A signal processing method for front-end circuit and front-end circuit

Abstract

The present invention discloses a signal processing method and a front-end circuit for a front-end circuit. The front-end circuit includes a plurality of operational amplifiers, a plurality of diodes, a plurality of resistors, a plurality of field-effect transistors, a switching switch, and a capacitor. An operational amplifier U3 among the plurality of operational amplifiers is connected to a first connection end of a switching switch S1 and one end of a resistor R3 in the same phase at a termination, a cathode of a diode D1, one end of a capacitor C1, a source of a field-effect transistor Q3, and an inverting end of an operational amplifier U4 in the opposite phase at a termination, and an output end is connected to an anode of a diode D1; an operational amplifier U4 is connected to a cathode of a diode D2 and one end of a resistor R4 in the same phase at a termination, and an output end is connected to an OUT3 end; a drain of the field-effect transistor Q3 is connected to one end of a resistor R5, and a gate and a positive pole of a switching switch S1 are connected to an IN2 end; a common end of the switching switch S1 is connected to an IN1 end, and a second connection end is connected to an anode of a diode D2; a negative pole of the switching 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 field of signal processing technology, and in particular to a signal processing method for a front-end circuit and a front-end circuit. Background Art

[0002] The core function of the front-end circuit is to pre-process 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 and voltage, it is necessary to determine the output type of the sensor and choose 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 changed on site, it is often necessary to redesign or adjust the front-end circuit. Therefore, a signal processing method and front-end circuit for the front-end circuit are proposed, which can automatically identify the sensor signal type and perform corresponding processing based on the sensor signal type. Summary of the Invention

[0003] In view of the above technical problems, an object of the present invention is to provide a signal processing method for a front-end circuit and 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. Among the several operational amplifiers, an operational amplifier U3 is connected to the first connection terminal of the switching switch S1 and one end of the resistor R3 in the same phase, and is connected to the cathode of the diode D1, one end of the capacitor C1, the source of the field-effect transistor Q3, and the inverting terminal of the operational amplifier U4 in the opposite phase. The output terminal is connected to the anode of the diode D1. The operational amplifier U4 is connected to the cathode of the diode D2 and one end of the resistor R4 in the same phase, and the output terminal is connected to the OUT3 terminal. The drain of the field-effect transistor Q3 is connected to one end of the resistor R5, and the gate of the field-effect transistor Q3 and the positive electrode of the switching switch S1 are connected to the IN2 terminal. The common terminal of the switching switch S1 is connected to the IN1 terminal, and the second connection terminal is connected to the anode of the diode D2. The cathode of the switching 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.

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

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

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

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

[0009] Furthermore, a signal processing method for a front-end circuit includes the following steps:

[0010] S1. Determine whether the circuit obtains the sensor signal and feedback the judgment signal based on the judgment result;

[0011] S2. When the judgment signal is obtained, the sensor type is detected and the measurement signal is fed back based on the detection result;

[0012] S3. Based on the feedback of the measurement signal, the signal output by the sensor is processed accordingly.

[0013] The beneficial effects of the present invention compared with the prior art are:

[0014] 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

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, a brief introduction is given below to the prior art and the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0016] Figure 1 This is a schematic structural diagram of the front-end circuit provided by the present invention. DETAILED DESCRIPTION

[0017] In order to make the objects and advantages of the present invention more clearly understood, the present invention is described in detail below with reference to the embodiments. It should be understood that the following text is only used to describe one or several specific implementation methods of the present invention and does not strictly limit the scope of protection specifically requested by the present invention.

[0018] The present invention discloses a front-end circuit, such as Figure 1As shown, it includes 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;

[0019] The operational amplifier U3 among the several operational amplifiers is connected to the first connection end of the switching switch S1 and one end of the resistor R3 in the same phase, and is connected to the cathode of the diode D1, one end of the capacitor C1, the source of the field effect transistor Q3, and the inverting end of the operational amplifier U4 in the opposite phase, and the output end is connected to the anode of the diode D1; the operational amplifier U4 is connected to the cathode of the diode D2 and one end of the resistor R4 in the same phase, and the output end is connected to the OUT3 end; the drain of the field effect transistor Q3 is connected to one end of the resistor R5, and the gate of the field effect transistor Q3 and the positive pole of the switching switch S1 are connected to the IN2 end; the common end of the switching switch S1 is connected to the IN1 end, and the second connection end is connected to the anode of the diode D2; the negative pole of the switching 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.

[0020] Specifically, it also includes a trigger and a triode, the trigger includes a trigger U1, the triode includes a triode Q2, the plurality of operational amplifiers also includes operational amplifier U2, the plurality of resistors also includes a resistor R1, a resistor R7, a resistor R9, and a resistor R15, and the plurality of field effect transistors includes a field effect transistor Q1;

[0021] The first pin of the trigger U1 is connected to one end of the resistor R1 and the collector of the transistor Q2, the second pin, the sixth pin and one end of the resistor R9 are connected to the OUT6 terminal, the third pin of the trigger U1, the source of the field effect transistor Q1 and one end of the resistor R7 are connected to the IN3 terminal, the fourth pin of the trigger U1 and the other end of the resistor R1 are connected to the power supply, the fifth pin of the trigger U1 and the inverting end of the operational amplifier U2 are connected to the OUT5 terminal; the reference signal is input to the non-inverting terminal of the operational amplifier U2; the gate of the field effect transistor Q1 is connected to the output terminal of the operational amplifier U2; one end of the resistor R15 is connected to the base of the transistor Q2, and the other end is connected to the IN4 terminal; the drain of the field effect transistor Q1, the emitter of the transistor Q2, the other end of the resistor R7 and the other end of the resistor R9 are grounded.

[0022] Specifically, the plurality of resistors further includes a resistor R2 , one end of the resistor R2 is connected to the gate of the field effect transistor Q1 , and the other end is grounded.

[0023] Specifically, the plurality of resistors further include a resistor R10 and a resistor R8. One end of the resistor R10 is connected to the power supply, and the other end is connected to one end of the resistor R8 and the non-inverting terminal of the operational amplifier U2. The other end of the resistor R8 is grounded.

[0024] Specifically, the plurality of resistors further includes a resistor R6 , one end of the resistor R6 is connected to the gate of the field effect transistor Q3 , and the other end is grounded.

[0025] Specifically, a signal processing method for a front-end circuit includes the following steps:

[0026] S1. Determine whether the circuit obtains the sensor signal and feedback the judgment signal based on the judgment result;

[0027] S2. When the judgment signal is obtained, the sensor type is detected and the measurement signal is fed back based on the detection result;

[0028] S3. Based on the feedback of the measurement signal, the signal output by the sensor is processed accordingly.

[0029] IN1 inputs the sensor signal, which is fed back by the sensor. A judgment unit is set in the circuit. IN2 inputs the judgment signal, which is input by the judgment unit. The judgment unit judges whether the IN1 terminal obtains the sensor signal. When the sensor signal is obtained, the judgment signal is fed back to IN2 after a hysteresis. The hysteresis time is set on the judgment unit. The judgment signal is fed back to the gate of the field effect tube Q3. The resistor R6 discharges the parasitic capacitance of the gate of the field effect tube Q3. When IN2 does not obtain the judgment signal, the voltage difference between the gate of the field effect tube Q3 and the source of the field effect tube Q3 is lower than the conduction threshold, and the field effect tube Q3 is turned on. The signal at the IN1 terminal is connected to the ground terminal through the switching switch S1 and the resistor R3. The signal at the resistor R3 terminal is fed back to the non-inverting terminal of the operational amplifier U3 and output by the operational amplifier U3. 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. The field effect tube Q3 is turned on. The signal at the capacitor C1 terminal is connected to the ground terminal through the source of the field effect tube Q3, the drain of the field effect tube Q3, and the resistor R5. The capacitor C1 terminal follows the signal output by the sensor. When IN2 obtains the judgment signal, I The N2 signal is fed back to the positive pole of the switch S1, and the switch S1 switches the path. At the same time, the field effect tube Q3 is turned off, and the capacitor C1 stops charging and discharging. The signal at the IN1 end passes through the diode D2 and the resistor R4 to the ground end. The resistance value of the resistor R4 end is set to be higher than the resistance value of the resistor R3 end. The signal at the capacitor C1 end is fed back to the inverting end of the operational amplifier U4, and the signal at the resistor R4 end is fed back to the non-inverting end of the operational amplifier U4. If the sensor output signal is a current signal, when IN2 obtains the signal feedback, the signal at the resistor R4 end is higher than the signal at the capacitor C1 end, and the operational amplifier U4 is in the output state. If the sensor output signal is a voltage signal, when IN2 obtains the signal feedback, the voltage drop of the IN1 end signal after passing through the diode D2 makes the signal at the resistor R4 end lower than the signal at the capacitor C1 end, and the operational amplifier U4 is in the cut-off state. The signal at the output end of the operational amplifier U4 is the measurement signal. When the output end of the operational amplifier U4 outputs, it is determined that the current sensor output signal is a current signal, otherwise it is determined as a voltage signal. In this way, the signal type of the sensor is automatically identified and the corresponding feedback is provided after identification.

[0030] IN3 receives the measurement signal, and the measurement signal is fed back to pin 3 of the trigger U1. Resistor R7 is the pull-down resistor of pin 3 of the trigger U1. In the initial state, when IN3 does not obtain the measurement signal, pin 5 of the trigger U1 is low level, pin 6 of the trigger U1 is low level, and resistor R9 is the pull-down resistor of pin 6 of the trigger U1. When IN3 obtains the measurement signal, the levels of pin 5 of the trigger U1 and pin 6 of the trigger U1 are swapped, pin 5 of the trigger U1 is high level, and pin 6 of the trigger U1 is low level. The reference signal is input to the inverting terminal of the operational amplifier U2, and the power supply signal is connected to the ground terminal through resistors R10 and R8. The reference signal The signal is fed back by the resistor R8 or input by the power supply, and the 5-pin of the trigger U1 is fed back to the inverting terminal of the operational amplifier U2. When the trigger U1 outputs the 5-pin high level, the operational amplifier U2 is cut off, and the output signal of the operational amplifier U2 is fed back to the gate of the field effect tube Q1. The resistor R2 is used to discharge the parasitic capacitance of the gate of the field effect tube Q1. The field effect tube Q1 is turned on, and the voltage difference between the gate of the field effect tube Q1 and the source of the field effect tube Q1 is lower than the turn-on threshold. The 3-pin terminal signal of the trigger U1 passes through the source of the field effect tube Q1 and the drain of the field effect tube Q1 to the ground terminal. When the field effect tube Q1 is turned on, the 3-pin terminal of the limit trigger U1 obtains a high level signal again, and the reset signal is generated by the upper Circuit or manual feedback, the power signal is fed back to the collector of transistor Q2 through resistor R1, and IN4 receives the reset signal. When IN4 obtains 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, and transistor Q2 is turned on. The 1-pin end signal of trigger U1 passes through the collector of transistor Q2 and the emitter of transistor Q2 to the ground terminal, and the 1-pin end signal of trigger U1 is pulled to the ground potential, and trigger U1 is reset. The 5-pin end signal of trigger U1 is low level, the 6-pin end signal of trigger U1 is high level, the op amp U2 outputs, the field effect transistor Q1 is cut off, and the 5-pin end signal of trigger U1 The signal at the 6-pin end of the trigger U1 is a channel switching signal. The channel switching signal is used to switch the signal channel of the sensor output end. A first processing unit and a second processing unit are set in the circuit. If the sensor output signal is a voltage signal, the sensor signal is output to the second processing unit, and the second processing unit performs differential amplification and filtering on it and then feeds it back to the lower-level circuit. If the electrical sensor output signal is a current signal, the sensor signal is output to the first processing unit, and 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.

[0031] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be encompassed therein. Any reference in a claim should not be construed as limiting the claim to which it relates.

Claims

1. A front-end circuit, characterized in that: The system comprises a plurality of operational amplifiers, a plurality of diodes, a plurality of resistors, a field effect transistor, a switching switch, and a capacitor. The operational amplifier U3 in the plurality of operational amplifiers is connected to the first connection end of the switching switch S1 and one end of the resistor R3 at the same phase, the cathode of the diode D1, one end of the capacitor C1, the source of the field effect transistor Q3, and the inverting end of the operational amplifier U4 at the opposite phase, and the output end is connected to the anode of the diode D1; the operational amplifier U4 is connected to the cathode of the diode D2 and one end of the resistor R4 at the same phase, and the output end is connected to the OUT3 end; the drain of the field effect transistor Q3 is connected to one end of the resistor R5, and the gate and the positive pole of the switching switch S1 are connected to the IN2 end; the common end of the switching switch S1 is connected to the IN1 end, and the second connection end is connected to the anode of the diode D2; the cathode of the switching switch S1, the other end of the resistor R3, the other end of the resistor R4, the other end of the resistor R5, and the other end of the capacitor C1 are grounded; IN1 inputs the sensor signal, which is fed back by the sensor. A judgment unit is set in the circuit, and IN2 inputs the judgment signal, which is input by the judgment unit. The judgment unit judges whether the IN1 end obtains the sensor signal, and feeds back a judgment signal to IN2 after obtaining it. When IN2 does not obtain the judgment signal, the IN1 end signal passes through S1 and R3 to the ground end. When IN2 obtains the judgment signal, the IN2 signal is fed back to the positive pole of S1, and S1 switches the path.

2. The front-end circuit according to claim 1, wherein: It also includes a trigger, a field-effect transistor, a transistor, an operational amplifier, and several resistors. The first pin of the trigger U1 is connected to one end of the resistor R1 and the collector of the transistor Q2, the second pin, the sixth pin, and one end of the resistor R9 are connected to the OUT6 end, the third pin, the source of the field-effect transistor Q1, and one end of the resistor R7 are connected to the IN3 end, the fourth pin and the other end of the resistor R1 are connected to the power supply, and the fifth pin and the inverting end of the operational amplifier U2 are connected to the OUT5 end; the reference signal is input to the non-inverting end of the operational amplifier U2; the gate of the field-effect transistor Q1 is connected to the output end of the operational amplifier U2; one end of the resistor R15 is connected to the base of the transistor Q2, and the other end is connected to the IN4 end; the drain of the field-effect transistor Q1, the emitter of the transistor Q2, the other end of the resistor R7, and the other end of the resistor R9 are grounded; IN3 receives a measurement signal, and IN4 receives a reset signal.

3. The front-end circuit according to claim 2, wherein: A resistor is also included. One end of the resistor R2 is connected to the gate of the field effect tube Q1, and the other end is grounded.

4. The front-end circuit according to claim 2, wherein: The system further includes a plurality of resistors, wherein one end of the resistor R10 is connected to the power supply, and the other end is connected to one end of the resistor R8 and the non-inverting end of the operational amplifier U2; the other end of the resistor R8 is grounded.

5. The front-end circuit according to claim 1, wherein: A resistor is also included, one end of the resistor R6 is connected to the gate of the field effect tube Q3, and the other end is grounded.

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