CN201886055U - Full-range high-linearity analog signal buffer circuit - Google Patents
Full-range high-linearity analog signal buffer circuit Download PDFInfo
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- CN201886055U CN201886055U CN2010202310226U CN201020231022U CN201886055U CN 201886055 U CN201886055 U CN 201886055U CN 2010202310226 U CN2010202310226 U CN 2010202310226U CN 201020231022 U CN201020231022 U CN 201020231022U CN 201886055 U CN201886055 U CN 201886055U
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Abstract
The utility model discloses a full-range high-linearity analog signal buffer circuit, comprising an input drive circuit, a buffer circuit and an output buffer circuit, wherein the analog signal to be tested is connected with an inverted input end of the input drive circuit, the output end of the input drive circuit is connected with the input end of the buffer circuit in series, a first feedback output end of the buffer circuit is connected with the inverted input end of the input drive circuit and a second output end of the buffer circuit is connected with the inverted input end of the output buffer circuit in series. The full-range high-linearity analog signal buffer circuit has features of small volume, low cost, simple circuit, high precision, large-scale application, good stability, good linearity and high bandwidth and capability of full-range buffer test of the input analog signal and is widely used in aspects of data communication, voltage current detection, switch power supply, measurement and test industry process control (converter buffer, thermocouple buffer) and etc.
Description
Technical field
The utility model relates to a kind of circuit, particularly enlarges the electrical isolation of gamut high linearity simulating signal buffer circuit import to(for) the batch simulating signal.
Background technology
In measuring system, in order to test the characteristic of simulating signal to be measured more accurately, avoid the interference of some peripheral environments, simultaneously also be for fear of system input signal to be produced to disturb, under the volume weight that allows requires, require circuit-under-test and test circuit on electric, to carry out isolation processing usually.Generally our isolation method of employing has common optoelectronic coupler isolation method and magnetic isolation method etc., but these two kinds of isolation methods all have its limitation.Wherein, in the common optoelectronic coupler isolation method, when the linear coupling regime that utilizes optocoupler is directly isolated transmission to simulating signal, because the volt-ampere characteristic of photoelectrical coupler internal illumination diode and photosensitive triode, make that " linear zone " of photoelectrical coupler is in fact smaller and have to a certain degree nonlinear distortion, make input signal can not be isolated by gamut.And for the high-frequency ac simulating signal, the magnetic isolation method is modal selection.The solution that has at present some producers to provide isolated amplifier to isolate abroad as simulating signal, AD202 as ADI company, the TIL300 of the TOAS of TI subsidiary company etc., this isolated amplifier to from direct current in a few KHz frequencies, the simulating signal of-5V in+5V amplitude can reach the nonlinearity up to 0.025% when isolating transmission, but the shortcoming of this integrated isolated amplifier is the internal circuit complexity, volume is big, the cost height, simultaneously restricted (as AD202 for the frequency of input signal, the highest signal frequency is 1kHz), be not suitable for large-scale application.Therefore adopt that above several method can't realize all that small product size is little, cost is low, the linear degree height of input and output, measured signal frequency height, the requirement isolated of measured signal gamut simultaneously.
Summary of the invention
But technical problem to be solved in the utility model is to provide, and a kind of volume is little, cost is low, circuit is simple, the high large-scale application of measuring accuracy, have good stability, the linearity and bandwidth simultaneously, the simulating signal insulation test circuit of gamut, thus overcome the deficiencies in the prior art.
For solving the problems of the technologies described above, the utility model adopts following technical scheme: gamut high linearity simulating signal buffer circuit.Comprise input driving circuit, buffer circuit and output buffer, simulating signal to be measured is received the inverting input of described input driving circuit, the output terminal of input driving circuit is concatenated into the input end of buffer circuit, first feedback output end of buffer circuit is received the inverting input of input driving circuit, and second output terminal of buffer circuit is concatenated into the inverting input of output buffer.
In the above-mentioned gamut high linearity simulating signal buffer circuit, described input driving circuit is made up of combined operational amplification circuit and driving resistor, at the end of oppisite phase of combined operational amplification circuit and connect feedback filtering electric capacity.
In the aforesaid gamut high linearity simulating signal buffer circuit, the photoelectrical coupler that uses in the described buffer circuit is preferably selected feedback-type linear analogue photoelectrical coupler for use, this photoelectrical coupler is inner mainly to be made up of with the output photodiode an aluminum gallium arsenide light emitting diode and two feedback photodiodes that are adjacent, the input end of light emitting diode is received the output terminal of input driving circuit, the output terminal of feedback photodiode inserts the inverting input of input driving circuit, and the output terminal of output photodiode inserts the inverting input of output buffer.
In the aforesaid gamut high linearity simulating signal buffer circuit, described output buffer is made up of combined operational amplification circuit and low-pass filter, the output terminal of buffer circuit is received the inverting input of combined operational amplification circuit, at the end of oppisite phase of combined operational amplification circuit and connect the low-pass filter that is made of resistance and electric capacity.
The beneficial effects of the utility model: compared with prior art, the utility model has concentrated that light isolation technology volume is little, circuit is simple, measured signal frequency height, and the advantage of magnetic isolation technology linearity height, signal testing gamut, and overcome the shortcoming of these two kinds of technology simultaneously, volume is little, cost is low, circuit is simple, precision degree high large-scale application but have, have good stability, the linearity and bandwidth simultaneously, can carry out the characteristics of gamut isolation test the input simulating signal.The applicant is by using the utility model on a kind of data acquisition unit, success in volume is the product of φ 154 (mm) * 76 (mm), realized isolating simultaneously 54 tunnel unipolarity simulating signals, and final composite measurement all nonlinearities of isolating analog quantitys are all less than 0.1% as a result, isolation effect is good.Wherein one road parametrical nonlinearity degree test result sees Table 1.The utility model is applicable to unipolar signal input measurement system, can under various modes such as bipolar signal input, AC-DC Circuit, change-over circuit, work after doing slightly to change, thereby can be widely used in data communication, electric current and voltage detection, Switching Power Supply, measurement and test industrial process control aspects such as (isolation of transducer, the isolation of thermopair).
Table 1 parametrical nonlinearity degree test result
Description of drawings
Fig. 1 is circuit theory diagrams of the present utility model; Vdd1 among the figure, Vss1 and Vdd2, Vss2 represent two groups of different power supplies respectively, illustrate that the power supply of optocoupler rear and front end needs to isolate;
Fig. 2 is a combined operational amplifier equivalent circuit diagram of the present utility model;
Fig. 3 is the cut-away view of photoelectrical coupler of the present utility model.
Below in conjunction with the drawings and specific embodiments the utility model is further described.
Embodiment
Embodiment.As shown in Figure 1, circuit comprises input driving circuit, buffer circuit and output buffer.Input driving circuit is made up of combined operational amplification circuit A1 and driving resistor R2, at the end of oppisite phase of combined operational amplification circuit A1 and connect feedback filtering capacitor C 1.The photoelectrical coupler OC1 that uses in the buffer circuit is inner mainly to be made up of with output photodiode PD2 an aluminum gallium arsenide LED and two feedback photodiode PD1 that are adjacent, the input end 1,2 of LED is received the output terminal of input driving circuit, the output terminal 3,4 of feedback photodiode PD1 inserts the inverting input of input driving circuit, and the output terminal 5,6 of output photodiode PD2 inserts the inverting input of output buffer.Output buffer is made up of combined operational amplification circuit A2 and low-pass filter, the output terminal of buffer circuit is received the inverting input of combined operational amplification circuit A2, at the end of oppisite phase of combined operational amplification circuit A2 and connect the low-pass filter that is made of resistance R 3 and capacitor C 2.Simulating signal to be measured is received the inverting input of described input driving circuit, the output terminal of input driving circuit is concatenated into the input end of buffer circuit, first feedback output end of buffer circuit is received the inverting input of input driving circuit, and second output terminal of buffer circuit is concatenated into the inverting input of output buffer.Combined operational amplifier A 1, the A2 that uses in input driving circuit and the output buffer is the double operational AD823 of ADI company, and the photoelectrical coupler OC1 that uses in the buffer circuit is high linearity analog photoelectricity coupling mechanism HCNR201.The effect of combined operational amplifier A 1 is the input driving stage circuit that constitutes the buffer circuit linear optical coupling in the circuit, the effect of combined operational amplifier A 2 is the output buffer stage circuit that constitute the buffer circuit linear optical coupling, the current signal of optocoupler output is converted to voltage signal uses for late-class circuit.All used combined operational amplifier in front end input driving circuit and the rear end output buffer among Fig. 1, promptly two operational amplifiers have been combined (equivalent electrical circuit as shown in Figure 2).The A end is combined operational amplifier inverting input among Fig. 2, and the B end is combined operational amplifier in-phase input end.Operational amplifier A D823 just is a dual operational amplifier, because two operational amplifiers are integrated on the same chip, utilize the approximately equalised characteristics of its offset voltage, make the equivalent offset voltage of composite operation amplifier be approximately zero, the great like this influence of operational amplifier input offset voltage to the circuit precision, the linearity of raising test parameter of having weakened.Drive current owing to optocoupler in the circuit is 1～25mA in addition, therefore selects for use the maximum output current of amplifier should be not less than 25mA.R1 is used for regulating the input bias current size of operational amplifier A 1 among Fig. 1, and C1 plays retroactive effect, filtering simultaneously the burr signal in the circuit, avoid the aluminum gallium arsenide light emitting diode (LED) among the linear optical coupling OC1 to be subjected to unexpected impact.The effect of R2 is the nonlinearity of regulating circuit in the circuit.Simultaneously because optocoupler generally all can produce the noise of some high frequencies, at the shunt capacitance C3 of R3 place, constitute the one-level low-pass filter in output buffer, be used for some unnecessary high frequency noises of filtering, the occurrence of electric capacity is calculated and is got by incoming frequency and noise frequency.Precision photoelectric coupler HCNR201 is a kind of device of being made up of three photovalves, it has the very high linearity and sensitivity, can accurately transmit voltage signal in detection system, this device has two kinds of mode of operations, is respectively photoconductive pattern and photovoltage pattern.It is a kind of feedback-type optocoupler, and its separation principle is the single-shot list of common optocoupler to be received pattern change a little, increases a light that is used to feed back and accepts circuit and be used for feeding back.Like this, all be non-linear though two light are accepted circuit, the nonlinear characteristic that two light is accepted circuit all is consistent, just can offset the non-linear of through path by the non-linear of feedback network, realizes linear purpose of isolating thereby reach.This device is mainly formed (as shown in Figure 3) by an aluminum gallium arsenide LED and two photodiode PD1, PD2 that are adjacent, wherein LED is the aluminum gallium arsenide light emitting diode, PD1, PD2 are the feedback photodiode and the output photodiodes of two adjacent couplings, this encapsulating structure has determined the illumination that each photodiode can both obtain being similar to from LED, thereby has eliminated the error that the non-linear and bias property of LED is brought.As drive current I F When flowing through LED, the light that LED sends shines PD1 and PD2 respectively, the part of feedback diode PD1 absorbing light flux, thus produce Control current I PD1 (I PD1 ≈ 0.005I F ), this electric current is used for regulating I F Non-linear with compensation LED, the output current I that output diode PD2 produces PD2 The luminous flux that sends with LED is linear scaling, makes current gain K 1 =I PD1 / I F , forward gain K 2 =I PD2 / I F , transmission gain K then 3 =K 2 / K 1 =I PD2 / I PD1 , K 3 Representative value be 1.In use, the input end 1,2 of LED can be inserted front end operational amplifier A 1 with the output terminal 3,4 of photodiode PD1, wherein the photodiode of the 3rd, 4 ends plays retroactive effect, it can feed back to the output current that produces on the LED of the 1st, 2 ends again, so that input signal is carried out FEEDBACK CONTROL.The output terminal 5,6 of photodiode PD2 inserts rear end operational amplifier A 2.Linear light idol HCNR201 among Fig. 1 is operated under the photovoltage pattern, and signal is the positive polarity input, positive polarity output.Amplifier A1 regulates electric current I F As input voltage V In During increase, I PD1 Increase, amplifier A1 "+" input terminal voltage increases simultaneously, impels electric current I F Increase.Owing to get in touch I between LED and the PD1 PD1 Will retract 0V to "+" input terminal voltage again, form negative feedback.If the input current of amplifier A1 is very little, the electric current of the R1 that flows through so just is 
Obviously, I PD1 With V In Between be the linear ratio relation.I PD1 Regulated linear changes, I F Also regulated linear changes.Because PD2 is subjected to LED illumination, I PD2 Also and then regulated linear changes 
In addition, regulate the resistance of nonlinearity in the circuit
, consider I F Help power transfer greatly, I F Line taking optocoupler HCNR201 maximum drive current is generally 25mA.Among Fig. 1, its input end 
, output terminal
So, have
This shows that its input is a kind of linear relationship with output, and the gain of its isolated amplifier can realize by the ratio of adjusting R1 and R3.Because the difference of device parameters, resistance R 1, R2, R3 also need to do certain adjustment, make every effort to make circuit to reach best linearity requirement.
Embodiment of the present utility model is not limited to the foregoing description, all belongs within the protection domain of the present utility model in the various variations of making under the prerequisite that does not break away from the utility model aim.
Claims (4)
1. gamut high linearity simulating signal buffer circuit, comprise input driving circuit, buffer circuit and output buffer, it is characterized in that: simulating signal to be measured is received the inverting input of described input driving circuit, the output terminal of input driving circuit is concatenated into the input end of buffer circuit, first feedback output end of buffer circuit is received the inverting input of input driving circuit, and second output terminal of buffer circuit is concatenated into the inverting input of output buffer.
2. gamut high linearity simulating signal buffer circuit according to claim 1, it is characterized in that: described input driving circuit is made up of combined operational amplification circuit A1 and driving resistor R2, at the end of oppisite phase of amplifying circuit A1 and connect feedback filtering capacitor C 1.
3. gamut high linearity simulating signal buffer circuit according to claim 1 and 2, it is characterized in that: the photoelectrical coupler OC1 that uses in the described buffer circuit is a high linearity analog photoelectricity coupling mechanism, photoelectrical coupler OC1 is inner mainly by an aluminum gallium arsenide LED and two feedback photodiodes that are adjacent and output photodiode PD1, PD2 forms, the input end (1 of light emitting diode, 2) receive the output terminal of input driving circuit, the output terminal (3 of feedback diode PD1,4) inverting input of access input driving circuit, the output terminal (5 of output diode PD2,6) inverting input of access output buffer.
4. according to claim 1 or 3 described gamut high linearity simulating signal buffer circuits, it is characterized in that: described output buffer is made up of combined operational amplification circuit A2 and low-pass filter, the output terminal of buffer circuit is received the inverting input of amplifying circuit A2, at the end of oppisite phase of amplifying circuit A2 and connect the low-pass filter that is made of resistance R 3 and capacitor C 2, the output end signal of combinatorial operation amplifying circuit A2 is the output of output buffer.
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| Application Number | Priority Date | Filing Date | Title |
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| CN2010202310226U CN201886055U (en) | 2010-06-21 | 2010-06-21 | Full-range high-linearity analog signal buffer circuit |
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| CN2010202310226U CN201886055U (en) | 2010-06-21 | 2010-06-21 | Full-range high-linearity analog signal buffer circuit |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102998502A (en) * | 2012-12-06 | 2013-03-27 | 陈实 | High-isolation voltage-resisting bidirectional signal sensor |
| CN109471013A (en) * | 2018-10-30 | 2019-03-15 | 北京航空航天大学 | For the pulse testing method of the bandwidth of HCNR200 linear optical coupling isolation circuit |
-
2010
- 2010-06-21 CN CN2010202310226U patent/CN201886055U/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102998502A (en) * | 2012-12-06 | 2013-03-27 | 陈实 | High-isolation voltage-resisting bidirectional signal sensor |
| CN102998502B (en) * | 2012-12-06 | 2015-03-04 | 陈实 | High-isolation voltage-resisting bidirectional signal sensor |
| CN109471013A (en) * | 2018-10-30 | 2019-03-15 | 北京航空航天大学 | For the pulse testing method of the bandwidth of HCNR200 linear optical coupling isolation circuit |
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| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20110629 Termination date: 20170621 |
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| CF01 | Termination of patent right due to non-payment of annual fee |