CN107643445A - Amplitude measurement method and system based on high-speed comparator and RC integrating circuit - Google Patents
Amplitude measurement method and system based on high-speed comparator and RC integrating circuit Download PDFInfo
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- CN107643445A CN107643445A CN201710459118.4A CN201710459118A CN107643445A CN 107643445 A CN107643445 A CN 107643445A CN 201710459118 A CN201710459118 A CN 201710459118A CN 107643445 A CN107643445 A CN 107643445A
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Abstract
The invention discloses a kind of amplitude measurement system based on high-speed comparator and RC integrating circuit, including：Input module, judge module, the first measurement module, the second measurement module and display module.Input module is used to receive pulse signal to be measured.Judge module is used to detect and judge pulse signal frequency, and judge module connects with input module.First measurement module is used to measure low frequency pulse signal amplitude, and the first measurement module connects with judge module.Second measurement module is used to measure high-frequency pulse signal amplitude, and the second measurement module connects with judge module.Display module is connected with the first measurement module and the second measurement module, for showing magnitude measurement data.The invention also discloses a kind of amplitude measurement method based on high-speed comparator and RC integrating circuit.
Description
Technical field
The invention belongs to technical field of semiconductors, more particularly to a kind of amplitude based on high-speed comparator and RC integrating circuit
Measuring method and system.
Background technology
The domestic mode for the pulse signal especially measuring amplitude of high-speed pulse signal is very deficient at present, typically all
It is to complete the process of measuring amplitude from the high peak detector of price and one piece of high-precision ADC chip.
When output of pulse signal, it is easy to because the influence of signal source or outside noise, the pulse letter of output
Number certain overshoot is carried, result mistake can be caused if now peak detector receives this overshoot as amplitude, very
High-precision adc wafer damage below can extremely be caused.
The amplitude that peak detection comes out will also be done corresponding if being mismatched with the input VPP of high-precision adc below
Attenuator circuit, may so cause the bandwidth of whole circuit to decline.If keeping bandwidth, high cost can be entered
One step rises.
Therefore, need badly at present it is a kind of simple and feasible, cost it is relatively low and can quick accurate measuring amplitude a sets of plan.
Therefore, measuring method of the present invention proposes a solution, first frequency is measured with single-chip microcomputer.
When the frequency values measured by single-chip microcomputer are relatively low, then directly variance algorithm is coordinated to obtain again using the ADC of single-chip microcomputer
The range value that must stablize.
To be measured and DAC output quantity is compared using high-speed comparator if at high frequencies, output
Waveform after RC is integrated into single-chip microcomputer ADC come judge DAC value whether with it is to be measured as, finally by DAC
Numerical value be just known that range value.
Pulse signal of the frequency less than 12.8kHz is regarded as low frequency signal by measuring method of the present invention, and frequency is higher than
12.8kHz pulse signal regards as high-frequency signal.
The content of the invention
The present invention proposes a kind of amplitude measurement system based on high-speed comparator and RC integrating circuit, including：For connecing
Receive the input module of pulse signal；For detecting and judging the judge module of pulse signal frequency, the judge module and described
Input module connects；For measuring the first measurement module of low frequency pulse signal amplitude, first measurement module and described sentence
Disconnected module connection；For measuring the second measurement module of high-frequency pulse signal amplitude, second measurement module and the judgement
Module connects；And for showing the display module of magnitude measurement data, the display module and the first measurement module and the second survey
Measure module connection.
In amplitude measurement system proposed by the present invention based on high-speed comparator and RC integrating circuit, the first measurement module is extremely
Have less as follows：Voltage follower, its input are connected with the judge module, for being consistently equal to the voltage magnitude of output
Pulse signal；And first converter, its input is connected with the output end of the voltage follower, for output pulse signal
Amplitude measurement data.
In amplitude measurement system proposed by the present invention based on high-speed comparator and RC integrating circuit, the second measurement module is extremely
Have less as follows：
Reference signal unit, it is used to export the reference signal with reference amplitude information；
Comparator, its positive output end and reverse input end connect reference signal unit and judge module respectively, for
Level value shows reference voltage and the magnitude relationship of measured signal amplitude；
RC integral units, its input are connected with the output end of comparator, for the level value for exporting the comparator
Signal is converted into DC voltage；And
Second converter, its input are connected with the output end of RC integral units, for according to difference d. c. voltage signal
The amplitude measurement data of output pulse signal.
In amplitude measurement system proposed by the present invention based on high-speed comparator and RC integrating circuit, further set positive and negative
Unit is presented, positive feedback unit connects the positive input and output end of comparator, for forming positive feedback to form hysteresis voltage.
The invention also provides a kind of amplitude measurement method based on high-speed comparator and RC integrating circuit, including following step
Suddenly：
Step 1：Pulse signal to be measured is obtained, and tentatively judges pulse signal for low frequency signal or high-frequency signal；
Step 2：When pulse signal is high-frequency signal, then difference pulse signal is exported through comparator based on reference signal,
Difference pulses signal obtains difference d. c. voltage signal through RC Integral Processings, then the amplitude survey of pulse signal is obtained through analog-to-digital conversion
Measure data；Or
When pulse signal is low frequency signal, then amplifies pulse signal and obtain pulse signal after analog-to-digital conversion, sampling
Amplitude measurement data；
Step 3：Show amplitude measurement data.
In amplitude measurement method proposed by the present invention based on high-speed comparator and RC integrating circuit, the frequency of pulse signal
During more than 12.8kHz, judge pulse signal for high-frequency signal；When the frequency of pulse signal is less than or equal to 12.8kHz, arteries and veins is judged
It is low frequency signal to rush signal.
In amplitude measurement method proposed by the present invention based on high-speed comparator and RC integrating circuit, for the pulse of low frequency
The measurement interval of signal is to obtain 20 efficiently sampling values as a cycle.
In amplitude measurement method proposed by the present invention based on high-speed comparator and RC integrating circuit, output difference pulses letter
Number process include：
Step a：Reference signal and pulse signal are inputted to two inputs of the comparator respectively, obtain the defeated of comparator
Go out signal；
Step b：Comparator output signal is through RC Integral Transformations into d. c. voltage signal；
Step c：D. c. voltage signal judges whether it is higher than threshold value through analog-to-digital conversion；
Step d：Reference signal is approached to the amplitude of pulse signal, the amplitude measurement data of output pulse signal by turn.
The beneficial effects of the present invention are：Technical solution of the present invention is measured just using state is compared in real time in high frequency
If switching amplitude meeting real time reaction is in the output of comparator, even low performance AD after being integrated by RC after true amplitude
Can easily it judge, single-chip microcomputer can remove the suitable new datum of switching until as new amplitude to be measured by DA immediately
And show new range value.And the principle of traditional peak detector preserves maximum level (the namely width in a period of time
Degree), connect high-performance AD in rear class and read, but the high level brush that will can not be preserved before if measured signal amplitude reduction
Newly, it is necessary to artificially reset, and it is highly susceptible to overshoot interference.So comparatively, the present invention effectively reduces into
This while reached with high costs scheme identical effect, it also avoid because the inaccurate feelings of numerical value caused by noise
Condition.
Brief description of the drawings
Fig. 1 is the FB(flow block) of measuring method of the present invention.
Fig. 2 is the hardware circuit schematic diagram of the high frequency measurement of measuring method of the present invention.
Fig. 3 is the hardware circuit schematic diagram of the low frequency measurement of measuring method of the present invention.
Fig. 4 is the influence part that a non-ideal impulse signal and non-ideal composition therein are brought to amplitude measurement.
Fig. 5 is the schematic diagram of the increase outputs of the programme-control DAC under high frequency measurement of measuring method of the present invention.
Fig. 6 is that the programme-control DAC under high frequency measurement of measuring method of the present invention reduces the schematic diagram of output.
Fig. 7 is the structural representation of measuring system of the present invention.
Embodiment
With reference to specific examples below and accompanying drawing, the present invention is described in further detail.The process of the implementation present invention,
Condition, experimental method etc., it is the universal knowledege and common knowledge of this area in addition to the following content specially referred to, this hair
It is bright that content is not particularly limited.
As shown in fig. 7, the amplitude measurement system of the invention based on high-speed comparator and RC integrating circuit includes：Input mould
Block, judge module, the first measurement module, the second measurement module and display module.Input module is used to receive pulse letter to be measured
Number.Judge module is used to detect and judge pulse signal frequency, and judge module connects with input module, and judge module, which has, to be judged
Module and judge module, judge module are used to export the pulse signal through being judged as low frequency, and judge module is used to export through judging
For the pulse signal of high frequency.First measurement module is used for the first measurement module for measuring low frequency pulse signal amplitude, the first measurement
Module connects with judge module.Second measurement module is used to measure high-frequency pulse signal amplitude, the second measurement module and judges mould
Block connects.Display module is connected with the first measurement module and the second measurement module, for showing magnitude measurement data.
More specifically, the first measurement module of the invention is at least made up of voltage follower and the first converter.As
The operational amplifier of voltage follower is formed, its positive input is connected with judge module, and output end connects with reverse input end,
The voltage magnitude for exporting operational amplifier is consistently equal to pulse signal.The input of first converter and operational amplifier it is defeated
Go out end to be connected, the amplitude measurement data for output pulse signal.
The second measurement module of the present invention is at least by reference signal unit, comparator, RC integral units and the second converter
Form.Reference signal unit is used to export the reference signal with reference amplitude information.The positive output end of comparator and reversely
Input connects reference signal unit and judge module respectively, and for exporting difference pulse signal, difference pulses signal is to be used for
Characterize amplitude height of the pulse signal compared to reference signal.The input of RC integral units is connected with the output end of comparator,
For difference pulses signal to be converted into difference d. c. voltage signal.The output of the input and RC integral units of second converter
End is connected, for the amplitude measurement data according to difference d. c. voltage signal output pulse signal.Further, comparator is being just
To positive feedback unit is provided between input and output end, positive feedback unit is used to form positive feedback to form hysteresis voltage.
(system hardware composition)
In the specific embodiment of measuring system of the present invention, measured signal is provided by the external world, and (that is, mould is inputted by sub-miniature A connector
Block) it is sent on circuit board.By measured signal simultaneously be sent into three pieces of chips input, one with the second is added sluggishness voltage
Comparator circuit (that is, comparator), the third is operational amplifier (that is, output end and reverse input end as voltage follower
The operational amplifier of connection).The purposes of this three is respectively：The GPIO of single-chip microcomputer is being output to input signal shaping, is being used for
Measurement frequency, and judge which kind of method more accurately to measure its amplitude using；RC integrations are connected in voltage comparator output end
Circuit (that is, RC integral units), it is then sent through what is be connected on single-chip microcomputer with analog-digital converter ADC (that is, the second converter) input
GPIO, for measuring the amplitude of high-frequency signal.Output end be sent directly into ADC (that is, the first converter) input be connected it is another
One GPIO, for measuring the amplitude of low frequency signal.
When measuring amplitude, line frequency first is entered to the signal frequency of the pulse signal of entrance with single-chip microcomputer (that is, it is judged that module)
Rate measure, if more than 12.8kHZ then signal feeding the second measurement module in, by high-speed comparator and RC integrating circuit Lai
Measure, if less than the first measurement module is sent directly into if 12.8kHZ, i.e., measured using the AD of single-chip microcomputer.
Because the AD performances that single-chip microcomputer carries in itself are not very strong, it is only a 1MHz left sides to be mainly manifested in its sample frequency
The right side, so the amplitude measurement of frequency of the processing less than 12.8kHZ is only used for, for the pulse signal of 12.8kHZ frequencies, even if single
The sample rate for carrying ADC of piece machine is also dealt with enough.In addition, the data that AD has been sampled can also carry out standard error analysis to it.
Voltage less than below 0.08V is not counted in the data of 20 readings of a cycle as invalid data, and to this
One group of data calculates standard deviation.If standard deviation is excessive, it is meant that this 20 data collection points have part fall rising edge, decline
It is not to fully fall on the high level of measured pulse signal flat stable, therefore give up this in edge, overshoot or other interference
Batch data, the display on screen is without modification.Measurement result can so be efficiently reduced by because pulse signal is undesirable and
Caused by influence, finally draw more accurate range value.
If frequency is higher than 12.8kHz, high frequency measurement scheme is used.Signal can be sent into high ratio by measuring method of the present invention
Measured compared with device and RC integrating circuit.High-speed comparator type selecting is TLV3501.The signal transacting port of high-speed comparator has together
Phase input, reverse input end and output end.Its operation principle is that reference voltage all the way is sent into an input of the comparator
End, then measured signal is inputted into another input, when the voltage of in-phase input end is higher than the voltage of reverse input end, output is high
Level, it is on the contrary then export low level.In measuring method of the present invention, measured signal enters the in-phase end of high-speed comparator, single-chip microcomputer
The DAC carried is output to end of oppisite phase.Therefore, when pulse signal amplitude to be measured is less than DAC output voltage, low level is exported, instead
Then output with pulse signal to be measured together frequency, same to dutycycle, the pulse signal with phase.
The DAC that single-chip microcomputer carries has the precision of 12, i.e., can reach 2.5/2 in theory12V ≈ 6.1mV precision.Journey
DAC 12 bit digital ends are set to binary number 1000-0000-0000 after sequence initialization, in analog end output reference voltage
The voltage of 2.5V half, i.e. 1.25V, it is entered into the end of oppisite phase of high-speed comparator.If the now width of pulse signal to be measured
Output voltage of the degree more than DAC, the now output of comparator is also one section of pulse signal, on the contrary then be normal low level.
The pulse signal of comparator output, which enters RC circuits integration, can then become steady dc voltage.The DC voltage is
The DC component of comparator output terminal pulse signal, and its average voltage.The DC voltage enters the ADC that single-chip microcomputer carries
The substantially amplitude of the value can be measured afterwards, if the value is bigger than 80mv (threshold value set to remove noise), judge DAC
The voltage for being output to comparator input terminal is less than the amplitude of measured signal, therefore retains the binary number first of DAC digital ends
For 1.
If the pulse amplitude now inputted is less than the 1.25V exported after DAC initialization, the output of comparator
It is often low, after RC is integrated and a low level, its amplitude close to 0V, but can due to exist various noises and interference etc. because
Element fluctuates around 20mV.When the output of RC integrations judges to be less than 80mv through ADC, then illustrate DAC output voltage higher than input
The amplitude of pulse signal, then the binary number first of DAC digital ends is changed to 0.
Because the DAC used is 12 precision, so said process needs circulation to perform 12 times altogether.Above-mentioned initial
After comparing for the first time after change, then a secondary high position for DAC digital ends is set to 1, similarly compared with measured signal.If DAC
Output be higher than measured signal amplitude, then the position is left 1, it is on the contrary then set to 0.After 12 times are circulated throughout, DAC digital ends
12 bits, which have been set, to be finished, and the numerical value should be equal to the amplitude of measured signal in the ideal case, actually can be because
30mV deviation is no more than for factors such as interference, comparator performances.
Because RC integrating circuit have the process of capacitor charge and discharge when input voltage changes, so output voltage will not be deposited
In the situation of mutation, but the speed of output voltage change is determined by the size of resistance value and capacitance product, if product is got over
Greatly, then output voltage change is slower, on the contrary then faster.Such as the output end in comparator, if it is low to sport length from pulse signal
Level, then the output of RC integrating circuit will be changed into about 0V from about 1.25V, and such change just needs the regular hour.
Because measuring method of the present invention will accomplish that near real-time shows the magnitude of voltage of pulse signal to be measured, if changing DAC output voltage
Stable output voltage is transformed to without waiting for RC integrating circuit just to sample it, certainly will cause measurement result mistake afterwards,
So the voltage transformation time can not be oversize, therefore require that RC products can not be too big.
RC products determine another index again, that is, pulse signals more than how many frequency could be only surplus after filtering
Lower DC component.RC products are bigger, and this lower-frequency limit is lower, on the contrary then lower-frequency limit is higher.This lower-frequency limit determines again
Measuring method of the present invention is using the separation of both measurement schemes of high frequency measurement Yu low frequency measurement, i.e. separation best outline
Higher than this lower-frequency limit.Therefore require that RC products can not be too small again.
Two reasons of summary, are set to 10k Ω by resistance, electric capacity are set into 27nF, can both expire under this parameter
Sufficient DAC changes an output voltage per 0.1s and RC integration outputs are stable (circulation 12 times, about 1.2s refresh a secondary screen), again
It can meet that lower-frequency limit is slightly below 10kHz.
If the frequency values obtained after single-chip microcomputer frequency measurement are less than 12.8kHz, the scheme of low frequency measurement is used.It will treat
Survey pulse signal and be sent into voltage follower.Voltage follower is substantially an operational amplifier, operational amplifier and voltage ratio compared with
Device is similar, including in the same direction, inverting input and output end., just can structure by operational amplifier output terminal and reverse input end short circuit
Into voltage follower, output voltage amplitude is set to be consistently equal to the amplitude of in-phase input end input voltage.The operational amplifier type selecting
For TLV4170.Measured signal is input to in-phase input end, ADC is accessed to determine its amplitude after following output.
Because the source of original measured signal is not known, the carrying load ability in unlike signal source is also different, i.e., its
Dai Weinan equivalent resistances may be either large or small., may be equivalent because of its Dai Weinan if such signal is sent directly into ADC
Resistance is unsatisfactory for the condition much smaller than ADC input resistances, and causes electric resistance partial pressure, the magnitude of voltage for being actually fed into ADC is less than original
The amplitude of beginning.Therefore measuring method of the present invention has just used voltage follower, plays duplication one and the original mould one of measured signal one
The signal of sample waveform and the effect for lifting its carrying load ability, even Dai Weinan equivalent resistances are the 1 Ω orders of magnitude, it is much smaller than
The 100k Ω orders of magnitude of ADC inputs.The signal come will be copied it is sent into ADC and measure, and will just be no longer possible to have ADC defeated
The problem of input resistance partial pressure.
The pulse signal that has stronger carrying load ability of voltage follower output enters ADC, it is necessary to which ADC reads this
The range value of signal.Because the signal is not a preferable pulse signal, noise, overshoot, longer rise time etc. be present
Undesirable element, it is easy for impacting the accuracy of the result of measurement.Therefore measuring method of the present invention exports to follower
In signal continuous sampling one sampling period of 20 conducts, judge that the sample in low level, is sentenced if value is less than 80mV
It is set to invalid value and abandons, is not counted within 20 virtual values；It is determined as virtual value if value is higher than 80mV.Due to ADC's
Sampling rate is far above the frequency of measured signal, and the sampled point of this 20 virtual values may partly fall in the upper of pulse signal to be measured
The positions such as edge, trailing edge, overshoot are risen, it could even be possible to above-mentioned position is fully fallen in, if being directly averaged will certainly cause to measure
Numerical value is inaccurate, and the result that each sampling period draws is different.
The overall framework and flow of measuring method of the present invention is shown in Fig. 1, specifically includes：
Step 1：Pulse signal to be measured is obtained, and tentatively judges pulse signal for low frequency signal or high-frequency signal；
Step 2：When pulse signal is high-frequency signal, then difference pulse signal is exported through comparator based on reference signal,
Difference pulses signal obtains difference d. c. voltage signal through RC Integral Processings, then the amplitude survey of pulse signal is obtained through analog-to-digital conversion
Measure data；Or when pulse signal is low frequency signal, then amplifies pulse signal and obtain pulse signal after analog-to-digital conversion, sampling
Amplitude measurement data；
Step 3：Show amplitude measurement data.
One pulse signal to be measured is inputted by SMA interfaces by the external world, the parameter of this pulse signal should be limited in frequency
Rate 0.83HZ -12.2MHZ, amplitude 0.1-2.5V, dutycycle about 10% -90%.This original measured signal is admitted to one
With the sluggish high-speed comparator TLV3501 of 20mV, the pulse signal with the 3.3V of same duty cycle with frequency is shaped to, for frequency
Rate measures.Single-chip microcomputer to after the signal frequency measurement by frequency compared with 12.8kHz, if just taking high frequency measurement method higher than 12.8kHz,
It is on the contrary then take low frequency measurement method.
(high-frequency detection)
The high frequency measurement fractional hardware circuit of measuring method of the present invention as shown in Figure 2.High-speed comparator type selecting is
TLV3501, meet track to track input and output, and switching rate is less than 5ns under 3.3V electric power thus supplieds.Measuring method of the present invention
In, measured signal enters the in-phase end of high-speed comparator, and the DAC that single-chip microcomputer carries is output to end of oppisite phase, and in connection two
Resistance forms positive feedback, one accelerates the rate of change of comparator output voltage, and two form about 20mV hysteresis voltage to subtract
Less due to false triggering phenomenon caused by noise.Therefore, when pulse signal amplitude to be measured is less than DAC output voltage, low electricity is exported
Flat, on the contrary then output is with pulse signal to be measured with frequency, same to phase, the pulse signal with dutycycle.
Single-chip microcomputer type selecting is STM32F4 minimum system development boards, carries 12 DAC, i.e., can enter in theory from 0-2.5V
The analog voltage output of row about 6.1mV steppings.After program initialization as shown in Fig. 1 flow charts, to change DAC digital ends by turn
Binary numeral adjusts the analogue value of output, it is gradually approached the amplitude of pulse signal to be measured.
As shown in Fig. 5, Fig. 6 first step, first, 12 binary number first (MSB) of DAC digital ends is put 1, remaining
11 bits are set to 0, i.e. the half in analog end output reference voltage, 1.25V, and be entered into high-speed comparator
End of oppisite phase compared with input signal.If output voltage of the pulse signal to be measured higher than DAC, the output of comparator are also
Pulse signal, it is on the contrary then be normal low level.
The pulse signal of comparator output, which enters RC circuits integration, can then become steady dc voltage.The DC voltage is
The DC component of comparator output terminal pulse signal, and its average voltage.The DC voltage enters the ADC that single-chip microcomputer carries
The substantially amplitude of the value can be measured afterwards, if the value is bigger than 80mv (threshold value set to remove noise), judge that DAC is defeated
The voltage gone out to comparator input terminal is less than the amplitude of measured signal, second step as shown in Figure 5, retains the two of DAC digital ends
System number first is 1.
Fig. 2, the node that RC integrating circuit connect with ADC are referred to, if comparator output, always to be low, RC integration outputs are also
It is low, but output voltage can be caused to be tens millivolts due to factors such as noises；If comparator output is square wave, RC integration output amplitudes
About measured signal amplitude * measured signal dutycycles, this value are far above tens millivolts.Such as, in the pulse amplitude of input
During less than 1.25V, the output of comparator is often low, and after RC is integrated and a low level, its amplitude is close to 0V, but meeting
Fluctuated due to various noises be present with factors such as interference around 20mV.When the output of RC integrations is less than 80mv through ADC judgements
When, illustrate that DAC output voltage is higher than the amplitude of input pulse signal, second step as shown in Figure 6, enter the two of DAC digital ends
Number first processed is changed to 0.
Because the DAC used is 12 precision, so said process needs circulation to perform 12 times altogether, that is, Fig. 5, figure
The the 3rd to the 12nd step omitted in 6：1 is set to after first time compares, then by a secondary high position for DAC digital ends, similarly with treating
Signal is surveyed to be compared.If DAC output is higher than measured signal amplitude, the position is left 1, it is on the contrary then set to 0.Until 12 times
After being circulated throughout, 12 bits of DAC digital ends, which have been set, to be finished, e.g., shown in Fig. 5, Fig. 6 final step.The numerical value
In the ideal case should and the deviation of amplitude of measured signal be no more than 6.1mV, that is, single-chip microcomputer carries DAC most small step
Enter value, but can actually because of factors such as interference, comparator performances measurement actual value and the amplitude of pulse signal to be measured be present
Deviation no more than 30mV.
Above-mentioned resistance value is 10k Ω, and electric capacity value is 27nF, can both meet that DAC was ensureing under this kind of parameter
Change an output voltage (circulation 12 times, about 1.2s refresh a secondary screen) in the case that RC integration outputs are stable per 0.1s, again
It can meet that the lower-frequency limit of the input pulse signal of high frequency measurement scheme is slightly below 10kHz.
(low frequency detection)
If measured signal frequency values are less than 12.8kHz, the scheme of low frequency measurement is used.Fig. 3 shows low frequency measurement side
The hardware circuit diagram of case.Operational amplifier type selecting is TLV4170, and it has a low maladjustment voltage, the characteristic of track to track input and output,
And slew rate exceeds well over required requirement.Operational amplifier output terminal and reverse input end short circuit are formed into voltage follower, made
Output voltage amplitude is consistently equal to the amplitude of in-phase input end input voltage.Measured signal is input to in-phase input end, followed
ADC is accessed after output to determine its amplitude, because original measured signal may wear dimension with larger in the extreme circumstances
Southern equivalent resistance, the resistance may be unsatisfactory for the requirement much smaller than ADC input impedance, cause electric resistance partial pressure so that be actually fed into
ADC magnitude of voltage is less than original amplitude.Therefore measuring method of the present invention replicates one and original letter to be measured with voltage follower
Signal as number, and its carrying load ability is lifted, even Dai Weinan equivalent resistances are much smaller than the 100k Ω numbers of ADC inputs
Magnitude.The signal come will be copied it is sent into ADC and will measure, can ADC be stable, is accurately read its magnitude of voltage to make.
As shown in fig. 6, because measured signal is not a preferable pulse signal, noise, overshoot, longer rising be present
The undesirable elements such as time, therefore direct measurement amplitude may be such that sampled point falls in rising edge, overshoot etc., cause the width measured
Value is inaccurate and constantly beats.Therefore 20 conducts of signal continuous sampling, one sampling that measuring method of the present invention exports to follower
In the cycle, judge that the sample in low level, is determined as invalid value and abandoned, being not counted in 20 has if value is less than 80mV
Within valid value；It is determined as virtual value if value is higher than 80mV.Because ADC sampling rate is far above the frequency of measured signal,
The sampled point of this 20 virtual values may partly fall at positions such as the rising edges, trailing edge, overshoot of pulse signal to be measured, or even have
Above-mentioned position may be fully fallen in, if being directly averaged will certainly cause measured value inaccurate, and each sampling period draws
Result it is all different.
Therefore measuring method of the present invention is using the algorithm for taking standard deviation.20 collected to the said one sampling period
Voltage value data calculates average value, then calculates standard deviation.Standard deviation reflects the degree of one group of data deviation average, if two groups
The average of data is identical, and difference is bigger between data individual numerical value, then the standard deviation calculated is bigger.Setting one is rational
Standard deviation threshold method, the data group that will be above the threshold value are determined as that invalid data group abandons, retain effective data group.If one group
The sampled point of data is on flat high level is stablized, then the difference between individual data should be smaller, calculates
Standard deviation should be smaller, can be less than threshold value；If instead sampled point exist fall along it is upper with interference along, then individual data it
Between differ greatly, the standard deviation calculated is larger, higher than the threshold value of setting.The average value of valid data group is delivered into screen
Curtain explicit function.
For the stabilization of high-speed comparator, 20mv hysteresis voltage is added in measuring method of the present invention to accelerate the anti-of it
Answer speed and lift its antijamming capability, so also this 20mv is maked corrections in output.Therefore above-mentioned every group of significant figure
According to adding 20mV after averaging.
Summarize above two measurement scheme：Under high frequency measurement scheme, DAC digital end is set as that binary number is real
Border magnitude of voltage；Under low frequency measurement scheme, the average value of the valid data group of ADC measurements is exactly actual magnitude of voltage.Illustrate
Bright, 12 bits measured are 1010-0100-0000 (meeting ADC and DAC two schemes), then represent output voltage as
1.25+1.25/4+1.25/32 ≈ 1.6V, plus being 1.62V after 20mv correction.
The protection content of the present invention is not limited to above example.Under the spirit and scope without departing substantially from inventive concept, this
Art personnel it is conceivable that change and advantage be all included in the present invention, and using appended claims as protect
Protect scope.
Claims (8)
- A kind of 1. amplitude measurement system based on high-speed comparator and RC integrating circuit, it is characterised in that including：Input module for return pulse signal；For detecting and judging the judge module of pulse signal frequency, the judge module connects with the input module；For measuring the first measurement module of low frequency pulse signal amplitude, first measurement module and the judge module connect Connect；For measuring the second measurement module of high-frequency pulse signal amplitude, second measurement module and the judge module connect Connect；AndFor showing that the display module of magnitude measurement data, the display module and the first measurement module and the second measurement module connect Connect.
- 2. the amplitude measurement system based on high-speed comparator and RC integrating circuit as claimed in claim 1, it is characterised in that the One measurement module at least has as follows：Voltage follower, its input are connected with the judge module, and the voltage magnitude for making output is consistently equal to pulse letter Number；AndFirst converter, its input are connected with the output end of the voltage follower, and the amplitude for output pulse signal is surveyed Measure data.
- 3. the amplitude measurement system based on high-speed comparator and RC integrating circuit as claimed in claim 1, it is characterised in that the Two measurement modules at least have as follows：Reference signal unit, it is used to export the reference signal with reference amplitude information；Comparator, its positive output end and reverse input end connect reference signal unit and judge module respectively, for level Value performance reference voltage and the magnitude relationship of measured signal amplitude；RC integral units, its input are connected with the output end of comparator, for the level value signal for exporting the comparator It is converted into DC voltage；AndSecond converter, its input are connected with the output end of RC integral units, for being exported according to difference d. c. voltage signal The amplitude measurement data of pulse signal.
- 4. the amplitude measurement system based on high-speed comparator and RC integrating circuit as claimed in claim 3, it is characterised in that enter One step sets positive feedback unit, and positive feedback unit connects the positive input and output end of the comparator, positive and negative for forming Present to form hysteresis voltage.
- A kind of 5. amplitude measurement method based on high-speed comparator and RC integrating circuit, it is characterised in that comprise the following steps：Step 1：Pulse signal to be measured is obtained, and tentatively judges pulse signal for low frequency signal or high-frequency signal；Step 2：When pulse signal is high-frequency signal, then difference pulse signal, difference are exported through comparator based on reference signal Pulse signal obtains difference d. c. voltage signal through RC Integral Processings, then the amplitude measurement number of pulse signal is obtained through analog-to-digital conversion According to；OrWhen pulse signal is low frequency signal, then amplifies pulse signal and the width of pulse signal is obtained after analog-to-digital conversion, sampling It is worth measurement data；Step 3：Show amplitude measurement data.
- 6. the amplitude measurement method based on high-speed comparator and RC integrating circuit as claimed in claim 5, it is characterised in that arteries and veins When rushing the frequency of signal and being more than 12.8kHz, judge pulse signal for high-frequency signal；The frequency of pulse signal is less than or equal to During 12.8kHz, judge pulse signal for low frequency signal.
- 7. the amplitude measurement method based on high-speed comparator and RC integrating circuit as claimed in claim 5, it is characterised in that pin To the measurement interval of the pulse signal of low frequency to obtain 20 efficiently sampling values as a cycle.
- 8. the amplitude measurement method based on high-speed comparator and RC integrating circuit as claimed in claim 5, it is characterised in that defeated Going out the process of difference pulse signal includes：Step a：Reference signal and pulse signal are inputted to two inputs of the comparator respectively, obtain the output letter of comparator Number；Step b：Comparator output signal is through RC Integral Transformations into d. c. voltage signal；Step c：D. c. voltage signal judges whether it is higher than threshold value through analog-to-digital conversion；Step d：Reference signal is approached to the amplitude of pulse signal, the amplitude measurement data of output pulse signal by turn.
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