CN212646471U - Signal processing circuit of infrared carbon-sulfur sensor - Google Patents
Signal processing circuit of infrared carbon-sulfur sensor Download PDFInfo
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- CN212646471U CN212646471U CN202021231133.7U CN202021231133U CN212646471U CN 212646471 U CN212646471 U CN 212646471U CN 202021231133 U CN202021231133 U CN 202021231133U CN 212646471 U CN212646471 U CN 212646471U
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- YQCIWBXEVYWRCW-UHFFFAOYSA-N methane;sulfane Chemical compound C.S YQCIWBXEVYWRCW-UHFFFAOYSA-N 0.000 title claims description 14
- 230000003321 amplification Effects 0.000 claims abstract description 44
- 238000003199 nucleic acid amplification method Methods 0.000 claims abstract description 44
- GJEAMHAFPYZYDE-UHFFFAOYSA-N [C].[S] Chemical compound [C].[S] GJEAMHAFPYZYDE-UHFFFAOYSA-N 0.000 claims abstract description 6
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 4
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 claims abstract description 4
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 4
- 229910052717 sulfur Inorganic materials 0.000 claims abstract description 4
- 239000011593 sulfur Substances 0.000 claims abstract description 4
- 239000003990 capacitor Substances 0.000 claims description 41
- 238000001514 detection method Methods 0.000 claims description 6
- 230000002401 inhibitory effect Effects 0.000 claims description 3
- 238000004458 analytical method Methods 0.000 abstract description 2
- 230000008878 coupling Effects 0.000 description 3
- 238000010168 coupling process Methods 0.000 description 3
- 238000005859 coupling reaction Methods 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 238000001914 filtration Methods 0.000 description 3
- 238000002955 isolation Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 2
- 230000003068 static effect Effects 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
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Abstract
The utility model relates to a carbon sulphur analysis field especially relates to an infrared carbon sulphur sensor's signal processing circuit, its characterized in that: the device comprises a preamplifier circuit and a filter circuit; the preamplification circuit comprises a high-pass filter, a low-noise JFET differential circuit, a servo compensation circuit and an operational amplification circuit; the input end of the high-pass filter is connected with the infrared carbon and sulfur sensor, the output end of the high-pass filter is connected with the input end of the low-noise JFET differential circuit, the servo compensation circuit is connected with the low-noise JFET differential circuit, the low-noise JFET differential circuit is connected with the operational amplification circuit, and the output end of the operational amplification circuit is connected with the filter circuit; the input end of the filter circuit is connected with the output end of the operational amplification circuit, and the filter circuit comprises a low-pass filter circuit with equidirectional proportional amplification and a second-order low-pass filter circuit; the low-pass filter circuit with the equidirectional proportional amplification is connected with the operational amplifier and is connected with the output end, and the output end of the second-order low-pass filter circuit is the output of the signal processing circuit. The utility model discloses low noise, high gain.
Description
Technical Field
The utility model relates to a carbon sulphur analysis field especially relates to an infrared carbon sulphur sensor's signal processing circuit.
Background
The preamplifier of the infrared carbon-sulfur sensor is a key component of the whole infrared carbon-sulfur analyzer, and the function of the infrared carbon-sulfur sensor is to amplify a weak signal received by an infrared detector and output the weak signal to a subsequent processing circuit; however, the response signal of the infrared pyroelectric detector is very weak, so that the requirements of low noise and high gain are provided for the signal processing of the infrared carbon-sulfur sensor.
Disclosure of Invention
The utility model aims at providing a signal processing circuit of infrared carbon sulphur sensor, low noise, high gain.
For solving the above technical problem, the technical scheme of the utility model is that: the signal processing circuit of the infrared carbon-sulfur sensor comprises a preamplifier circuit and a filter circuit;
the preamplifier circuit includes: the high-pass filter, the low-noise JFET differential circuit, the servo compensation circuit and the operational amplification circuit; the input end of the high-pass filter is connected with the infrared carbon and sulfur sensor, the output end of the high-pass filter is connected with the input end of the low-noise JFET differential circuit, the output end of the servo compensation circuit is connected with the input end of the low-noise JFET differential circuit, the low-noise JFET differential circuit is connected with the operational amplification circuit, the output end of the operational amplification circuit is connected with the filter circuit, and the output end of the operational amplification circuit is also connected with the servo compensation circuit; the high-pass filter is used for connecting detection signals of the sensor and isolating low-frequency signals; the low-noise JFET differential circuit is used for reducing the noise coefficient in the pre-amplification circuit; the servo compensation circuit is used for inhibiting offset voltage and zero drift of a JFET tube in the low-noise JFET differential circuit; the operational amplification circuit is used for amplifying the detection signal;
the input end of the filter circuit is connected with the output end of the operational amplification circuit, and the filter circuit comprises a low-pass filter circuit with equidirectional proportional amplification and a second-order low-pass filter circuit connected with the output end of the low-pass filter circuit with equidirectional proportional amplification; the low-pass filter circuit with the equidirectional proportional amplification is connected to the operational amplifier amplification connection output end, and the output end of the second-order low-pass filter circuit is the output of the signal processing circuit.
According to the scheme, the high-pass filter comprises a capacitor C1 and a resistor R1, one end of the capacitor C1 is connected with the sensor, one end of the resistor R1 is connected with the other end of the capacitor C1, and the other end of the resistor R1 is grounded.
According to the scheme, the low-noise JFET differential circuit comprises a JFET tube J1, a JFET tube J2, pull-up resistors R5, R6, R7 and R8, wherein the grid electrode of the JFET tube J1 is connected with the connection node of a capacitor C1 and a resistor R1, the source electrode of the JFET tube J1 is connected with the resistor R9 and then grounded, the drain electrode of the JFET tube J1 is connected with the resistor R7 and then connected with positive voltage, and one end of the resistor R5 is connected with the middle node between the resistor R7 and the positive voltage; the gate of the JFET tube J2 is connected with the operational amplifier circuit, the source of the JFET tube J2 is connected with the resistor R9 and then grounded, the drain of the JFET tube J2 is connected with the resistor R8 and then connected with the positive voltage, one end of the resistor R6 is connected with the middle node between the resistor R7 and the positive voltage, and the other end of the resistor R6 is connected with the middle node between the resistor R8 and the positive voltage.
According to the scheme, the servo compensation circuit comprises an operational amplifier A1, a triode Q1, capacitors C2, C3, resistors R2, R3 and R4, wherein the homodromous input end of the operational amplifier A1 is connected with the capacitor C2 in series and then grounded, and one end of the resistor R2 is connected with the homodromous input end of the operational amplifier A1 and the middle node of the capacitor C2; the reverse input end of the operational amplifier A1 is connected with a resistor R3 in series and then grounded, the output end of the operational amplifier A1 is connected with a resistor R4 in series and then connected with the base electrode of a triode Q1, the collector electrode of the triode Q1 is grounded, the emitter electrode of the triode Q1 is connected with a capacitor C3 in series and then connected with the reverse input end of the operational amplifier A1, and the emitter electrode of the triode Q1 is also connected with the other end of the resistor R5.
According to the scheme, the operational amplifier circuit comprises an operational amplifier A2, feedback resistors R10 and R11, wherein the homodromous input end of the operational amplifier A2 is connected with the drain electrode of a JFET tube J2, the inverting input end of the operational amplifier A2 is connected with the drain electrode of a JFET tube J1, the output end of the operational amplifier A2 is sequentially connected with the feedback resistors R10 and R11 in series and then grounded, and the middle node of the feedback resistors R10 and R11 is connected with the gate electrode of the JFET tube J2; the output end of the operational amplifier A2 is also connected with the other end of the resistor R2.
According to the scheme, the low-pass filter circuit with the equidirectional proportional amplification comprises an operational amplifier A3, a resistor R12, a resistor R13 and a resistor R14, one end of the resistor R12 is connected to the output end of the operational amplifier A2, the other end of the resistor R12 is connected in series with a capacitor C4 and then grounded, the other end of the resistor R12 is also connected to the equidirectional input end of the operational amplifier A3, the output end of the operational amplifier A3 is sequentially connected in series with resistors R13 and R14 and then grounded, and the reverse input end of the operational amplifier A3 is connected to the middle node of the.
According to the scheme, the second-order low-pass filter circuit comprises an operational amplifier A4, resistors R16, R17, R19, R20, a variable resistor R15, R18, capacitors C5, C6 and C7, wherein two ends of the resistor R7 are respectively connected with the variable resistor R7 and the R7, a sliding end of the variable resistor R7 is connected to an output end of the operational amplifier A7, a sliding end of the variable resistor R7 is connected in series with the resistor R7 and then connected to a homodromous input end of the operational amplifier A7, a homodromous input end of the operational amplifier A7 is further connected in series with the capacitor C7 and then connected to the ground, an output end of the operational amplifier A7 is connected in series with the resistors R7 and then connected to the ground, an output end of the operational amplifier A7 is further connected in series with a middle node of the resistors R7 and R7, and an inverting input.
The utility model discloses following beneficial effect has:
the utility model discloses an among the preamplification circuit, the input stage front end of preamplification circuit uses RC high pass filter to carry out low frequency signal isolation, the noise factor that preamplification circuit was guaranteed in low noise JFET differential circuit's use is lower, JFET pipe J1, JFET pipe J2 has very good low noise characteristic, still set up the pull-up resistance among the low noise JFET differential circuit, low noise JFET differential circuit is equipped with servo compensation circuit and adds triode Q1 as the current source in resistance R7 place branch, triode Q1 catches behind the differential signal of differential circuit and the output value of the operational amplifier A2 that operational amplifier A1 sampled and compare, triode Q1 adjusts the electric current of JFET pipe J1 place branch in order to reduce the differential component of JFET pipe J1 and JFET pipe J2 difference to the input, zero drift has been suppressed, the pull-up resistance of JFET pipe J1 place branch has guaranteed that operational amplifier A1 can effectively catch offset voltage;
the utility model discloses an including the low pass filter circuit who takes cophase proportion amplifier circuit in the filter circuit, be by electric capacity C4 and the basis of the one-order active low pass filter that resistance R12 constitutes, the cophase proportion operational amplifier circuit who comprises R13 and R14 constitutes, realizes filtering and high gain, designs second order low pass filter circuit after taking cophase proportion amplifier circuit's low pass filter circuit simultaneously, further obtains better low pass filter effect.
Drawings
FIG. 1 is a block diagram of the overall structure of an embodiment of the present invention;
FIG. 2 is a schematic circuit diagram of a preamplifier circuit according to the embodiment;
fig. 3 is a schematic circuit diagram of the filter circuit in this embodiment.
Reference numerals:
1. a pre-amplification circuit; 101. a high-pass filter; 102. a low noise JFET differential circuit; 103. a servo compensation circuit; 104. an operational amplifier circuit; 2. a filter circuit; 201. a low-pass filter circuit with equidirectional proportional amplification; 202. and a second-order low-pass filter circuit.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more clearly understood, the present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.
Referring to fig. 1 to 3, the present invention relates to a signal processing circuit of an infrared carbon-sulfur sensor, which includes a pre-amplification circuit 1 and a filter circuit 2;
the preamplifier circuit 1 includes: a high-pass filter 101, a low-noise JFET differential circuit 102, a servo compensation circuit 103, and an operational amplifier circuit 104; the input end of the high-pass filter 101 is connected with the infrared carbon and sulfur sensor, the output end of the high-pass filter 101 is connected with the input end of the low-noise JFET differential circuit 102, the output end of the servo compensation circuit 103 is connected with the input end of the low-noise JFET differential circuit 102, the low-noise JFET differential circuit 102 is connected with the operational amplification circuit 104, the output end of the operational amplification circuit 104 is connected with the filter circuit 2, and the output end of the operational amplification circuit 104 is also connected with the servo compensation; the high-pass filter 101 is used for connecting detection signals of the sensor and isolating low-frequency signals; the low-noise JFET differential circuit 102 is used for reducing the noise coefficient in the preamplifier circuit 1; the servo compensation circuit 103 is used for inhibiting offset voltage and zero drift of a JFET tube in the low-noise JFET differential circuit 102; the operational amplifier circuit 104 is used for amplifying the detection signal; the input end of the filter circuit 2 is connected with the output end of the operational amplifier circuit 104, and the filter circuit 2 comprises a low-pass filter circuit 201 with equidirectional proportional amplification and a second-order low-pass filter circuit 202 connected with the output end of the low-pass filter circuit 201 with equidirectional proportional amplification; the low-pass filter circuit 201 with the equidirectional proportional amplification is connected to the operational amplifier amplification connection output end, and the output end of the second-order low-pass filter circuit 202 is the output of the signal processing circuit.
Referring to fig. 2, the high pass filter 101 includes a capacitor C1 and a resistor R1, one end of the capacitor C1 is connected to the sensor, one end of the resistor R1 is connected to the other end of the capacitor C1, and the other end of the resistor R1 is grounded; since the pre-amplifier circuit 1 has a high gain, a small noise source at the input will be amplified to a very high voltage level, so RC low frequency isolation in front of the input is important. The capacitor leakage current of the RC high-pass filter 101 is required to be less than 5 nA to reduce the dc error and the noise introduced by the capacitor, in this embodiment, the capacitor C1 is a CA35 series load capacitor produced by shahua corporation of china, and the capacitance value of the capacitor is 1500 μ F.
The low-noise JFET differential circuit 102 comprises a JFET tube J1, a JFET tube J2, pull-up resistors R5, R6, R7 and R8, the gate of the JFET tube J1 is connected with the connection node of a capacitor C1 and a resistor R1, the source of the JFET tube J1 is connected with the rear of the resistor R9 and then grounded, the drain of the JFET tube J1 is connected with the rear of the resistor R7 and then connected with a positive voltage, and one end of the resistor R5 is connected with the middle node between the resistor R7 and the positive voltage; the gate of the JFET J2 is connected to the operational amplifier circuit 104, the source of the JFET J2 is connected to the resistor R9 and then grounded, the drain of the JFET J2 is connected to the resistor R8 and then connected to a positive voltage, one end of the resistor R6 is connected to an intermediate node between the resistor R7 and the positive voltage, and the other end of the resistor R6 is connected to an intermediate node between the resistor R8 and the positive voltage. The use of the low noise JFET differential circuit 102 may ensure that the noise figure of the preamplifier circuit 1 is low. After low-frequency isolation is carried out by the high-pass filter 101, the signal is sent to a JFET tube J1, and is output to an operational amplifier A2 after differential amplification; in this embodiment, JFET pipe J1, JFET pipe J2 adopt high-accuracy JFET device LSK389 of Linear Systems company, and LSK389 is the two N channel JFET amplifiers that have super low noise characteristic, and the offset voltage is introduced to LSK389, consequently, the utility model discloses a servo compensation circuit 103 compensates, suppresses the offset voltage and the drift of zero point of JFET pipe in the low noise JFET difference circuit 102.
The servo compensation circuit 103 comprises an operational amplifier A1, a triode Q1, capacitors C2, C3, resistors R2, R3 and R4, wherein the same-direction input end of the operational amplifier A1 is connected with the capacitor C2 in series and then grounded, and one end of a resistor R2 is connected with the middle node of the same-direction input end of the operational amplifier A1 and the capacitor C2; the reverse input end of the operational amplifier A1 is connected with a resistor R3 in series and then grounded, the output end of the operational amplifier A1 is connected with a resistor R4 in series and then connected with the base electrode of a triode Q1, the collector electrode of the triode Q1 is grounded, the emitter electrode of the triode Q1 is connected with a capacitor C3 in series and then connected with the reverse input end of the operational amplifier A1, and the emitter electrode of the triode Q1 is also connected with the other end of the resistor R5. The operational amplifier a1 of the servo compensation circuit 103 employs a LT1012 chip of Linear Technology, which also has the characteristics of small input offset voltage, small low-frequency input noise and high voltage gain.
The operational amplifier circuit 104 comprises an operational amplifier A2, feedback resistors R10 and R11, the homodromous input end of the operational amplifier A2 is connected with the drain electrode of a JFET J2, the reverse input end of the operational amplifier A2 is connected with the drain electrode of a JFET J1, the output end of the operational amplifier A2 is sequentially connected with the feedback resistors R10 and R11 in series and then grounded, and the middle node of the feedback resistors R10 and R11 is connected with the gate electrode of the JFET J2; the output end of the operational amplifier A2 is also connected with the other end of the resistor R2; the gain of the operational amplifier A2 is determined by the feedback resistance A2= R10/R11.
Referring to fig. 3, the low-pass filter circuit 201 with the equidirectional proportional amplification includes an operational amplifier A3, resistors R12, R13 and R14, one end of a resistor R12 is connected to an output end of the operational amplifier a2, the other end of the resistor R12 is grounded after being connected in series with a capacitor C4, the other end of a resistor R12 is also connected to an equidirectional input end of the operational amplifier A3, an output end of the operational amplifier A3 is grounded after being sequentially connected in series with resistors R13 and R14, and an inverting input end of the operational amplifier A3 is connected to a middle node of the resistors R13.
The second-order low-pass filter circuit 202 comprises an operational amplifier A4, resistors R16, R17, R19, R20, variable resistors R15, R18, capacitors C5, C6 and C7, wherein two ends of the resistor R7 are respectively connected with the variable resistors R7 and R7, a sliding end of the variable resistor R7 is connected to an output end of the operational amplifier A7, a sliding end of the variable resistor R7 is connected in series with the resistor R7 and then connected to a same-direction input end of the operational amplifier A7, a same-direction input end of the operational amplifier A7 is further connected in series with the capacitor C7 and then connected to the ground, an output end of the operational amplifier A7 is connected in series with the resistors R7 and then connected to the ground, an output end of the operational amplifier A7 is further connected in series with the capacitor C7 and then connected to a middle node of the resistors R7 and R7.
In the filter circuit 2, the two stages of operational amplifiers are connected in a resistance-capacitance coupling mode through a resistor and a capacitor, and the resistance-capacitance coupling has the advantages that: because of the blocking function of the capacitor, the direct current paths in each circuit are not communicated, so that the static working points of each stage are mutually independent, the temperature drift signal caused by the instability of the static working points is avoided, and the design and calculation of the amplifier can be simpler and more convenient by adopting a resistance-capacitance coupling mode.
The utility model has the advantages that:
in the pre-amplification circuit 1 of the utility model, the front end of the input stage of the pre-amplification circuit 1 uses RC high-pass filtering to isolate low-frequency signals, the use of the low-noise JFET differential circuit 102 ensures that the noise coefficient of the pre-amplification circuit 1 is lower, the JFET tube J1, the JFET tube J2 has good low-noise characteristics, a pull-up resistor is further arranged in the low-noise JFET differential circuit 102, the low-noise JFET differential circuit 102 is provided with a servo compensation circuit 103, a triode Q1 is added to a branch where the resistor R7 is located to serve as a current source, the triode Q1 captures a differential signal of the differential circuit and then compares the differential signal with an output value of an operational amplifier A2 sampled by the operational amplifier A1, a triode Q1 adjusts the current of the branch where the JFET tube J1 is located to reduce the differential component input by a differential pair of the JFET tube J1 and the JFET tube J2, zero drift is inhibited, and the pull-up resistor of the branch where the JFET tube J1 is located ensures that the operational amplifier A1 can effectively capture;
the utility model discloses an including the low pass filter circuit 2 who takes cophase proportion amplifier circuit in filter circuit 2, on the basis of the one-order active low pass filter who comprises electric capacity C4 and resistance R12, the cophase proportion operational amplifier circuit who comprises R13 and R14 constitutes, realize filtering and high gain, design second order low pass filter circuit 202 after taking cophase proportion amplifier circuit's low pass filter circuit 2 simultaneously, further obtain better low pass filter effect.
The utility model discloses the part that does not relate to all is the same with prior art or adopts prior art to realize.
The foregoing is a more detailed description of the present invention that is presented in conjunction with specific embodiments, and it is not to be understood that the specific embodiments of the present invention are limited to these descriptions. To the utility model belongs to the technical field of ordinary technical personnel, do not deviate from the utility model discloses under the prerequisite of design, can also make a plurality of simple deductions or replacement, all should regard as belonging to the utility model discloses a protection scope.
Claims (7)
1. Infrared carbon sulphur sensor's signal processing circuit, its characterized in that: the device comprises a preamplifier circuit (1) and a filter circuit (2);
a preamplifier circuit (1) comprises: a high-pass filter (101), a low-noise JFET differential circuit (102), a servo compensation circuit (103) and an operational amplifier circuit (104); the input end of a high-pass filter (101) is connected with an infrared carbon and sulfur sensor, the output end of the high-pass filter (101) is connected with the input end of a low-noise JFET differential circuit (102), the output end of a servo compensation circuit (103) is connected with the input end of the low-noise JFET differential circuit (102), the low-noise JFET differential circuit (102) is connected with an operational amplification circuit (104), the output end of the operational amplification circuit (104) is connected with a filter circuit (2), and the output end of the operational amplification circuit (104) is also connected with the servo compensation circuit (103);
the high-pass filter (101) is used for switching on a detection signal of the sensor and isolating a low-frequency signal;
the low-noise JFET differential circuit (102) is used for reducing the noise coefficient in the pre-amplification circuit (1);
the servo compensation circuit (103) is used for inhibiting offset voltage and zero drift of a JFET tube in the low-noise JFET differential circuit (102);
the operational amplification circuit (104) is used for amplifying the detection signal;
the input end of the filter circuit (2) is connected with the output end of the operational amplification circuit (104), and the filter circuit (2) comprises a low-pass filter circuit (201) with equidirectional proportional amplification and a second-order low-pass filter circuit (202) connected with the output end of the low-pass filter circuit (201) with equidirectional proportional amplification; the low-pass filter circuit (201) with the equidirectional proportional amplification is connected with the operational amplifier amplification connection output end, and the output end of the second-order low-pass filter circuit (202) is the output of the signal processing circuit.
2. The signal processing circuit of the infrared carbon sulfur sensor according to claim 1, characterized in that: the high-pass filter (101) comprises a capacitor C1 and a resistor R1, wherein one end of the capacitor C1 is connected with the sensor, one end of the resistor R1 is connected with the other end of the capacitor C1, and the other end of the resistor R1 is grounded.
3. The signal processing circuit of the infrared carbon sulfur sensor according to claim 2, characterized in that: the low-noise JFET differential circuit (102) comprises a JFET tube J1, a JFET tube J2, pull-up resistors R5, R6, R7 and R8, the gate of the JFET tube J1 is connected with the connection node of a capacitor C1 and a resistor R1, the source of the JFET tube J1 is connected with the resistor R9 and then grounded, the drain of the JFET tube J1 is connected with the resistor R7 and then connected with a positive voltage, and one end of the resistor R5 is connected with the middle node between the resistor R7 and the positive voltage; the gate of the JFET tube J2 is connected with an operational amplifier circuit (104), the source of the JFET tube J2 is connected with a resistor R9 and then grounded, the drain of the JFET tube J2 is connected with a resistor R8 and then connected with a positive voltage, one end of a resistor R6 is connected with an intermediate node between the resistor R7 and the positive voltage, and the other end of the resistor R6 is connected with an intermediate node between the resistor R8 and the positive voltage.
4. The signal processing circuit of the infrared carbon sulfur sensor according to claim 3, characterized in that: the servo compensation circuit (103) comprises an operational amplifier A1, a triode Q1, capacitors C2, C3, resistors R2, R3 and R4, wherein the homodromous input end of the operational amplifier A1 is connected with the capacitor C2 in series and then grounded, and one end of a resistor R2 is connected with the middle node of the homodromous input end of the operational amplifier A1 and the capacitor C2; the reverse input end of the operational amplifier A1 is connected with a resistor R3 in series and then grounded, the output end of the operational amplifier A1 is connected with a resistor R4 in series and then connected with the base electrode of a triode Q1, the collector electrode of the triode Q1 is grounded, the emitter electrode of the triode Q1 is connected with a capacitor C3 in series and then connected with the reverse input end of the operational amplifier A1, and the emitter electrode of the triode Q1 is also connected with the other end of the resistor R5.
5. The signal processing circuit of the infrared carbon sulfur sensor according to claim 4, characterized in that: the operational amplifier circuit (104) comprises an operational amplifier A2, feedback resistors R10 and R11, the homodromous input end of the operational amplifier A2 is connected with the drain electrode of a JFET J2, the inverting input end of the operational amplifier A2 is connected with the drain electrode of a JFET J1, the output end of the operational amplifier A2 is sequentially connected with the feedback resistors R10 and R11 in series and then grounded, and the middle node of the feedback resistors R10 and R11 is connected with the gate electrode of the JFET J2; the output end of the operational amplifier A2 is also connected with the other end of the resistor R2.
6. The signal processing circuit of the infrared carbon sulfur sensor according to claim 5, characterized in that: the low-pass filter circuit (201) with the equidirectional proportional amplification comprises an operational amplifier A3, a resistor R12, a resistor R13 and a resistor R14, one end of the resistor R12 is connected to the output end of the operational amplifier A2, the other end of the resistor R12 is grounded after being connected in series with a capacitor C4, the other end of the resistor R12 is also connected to the equidirectional input end of the operational amplifier A3, the output end of the operational amplifier A3 is sequentially connected in series with resistors R13 and R14 and then grounded, and the reverse input end of the operational amplifier A3 is connected to the middle node of the resistors R.
7. The signal processing circuit of the infrared carbon sulfur sensor according to claim 6, characterized in that: the second-order low-pass filter circuit (202) comprises an operational amplifier A4, resistors R16, R17, R19, R20, a variable resistor R15, R18, a capacitor C5, C6 and C7, wherein two ends of the resistor R7 are respectively connected with the variable resistor R7 and the R7, a sliding end of the variable resistor R7 is connected to an output end of the operational amplifier A7, a sliding end of the variable resistor R7 is connected in series with the resistor R7 and then connected to a same-direction input end of the operational amplifier A7, a same-direction input end of the operational amplifier A7 is further connected in series with the capacitor C7 and then connected to the ground, an output end of the operational amplifier A7 is connected in series with the resistors R7 and then connected to the ground, an output end of the operational amplifier A7 is further connected in series with a middle node of the resistors R7 and R7, and an inverting input end of the.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202021231133.7U CN212646471U (en) | 2020-06-29 | 2020-06-29 | Signal processing circuit of infrared carbon-sulfur sensor |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202021231133.7U CN212646471U (en) | 2020-06-29 | 2020-06-29 | Signal processing circuit of infrared carbon-sulfur sensor |
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| Publication Number | Publication Date |
|---|---|
| CN212646471U true CN212646471U (en) | 2021-03-02 |
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|---|---|---|---|
| CN202021231133.7U Expired - Fee Related CN212646471U (en) | 2020-06-29 | 2020-06-29 | Signal processing circuit of infrared carbon-sulfur sensor |
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2020
- 2020-06-29 CN CN202021231133.7U patent/CN212646471U/en not_active Expired - Fee Related
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