terminal + ADC signal present before di ⁇ it is gitalinstrument.
• the superimposition does not take place via a summation or subtraction, but via a division.
• the microcontroller yC is programmed such that it also forms average values, but taking into account the differently superposed distortion signal. This can be done in the same way, a conversion of temporal resolution in a better sampling resolution.
• FIG. 3 shows a microcontroller yC with a circuit according to a third exemplary embodiment.
• the distortion signal is not coupled directly to the microcontroller yC, but rather the distortion signal is superimposed on the signal VS to be digitized.
• the digitizing signal VS is coupled by means of a capacitor C1, so that it is AC voltage coupled. A DC component of the signal VS is thus hidden.
• the digital output D of the microcontroller yC is connected in the same way as in FIG. 1 to a voltage divider S which has two resistors R1, R2 and is connected to ground at its end opposite the digital output D.
• the output of the voltage divider S which lies between the resistors Rl, R2, is connected to the capacitor Cl.
• connection ADC + connected to the positive connection ADC + connected.
• it is connected to a third resistor R3, which in turn is connected at its opposite terminal to a supply voltage VDD.
• the reference input Ref of the microcontroller yC is fixedly connected to a reference potential VR in the present case.
• the distortion signal which is already adjusted as described above by means of the voltage divider S in its amount, directly superimposed on the signal to be digitized VS before it is coupled into the analog-to-digital converter ADC .
• the circuit shown in FIG. 3 has a somewhat different transfer characteristic than an adder with active components such as operational amplifiers, this transfer characteristic is sufficient for typical applications. In particular, it can be compensated for the calculations performed by the microcontroller yC. By eliminating active components, a significant reduction in effort and cost is achieved.

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• 2014
  • 2014-09-26 DE DE102014219531.4A patent/DE102014219531A1/de active Pending
• 2015
  • 2015-09-25 KR KR1020177008073A patent/KR101907329B1/ko active IP Right Grant
  • 2015-09-25 WO PCT/EP2015/072075 patent/WO2016046356A1/de active Application Filing
  • 2015-09-25 CN CN201580048430.3A patent/CN106716844A/zh active Pending
  • 2015-09-25 US US15/504,150 patent/US10027337B2/en active Active
  • 2015-09-25 EP EP15767518.2A patent/EP3198726A1/de not_active Ceased

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