CN212341759U - Signal transmitting circuit of analog optocoupler - Google Patents
Signal transmitting circuit of analog optocoupler Download PDFInfo
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- CN212341759U CN212341759U CN202021475715.XU CN202021475715U CN212341759U CN 212341759 U CN212341759 U CN 212341759U CN 202021475715 U CN202021475715 U CN 202021475715U CN 212341759 U CN212341759 U CN 212341759U
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Abstract
The utility model provides a signal transmission circuit of simulation opto-coupler, signal transmission circuit includes the back pressure protection module, voltage clamp module and the isolation transmission module that connect gradually, back pressure protection module is linked together with the power positive pole in order to convey the current signal to voltage clamp module; the voltage clamping module comprises a positive temperature coefficient branch and a negative temperature coefficient branch which are connected in series, and the output voltage of the voltage clamping module is the sum of positive temperature coefficient voltage at two ends of the positive temperature coefficient branch and negative temperature coefficient voltage at two ends of the negative temperature coefficient branch. The back-voltage protection module is arranged firstly to prevent the voltage of the negative electrode of the power supply from being higher than the positive electrode of the power supply, which is equivalent to simulating the reverse bias cut-off characteristic of the optical coupler. In addition, the output voltage of the voltage clamping module can be close to a zero temperature coefficient by adjusting parameters in the positive temperature coefficient branch and the negative temperature coefficient branch, so that the precision and the time delay of the output voltage are improved.
Description
Technical Field
The utility model relates to an keep apart the driver chip field, especially a signal transmission circuit of simulation opto-coupler.
Background
Among the prior art, when signal transmission, can adopt the opto-coupler to carry out signal transmission, for example when electric current flows in the negative pole from the positive pole and flows out, can make the LED lamp of opto-coupler luminous to make the phototriode of opto-coupler opposite side receive the light signal, in order to realize keeping apart the transmission of left signal and give the right side.
However, optical attenuation exists in the optical coupler in the signal transmission process, and the current conversion ratio can change along with the time and the temperature, so that the time delay and the precision of an output signal are influenced. In addition, the optical coupling transmission is slow and is not suitable for a high-speed system. In addition, the common mode rejection ratio of the optical coupler is poor, and erroneous pulses are easily generated.
Therefore, it is necessary to design a signal transmission circuit which simulates an optical coupler and has higher efficiency.
SUMMERY OF THE UTILITY MODEL
In order to solve one of the above problems, the present invention provides a signal transmission circuit of an analog optocoupler, wherein the signal transmission circuit comprises a back-pressure protection module, a voltage clamping module and an isolation transmission module, which are connected in sequence, and the back-pressure protection module is communicated with a power supply anode to transmit a current signal to the voltage clamping module; the voltage clamping module comprises a positive temperature coefficient branch and a negative temperature coefficient branch which are connected in series, and the output voltage of the voltage clamping module is the sum of positive temperature coefficient voltage at two ends of the positive temperature coefficient branch and negative temperature coefficient voltage at two ends of the negative temperature coefficient branch.
As a further improvement of the utility model, the negative temperature coefficient branch road includes first triode and second triode, the base interconnection of first triode and second triode, projecting pole are the power negative pole of all connecting, the base and the collecting electrode interconnect of first triode.
As a further improvement of the present invention, the area of the second triode is N times that of the first triode, wherein N > 1.
As a further improvement of the present invention, the positive temperature coefficient branch comprises a first resistor, one end of the first resistor is connected to the output end of the back pressure protection module, and the other end of the first resistor is connected in series with the negative temperature coefficient branch; the negative temperature coefficient branch circuit further comprises a second resistor, and an emitting electrode of the second triode is connected to the negative electrode of the power supply through the second resistor.
As a further improvement of the present invention, the negative temperature coefficient branch further comprises a first mos tube and a second mos tube, and gates of the first mos tube and the second mos tube are connected to each other and interconnected with a base of the first triode; the first resistors are connected with the input ends of the first mos tube and the second mos tube, and the output ends of the first mos tube and the second mos tube are respectively connected to the collector electrodes of the first triode and the second triode.
As a further improvement of the utility model, first mos pipe and second mos pipe are the PMOS pipe, and threshold voltage is the same.
As a further improvement of the present invention, the output voltage Vclamp of the voltage clamp module is:
wherein, Δ VbeThe Vbe voltage difference between the second triode and the first triode, R1 is a first resistor, R2 is a second resistor, V1be is the voltage difference between the base electrode and the emitter electrode of the first triode, and Vth is the threshold voltage of the first mos tube.
As a further improvement of the present invention, the voltage clamping module further comprises a loop gain branch, wherein the loop gain branch comprises a third resistor and a third triode; and the base electrode of the third triode is connected to the collector electrode of the second triode, the emitter electrode of the third triode is connected with the negative electrode of the power supply, and the collector electrode of the third triode is connected to the positive electrode of the power supply through a third resistor.
As the utility model discloses a further improvement, the loop gain branch road still includes the third mos pipe, the third mos pipe is the PMOS, the grid of third mos pipe inserts between the collecting electrode of third resistance and third triode, the source electrode of third mos pipe is connected the positive pole of power, drain electrode power negative pole.
As the utility model discloses a further improvement, the back pressure protection module includes the fourth MOS pipe, the fourth MOS pipe is the PMOS pipe, the grid of fourth MOS pipe inserts the power negative pole, and source electrode connection power is anodal, the drain electrode with the voltage clamp module is connected.
Compared with the prior art, the utility model discloses in, set up the voltage that back pressure protection module prevented the power negative pole earlier and be higher than the power positive pole, this is equivalent to the reverse bias cut-off characteristic of simulation opto-coupler. And the voltage clamping module can start to work according to the transmitted current signal and clamp the output voltage to a proper value for subsequent transmission. And the voltage clamping module comprises a positive temperature coefficient branch and a negative temperature coefficient branch, the positive temperature coefficient branch generates positive temperature coefficient voltage, and the negative temperature coefficient generates negative temperature coefficient voltage, so that the output voltage of the voltage clamping module is close to zero temperature coefficient by adjusting parameters in the positive temperature coefficient branch and the negative temperature coefficient branch, and the precision and the time delay of the output voltage are improved. And finally, the output voltage is transmitted to a rear-stage receiving circuit through the isolation transmission module.
Drawings
Fig. 1 is a schematic structural diagram of a signal transmission circuit of the analog optocoupler of the present invention;
fig. 2 is the circuit diagram of the signal transmission circuit of the analog optocoupler of the present invention.
DETAILED DESCRIPTION OF EMBODIMENT (S) OF INVENTION
In order to make the technical solutions in the present invention better understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, but not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative efforts shall belong to the protection scope of the present invention.
As shown in fig. 1 to 2, a signal transmitting circuit of an analog optical coupler is provided, where the signal transmitting circuit includes a back-voltage protection module 1, a voltage clamping module 2, and an isolation transmission module 3, which are connected in sequence, and the back-voltage protection module 1 is communicated with a positive electrode of a power supply to transmit a current signal to the voltage clamping module 2; the voltage clamping module 2 comprises a positive temperature coefficient branch and a negative temperature coefficient branch which are connected in series, and the output voltage Vclamp of the voltage clamping module 2 is the sum of positive temperature coefficient voltage at two ends of the positive temperature coefficient branch and negative temperature coefficient voltage at two ends of the negative temperature coefficient branch.
The utility model discloses in, in signal transmission circuit, set up earlier that back pressure protection module 1 prevents that the voltage of power negative pole is higher than the power positive pole, this is equivalent to the reverse bias cut-off characteristic of simulation opto-coupler. The voltage clamping module 2 may start to operate according to the transmitted current signal, and may clamp the output voltage Vclamp to a suitable value for subsequent transmission. And the voltage clamping module 2 comprises a positive temperature coefficient branch and a negative temperature coefficient branch, the positive temperature coefficient branch generates positive temperature coefficient voltage, and the negative temperature coefficient generates negative temperature coefficient voltage, so that the output voltage Vclamp of the voltage clamping module 2 can be close to zero temperature coefficient by adjusting parameters in the positive temperature coefficient branch and the negative temperature coefficient branch, and the precision and the time delay of the output voltage Vclamp are improved. Finally, the output voltage Vclamp is transmitted via the isolated transmission module 3.
As shown in fig. 2, the negative temperature coefficient branch comprises a first transistor Q1 and a second transistor Q2, wherein the bases and the emitters of the first transistor Q1 and the second transistor Q2 are connected with the negative electrode of the power supply, and the base and the collector of the first transistor Q1 are connected with each other.
It is known that the voltage Vbe between the base and the emitter of the transistor has a temperature coefficient, and decreases with increasing temperature, i.e. a negative temperature coefficient. Thus, in this embodiment of the present invention, the voltage V1be between the base and the emitter of the first transistor Q1 is a negative temperature coefficient, and the voltage V2be between the base and the emitter of the second transistor Q2 is also a negative temperature coefficient. And, since the bases of the two are interconnected, the base voltages of the first transistor Q1 and the second transistor Q2 are equal.
Further, the area of the second triode Q2 is N times that of the first triode Q1, wherein N is more than 1. The difference value of Vbe of the triodes with the two interconnected bases, namely delta Vbe, also has a temperature coefficient and is increased along with the increase of the temperature, namely positive temperature coefficient. Since only the second transistor Q2 has an area N times that of the first transistor Q1 and N > 1, Δ Vbe is VT — ln (N), where VT is a positive temperature coefficient, and thus Δ Vbe is positively correlated with temperature. Therefore, with the above characteristics, the positive temperature coefficient branch can be designed.
Specifically, the positive temperature coefficient branch comprises a first resistor R1, one end of the first resistor R1 is connected to the output end of the back-voltage protection module 1, and the other end of the first resistor R1 is connected in series with the negative temperature coefficient branch; the negative temperature coefficient branch circuit further comprises a second resistor R2, and an emitter of the second triode Q2 is connected to the negative electrode of the power supply through a second resistor R2.
Therefore, since the emitter of the second transistor Q2 is connected to the negative terminal of the power supply through the second resistor R2, the ptc voltage Vtep + of the ptc branch is:
therefore, in the negative temperature coefficient branch, the negative temperature coefficient voltage Vtep-is:
Vtep-＝V1be；
where V1be is the voltage between the base and emitter of the first transistor Q1, and since the base and collector of the first transistor Q1 are interconnected, V1be is also the voltage between the collector and emitter of the first transistor Q1.
Additionally, in the utility model discloses in, negative temperature coefficient branch road still includes first mos pipe M1 and second mos pipe M2, the grid interconnection of first mos pipe M1 and second mos pipe M2 and with the base interconnection of first triode Q1, the collecting electrode of first triode Q1 and second triode Q2 is inserted respectively to first mos pipe M1 and second mos pipe M2's output.
Therefore, the first resistor R1 is not directly connected to the transistor, but is connected to the first transistor Q1 and the second transistor Q2 through the first mos transistor M1 and the second mos transistor M2, respectively, so that a negative temperature coefficient branch capable of adjusting a negative temperature coefficient is further added to the voltage clamping module 2, so as to make the output voltage Vclamp of the voltage clamping module 2 more reasonable.
Specifically, the first mos tube M1 and the second mos tube M2 are both PMOS tubes, and have the same threshold voltage. Therefore, the sources of the first mos transistor M1 and the second mos transistor M2 are connected to the first resistor R1, and the drains are connected to the collectors of the first transistor Q1 and the second transistor Q2, respectively. Since the threshold voltages Vth of the first mos tube M1 and the second mos tube M2 are also negative temperature coefficients, in this embodiment, the negative temperature coefficient voltage Vtep — is actually:
Vtep-＝V1be+Vth；
where Vth is the threshold voltage of the first mos transistor M1 and the second mos transistor M2.
Therefore, in combination with the negative temperature coefficient branch and the positive temperature coefficient branch, the output voltage Vclamp of the voltage clamp module 2 is:
therefore, by adjusting the first resistor R1, the second resistor R2, the first mos transistor M1 and the second mos transistor M2, the output voltage Vclamp of the voltage clamp module 2 can have a low temperature coefficient, and even under ideal conditions, the output voltage Vclamp can be adjusted to a zero temperature coefficient, so as to provide a clamped output voltage Vclamp with a low temperature coefficient. Therefore, utilize the utility model provides a signaling circuit simulates the opto-coupler, can solve the opto-coupler along with the big problem of temperature variation, has enlarged the scene of using.
The utility model discloses voltage clamp module 2 among this embodiment is connected with back pressure protection module 1 to and receive the current signal that back pressure protection module 1 transmitted and come, thereby make this voltage clamp module 2 work. The voltage clamp module 2 can output the clamped output voltage Vclamp in a working state. And since the voltage clamping module 2 includes a positive temperature coefficient branch and a negative temperature coefficient branch, the output voltage Vclamp of the voltage clamping module 2 is the sum of the positive temperature coefficient voltage and the negative temperature coefficient voltage. Therefore, the output voltage Vclamp of the voltage clamping module 2 may be a zero temperature coefficient as much as possible, and the influence of temperature on the output voltage Vclamp is reduced.
The voltage clamping module 2 further comprises a loop gain branch, wherein the loop gain branch comprises a third resistor R3 and a third triode Q3; the base of the third triode Q3 is connected to the collector of the second triode Q2, the emitter is connected to the negative electrode of the power supply, and the collector is connected to the positive electrode of the power supply through a third resistor R3.
Further, the loop gain branch further comprises a third mos tube M3, the third mos tube M3 is a PMOS tube, a gate of the third mos tube M3 is connected between a third resistor R3 and a collector of a third triode Q3, and a source of the third mos tube M3 is connected to a positive electrode of a power supply and a drain of the third mos tube is connected to a negative electrode of the power supply.
Therefore, the third resistor R3, the third transistor Q3 and the third mos transistor M3 provide loop gain. In addition, after the third mos transistor M3 is turned on, the third mos transistor M3 can absorb a part of current, so that the voltage clamping module 2 can provide a high-precision clamping voltage when the current signal output by the back-voltage protection module 1 is within a certain range, and power is supplied to the subsequent isolation transmission module 3. And because the loop bandwidth is fast and the establishment time is short, the transmission of high-speed signals can be realized.
The output voltage Vclamp passing through the loop gain branch is transmitted to a signal receiving circuit of a subsequent stage through the isolation transmission module 3.
In addition, the back-voltage protection module 1 includes a fourth mos transistor M4, the fourth mos transistor M4 is a PMOS transistor, a gate of the fourth mos transistor M4 is connected to a negative electrode of a power supply, a source of the fourth mos transistor M4 is connected to a positive electrode of the power supply, and a drain of the fourth mos transistor M is connected to the voltage clamping module 2. Since the PMOS transistor is characterized by low-level conduction, when the negative terminal of the power supply is connected to low level, the fourth mos transistor M4 is turned on to transmit the current of the positive terminal of the power supply to the voltage clamping module 2. If the voltage of the negative electrode of the power supply is higher than that of the positive electrode of the power supply, the fourth mos tube M4 is turned off, and no current is generated in the fourth mos tube M4. Thus, the fourth mos tube M4 can simulate the reverse bias cutoff characteristics of the optical coupler.
To sum up, the utility model provides a signal transmission circuit of simulation opto-coupler, wherein, through setting up back pressure protection module 1, can simulate the reverse bias cut-off characteristic of opto-coupler, when the voltage of the positive pole of power is higher than the voltage of power negative pole, have the electric current to flow through in the fourth mos pipe M4 of back pressure protection module 1, and transmit this electric current signal to voltage clamp module 2;
further, the voltage clamping module 2 may clamp the output voltage Vclamp to ensure the stability of the output voltage Vclamp; the voltage clamping module 2 comprises a positive temperature coefficient branch and a negative temperature coefficient branch which are connected in series, so that the output voltage Vclamp is the sum of the positive temperature coefficient voltage and the negative temperature coefficient voltage, and the output voltage Vclamp has a lower temperature coefficient;
in addition, the voltage clamping module 2 further comprises a loop gain branch which can be rapidly adjusted through a loop, and the third mos tube M3 also has current absorption capacity, so that high-speed and high-precision voltage clamping can be realized within a certain input current range;
finally, the back-voltage protection module 1 and the voltage clamping module 2 can provide stable power supply for the rear-stage isolation transmission module 3, and the signal transmission effect of the optical coupler is achieved. Compared with the traditional optical coupler, the temperature coefficient influence is reduced as much as possible, the signal transmission precision is improved, and the time delay is lower. And can be suitable for high speed systems with low common mode interference.
Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should make the description as a whole, and the embodiments may be appropriately combined to form other embodiments understood by those skilled in the art.
The above list of details is only for the feasible embodiments of the present invention, and is not intended to limit the scope of the present invention, and all equivalent embodiments or modifications that do not depart from the technical spirit of the present invention are intended to be included within the scope of the present invention.
Claims (10)
1. A signal sending circuit of an analog optocoupler is characterized by comprising a back-voltage protection module, a voltage clamping module and an isolation transmission module which are sequentially connected, wherein the back-voltage protection module is communicated with a positive electrode of a power supply to transmit a current signal to the voltage clamping module; the voltage clamping module comprises a positive temperature coefficient branch and a negative temperature coefficient branch which are connected in series, and the output voltage of the voltage clamping module is the sum of positive temperature coefficient voltage at two ends of the positive temperature coefficient branch and negative temperature coefficient voltage at two ends of the negative temperature coefficient branch.
2. The signal transmission circuit according to claim 1, wherein the negative temperature coefficient branch circuit comprises a first triode and a second triode, the base electrodes of the first triode and the second triode are connected with each other, the emitter electrodes of the first triode and the second triode are connected with the negative electrode of the power supply, and the base electrode and the collector electrode of the first triode are connected with each other.
3. The signaling circuit of claim 2, wherein the second transistor has an area N times larger than the first transistor, where N > 1.
4. The signal transmission circuit according to claim 2, wherein the positive temperature coefficient branch comprises a first resistor, one end of the first resistor is connected to the output end of the back-voltage protection module, and the other end of the first resistor is connected in series with the negative temperature coefficient branch; the negative temperature coefficient branch circuit further comprises a second resistor, and an emitting electrode of the second triode is connected to the negative electrode of the power supply through the second resistor.
5. The signal transmitting circuit as claimed in claim 4, wherein the negative temperature coefficient branch further comprises a first mos transistor and a second mos transistor, and gates of the first mos transistor and the second mos transistor are connected with each other and with a base of the first triode; the first resistors are connected with the input ends of the first mos tube and the second mos tube, and the output ends of the first mos tube and the second mos tube are respectively connected to the collector electrodes of the first triode and the second triode.
6. The signal transmission circuit of claim 5, wherein the first mos transistor and the second mos transistor are both PMOS transistors and have the same threshold voltage.
7. The signaling circuit of claim 5, wherein the output voltage Vclamp of the voltage clamping module is:
wherein, Δ VbeThe Vbe voltage difference between the second triode and the first triode, R1 is a first resistor, R2 is a second resistor, V1be is the voltage difference between the base electrode and the emitter electrode of the first triode, and Vth is the threshold voltage of the first mos tube.
8. The signal transmitting circuit of claim 2, wherein the voltage clamping module further comprises a loop gain branch, the loop gain branch comprising a third resistor, a third transistor; and the base electrode of the third triode is connected to the collector electrode of the second triode, the emitter electrode of the third triode is connected with the negative electrode of the power supply, and the collector electrode of the third triode is connected to the positive electrode of the power supply through a third resistor.
9. The signal transmitting circuit of claim 8, wherein the loop gain branch further comprises a third mos transistor, the third mos transistor is a PMOS, a gate of the third mos transistor is connected between a third resistor and a collector of a third triode, and a source of the third mos transistor is connected to a positive electrode of the power supply and a drain of the third mos transistor is connected to a negative electrode of the power supply.
10. The signal transmission circuit according to claim 1, wherein the back-voltage protection module comprises a fourth MOS transistor, the fourth MOS transistor is a PMOS transistor, a gate of the fourth MOS transistor is connected to a negative electrode of a power supply, a source of the fourth MOS transistor is connected to a positive electrode of the power supply, and a drain of the fourth MOS transistor is connected to the voltage clamping module.
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| CN202021475715.XU CN212341759U (en) | 2020-07-23 | 2020-07-23 | Signal transmitting circuit of analog optocoupler |
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| CN202021475715.XU CN212341759U (en) | 2020-07-23 | 2020-07-23 | Signal transmitting circuit of analog optocoupler |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2022016738A1 (en) * | 2020-07-23 | 2022-01-27 | 苏州纳芯微电子股份有限公司 | Signal sending circuit simulating optical coupler |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2022016738A1 (en) * | 2020-07-23 | 2022-01-27 | 苏州纳芯微电子股份有限公司 | Signal sending circuit simulating optical coupler |
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