CN109212448A - Auto zeroing circuit - Google Patents
Auto zeroing circuit Download PDFInfo
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- CN109212448A CN109212448A CN201810961677.XA CN201810961677A CN109212448A CN 109212448 A CN109212448 A CN 109212448A CN 201810961677 A CN201810961677 A CN 201810961677A CN 109212448 A CN109212448 A CN 109212448A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R35/00—Testing or calibrating of apparatus covered by the other groups of this subclass
- G01R35/005—Calibrating; Standards or reference devices, e.g. voltage or resistance standards, "golden" references
- G01R35/007—Standards or reference devices, e.g. voltage or resistance standards, "golden references"
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Abstract
The invention discloses a kind of Auto zeroing circuits, including modules A and module B.Modules A includes: main amplifier and zero amplifier, and main amplifier and zero amplifier are equipped with corresponding primary feedback network and zeroing feedback network, when all K1 are closed, when K2 is disconnected, since the system is in profound and negative feedbck state, output voltage VoA obtains the signal for eliminating offset voltage and is stored on capacitor Cos, and the offset voltage of main amplifier is obtained on capacitor Cos；When all K1 disconnect K2 closure, the net input of main amplifier will obtain the pure amplification signal of input signal by primary feedback network again after the main amplifier offset voltage subtracted on capacitor, to realize the purpose of offset voltage elimination.The structure of module B and the structure of the modules A are completely the same, realize the complementation of two modules.The present invention guarantees that whole system works in linear zone, and eliminates injection charge noise and steady zero switching noise.
Description
Technical field
The present invention relates to Auto zeroing field of circuit technology, in particular to a kind of injection charge for overcoming steady zero copped wave causes
Distortion, guarantee that whole system work in linear zone, and eliminates injection charge noise and steady zero switching noise, can hold very much
It changes places the Auto zeroing circuit taken in laboratory using commonplace components.Overcome the bands such as the offset voltage of device and the temperature drift of offset current
The intrinsic 1/f noise of the noise and device come.
Background technique
Conventional operational amplifiers are due to the influence of offset voltage, and there are errors for output end, as shown in Figure 1, a reverse phase
Ratio amplifier amplifier, offset voltage 1mV input the 10Hz sine wave signal of a 10mV, wherein R=Rf, R '=R//
Rf。
As shown in Fig. 1 a, 1b, thick line indicates output signal, and filament indicates input signal, it can be seen that offset voltage is by one
It rising and has been sent to output end, output signal has integrally been lifted 1mV upwards, if ratio amplifier amplification factor is 10, output letter
Number will whole lifting 10mV upwards, to bring the error of measuring signal.In fine measuring instrument, due to offset voltage,
Offset current, the brings such as temperature drift and low frequency 1/f noise measurement error can the equivalent input imbalance electricity at amplifier
Pressure is to handle, so in fine measuring instrument, it is necessary to eliminate by offset voltage bring error.
Auto zeroing is a kind of offset voltage of dynamic neutralization amplifier and the technology of offset voltage drift, which can will lose
The influence of voltage and offset voltage drift to amplifier is adjusted to be preferably minimized, meanwhile, Auto zeroing can also reduce low-frequency noise, especially
1/f noise, basic thought are: by two input terminal shortcircuits of amplifier or common mode input signal is added, measures under the state
Output voltage, and electricity container saves, then is subtracted each other with this voltage and output voltage when normal amplifier operation, then may be used
The influence that offset voltage and its temperature change export amplifier is effectively reduced, while common-mode signal can also be effectively inhibited.
In fine measuring instrument, measuring signal is very faint, the measurement of offset voltage and its temperature drift to signal at this time
Influence is very big, and the method for traditional data acquisition is to use analog-digital converter first input short or after common mode input signal is added
(ADC) it is acquired, then accesses normal measuring signal again, then be acquired with analog-digital converter (ADC), two sides measurement
As a result subtracted each other, to obtain steady zero, this technical effect is good, and precision is high, but needing ADC volume is to stay for some time to acquire
Zero point, it is discontinuous that there are signal acquisitions, and with the variation of offset voltage, then biggish amplification factor under the conditions of, amplifier
It is easily accessible inelastic region, influences measurement accuracy.Another method for eliminating offset voltage is wave chopping technology, but the method for copped wave
The frequency that must satisfy input signal is lower than the half of chopping frequency, and to avoid aliasing, and copped wave also results in appearance significantly
Burr, need to filter out ripple, but since the frequency content of burr is very rich, then under special occasions, filter out burr with one
Fixed complexity.Representative as newest Auto zeroing technology is copped wave stable state amplifier integrated circuit, which has used two
Amplifier, is " master " amplifier and " zeroing " amplifier respectively, after zero amplifier is by input terminal shortcircuit and to zero itself,
Monitor and correct the imbalance of main amplifier.Because main amplifier clock is connected to input and output side, the band of input signal
Width is determined by the bandwidth of main amplifier, and depends no longer on chopping frequency.But this technology is switching the note of charge caused by operation
Entering is still very big problem, this may cause signal transients, and injects charge and can couple with input signal, and intermodulation is caused to lose
Very.
It is to stay for some time to acquire zero point that the method for traditional data acquisition, which needs ADC volume, and there are signal acquisitions not to connect
It is continuous, and with the variation of offset voltage, then biggish amplification factor under the conditions of, amplifier is easily accessible inelastic region, influences
Measurement accuracy.
The frequency that the method for traditional copped wave must satisfy input signal is lower than the half of chopping frequency, to avoid aliasing,
And copped wave also results in and significant burr occurs, needs to filter out ripple, but since the frequency content of burr is very rich, then special
Under different occasion, burr is filtered out with certain complexity.
Newest Auto zeroing stable state copped wave is still very big problem switching the injection of charge caused by operation, this may cause
Signal transients, and inject charge and can be coupled with input signal, cause intermodulation distortion.
Summary of the invention
The present invention is directed to overcome the deficiencies of existing technologies, lost caused by the injection charge the present invention overcomes stable state copped wave
Very, it ensure that whole system work in linear zone, and eliminates injection charge noise and steady zero switching noise, engineer can be with
It is easy to build this circuit using commonplace components in laboratory, and engineer can select commonly according to the engineering demand of oneself
Amplifier or high performance amplifier, without handling simple engineering application problem using expensive chip, the circuit
Theoretical foundation is clear, easy to use, easily promotes.
To achieve the above object, the invention adopts the following technical scheme: providing a kind of Auto zeroing circuit, including modules A and
Module B:
The modules A, comprising: main amplifier and zero amplifier, and the main amplifier and zero amplifier are set respectively
There are corresponding primary feedback network and zeroing feedback network, measuring signal is connected to main amplifier by the analog switch that K2 is controlled
The positive-negative input end of negative terminal, main amplifier is connected by the analog switch that K1 is controlled, one capacitor of positive termination of main amplifier
Cos, and the output end of zero amplifier, capacitor Cos other end ground connection are connected to by the analog switch that K1 is controlled；Primary feedback net
Network inputs the negative terminal for terminating to main amplifier, and output end is connected to the output of main amplifier by the analog switch that K2 is controlled respectively
End, the analog switch of K1 control are connected to the output end of zero amplifier, output V of the analog switch of K3 control as modules AoA,
Zeroing feedback network is coupled with the input terminal and output end of zero amplifier；
The structure of the structure and the modules A of the module B is completely the same, in the modules A and module B, the module B
Switching drive signal have a translation in time relative to the switching drive signal of the modules A, for realizing two moulds
The complementary duty of block, modules A and module B pass through the equal resistance R output of two resistance values respectively, and the another of two resistance R
Hold the output Vo to connect as entire circuit.
In the modules A and module B: when all K1 are closed, K2 is disconnected, defeated since the system is in profound and negative feedbck state
Voltage V outoAIt obtains the signal for eliminating offset voltage and is stored on capacitor Cos, the mistake of main amplifier is obtained on capacitor Cos
Adjust voltage；When all K1 are disconnected, K2 closure, the net of main amplifier is inputted after the main amplifier offset voltage that will be subtracted on capacitor again
The pure amplification signal of input signal is obtained by primary feedback network, to realize the purpose of offset voltage elimination.The modules A
In module B, the main amplifier and zero amplifier work in linear zone.In the modules A and module B, the module B
Switching drive signal be delayed in time half period relative to the switching drive signal of the modules A.
In the modules A and module B, the modules A and module B at least guarantee have one to work in signal measurement state,
And the modules A and module B alternately enter signal measurement state.
The modules A and module B work are in signal measurement state and zero padding state, the frequency of measuring signal and zero padding frequency
It is full decoupled relationship between rate.
The beneficial effects of the present invention are: distortion caused by the injection charge of stable state copped wave is overcome, ensure that entire system
Work unite in linear zone, and eliminates injection charge noise and steady zero switching noise problem.Engineer can be easy in reality
It tests room and builds this circuit using commonplace components, and engineer can select base amplifier or height according to the engineering demand of oneself
Performance amplifier changes Circuit theory according to bright without handling simple engineering application problem using expensive chip
Really, easy to use, easily promote.
Detailed description of the invention
Fig. 1 a show the circuit structure diagram of conventional inverter ratio amplifier.
Fig. 1 b show shown in FIG. 1 reversely than the signal input and output schematic diagram of phase example operational amplifier circuit.
Fig. 2 show the circuit structure diagram of one embodiment of Auto zeroing circuit of the present invention.
Fig. 3 show the switching drive signal schematic diagram of Auto zeroing circuit as shown in Figure 2.
Output waveform diagram when Fig. 4 show modules A work.
Fig. 5 show the bimodulus output waveform diagram of Auto zeroing circuit as shown in Figure 2.
Fig. 6 show the main amplifier output signal schematic diagram that measuring signal frequency is greater than zero padding frequency.
Fig. 7 show modules A output and Dual module output signal contrast schematic diagram.
Specific embodiment
In order to make the objectives, technical solutions, and advantages of the present invention clearer, below in conjunction with attached drawing and specific implementation
Example, the present invention will be described in further detail.It should be appreciated that specific embodiment described herein is only to explain this hair
It is bright, but not to limit the present invention.
As shown in Figures 2 and 3, Auto zeroing circuit provided in an embodiment of the present invention, including modules A and module B, two module knots
Structure is completely the same, the difference is that modules A and the switching drive signal difference in module B, and the driving of two modules is in the time
The upper delay with a half period, to realize the complementary duty of two modules.
As shown in Fig. 2, by taking modules A as an example, modules A includes main amplifier and zero amplifier, and the main amplifier and
Zero amplifier is respectively equipped with corresponding primary feedback network and zeroing feedback network, it is ensured that two main amplifiers and zero amplifier
Always work in linear zone.As shown in Fig. 2, measuring signal is connected to the negative terminal of main amplifier by the analog switch that K2 is controlled,
The positive-negative input end of main amplifier is connected by the analog switch that K1 is controlled, one capacitor Cos of positive termination of main amplifier, and is led to
The analog switch for crossing K1 control is connected to the output end of zero amplifier, capacitor Cos other end ground connection；Primary feedback network input
It is connected to the negative terminal of main amplifier, output end is connected to the output end of main amplifier, K1 control by the analog switch that K2 is controlled respectively
Analog switch be connected to the output end of zero amplifier, output V of the analog switch of K3 control as modules AoA, return to zero feedback net
Network is coupled with the input terminal and output end of zero amplifier；
Since modules A work is in zeroing state and signal measurement state, and the movement that two states switch there are moment, it is defeated
Voltage has many burr spikes out, it is assumed that input signal is 10mV, and zero padding switching frequency is 1kHz, and output is low by a RC
Bandpass filter, wherein resistance is 100 Ω, capacitor 20nF, then the waveform for filtering front and back is as shown in Figure 4.
Shown in Fig. 4, wherein filament is the output waveform of modules A, and thick line is to the filtered waveform of modules A output waveform.
Although increase RC can be passed through figure 4, it is seen that RC filter can preferably filter out burr, but still not smooth enough
The problem of resistance value or capacitance of filter improve, but there is also phase shifts, and with the increase of measuring signal frequency, RC is filtered
The passband of device has certain restriction.There are high-frequency input signal good wave filtering effects, and low frequency signal filter effect is poor, or is low
Yupin effect is good, the problem of high-frequency effect difference.
To solve the above-mentioned problems, needing to introduce module B co-operation, two modular structures are completely the same, unlike
Modules A is different with the switching drive signal in module B, and the driving of two modules has the delay of a half period.Such as Fig. 3 institute
Show, while improving the switching drive signal of two module, that is, modules As and module B, so that two modules are at any time all at least
Guarantee has a module job in measuring state, and the process of zero padding only takes up the system less time, as shown in Fig. 2, for
Modules A or module B, when K1 is driven to high level, K1 closure, module works in measuring state, when K2 is driven to high level
When, K2 closure, module works in zero padding state.As the index of measuring signal and amplifier and Fig. 2,3 consistent, and amplify
When multiple is 10, filter resistance 1k Ω, filter capacitor 200nF, output waveform is as shown in Figure 5.
As shown in Figure 5, thick line is that the influence for completely eliminating amplifier offset parameter is realized using the circuit of the invention patent
Output signal, filament are input signals, by two module outputs alternate with each other, obtain ideal smooth no measurement error
Measuring signal ratio enlargement purpose.And output filtering is not needed, realize high bandwidth, high-accuracy signal operation.
It can also be applied to high-frequency signal measurement simultaneously in order to illustrate the invention patent, for example measuring signal is zero padding frequency
10 times, be 10kHz, other parameters are constant, obtain module in main amplifier output signal and input signal it is as shown in Figure 6.
As shown in Figure 6, main amplifier does not export when zero padding working condition, and at this time due to another mould
Block is for measuring state, so not influencing for output signal, system obtains a stable output waveform, module output
Signal is as shown in Figure 7 with system output signal.
Fig. 7 show modules A output and Dual module output signal contrast schematic diagram.From figure 7 it can be seen that working as measurement frequency
When greater than zero padding frequency, modules A or module B will lose a part of measuring signal, and since another module is in measurement shape
State, so total output signal is not lost, to export complete measuring signal, and the offset voltage of system also by
It fully curbs, obtains the faint measuring signal amplification of not error.
As can be seen that some module will lose a part of measuring signal when measurement frequency is greater than zero padding frequency, and
Since another module is in measuring state, so total output signal is not lost, thus the complete measurement letter of output
Number, and the offset voltage of system is also fully curbed, and the faint measuring signal amplification of not error is obtained.
The above described specific embodiments of the present invention are not intended to limit the scope of the present invention..Any basis
Any other various changes and modifications made by technical concept of the invention should be included in the guarantor of the claims in the present invention
It protects in range.
Claims (6)
1. a kind of Auto zeroing circuit, which is characterized in that including modules A and module B:
The modules A, comprising: main amplifier and zero amplifier, and the main amplifier and zero amplifier are respectively equipped with pair
The primary feedback network and zeroing feedback network answered, measuring signal are connected to the negative of main amplifier by the analog switch that K2 is controlled
The positive-negative input end at end, main amplifier is connected by the analog switch that K1 is controlled, one capacitor Cos of positive termination of main amplifier,
And the output end of zero amplifier is connected to by the analog switch that K1 is controlled, capacitor Cos other end ground connection；Primary feedback network is defeated
Enter to terminate to the negative terminal of main amplifier, output end is connected to the output end of main amplifier, K1 by the analog switch that K2 is controlled respectively
The analog switch of control is connected to the output end of zero amplifier, output V of the analog switch of K3 control as modules AoA, zeroing is instead
Feedback network is coupled with the input terminal and output end of zero amplifier；
The structure of the structure and the modules A of the module B is completely the same, and in the modules A and module B, the module B's is opened
Close driving signal relative to the switching drive signal of the modules A has a translation in time, for realizing two modules
Complementary duty, modules A and module B pass through the equal resistance R output of two resistance values respectively, and the other end phase of two resistance R
Meet the output Vo as entire circuit.
2. Auto zeroing circuit as described in claim 1, which is characterized in that in the modules A and module B: when all K1 be closed,
K2 is disconnected, since the system is in profound and negative feedbck state, output voltage VoAIt obtains the signal for eliminating offset voltage and is stored in
On capacitor Cos, the offset voltage of main amplifier is obtained on capacitor Cos；When all K1 disconnect, K2 closure, main amplifier it is net
Input will obtain the pure amplification signal of input signal by primary feedback network again after the main amplifier offset voltage subtracted on capacitor,
To realize the purpose of offset voltage elimination.
3. Auto zeroing circuit as described in claim 1, which is characterized in that in the modules A and module B, the main amplifier
It works with zero amplifier in linear zone.
4. Auto zeroing circuit as described in claim 1, which is characterized in that in the modules A and module B, the module B's is opened
Driving signal is closed to be delayed in time half period relative to the switching drive signal of the modules A.
5. Auto zeroing circuit as claimed in claim 4, which is characterized in that in the modules A and module B, the modules A and mould
Block B at least guarantees have a job in signal measurement state, and the modules A and module B alternately enter signal measurement state.
6. Auto zeroing circuit as claimed in any one of claims 1 to 5, which is characterized in that the modules A and module B work exist
It is full decoupled relationship between the frequency and zero padding frequency of measuring signal when signal measurement state and zero padding state.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810961677.XA CN109212448B (en) | 2018-08-22 | 2018-08-22 | Self-stabilizing zero circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810961677.XA CN109212448B (en) | 2018-08-22 | 2018-08-22 | Self-stabilizing zero circuit |
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| CN109212448A true CN109212448A (en) | 2019-01-15 |
| CN109212448B CN109212448B (en) | 2020-06-16 |
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| CN201810961677.XA Expired - Fee Related CN109212448B (en) | 2018-08-22 | 2018-08-22 | Self-stabilizing zero circuit |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110687432A (en) * | 2019-10-18 | 2020-01-14 | 中国电子科技集团公司第五十八研究所 | Signal processing circuit for ATE |
| CN113551693A (en) * | 2021-07-26 | 2021-10-26 | 联合微电子中心有限责任公司 | Step-by-step self-zero-adjusting detection circuit and method |
| CN114978054A (en) * | 2022-06-20 | 2022-08-30 | 圣邦微电子（北京）股份有限公司 | Self-stabilizing zero operational amplifier |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110687432A (en) * | 2019-10-18 | 2020-01-14 | 中国电子科技集团公司第五十八研究所 | Signal processing circuit for ATE |
| CN113551693A (en) * | 2021-07-26 | 2021-10-26 | 联合微电子中心有限责任公司 | Step-by-step self-zero-adjusting detection circuit and method |
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