A sensor simulator circuit with freely settable bridge input resistance

Abstract

This invention provides a sensor simulator circuit with freely adjustable bridge input resistance. The non-inverting input of operational amplifier A1 is connected to the power supply terminal E+, and the inverting input is connected to the output of operational amplifier A1. The output is also connected to one end of the bridge input resistance adjuster R10. The non-inverting input of I / V converter A3 is connected to the power supply terminal E+, and the inverting input is connected to the collector of transistor Q1. The output is connected to the inverting input of I / V converter A2. The non-inverting input of V / I converter A2 is connected to the adjustable terminal of the bridge input resistance adjuster R10, and the output is connected to the base of transistor Q1. Its advantages include a simple and reliable circuit structure, reduced use of precision resistors in the bridge circuit, elimination of the effect of potentiometer temperature drift on the bridge input resistance, and continuous and precise adjustment of the bridge input resistance.

Description

Technical Field

[0001] This invention relates to a sensor simulator circuit. Background Technology

[0002] Existing sensor simulator circuits using the single Wheatstone bridge principle have input resistances determined by the bridge arm resistors and external circuitry, making them unadjustable. Current bridge-type sensor simulators can only provide a single bridge input resistance, or use band switches to switch between bridges with different input resistances. This requires numerous precision resistors and a long-term stable switching switch, resulting in complex circuitry, high cost, and impacting output signal stability. The existing method of directly connecting an adjustable resistor in parallel across the bridge excitation voltage introduces temperature drift and long-term stability issues. Summary of the Invention

[0003] This invention provides a sensor simulator circuit with freely adjustable bridge input resistance. The circuit structure is simple and reliable, reducing the number of precision resistors used in the bridge circuit; eliminating the influence of potentiometer temperature drift on the bridge input resistance; allowing continuous and precise adjustment of the bridge input resistance; and eliminating the bridge switching switch that causes circuit instability, thus overcoming the shortcomings of the prior art.

[0004] This invention provides a sensor simulator circuit with freely adjustable bridge input resistance, comprising: operational amplifier A1, bridge input resistance adjuster R10, I / V converter A3, V / I converter A2, transistor Q1, bridge circuit, coupling resistor R5, operational amplifier A4, and simulator output voltage adjuster R20; the non-inverting input terminal of operational amplifier A1 is connected to the power supply terminal E+, and the inverting input terminal is connected to the output terminal of operational amplifier A1; the output terminal of operational amplifier A1 is also connected to one end of bridge input resistance adjuster R10; the other end of bridge input resistance adjuster R10 is connected to power supply terminal E-; the non-inverting input terminal of I / V converter A3 is connected to the power supply terminal E+, the inverting input terminal is connected to the collector of transistor Q1, and the output terminal is connected to the inverting input terminal of I / V converter A2; the non-inverting input terminal of V / I converter A2 is connected to the bridge input resistance adjuster R20. The adjustable terminal of resistor regulator R10 is connected, and its output terminal is connected to the base of transistor Q1; the collector of transistor Q1 is also connected to the first terminal of the bridge circuit; the emitter of transistor Q1 is connected to the power supply terminal E-; the first terminal of the bridge circuit is connected to the collector of transistor Q1, the second terminal of the bridge circuit is connected to the power supply terminal E-, the third terminal of the bridge circuit is connected to the simulator bridge signal output terminal S+; the fourth terminal of the bridge circuit is connected to the simulator bridge signal output terminal S-; one end of simulator output voltage regulator R20 is connected to the output terminal of operational amplifier A1, and the other end is connected to the power supply terminal E-; the non-inverting input terminal of operational amplifier A4 is connected to the adjustable terminal of simulator output voltage regulator R20, the inverting input terminal is connected to the output terminal of operational amplifier A4, and the output terminal is connected to one end of coupling resistor R5; the other end of coupling resistor R5 is connected to the third terminal of the bridge circuit.

[0005] Furthermore, the present invention provides a sensor simulator circuit with freely adjustable bridge input resistance, which may also have the following features: the bridge circuit includes: bridge arm resistors R1, R2, isolation resistors R3 and R4; one end of bridge arm resistor R1 is connected to the collector of transistor Q1 as the first terminal of the bridge circuit, and the other end is connected to one end of bridge arm resistors R2, R3, and R4 respectively; the other end of bridge arm resistor R2 is connected to the power supply terminal E- as the second terminal of the bridge circuit; the other end of isolation resistor R3 is connected to the simulator bridge signal output terminal S+ as the third terminal of the bridge circuit; the other end of isolation resistor R4 is connected to the simulator bridge signal output terminal S- as the fourth terminal of the bridge circuit.

[0006] Furthermore, the present invention provides a sensor simulator circuit with freely adjustable bridge input resistance, which may also have the following features: it further includes a balancing resistor R6; one end of the balancing resistor R6 is connected to the other end of the bridge arm resistor R2, and the other end is connected to the other end of the isolation resistor R4.

[0007] Furthermore, the present invention provides a sensor simulator circuit with freely adjustable bridge input resistance, which may also have the following features: it further includes a detection resistor Rs; one end of the detection resistor Rs is connected to the non-inverting input terminal of the I / V converter A3, and the other end is connected to the inverting input terminal of the I / V converter A3.

[0008] Furthermore, the present invention provides a sensor simulator circuit with freely adjustable bridge input resistance, which may also have the following feature: the bridge input resistance adjuster R10 adopts an adjustable resistor, a DAC, or a band switch.

[0009] Furthermore, the present invention provides a sensor simulator circuit with freely adjustable bridge input resistance, and may also have the following feature: the simulator output voltage regulator R20 adopts an adjustable resistor, a DAC, or a band switch.

[0010] This invention provides a sensor simulator circuit with freely adjustable bridge input resistance. It uses a single bridge, which reduces the use of precision resistors, lowers circuit complexity and cost, allows for continuous and precise adjustment of the bridge input resistance, avoids the effects of potentiometer temperature drift, improves the stability of the output signal, and eliminates the influence and limitations on the excitation voltage. Attached Figure Description

[0011] Figure 1 This is a circuit diagram of a sensor simulator with freely adjustable bridge input resistance, as shown in the embodiment. Detailed Implementation

[0012] The present invention will now be further described with reference to the accompanying drawings and specific embodiments.

[0013] Example

[0014] In this embodiment, the sensor simulator circuit with freely adjustable bridge input resistance includes: operational amplifier A1, bridge input resistance regulator R10, I / V converter A3, V / I converter A2, transistor Q1, bridge circuit, coupling resistor R5, operational amplifier A4, simulator output voltage regulator R20, balancing resistor R6, and detection resistor Rs.

[0015] The bridge circuit includes: bridge arm resistors R1, R2, isolation resistor R3, and isolation resistor R4. The sum of bridge arm resistors R1 and R2 ensures the maximum input resistance value of the simulator.

[0016] The non-inverting input of operational amplifier A1 is connected to the power supply terminal E+, and the inverting input is connected to the output of operational amplifier A1. The output of operational amplifier A1 is also connected to one end of the bridge input resistor regulator R10. The other end of the bridge input resistor regulator R10 is connected to the power supply terminal E-.

[0017] The non-inverting input of I / V converter A3 is connected to the power supply terminal E+, the inverting input is connected to the collector of transistor Q1, and the output is connected to the inverting input of I / V converter A2. The non-inverting input of I / V converter A2 is connected to the adjustable terminal of the bridge input resistor regulator R10, and the output is connected to the base of transistor Q1. The collector of transistor Q1 is also connected to the first terminal of the bridge circuit, i.e., to one end of the bridge arm resistor R1. The emitter of transistor Q1 is connected to the power supply terminal E-. One end of the sensing resistor Rs is connected to the non-inverting input of I / V converter A3, and the other end is connected to the inverting input of I / V converter A3.

[0018] One end of bridge arm resistor R1 serves as the first terminal of the bridge circuit, connected to the collector of transistor Q1. The other end is connected to one end of bridge arm resistors R2, R3, and R4, respectively. The other end of bridge arm resistor R2 serves as the second terminal of the bridge circuit, connected to the power supply terminal E-. The other end of isolation resistor R3 serves as the third terminal of the bridge circuit, connected to the simulator bridge signal output terminal S+. The other end of isolation resistor R4 serves as the fourth terminal of the bridge circuit, connected to the simulator bridge signal output terminal S-. One end of balancing resistor R6 is connected to the other end of bridge arm resistor R2, and the other end is connected to the other end of isolation resistor R4.

[0019] One end of the simulator output voltage regulator R20 is connected to the output of operational amplifier A1, and the other end is connected to the power supply terminal E-. The non-inverting input of operational amplifier A4 is connected to the adjustable terminal of the simulator output voltage regulator R20, the inverting input is connected to the output of operational amplifier A4, and the output is connected to one end of coupling resistor R5. The other end of coupling resistor R5 is connected to the third terminal of the bridge circuit, that is, to the other end of isolation resistor R3.

[0020] The sensor simulator circuit with freely adjustable bridge input resistance has a current detection resistor Rs connected in series in the excitation power supply circuit. The bridge current I1, corresponding to the bridge input resistance adjustment voltage V1, is accurately provided by I / V conversion and V / I conversion. Let ΔE = E+ - E-, then the basic bridge current I0 = ΔE / (R1 + R2), and the bridge input resistance Rin = ΔE / (I1 + I0). Therefore, controlling V1 can set the required Rin.

[0021] The simulator bridge signal output S+ of the sensor simulator circuit with freely adjustable bridge input resistance can be changed by inputting a voltage V2 through coupling resistor R5, thereby changing the bridge balance and making the simulator output a voltage signal that is linearly related to V2.

[0022] In this embodiment, the bridge input resistance regulator R10 and the simulator output voltage regulator R20 can be adjustable resistors, DACs, or band switches. All components in the sensor simulator circuit, where the bridge input resistance can be freely set, are independently powered.

[0023] The embodiments described above are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

Claims

1. A sensor simulator circuit with freely adjustable bridge input resistance, characterized in that: include: Operational amplifier A1, bridge input resistor regulator R10, I / V converter A3, V / I converter A2, transistor Q1, bridge circuit, coupling resistor R5, operational amplifier A4, simulator output voltage regulator R20; The non-inverting input of operational amplifier A1 is connected to the power supply terminal E+, and the inverting input is connected to the output of operational amplifier A1. The output of operational amplifier A1 is also connected to one end of the bridge input resistor regulator R10; the other end of the bridge input resistor regulator R10 is connected to the power supply terminal E-. The non-inverting input of I / V converter A3 is connected to the power supply terminal E+, the inverting input is connected to the collector of transistor Q1, and the output is connected to the inverting input of I / V converter A2; the non-inverting input of V / I converter A2 is connected to the adjustable terminal of bridge input resistor regulator R10, and the output is connected to the base of transistor Q1; the collector of transistor Q1 is also connected to the first terminal of the bridge circuit; the emitter of transistor Q1 is connected to the power supply terminal E-. The first terminal of the bridge circuit is connected to the collector of transistor Q1; the second terminal of the bridge circuit is connected to the power supply terminal E-; the third terminal of the bridge circuit is connected to the simulator bridge signal output terminal S+; and the fourth terminal of the bridge circuit is connected to the simulator bridge signal output terminal S-. One end of the simulator output voltage regulator R20 is connected to the output terminal of operational amplifier A1, and the other end is connected to the power supply terminal E-; the non-inverting input terminal of operational amplifier A4 is connected to the adjustable terminal of simulator output voltage regulator R20, the inverting input terminal is connected to the output terminal of operational amplifier A4, and the output terminal is connected to one end of coupling resistor R5; the other end of coupling resistor R5 is connected to the third terminal of the bridge circuit.

2. The sensor simulator circuit with freely adjustable bridge input resistance as described in claim 1, characterized in that: in, The bridge circuit includes: bridge arm resistor R1, bridge arm resistor R2, isolation resistor R3, and isolation resistor R4; One end of bridge arm resistor R1 is connected to the collector of transistor Q1 as the first terminal of the bridge circuit, and the other end is connected to one end of bridge arm resistor R2, isolation resistor R3, and isolation resistor R4 respectively; the other end of bridge arm resistor R2 is connected to the power supply terminal E- as the second terminal of the bridge circuit; the other end of isolation resistor R3 is connected to the simulator bridge signal output terminal S+ as the third terminal of the bridge circuit; and the other end of isolation resistor R4 is connected to the simulator bridge signal output terminal S- as the fourth terminal of the bridge circuit.

3. The sensor simulator circuit with freely adjustable bridge input resistance as described in claim 1, characterized in that: It also includes the balancing resistor R6; One end of the balancing resistor R6 is connected to the other end of the bridge arm resistor R2, and the other end is connected to the other end of the isolation resistor R4.

4. The sensor simulator circuit with freely adjustable bridge input resistance as described in claim 1, characterized in that: It also includes the sensing resistor Rs; One end of the sensing resistor Rs is connected to the non-inverting input of the I / V converter A3, and the other end is connected to the inverting input of the I / V converter A3.

5. The sensor simulator circuit with freely adjustable bridge input resistance as described in claim 1, characterized in that: in, The bridge input resistance regulator R10 can be an adjustable resistor, a DAC, or a band switch.

6. The sensor simulator circuit with freely adjustable bridge input resistance as described in claim 1, characterized in that: in, The simulator output voltage regulator R20 uses an adjustable resistor, a DAC, or a band switch.

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