CN214277890U - Gain automatic adjusting circuit for infrared gas analyzer - Google Patents
Gain automatic adjusting circuit for infrared gas analyzer Download PDFInfo
- Publication number
- CN214277890U CN214277890U CN202022781854.1U CN202022781854U CN214277890U CN 214277890 U CN214277890 U CN 214277890U CN 202022781854 U CN202022781854 U CN 202022781854U CN 214277890 U CN214277890 U CN 214277890U
- Authority
- CN
- China
- Prior art keywords
- circuit
- resistor
- input
- amplifier
- output
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Landscapes
- Investigating Or Analysing Materials By Optical Means (AREA)
Abstract
The utility model discloses an automatic gain adjusting circuit for an infrared gas analyzer, which comprises a two-stage amplifying circuit, a feedback adjusting circuit and an integral adjusting circuit; the two-stage amplifying circuit comprises a fixed gain amplifying circuit and a gain controlled amplifying circuit; the feedback adjusting circuit comprises a feedback circuit and an adjusting circuit; the input end of the feedback circuit is connected with the output end of the gain controlled amplifying circuit, and the output end of the feedback circuit is connected with the input end of the adjusting circuit; the input end of the adjusting circuit is connected with a power supply voltage; the integration adjusting circuit comprises an integration circuit and a linear optocoupler; the input end of the integrating circuit is connected with the output end of the adjusting circuit, the output end of the integrating circuit is connected with the input circuit of the linear optocoupler, and the output circuit of the linear optocoupler is connected with the input end of the gain controlled amplifying circuit. The automatic gain adjusting circuit can ensure the amplitude of the output signal to be stable through the feedback adjusting circuit and the integral adjusting circuit.
Description
Technical Field
The utility model relates to an infrared spectroscopy gas analysis technical field, concretely relates to gain automatic regulating circuit for infrared gas analysis appearance.
Background
The infrared spectrum absorption method is an important method for gas component analysis and concentration measurement, and a sensor adopted by the method is mainly a semiconductor infrared detector. The amplitude of the output signal of the semiconductor infrared detector is greatly influenced by the temperature, and the amplitude change of the equivalent induction signal can reach 10 times within the range of-20 ℃ to 40 ℃; other electronic component parameters in the circuit may also change with temperature changes. If fixed gain amplification is adopted, when the output signal of the infrared detector is small, the signal-to-noise ratio of the signal is low, and when the signal is too strong, output saturation is easily caused. Both of these conditions will severely affect the accuracy of the infrared gas analyzer measurements.
SUMMERY OF THE UTILITY MODEL
In view of this, the utility model provides a gain automatic regulating circuit for infrared gas analysis appearance can guarantee that output signal amplitude is stable.
The utility model adopts the following specific technical proposal:
an automatic gain adjusting circuit for an infrared gas analyzer comprises a two-stage amplifying circuit, a feedback adjusting circuit and an integral adjusting circuit;
the two-stage amplifying circuit comprises a fixed gain amplifying circuit and a gain controlled amplifying circuit; the input end of the fixed gain amplifying circuit is connected with an input signal, and the output end of the fixed gain amplifying circuit is connected with the input end of the gain controlled amplifying circuit;
the feedback adjusting circuit comprises a feedback circuit and an adjusting circuit; the input end of the feedback circuit is connected with the output end of the gain controlled amplification circuit, and the output end of the feedback circuit is connected with the input end of the adjusting circuit, and the feedback circuit is used for capturing the maximum value of the reference signal in the output signal and feeding the maximum value back to the adjusting circuit; the input end of the adjusting circuit is connected with a power supply voltage;
the integral adjusting circuit comprises an integral circuit and a linear optocoupler and is used for dynamically adjusting the gain of the two-stage amplifying circuit in an integral mode according to the signal input by the feedback adjusting circuit so as to realize the stable amplitude of the integral output signal; the input end of the integrating circuit is connected with the output end of the adjusting circuit, the output end of the integrating circuit is connected with the input circuit of the linear optocoupler, and the output circuit of the linear optocoupler is connected with the input end of the gain controlled amplifying circuit; the input circuit of the linear optocoupler is connected with the input circuit of the linear optocoupler through a resistor R7The input signal is connected.
Still further, the linear optocoupler comprises an input light emitting diode D1And an output potentiometer R8(ii) a The output potentiometer R8One end of the second switch is grounded, and the other end of the second switch is connected with the input end of the gain controlled amplifying circuit;
the integration circuit comprises a resistor R10Capacitor C1And an amplifier U3；
The resistor R10One end of the output terminal of the adjusting circuit is connected with the amplifier U, and the other end of the output terminal of the adjusting circuit is connected with the amplifier U3And said capacitor C1One end of (a);
the capacitor C1Is connected with the resistor R at the other end7And said input light emitting diode D1The positive electrode of (1);
the amplifier U3Has its positive input end grounded and its output end connected with the input LED D1The negative electrode of (1).
Further, the fixed gain amplifying circuit includes a resistor R4Resistance R2And an amplifier U2Wherein:
the resistor R4Is grounded, and the other end is connected with the amplifier U2And said resistor R2One end of (a);
the resistor R2Is connected with the amplifier U at the other end2And an input of the gain controlled amplification circuit;
the amplifier U2Is connected to the input signal.
Further, the gain controlled amplification circuit comprises an amplifier U1Resistance R1Resistance R3Resistance R5And an output potentiometer R8；
The resistor R1Is grounded, and the other end is connected with the negative input end of the amplifier and the resistor R3；
The resistor R3Is connected with the amplifier U at the other end1An output terminal of (a);
the resistor R5Is connected to the amplifier U2The other end of the output end is connected with the amplifier U1And said output potentiometer R8；
The amplifier U1Is connected to the input of the feedback circuit.
Further, the adjusting circuit comprises a resistor R9Potentiometer R11Resistance R12And a resistance R13；
The resistor R9One end of which is connected with a power supply voltage and the potentiometer R11A first end of (a);
the potentiometer R11The second end of the resistor is grounded, and the control end is connected with the resistor R12One end of (a);
the resistor R13One end of the feedback circuit is connected with a reference signal and the output end of the feedback circuit;
the resistor R9Another terminal of (3), the resistor R12And the other end of (2) and the resistor R13The other end of the resistor R is connected with the resistor R10And (4) connecting.
Further, a resistor R is included6；
The resistor R6Is connected to the input signal,the second end is grounded and connected with the resistor R7The control end is connected with the amplifier U2To the positive input end of the switch.
Has the advantages that:
the automatic gain adjusting circuit for the infrared gas analyzer comprises a two-stage amplifying circuit, a feedback adjusting circuit and an integral adjusting circuit; the two-stage amplification circuit realizes the amplification of an input signal by 'fixed gain amplification + gain controlled amplification', and the gain of the gain controlled amplification circuit is controlled by an integral adjustment circuit; a feedback circuit in the feedback adjusting circuit captures the maximum value of the reference signal in the output signal and feeds the maximum value back to the adjusting circuit, and the output of the feedback adjusting circuit is connected with the integral adjusting circuit; the integral adjusting circuit dynamically adjusts the gain of the two-stage amplifying circuit in an integral mode according to the signal given by the feedback adjusting circuit, and therefore the amplitude of the overall output signal is stable.
Drawings
Fig. 1 is a circuit diagram of the automatic gain adjustment circuit according to the present invention.
Wherein, the 1-feedback circuit
Detailed Description
The present invention will be described in detail below with reference to the accompanying drawings by way of examples.
The utility model provides an automatic gain adjusting circuit for an infrared gas analyzer, which refers to the figure 1 and comprises a two-stage amplifying circuit, a feedback adjusting circuit and an integral adjusting circuit;
the two-stage amplifying circuit comprises a fixed gain amplifying circuit and a gain controlled amplifying circuit; the input end of the fixed gain amplifying circuit is connected with an input signal, and the output end of the fixed gain amplifying circuit is connected with the input end of the gain controlled amplifying circuit;
the feedback adjusting circuit comprises a feedback circuit 1 and an adjusting circuit; the input end of the feedback circuit 1 is connected with the output end of the gain controlled amplifying circuit, and the output end of the feedback circuit is connected with the input end of the adjusting circuit, and the feedback circuit is used for capturing the maximum value of the reference signal in the output signal and feeding the maximum value back to the adjusting circuit; the input end of the adjusting circuit is connected with a power supply voltage;
the integral regulating circuit comprises an integral circuit and a linear optical coupler and is used for regulating the output of the circuit according to feedbackThe input signal dynamically adjusts the gain of the two-stage amplifying circuit in an integral mode, and the amplitude of the integral output signal is stable; the input end of the integrating circuit is connected with the output end of the adjusting circuit, the output end of the integrating circuit is connected with the input circuit of the linear optocoupler, and the output circuit of the linear optocoupler is connected with the input end of the gain controlled amplifying circuit; input circuit of linear optocoupler passes through resistor R7The input signal is connected.
The automatic gain adjusting circuit for the infrared gas analyzer comprises a two-stage amplifying circuit, a feedback adjusting circuit and an integral adjusting circuit; the two-stage amplification circuit realizes the amplification of an input signal by 'fixed gain amplification + gain controlled amplification', and the gain of the gain controlled amplification circuit is controlled by an integral adjustment circuit; a feedback circuit 1 in the feedback adjusting circuit captures the maximum value of a reference signal in an output signal and feeds the maximum value back to the adjusting circuit, and the output of the feedback adjusting circuit is connected with the integral adjusting circuit; the integral adjusting circuit dynamically adjusts the gain of the two-stage amplifying circuit in an integral mode according to a signal given by the feedback adjusting circuit, and the dynamic adjusting range of the gain is not less than 1:20, so that the amplitude of the overall output signal is stable.
In one specific embodiment, as shown in FIG. 1, the linear optocoupler includes an input light emitting diode D1And an output potentiometer R8(ii) a Output potentiometer R8One end of the second switch is grounded, and the other end of the second switch is connected with the input end of the gain controlled amplifying circuit;
the integrating circuit comprises a resistor R10Capacitor C1And an amplifier U3；
Resistance R10One end of the output terminal is connected with the output end of the adjusting circuit, and the other end of the output terminal is connected with the amplifier U3Negative input terminal and capacitor C1One end of (a);
capacitor C1Another end of the resistor R is connected with a resistor R7And an input light emitting diode D1The positive electrode of (1);
amplifier U3The positive input end of the input LED is grounded, and the output end of the input LED is connected with an input LED D1The negative electrode of (1).
Further, as shown in FIG. 1, the fixed gain amplifier circuit includes a resistor R4Resistance R2And putAmplifier U2Wherein:
resistance R4One end of the first and second switches is grounded, and the other end is connected with an amplifier U2Negative input terminal and resistor R2One end of (a);
resistance R2The other end of the amplifier is connected with an amplifier U2And an input of the gain controlled amplification circuit;
amplifier U2The positive input of which is connected to the input signal.
In particular, the gain-controlled amplification circuit comprises an amplifier U1Resistance R1Resistance R3Resistance R5And an output potentiometer R8；
Resistance R1One end of the first resistor is grounded, and the other end of the first resistor is connected with the negative input end of the amplifier and the resistor R3；
Resistance R3The other end of the amplifier is connected with an amplifier U1An output terminal of (a);
resistance R5One end of is connected with an amplifier U2The other end of the output end of the amplifier is connected with an amplifier U1Positive input terminal and output potentiometer R of8；
Amplifier U1Is connected to the input of the feedback circuit 1.
Further, the adjusting circuit includes a resistor R9Potentiometer R11Resistance R12And a resistance R13；
Resistance R9One end of which is connected with a power supply voltage and a potentiometer R11A first end of (a);
potentiometer R11The second end of the resistor is grounded, and the control end is connected with a resistor R12One end of (a);
resistance R13One end of which is connected to the reference signal and the output end of the feedback circuit 1;
resistance R9Another terminal of (1), a resistor R12And the other end of (3) and a resistor R13The other ends of the resistors R and R are connected10And (4) connecting.
On the basis of the various embodiments, the automatic gain adjusting circuit for the infrared gas analyzer further comprises a resistor R6；
Resistance R6Has a first end connected with an input signal and a second end grounded and connected with a resistor R7The control end is connected with an amplifier U2To the positive input end of the switch.
According to the automatic gain adjusting circuit for the infrared gas analyzer, the maximum amplitude of the reference signal in the output signal of the infrared gas analyzer is fed back and adjusted through the feedback adjusting circuit and the integral adjusting circuit, and the output signal amplitude is ensured to be stable through the gain of the linear optical coupler dynamic adjusting circuit.
The operation principle of the automatic gain adjustment circuit will be described with reference to fig. 1.
UinFor input signal, a resistor R6A portion of the input signal is picked up to prevent the subsequent stage from saturating, assuming a pick-up coefficient of k, where 0 ≦ k ≦ 1.
The pick-up signal is accessed to the second stage after being amplified in the same phase by the first stage, and the amplification factor meets the following formula (1):
the second stage is composed of a voltage division circuit and an amplifying circuit, and the amplification factor of the second stage satisfies the following formula (2):
to this end, the amplification factor of the entire circuit satisfies the following formula (3):
in the formula, a resistance R1Resistance R2Resistance R3Resistance R4Resistance R5All are constant value resistors; r8An output potentiometer being a linear optocoupler whose resistance is input by the light emitting diode D1The illumination changes. It can be seen that only the output potential is changedDevice R8The gain of the circuit changes.
The feedback unit is used for extracting the maximum value U of the reference signal in the output signalrefIs integrated by U3、R10、C1Equal-composition integrating circuit for controlling input light-emitting diode D1The control principle of the luminance of (1) will be briefly described below.
First, when the integration circuit is in steady state, the resistor R10No current flows in this case UbAnd U3No potential difference between the inverting terminals, UbVoltage of 0; at this time Ua、U ref12V satisfies the following formula (4):
the above simplification gives the following formula (5):
due to the resistance R9Resistance R12Resistance R13Are all constant values, and UaCan be composed of a potentiometer R11Control once U is turned onaDetermine then UrefAnd must be determined. This means that only the input signal U is presentinWithin a certain suitable range, outputs a signal UoThe amplitude of the reference signal must be stabilized
To (3).
Second, the integration circuit is in a changing state when the input signal amplitude decreases. At the moment, the output signal is reduced, and the maximum value U of the reference signal extracted in the feedback linkrefWill be reduced due to-12V and UaAre all negative voltages and are unchanged, so that the voltage UbLess than 0; capacitor C1By R10Discharge, C1Two-terminal voltage reduction, input to the LED D1Two endsThe voltage is also reduced, the current iDReducing, inputting light emitting diodes D1The luminous intensity is weakened and the output potentiometer R8The resistance of the amplifier increases, the amplification factor A of the whole circuit increases, and the output signal becomes larger.
Third, the integration circuit is also in a changing state when the input signal amplitude increases. At the moment, the output signal is increased, and the maximum value U of the reference signal extracted in the feedback linkrefWill increase due to-12V and UaAre all negative voltages and are unchanged, so that the voltage Ub＞0；UbThrough a resistance R10To the capacitor C1Charging, capacitance C1The voltage at both ends is increased and is input into the light emitting diode D1The voltage across the terminals also increases, the current iDIncreased to input into the light emitting diode D1Luminous intensity enhanced output potentiometer R8The resistance of (2) is reduced, the amplification factor A of the whole circuit is also reduced, and the output signal is weakened.
Through the gain automatic adjusting circuit, the reference signal of the final output signal is kept fixed, the amplitude of the output signal is kept within a certain range, the influence caused by temperature change, light source change or other environmental changes is reduced, meanwhile, the acquisition error caused by the nonlinearity of the analog-to-digital converter is reduced, and the final detection precision is improved.
The following is an example of an application, resistor R9Resistance R12All take 10k, potentiometer R11With 10k, resistance R13Taking 3k, adjusting potentiometer R11So that the voltage Uais-4.67V, the amplitude of the reference signal in the output signal satisfies the following formula (6):
in addition, a potentiometer R is adjusted11Take different UaDifferent output signal amplitudes (reference signals) can be obtained, as shown in table 1 below.
TABLE 1 different UaReference signal amplitude corresponding table in output signal under value
In summary, the above is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (6)
1. A gain automatic regulating circuit for an infrared gas analyzer is characterized by comprising a two-stage amplifying circuit, a feedback regulating circuit and an integral regulating circuit;
the two-stage amplifying circuit comprises a fixed gain amplifying circuit and a gain controlled amplifying circuit; the input end of the fixed gain amplifying circuit is connected with an input signal, and the output end of the fixed gain amplifying circuit is connected with the input end of the gain controlled amplifying circuit;
the feedback adjusting circuit comprises a feedback circuit and an adjusting circuit; the input end of the feedback circuit is connected with the output end of the gain controlled amplification circuit, and the output end of the feedback circuit is connected with the input end of the adjusting circuit, and the feedback circuit is used for capturing the maximum value of the reference signal in the output signal and feeding the maximum value back to the adjusting circuit; the input end of the adjusting circuit is connected with a power supply voltage;
the integral adjusting circuit comprises an integral circuit and a linear optocoupler and is used for dynamically adjusting the gain of the two-stage amplifying circuit in an integral mode according to the signal input by the feedback adjusting circuit so as to realize the stable amplitude of the integral output signal; the input end of the integrating circuit is connected with the output end of the adjusting circuit, the output end of the integrating circuit is connected with the input circuit of the linear optocoupler, and the output circuit of the linear optocoupler is connected with the input end of the gain controlled amplifying circuit; the input circuit of the linear optocoupler is connected with the input circuit of the linear optocoupler through a resistor R7The input signal is connected.
2. The gain automatic adjustment circuit of claim 1, wherein the linear optocoupler comprises an input light emitting diode D1And outputPotentiometer R8(ii) a The output potentiometer R8One end of the second switch is grounded, and the other end of the second switch is connected with the input end of the gain controlled amplifying circuit;
the integration circuit comprises a resistor R10Capacitor C1And an amplifier U3；
The resistor R10One end of the output terminal of the adjusting circuit is connected with the amplifier U, and the other end of the output terminal of the adjusting circuit is connected with the amplifier U3And said capacitor C1One end of (a);
the capacitor C1Is connected with the resistor R at the other end7And said input light emitting diode D1The positive electrode of (1);
the amplifier U3Has its positive input end grounded and its output end connected with the input LED D1The negative electrode of (1).
3. The automatic gain adjustment circuit of claim 2, wherein the fixed gain amplification circuit comprises a resistor R4Resistance R2And an amplifier U2Wherein:
the resistor R4Is grounded, and the other end is connected with the amplifier U2And said resistor R2One end of (a);
the resistor R2Is connected with the amplifier U at the other end2And an input of the gain controlled amplification circuit;
the amplifier U2Is connected to the input signal.
4. The automatic gain adjustment circuit of claim 3, wherein the gain controlled amplification circuit comprises an amplifier U1Resistance R1Resistance R3Resistance R5And an output potentiometer R8；
The resistor R1Is grounded, and the other end is connected with the negative input end of the amplifier and the resistor R3；
The resistor R3Another end of (a) is connected toIs connected with the amplifier U1An output terminal of (a);
the resistor R5Is connected to the amplifier U2The other end of the output end is connected with the amplifier U1And said output potentiometer R8；
The amplifier U1Is connected to the input of the feedback circuit.
5. The automatic gain adjustment circuit of claim 4, wherein the adjustment circuit comprises a resistor R9Potentiometer R11Resistance R12And a resistance R13；
The resistor R9One end of which is connected with a power supply voltage and the potentiometer R11A first end of (a);
the potentiometer R11The second end of the resistor is grounded, and the control end is connected with the resistor R12One end of (a);
the resistor R13One end of the feedback circuit is connected with a reference signal and the output end of the feedback circuit;
the resistor R9Another terminal of (3), the resistor R12And the other end of (2) and the resistor R13The other end of the resistor R is connected with the resistor R10And (4) connecting.
6. The automatic gain adjustment circuit of claim 5, further comprising a resistor R6；
The resistor R6Is connected to the input signal, and has a second end connected to ground and to the resistor R7The control end is connected with the amplifier U2To the positive input end of the switch.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202022781854.1U CN214277890U (en) | 2020-11-25 | 2020-11-25 | Gain automatic adjusting circuit for infrared gas analyzer |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202022781854.1U CN214277890U (en) | 2020-11-25 | 2020-11-25 | Gain automatic adjusting circuit for infrared gas analyzer |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN214277890U true CN214277890U (en) | 2021-09-24 |
Family
ID=77777757
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202022781854.1U Active CN214277890U (en) | 2020-11-25 | 2020-11-25 | Gain automatic adjusting circuit for infrared gas analyzer |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN214277890U (en) |
-
2020
- 2020-11-25 CN CN202022781854.1U patent/CN214277890U/en active Active
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| TWI302194B (en) | Apparatus and method for sensing ambient light | |
| TW201627791A (en) | System and method for controlling excess bias of single photon avalanche photo diode | |
| US4096382A (en) | Photo-current log-compression circuit | |
| CN103767712B (en) | A kind of blood oxygen measuring device of environment resistant light interference and method thereof | |
| CN111398878B (en) | Hall programmable chip with ripple suppression function | |
| US8901475B1 (en) | Avalanche photodiode biasing system including a current mirror, voltage-to-current converter circuit, and a feedback path sensing an avalanche photodiode voltage | |
| JP2006303524A (en) | Bias voltage control circuit for avalanche photodiode and its adjusting method | |
| US6933786B1 (en) | Amplifier circuit and method | |
| CN109738065B (en) | Blood oxygen detection chip with rapid light intensity tracking capability | |
| CN214277890U (en) | Gain automatic adjusting circuit for infrared gas analyzer | |
| CN116979369B (en) | Laser driving circuit and method for particulate matter concentration sensor | |
| CN107816938B (en) | Circuit for automatically zeroing and modulating amplitude of interference system under low contrast and using method thereof | |
| CN107782687A (en) | A kind of medical integrated photometer device | |
| JP6372780B2 (en) | Infrared detector | |
| TW201522923A (en) | Dual switching sensing device and dual switching sensing circuit | |
| CN208874546U (en) | Bridge circuit zero offset on-line correction circuit based on electric current injection | |
| JPS5968629A (en) | Method and device for stabilizing gain of photosensitive av-alanche member | |
| CN210803208U (en) | Marine diesel engine crankcase oil mist detection device | |
| CN114659628A (en) | Light measuring device | |
| TW201939013A (en) | Multi-channel detecting system | |
| US20220397454A1 (en) | Photoconductor Readout Circuit | |
| CN210157439U (en) | LED current sampling circuit and LED driving power supply | |
| CN106791512A (en) | A kind of automatic adjustable reading circuit of integrating capacitor | |
| CN106706993A (en) | Optocoupler current detection circuit | |
| CN106341189A (en) | Optical module |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| GR01 | Patent grant | ||
| GR01 | Patent grant |