Signal processing method for front-end circuit and front-end circuit

Abstract

The invention discloses a signal processing method for a front-end circuit and the front-end circuit, the front-end circuit comprises a plurality of operational amplifiers, a plurality of diodes, a plurality of resistors, a plurality of field effect transistors, a change-over switch and a capacitor, the in-phase end of an operational amplifier U3 in the plurality of operational amplifiers is connected with the first connecting end of the change-over switch S1 and one end of a resistor R3; the anti-phase end is connected with the cathode of the diode D1, one end of the capacitor C1, the source electrode of the field effect transistor Q3 and the anti-phase end of the operational amplifier U4, and the output end is connected with the anode of the diode D1; the in-phase end of the operational amplifier U4 is connected with the cathode of the diode D2 and one end of the resistor R4, and the output end is connected with the OUT3 end; the drain electrode of the field effect transistor Q3 is connected with one end of the resistor R5, and the positive electrode of the change-over switch S1 is connected with the IN2 end; the common end of the change-over switch S1 is connected with the IN1 end, and the second connecting end is connected with the anode of the diode D2; the cathode of the change-over switch S1, the other end of the resistor R3, the other end of the resistor R4 and the other end of the resistor R5 are grounded.

Description

Technical Field

[0001] The present invention relates to the technical field of signal processing, and particularly to a signal processing method and a front-end circuit for a front-end circuit. Background Art

[0002] The core function of the front-end circuit is to preprocess the analog signal output by the sensor to ensure that it meets the input voltage range requirements of the analog-to-digital converter (ADC). Since industrial sensors generally have two output forms, namely current type and voltage type, it is necessary to determine the output type of the sensor and select whether to configure an I / V conversion circuit before configuring the front-end circuit. However, this method has obvious limitations in practical applications. When the sensor type is replaced on-site, it is often necessary to redesign or adjust the front-end circuit. Therefore, a signal processing method and a front-end circuit for a front-end circuit are proposed, which can automatically identify the sensor signal type and perform corresponding processing according to the sensor signal type. Summary of the Invention

[0003] Aiming at the above technical problems, the purpose of the present invention is to provide a signal processing method and a front-end circuit for a front-end circuit.

[0004] A front-end circuit includes several operational amplifiers, several diodes, several resistors, several field-effect transistors, a switching switch, and a capacitor. The non-inverting input terminal of operational amplifier U3 among the several operational amplifiers is connected to the first connection terminal of switching switch S1 and one end of resistor R3, the inverting input terminal is connected to the cathode of diode D1, one end of capacitor C1, the source electrode of field-effect transistor Q3, and the inverting input terminal of operational amplifier U4, and the output terminal is connected to the anode of diode D1; the non-inverting input terminal of operational amplifier U4 is connected to the cathode of diode D2 and one end of resistor R4, and the output terminal is connected to OUT3 terminal; the drain electrode of field-effect transistor Q3 is connected to one end of resistor R5, the gate electrode of field-effect transistor Q3 and the positive electrode of switching switch S1 are connected to IN2 terminal; the common terminal of switching switch S1 is connected to IN1 terminal, and the second connection terminal is connected to the anode of diode D2; the negative electrode of switching switch S1, the other end of resistor R3, the other end of resistor R4, and the other end of resistor R5 are grounded.

[0005] Further, it further includes a flip-flop and a triode. The first pin of flip-flop U1 is connected to one end of resistor R1 and the collector of triode Q2, the second pin, the sixth pin of flip-flop U1 and one end of resistor R9 are connected to OUT6 terminal, the third pin of flip-flop U1, the source electrode of field-effect transistor Q1, and one end of resistor R7 are connected to IN3 terminal, the fourth pin of flip-flop U1 and the other end of resistor R1 are connected to the power supply, the fifth pin of flip-flop U1 and the inverting input terminal of operational amplifier U2 are connected to OUT5 terminal; the non-inverting input terminal of operational amplifier U2 inputs a reference signal; the gate electrode of field-effect transistor Q1 is connected to the output terminal of operational amplifier U2; one end of resistor R15 is connected to the base of triode Q2, and the other end is connected to IN4 terminal; the drain electrode of field-effect transistor Q1, the emitter of triode Q2, the other end of resistor R7, and the other end of resistor R9 are grounded.

[0006] Further, one end of the resistor R2 among the several resistors is connected to the gate of the field - effect transistor Q1, and the other end is grounded.

[0007] Further, one end of the resistor R10 among the several resistors is connected to the power supply, and the other end is connected to one end of the resistor R8 and the non - inverting input terminal of the operational amplifier U2; the other end of the resistor R8 is grounded.

[0008] Further, one end of the resistor R6 among the several resistors is connected to the gate of the field - effect transistor Q3, and the other end is grounded.

[0009] Further, a signal processing method for a front - end circuit includes the following steps: S1. Judge whether the circuit obtains a sensor signal, and feedback a judgment signal based on the judgment result; S2. When obtaining the judgment signal, detect the sensor type, and feedback a measurement signal based on the detection result; S3. Based on the feedback of the measurement signal, perform corresponding processing on the signal output by the sensor.

[0010] The beneficial effects of the present invention compared with the prior art are: The present invention can automatically identify the sensor signal type and perform corresponding processing according to the sensor signal type. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the prior art and the embodiments. Obviously, the following - described drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0012] Figure 1 It is a schematic structural diagram of the front - end circuit provided by the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0013] In order to make the purpose and advantages of the present invention clearer, the following will specifically describe the present invention in combination with embodiments. It should be understood that the following text only describes one or several specific implementation manners of the present invention, and does not strictly limit the scope of protection specifically claimed by the present invention.

[0014] The present invention discloses a front - end circuit, as Figure 1 shown, including several operational amplifiers, several diodes, several resistors, several field - effect transistors, a switching switch, and a capacitor; the several operational amplifiers include operational amplifier U3 and operational amplifier U4, the several diodes include diode D1 and diode D2, the several resistors include resistor R3, resistor R4, and resistor R5, the several field - effect transistors include field - effect transistor Q3, the switching switch includes switching switch S1, and the capacitor includes capacitor C1; The non-inverting input terminal of operational amplifier U3 among the several operational amplifiers is connected to the first connection terminal of switch S1 and one end of resistor R3, the inverting input terminal is connected to the cathode of diode D1, one end of capacitor C1, the source electrode of field effect transistor Q3, and the inverting input terminal of operational amplifier U4, and the output terminal is connected to the anode of diode D1; the non-inverting input terminal of operational amplifier U4 is connected to the cathode of diode D2 and one end of resistor R4, and the output terminal is connected to OUT3 terminal; the drain electrode of field effect transistor Q3 is connected to one end of resistor R5, and the gate electrode of field effect transistor Q3 and the positive electrode of switch S1 are connected to IN2 terminal; the common terminal of switch S1 is connected to IN1 terminal, and the second connection terminal is connected to the anode of diode D2; the negative electrode of switch S1, the other end of resistor R3, the other end of resistor R4, and the other end of resistor R5 are grounded.

[0015] Specifically, it further includes a flip-flop and a triode. The flip-flop includes flip-flop U1, the triode includes triode Q2, the several operational amplifiers further include operational amplifier U2, the several resistors further include resistors R1, R7, R9, and R15, and the several field effect transistors include field effect transistor Q1; The first pin of flip-flop U1 is connected to one end of resistor R1 and the collector of triode Q2, the second pin, the sixth pin of flip-flop U1 and one end of resistor R9 are connected to OUT6 terminal, the third pin of flip-flop U1, the source electrode of field effect transistor Q1, and one end of resistor R7 are connected to IN3 terminal, the fourth pin of flip-flop U1 and the other end of resistor R1 are connected to the power supply, and the fifth pin of flip-flop U1 and the inverting input terminal of operational amplifier U2 are connected to OUT5 terminal; a reference signal is input to the non-inverting input terminal of operational amplifier U2; the gate electrode of field effect transistor Q1 is connected to the output terminal of operational amplifier U2; one end of resistor R15 is connected to the base of triode Q2, and the other end is connected to IN4 terminal; the drain electrode of field effect transistor Q1, the emitter of triode Q2, the other end of resistor R7, and the other end of resistor R9 are grounded.

[0016] Specifically, the several resistors further include resistor R2. One end of resistor R2 is connected to the gate electrode of field effect transistor Q1, and the other end is grounded.

[0017] Specifically, the several resistors further include resistors R10 and R8. One end of resistor R10 is connected to the power supply, and the other end is connected to one end of resistor R8 and the non-inverting input terminal of operational amplifier U2; the other end of resistor R8 is grounded.

[0018] Specifically, the several resistors further include resistor R6. One end of resistor R6 is connected to the gate electrode of field effect transistor Q3, and the other end is grounded.

[0019] Specifically, a signal processing method for a front-end circuit includes the following steps: S1. Judge whether the circuit obtains a sensor signal, and feedback a judgment signal based on the judgment result; S2. When obtaining the judgment signal, detect the sensor type, and feedback a measurement signal based on the detection result; S3. Based on the feedback of the measurement signal, perform corresponding processing on the signal output by the sensor.

[0020] IN1 inputs the sensor signal, which is fed back by the sensor. A judgment unit is set inside the circuit. IN2 inputs the judgment signal, which is input by the judgment unit. The judgment unit judges whether a sensor signal is obtained at the IN1 terminal. When obtained, a judgment signal is fed back to IN2 with a time lag. The time lag is set on the judgment unit. The judgment signal is fed back to the gate of the field effect transistor Q3. The resistor R6 discharges the parasitic capacitance of the gate of the field effect transistor Q3. When the judgment signal is not obtained at IN2, the voltage difference between the gate and the source of the field effect transistor Q3 is lower than the conduction threshold, and the field effect transistor Q3 conducts. The signal at the IN1 terminal passes through the switching switch S1 and the resistor R3 to the ground terminal. The signal at the resistor R3 terminal is fed back to the non-inverting terminal of the operational amplifier U3. The operational amplifier U3 outputs. The signal at the output terminal of the operational amplifier U3 is fed back to the inverting terminal of the operational amplifier U3 through the diode D1. When the field effect transistor Q3 conducts, the signal at the capacitor C1 terminal passes through the source, drain of the field effect transistor Q3, and the resistor R5 to the ground terminal. The signal at the capacitor C1 terminal follows the signal output by the sensor. When the judgment signal is obtained at IN2, the IN2 signal is fed back to the positive pole of the switching switch S1. The switching switch S1 switches the path. At the same time, the field effect transistor Q3 is cut off, and the capacitor C1 stops charging and discharging. The signal at the IN1 terminal passes through the diode D2 and the resistor R4 to the ground terminal. The resistance value of the resistor R4 terminal is set higher than that of the resistor R3 terminal. The signal at the capacitor C1 terminal is fed back to the inverting terminal of the operational amplifier U4. The signal at the resistor R4 terminal is fed back to the non-inverting terminal of the operational amplifier U4. If the sensor output signal is a current signal, when the signal feedback is obtained at IN2, the signal at the resistor R4 terminal is higher than the signal at the capacitor C1 terminal, and the operational amplifier U4 is in the output state. If the sensor output signal is a voltage signal, when the signal feedback is obtained at IN2, the voltage drop after the IN1 terminal signal passes through the diode D2 makes the signal at the resistor R4 terminal lower than the signal at the capacitor C1 terminal, and the operational amplifier U4 is in the cut-off state. The signal at the output terminal of the operational amplifier U4 is the measured signal. When the output terminal of the operational amplifier U4 outputs, it is measured that the current sensor output signal is a current signal, otherwise it is measured as a voltage signal. In this way, the signal type of the sensor is automatically identified and the corresponding feedback after identification is performed.

[0021] IN3 receives the measurement signal, and the measurement signal is fed back to pin 3 of flip-flop U1. Resistor R7 is the pull-down resistor for pin 3 of flip-flop U1. When IN3 does not receive the measurement signal in the initial state, pin 5 of flip-flop U1 is at a low level, and pin 6 of flip-flop U1 is at a low level. Resistor R9 is the pull-down resistor for pin 6 of flip-flop U1. When IN3 receives the measurement signal, the levels of pin 5 and pin 6 of flip-flop U1 are swapped. Pin 5 of flip-flop U1 is at a high level, and pin 6 of flip-flop U1 is at a low level. The non-inverting input terminal of operational amplifier U2 inputs the reference signal. The power supply signal passes through resistor R10 and resistor R8 to the ground terminal. The reference signal is fed back from the resistor R8 terminal or input from the power supply. The signal of pin 5 of flip-flop U1 is fed back to the inverting input terminal of operational amplifier U2. When the output of pin 5 of flip-flop U1 is at a high level, operational amplifier U2 is cut off. The signal at the output terminal of operational amplifier U2 is fed back to the gate of field-effect transistor Q1. Resistor R2 is used to discharge the parasitic capacitance of the gate of field-effect transistor Q1. Field-effect transistor Q1 conducts. The voltage difference between the gate and the source of field-effect transistor Q1 is lower than the conduction threshold. The signal at pin 3 of flip-flop U1 passes through the source and drain of field-effect transistor Q1 to the ground terminal. When field-effect transistor Q1 conducts, it restricts the signal at pin 3 of flip-flop U1 from obtaining a high-level signal again. The reset signal is fed back by the upper-level circuit or manually. The power supply signal is fed back to the collector of transistor Q2 through resistor R1. IN4 receives the reset signal. When IN4 receives the signal feedback, the reset signal passes through resistor R15, the base of transistor Q2, and the emitter of transistor Q2 to the ground terminal. Transistor Q2 conducts. The signal at pin 1 of flip-flop U1 passes through the collector and emitter of transistor Q2 to the ground terminal. The signal at pin 1 of flip-flop U1 is pulled to the ground potential. Flip-flop U1 is reset. Pin 5 of flip-flop U1 is at a low level, and pin 6 of flip-flop U1 is at a high level. Operational amplifier U2 outputs. Field-effect transistor Q1 is cut off. The signals at pin 5 and pin 6 of flip-flop U1 are channel switching signals. The channel switching signals are used to switch the signal channels at the output end of the sensor. A first processing unit and a second processing unit are provided in the circuit. If the sensor output signal is a voltage signal, the sensor signal is output to the second processing unit. The second processing unit performs differential amplification and filtering processing on it and then feeds it back to the lower-level circuit. If the sensor output signal is a current signal, the sensor signal is output to the first processing unit. The first processing unit performs I / V conversion on it and then feeds it back to the second processing unit. The second processing unit performs subsequent processing, so as to perform corresponding processing according to the signal type of the sensor.

[0022] It is obvious to those skilled in the art that the present invention is not limited to the details of the above-described exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, in all respects, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes that fall within the meaning and scope of the equivalent elements of the claims are intended to be embraced within the present invention. Any reference signs in the claims should not be construed as limiting the claim concerned.

Claims

1. A front-end circuit, characterized in that, It includes several operational amplifiers, several diodes, several resistors, several field effect transistors, a switching switch, and a capacitor. The non-inverting input terminal of operational amplifier U3 among the several operational amplifiers is connected to the first connection terminal of switching switch S1 and one end of resistor R3. The inverting input terminal is connected to the cathode of diode D1, one end of capacitor C1, the source electrode of field effect transistor Q3, and the inverting input terminal of operational amplifier U4. The output terminal is connected to the anode of diode D1. The non-inverting input terminal of operational amplifier U4 is connected to the cathode of diode D2 and one end of resistor R4. The output terminal is connected to OUT3 terminal. The drain electrode of field effect transistor Q3 is connected to one end of resistor R5. The gate electrode of field effect transistor Q3 and the positive electrode of switching switch S1 are connected to IN2 terminal. The common terminal of switching switch S1 is connected to IN1 terminal, and the second connection terminal is connected to the anode of diode D2. The negative electrode of switching switch S1, the other end of resistor R3, the other end of resistor R4, and the other end of resistor R5 are grounded.

2. The front-end circuit according to claim 1, wherein It further includes a flip-flop and a triode. The first pin of flip-flop U1 is connected to one end of resistor R1 and the collector electrode of triode Q2. The second pin, the sixth pin of flip-flop U1, and one end of resistor R9 are connected to OUT6 terminal. The third pin of flip-flop U1, the source electrode of field effect transistor Q1, and one end of resistor R7 are connected to IN3 terminal. The fourth pin of flip-flop U1 and the other end of resistor R1 are connected to the power supply. The fifth pin of flip-flop U1 and the inverting input terminal of operational amplifier U2 are connected to OUT5 terminal. The non-inverting input terminal of operational amplifier U2 inputs a reference signal. The gate electrode of field effect transistor Q1 is connected to the output terminal of operational amplifier U2. One end of resistor R15 is connected to the base electrode of triode Q2, and the other end is connected to IN4 terminal. The drain electrode of field effect transistor Q1, the emitter electrode of triode Q2, the other end of resistor R7, and the other end of resistor R9 are grounded.

3. The front-end circuit according to claim 2, characterized in that, One end of resistor R2 among the several resistors is connected to the gate electrode of field effect transistor Q1, and the other end is grounded.

4. The front-end circuit according to claim 2, wherein One end of resistor R10 among the several resistors is connected to the power supply, and the other end is connected to one end of resistor R8 and the non-inverting input terminal of operational amplifier U2. The other end of resistor R8 is grounded.

5. The front-end circuit according to claim 1, wherein One end of resistor R6 among the several resistors is connected to the gate electrode of field effect transistor Q3, and the other end is grounded.

6. A signal processing method for a front-end circuit, characterized in that, It includes the following steps: S1. Judge whether the circuit obtains a sensor signal, and feedback a judgment signal based on the judgment result; S2. When obtaining the judgment signal, detect the sensor type, and feedback a measurement signal based on the detection result; S3. Based on the feedback of the measurement signal, perform corresponding processing on the signal output by the sensor.

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