CN209541776U - A kind of sensor front end signal processing circuit - Google Patents
A kind of sensor front end signal processing circuit Download PDFInfo
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- CN209541776U CN209541776U CN201920122863.4U CN201920122863U CN209541776U CN 209541776 U CN209541776 U CN 209541776U CN 201920122863 U CN201920122863 U CN 201920122863U CN 209541776 U CN209541776 U CN 209541776U
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Abstract
The utility model proposes a kind of sensor front end signal processing circuits comprising sensor, programmable amplifier, programmable filter, single-chip microcontroller and power supply, it is characterised in that: further includes electrostatic discharge protective circuit；The programmable amplifier includes operational amplifier and digital analog converter；The programmable filter includes filtering chip and trigger；The sensor, electrostatic discharge protective circuit, operational amplifier, filtering chip are sequentially electrically connected, and digital analog converter is electrically connected with operational amplifier and single-chip microcontroller respectively, and trigger is electrically connected with filtering chip and single-chip microcontroller respectively.By the way that electrostatic discharge protective circuit is arranged, it can prevent sensor from passing through cable connection into the circuit of operational amplifier by the damage of static discharge.
Description
Technical field
The utility model relates to sensor field more particularly to a kind of sensor front end signal processing circuits.
Background technique
The analog signal of sensor output is transported in single-chip microcontroller after generally being converted by A/D and is handled.Sensor
It is the front end of detection system, the circuit of sensor output signal processing has vital effect to detection system, directly
Determine the correctness of testing result.The signal of usual sensor output is the small-signal for being mingled with noise and interference, Er Qiexin
Number intensity, noise and the frequency of interference are also variation, in order to obtain the output signal of high s/n ratio, it is desirable to signal processing electricity
Road has amplification and a filter function, and can according to the difference of input signal strength, and interference, noise frequency difference and change
The amplification factor and filter of varying signal processing circuit are arranged.Program control filtering and programmable amplifier are all to pass through tune in the prior art
The resistance value of economize on electricity resistance is changed the multiple or filtering mode of gain, and the degree of regulation of this mode is not high, and sensor
Cable connection may be damaged to amplifier circuit by ESD (static discharge), and electrostatic protection technology in the prior art works as biography
When the input impedance of sensor is very big, Ren Huiyou very big offset voltage.Therefore to solve the above problems, the utility model provides one
Kind adjustable gain filters adjustable and with good electrostatic protection sensor front end signal processing circuit.
Utility model content
In view of this, the utility model proposes a kind of adjustable gain, filtering is adjustable and with good electrostatic protection
Sensor front end signal processing circuit.
The technical solution of the utility model is achieved in that the utility model provides at a kind of sensor front end signal
Manage circuit comprising sensor, programmable amplifier, programmable filter, single-chip microcontroller and power supply further include electrostatic discharge protective circuit；
Programmable amplifier includes operational amplifier and digital analog converter；
Programmable filter includes filtering chip and trigger；
Sensor, electrostatic discharge protective circuit, operational amplifier, filtering chip are sequentially electrically connected, digital analog converter respectively with
Operational amplifier and single-chip microcontroller are electrically connected, and trigger is electrically connected with filtering chip and single-chip microcontroller respectively.
On the basis of above technical scheme, it is preferred that single-chip microcontroller 89C51.
It is further preferred that operational amplifier is AD8603, digital analog converter includes AD7524 chip；
OUT1 the and OUT2 pin of AD7524 chip is a pair of with the non-inverting input terminal of AD8603 and inverting input terminal one respectively
Electrotropism connection, the DB1-DB7 pin of AD7524 chip is corresponded with the P1.0-P1.7 pin of 89C51 respectively electrically to be connected
It connects.
It is further preferred that electrostatic discharge protective circuit includes capacitor C31, resistance R22, resistance R41, resistance R42 and diode
D22-D25；
The output end of the sensor negative electricity with one end of resistance R22, the anode of diode D22 and diode D23 respectively
Property connection, the anode of the cathode of diode D22 and diode D23 is electrically connected, the other end and operational amplifier of resistance R22
The reverse input end of AD8603 is electrically connected, one end of resistance R41 respectively with the anode of diode D23 and one end of capacitor C31
It is electrically connected, the other end of resistance R41 and the non-inverting input terminal of operational amplifier AD8603 are electrically connected, operational amplifier
The output end of AD8603 respectively with one end of filtering chip and resistance R42 be electrically connected, the other end of resistance R42 respectively with capacitor
The cathode of one end of C31, the anode of diode D24 and diode D25 is electrically connected, the other end ground connection of capacitor C31, diode
The cathode of D24 and the anode of diode D25 are electrically connected with the power supply respectively.
It is further preferred that filtering chip is MAX261 chip；
The output end of AD8603 and the INA pin of MAX261 chip are electrically connected, A0-A3, D0, D1 of MAX261 chip
Pin is electrically connected with trigger respectively.
It is further preferred that trigger is 74HC374 trigger；
The Q0-Q5 pin of 74HC374 trigger corresponds electrically with A0-A3, D0, D1 pin of MAX261 chip respectively
Connection, the CP pin of 74HC374 trigger and the WR pin of MAX261 chip are electrically connected, the D0-D5 of 74HC374 trigger
Pin corresponds with the P0.0-P0.5 pin of 89C51 be electrically connected respectively, the OE pin and 89C51 of 74HC374 trigger
P0.6 pin be electrically connected.
A kind of sensor front end signal processing circuit of the utility model has the advantages that compared with the existing technology
(1) by setting electrostatic discharge protective circuit, it can prevent sensor from passing through the circuit of cable connection to operational amplifier
In damage by static discharge, under normal circumstances, the voltage of the output end of operational amplifier AD8603 is equal to its input terminal
The voltage of voltage, diode D22 and diode D23 are almost 0V, then the leakage current of diode D22 and diode D23 will not
Influence the output signal of sensor；When there is esd event, the high pressure spike in circuit passes through diode D22 and diode D23
Electric discharge enters positive or negative power supply, and capacitor C31 stores charge, reduces the climbing speed of ESM spike, and in diode D24 or
Before ESD transient state is transferred to positive or negative power supply by diode D25, the output stage of operational amplifier AD8603 is protected not to be blocked.When
When the input terminal voltage of operational amplifier AD8603 is more than the voltage of diode D22 and diode D23, resistance R22 and resistance R41
The current limit of the input terminal of operational amplifier AD8603 below 5mA electric current；
It (2) include operational amplifier and digital analog converter by setting programmable amplifier, digital analog converter is defeated single-chip microcontroller
Digital signal out is converted into analog signal, and then changes voltage and the operational amplifier amplification of opamp input terminal
Multiple, by single-chip microcontroller and digital analog converter, so that the degree of regulation of programmable amplifier is high；
(3) setting programmable filter includes filtering chip and trigger, can be changed by the trigger condition of trigger and be filtered
The filtering mode of wave chip, regulative mode are simple；
(4) whole device may be implemented adjustable gain, filtering mode it is adjustable and have electrostatic protection function.
Detailed description of the invention
In order to illustrate the embodiment of the utility model or the technical proposal in the existing technology more clearly, below will be to embodiment
Or attached drawing needed to be used in the description of the prior art is briefly described, it should be apparent that, the accompanying drawings in the following description is only
It is some embodiments of the utility model, for those of ordinary skill in the art, in the premise not made the creative labor
Under, it is also possible to obtain other drawings based on these drawings.
Fig. 1 is a kind of structure chart of sensor front end signal processing circuit of the utility model；
Fig. 2 is electrostatic discharge protective circuit and programmable amplifier in a kind of sensor front end signal processing circuit of the utility model
Circuit diagram；
Fig. 3 is the circuit diagram of programmable filter in a kind of sensor front end signal processing circuit of the utility model.
Specific embodiment
Below in conjunction with the utility model embodiment, the technical solution in the utility model embodiment is carried out clear
Chu is fully described by, it is clear that and described embodiment is only a part of embodiment of the utility model, rather than all
Embodiment.Based on the embodiment in the utility model, those of ordinary skill in the art are not making creative work
Under the premise of every other embodiment obtained, fall within the protection scope of the utility model.
As shown in Figure 1, a kind of sensor front end signal processing circuit of the utility model comprising sensor program-controlled is put
Big device, programmable filter, single-chip microcontroller, power supply and electrostatic discharge protective circuit；Wherein, programmable amplifier includes operational amplifier and digital-to-analogue
Converter；Programmable filter includes filtering chip and trigger.
In the present embodiment, by single-chip microcontroller come control gain multiple and filtering in the way of, in simple checkout area
Jing Zhong, single-chip microcontroller and serves as the function as central processing unit, is in cost consideration, and the present embodiment single-chip microcontroller is special using 89C51
Door control gain factor and filtering mode can increase a master control if system detection precision is high and control equipment is more
Chip is responsible for the task of signal processing.
In the present embodiment, programmable amplifier includes operational amplifier and digital analog converter.Single-chip microcontroller is put gain is represented
The digital signal of big multiple is sent to digital analog converter, and digital analog converter switches according to digital signal to be switched, so that digital-to-analogue conversion
The analog signal of device output is different, and different analog signals represents different gain factors.In the present embodiment, digital analog converter
Including AD7524 chip；AD7524 chip interior is integrated with the resistor network of 8 analog switches control, different by switching
Analog switch exports the analog signal for representing different gains, and then realizes that gain amplifier is adjustable.Operational amplifier is defeated to sensor
Signal out amplifies, and in the present embodiment, operational amplifier is using low input bias current, low drift current
AD8603, as shown in Fig. 2, specifically, OUT1 the and OUT2 pin of AD7524 chip respectively with the non-inverting input terminal of AD8603 and
Inverting input terminal correspond be electrically connected, the DB1-DB7 pin of AD7524 chip respectively with the P1.0-P1.7 pin of 89C51
It corresponds and is electrically connected.
Electrostatic discharge protective circuit prevents sensor from passing through cable connection into the circuit of operational amplifier by static discharge
Damage.When the common electrostatic protection method of the prior art is big there are sensor output impedance, electrostatic discharge protective circuit, which is appointed, will appear leakage
Electric current.In the present embodiment, as shown in Fig. 2, electrostatic discharge protective circuit includes capacitor C31, resistance R22, resistance R41, resistance R42
With diode D22-D25；Specifically, the output end of sensor respectively with one end of resistance R22, the anode of diode D22 and two
The cathode of pole pipe D23 is electrically connected, and the cathode of diode D22 and the anode of diode D23 are electrically connected, and resistance R22's is another
End is electrically connected with the reverse input end of operational amplifier AD8603, one end of resistance R41 anode with diode D23 respectively
It is electrically connected with one end of capacitor C31, the other end of resistance R41 electrically connects with the non-inverting input terminal of operational amplifier AD8603
It connects, the output end of operational amplifier AD8603 is electrically connected with one end of filtering chip and resistance R42 respectively, and resistance R42's is another
One end is electrically connected with the cathode of one end of capacitor C31, the anode of diode D24 and diode D25 respectively, and capacitor C31's is another
One end ground connection, the cathode of diode D24 and the anode of diode D25 are electrically connected with the power supply respectively.Wherein, under normal circumstances,
The voltage of the output end of operational amplifier AD8603 is equal to the voltage of its input terminal, and the voltage of diode D22 and diode D23 are close
It is 0V, then the leakage current of diode D22 and diode D23 will not influence the output signal of sensor；When there is esd event
When, the high pressure spike in circuit enters positive or negative power supply, capacitor C31 storage electricity by diode D22 and diode D23 electric discharge
Lotus reduces the climbing speed of ESM spike, and ESD transient state is transferred to positive or negative power supply in diode D24 or diode D25
Before, the output stage of operational amplifier AD8603 is protected not to be blocked.When the input terminal voltage of operational amplifier AD8603 is more than
When the voltage of diode D22 and diode D23, resistance R22 and resistance R41 are the input terminal of operational amplifier AD8603
Current limit is below 5mA electric current.
Programmable filter, according to interference, noise frequency difference and change different filtering modes.In the present embodiment,
Programmable filter includes filtering chip and trigger.Filtering chip require controllable 64 different centre frequency f0,128 not
Same quality factor q and four kinds of operating modes, Lai Shixian all-pass, low pass, high pass, bandreject filtering function.In the present embodiment, such as
Shown in Fig. 3, filtering chip is MAX261 chip；Trigger is 74HC374 trigger；Specifically, the Q0- of 74HC374 trigger
Q5 pin corresponds with A0-A3, D0, D1 pin of MAX261 chip be electrically connected respectively, and the CP of 74HC374 trigger draws
The WR pin of foot and MAX261 chip is electrically connected, the D0-D5 pin of 74HC374 trigger respectively with the P0.0-P0.5 of 89C51
Pin, which corresponds, to be electrically connected, and the OE pin of 74HC374 trigger and the P0.6 pin of 89C51 are electrically connected.
The foregoing is merely the better embodiments of the utility model, are not intended to limit the utility model, it is all
Within the spirit and principles of the utility model, it is practical new to should be included in this for any modification, equivalent replacement, improvement and so on
Within the protection scope of type.
Claims (6)
1. a kind of sensor front end signal processing circuit comprising sensor, programmable amplifier, programmable filter, single-chip microcontroller and
Power supply, it is characterised in that: further include electrostatic discharge protective circuit；
The programmable amplifier includes operational amplifier and digital analog converter；
The programmable filter includes filtering chip and trigger；
The sensor, electrostatic discharge protective circuit, operational amplifier, filtering chip are sequentially electrically connected, digital analog converter respectively with
Operational amplifier and single-chip microcontroller are electrically connected, and trigger is electrically connected with filtering chip and single-chip microcontroller respectively.
2. a kind of sensor front end signal processing circuit as described in claim 1, it is characterised in that: the single-chip microcontroller is
89C51。
3. a kind of sensor front end signal processing circuit as claimed in claim 2, it is characterised in that: the operational amplifier is
AD8603, digital analog converter include AD7524 chip；
OUT1 the and OUT2 pin of the AD7524 chip is a pair of with the non-inverting input terminal of AD8603 and inverting input terminal one respectively
Electrotropism connection, the DB1-DB7 pin of AD7524 chip correspond with the P1.0-P1.7 pin of 89C51 be electrically connected respectively.
4. a kind of sensor front end signal processing circuit as claimed in claim 3, it is characterised in that: the electrostatic discharge protective circuit
Including capacitor C31, resistance R22, resistance R41, resistance R42 and diode D22-D25；
The output end of the sensor negative electricity with one end of resistance R22, the anode of diode D22 and diode D23 respectively
Property connection, the anode of the cathode of diode D22 and diode D23 is electrically connected, the other end and operational amplifier of resistance R22
The reverse input end of AD8603 is electrically connected, one end of resistance R41 respectively with the anode of diode D23 and one end of capacitor C31
It is electrically connected, the other end of resistance R41 and the non-inverting input terminal of operational amplifier AD8603 are electrically connected, operational amplifier
The output end of AD8603 respectively with one end of filtering chip and resistance R42 be electrically connected, the other end of resistance R42 respectively with capacitor
The cathode of one end of C31, the anode of diode D24 and diode D25 is electrically connected, the other end ground connection of capacitor C31, diode
The cathode of D24 and the anode of diode D25 are electrically connected with the power supply respectively.
5. a kind of sensor front end signal processing circuit as claimed in claim 3, it is characterised in that: the filtering chip is
MAX261 chip；
The output end of the AD8603 and the INA pin of MAX261 chip are electrically connected, and A0-A3, D0, D1 of MAX261 chip draw
Foot is electrically connected with trigger respectively.
6. a kind of sensor front end signal processing circuit as claimed in claim 5, it is characterised in that: the trigger is
74HC374 trigger；
The Q0-Q5 pin of the 74HC374 trigger corresponds electrically with A0-A3, D0, D1 pin of MAX261 chip respectively
Connection, the CP pin of 74HC374 trigger and the WR pin of MAX261 chip are electrically connected, and the D0-D5 of 74HC374 trigger draws
Foot corresponds with the P0.0-P0.5 pin of 89C51 be electrically connected respectively, the OE pin of 74HC374 trigger and 89C51's
P0.6 pin is electrically connected.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201920122863.4U CN209541776U (en) | 2019-01-24 | 2019-01-24 | A kind of sensor front end signal processing circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201920122863.4U CN209541776U (en) | 2019-01-24 | 2019-01-24 | A kind of sensor front end signal processing circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN209541776U true CN209541776U (en) | 2019-10-25 |
Family
ID=68271299
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201920122863.4U Expired - Fee Related CN209541776U (en) | 2019-01-24 | 2019-01-24 | A kind of sensor front end signal processing circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN209541776U (en) |
-
2019
- 2019-01-24 CN CN201920122863.4U patent/CN209541776U/en not_active Expired - Fee Related
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| Date | Code | Title | Description |
|---|---|---|---|
| GR01 | Patent grant | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20191025 Termination date: 20210124 |