CN203872147U - High-precision grouting data acquisition circuit - Google Patents

Abstract

The utility model discloses a high-precision grouting data acquisition circuit, which comprises a sensor on a grouting work site, an amplifying circuit, a filter circuit, an analog-to-digital conversion circuit and a central processing unit which are sequentially connected. The amplifier circuit is a differential amplifier circuit, and the filter circuit is a first-order switched capacitor filter circuit. The differential amplifier circuit has high input impedance, high common-mode rejection ratio and open-loop gain. It is very sensitive to tiny differential-mode voltage, and can amplify the weak analog signal sent by the sensor well, while effectively suppressing noise. The system is simple ,low cost. The first-order switched capacitor filter circuit, compared with the general-purpose RC low-pass filter circuit, uses a grounded capacitor C1 and an enhanced MOSFET T1, T2 that is used as a switch to replace the input resistor with interchangeable drain-source poles, and can obtain accurate maximum time Constant, suppressing the second and multiple harmonics, greatly improving the accuracy of data collection.

Description

A high-precision grouting data acquisition circuit

technical field

The utility model relates to a high-precision grouting data acquisition circuit, which belongs to the field of electronic circuits.

Background technique

In grouting construction, in order to improve work efficiency and project quality, it is necessary to measure and record control grouting pressure, flow, density and other data. In the process of measuring data, the signal output by the sensor (pressure, flow, density) is often weak, and it also contains common mode interference such as power frequency, electrostatic and electromagnetic coupling, so the analog signal output by the sensor must be amplified and filtered. The analog quantity is suitable for the voltage conversion range of the analog-to-digital converter, and then sent to the central processing unit for recording and processing control. Therefore, the amplifying circuit is required to have a high common-mode rejection ratio, high gain, low noise and high input impedance, and the filter circuit has an accurate large time constant to suppress the second and multiple harmonics to obtain accurate and effective data.

Utility model content

The technical problem to be solved by the utility model is to provide a high-precision grouting data acquisition circuit, including a differential amplifier circuit, which has high input impedance, high common-mode rejection ratio and open-loop gain, is sensitive to tiny differential-mode voltages, and It is suitable for measuring signals transmitted over long distances. It can amplify the weak analog signals sent by the sensor well, and at the same time effectively suppress noise. The system is simple and the cost is low. At the same time, it includes a first-order switched capacitor filter circuit. Compared with the general-purpose RC low-pass filter circuit, a grounded capacitor C1 and an enhanced MOSFET T1 and T2 used as a switch with interchangeable drain-source poles instead of the input resistor can obtain accurate The large time constant can suppress the second and multiple harmonics, which greatly improves the accuracy of data collection.

The technical scheme that the utility model adopts for solving the problems of the technologies described above is:

A high-precision grouting data acquisition circuit includes a sensor on a grouting work site, an amplification circuit, a filter circuit, an analog-to-digital conversion circuit and a central processing unit connected in sequence. The amplifying circuit is a differential amplifier circuit, comprising three operational amplifiers A1, A2 and A3, the operational amplifiers A1 and A2 form an in-phase parallel differential operational amplifier, the in-phase input of the operational amplifier A1 is connected to the signal output of the sensor, and the operational amplifier The input end of A2 is grounded, and the output end of the in-phase parallel differential operational amplifier is connected to operational amplifier A3, and operational amplifier A3 is used as a differential follower. The filter circuit is a first-order switched capacitor filter circuit, including two enhanced MOSFETs T1, T2, two interchangeable drain-source poles used as switches, two grounding capacitors C1, C2 and a voltage follower A4; MOSFET T1, Ground capacitor C1, MOSFET T2, ground capacitor C2, and voltage follower A4 are connected in sequence.

Beneficial effect

The high-precision grouting data acquisition circuit of the utility model includes a differential amplifier circuit, which has high input impedance, high common-mode rejection ratio and open-loop gain, is sensitive to tiny differential-mode voltage, and is suitable for measuring long-distance transmission The signal can amplify the weak analog signal sent by the sensor well, and at the same time effectively suppress the noise. The system is simple and the cost is low. At the same time, the filter circuit is a first-order switched capacitor filter circuit. Compared with the general RC low-pass filter circuit, a grounded capacitor C1 and an enhanced MOSFET T1 and T2 used as a switch with interchangeable drain and source poles instead of the input resistor can be used. Accurate large time constants are obtained, the second and multiple harmonics are suppressed, and the accuracy of data collection is greatly improved.

Description of drawings

Fig. 1 is the overall principle block diagram of the utility model high-precision grouting data acquisition circuit.

Detailed ways

Below in conjunction with accompanying drawing and specific embodiment the utility model is further described.

Example 1:

As shown in Figure 1, a high-precision grouting data acquisition circuit includes sensors, amplifier circuits, filter circuits, analog-to-digital conversion circuits and a central processing unit connected in sequence on the grouting job site.

The amplifier circuit is a differential amplifier circuit, including three operational amplifiers A1, A2 and A3. The operational amplifiers A1 and A2 form an in-phase parallel differential operational amplifier. The in-phase input terminal of the operational amplifier A1 is connected to the signal output terminal of the sensor, and the operational amplifier A2 The input end is grounded, and the output end of the in-phase parallel differential operational amplifier is connected to the operational amplifier A3, and the operational amplifier A3 is used as a differential follower. The three operational amplifiers A1, A2 and A3 can use the general-purpose instrumentation single-chip amplifier ad522 produced by ad company. ad522 can be mainly used in occasions requiring high-precision data acquisition in harsh environments, with low voltage drift, low nonlinearity, high common Mode rejection ratio, low noise, low offset voltage and so on. The differential amplifier circuit adopts a symmetrical circuit structure, and the signal sent by the sensor is directly added to the input terminal, so it has a strong ability to suppress common-mode signals, and has high input impedance, high common-mode rejection ratio and open-loop gain. It can amplify the weak analog signal sent by the sensor very well, and at the same time add the resistance Rf, Rf1, Rf2, Rw, R, R1 of the feedback loop, input loop and output loop. The amplification factor of the amplifier circuit is: The magnification can be adjusted by adjusting the size of the resistor Rw, and noise can be effectively suppressed at the same time, the system is simple and the cost is low.

The filter circuit in the utility model is a first-order switched capacitor filter circuit, including two enhanced MOSFETs T1 and T2, two interchangeable drain-source poles used as switches, two grounding capacitors C1, C2 and a voltage follower A4, MOSFET T1, ground capacitor C1, MOSFET T2, ground capacitor C2, and voltage follower A4 are connected in sequence. The voltage follower A4 isolates the filter circuit from the load very well, has high input impedance and low output impedance, so it has a strong load carrying capacity. Compared with the general-purpose RC low-pass filter circuit, this first-order switched capacitor filter circuit uses a grounded capacitor C1 and an enhanced MOSFET T1 and T2 that are interchangeable between the drain and source poles of the switch instead of the input resistor R. The switched capacitor filter circuit is in The input signal is sampled once every clock cycle. The time constant that affects the frequency response of the filter depends on the clock cycle and the capacitance ratio C2/C1. In the RC filter circuit, a large capacitance and an accurate RC time constant are required. It is difficult to manufacture integrated components on the chip, and even it is not Possibly, in the MOS process, the accuracy of the capacitance ratio can be controlled within 0.1%. Therefore, using the unique advantages of MOS devices in terms of speed, integration, relative precision control and micro power consumption, the size of the module can be reduced while obtaining accurate The large time constant can suppress the second and multiple harmonics, which greatly improves the accuracy of data collection.

Claims (1)

1. a high accuracy grouting data acquisition circuit, is characterized by, and comprises transducer, amplifying circuit, filter circuit, analog to digital conversion circuit and central processing unit on the grouting operation building site connecting successively;

Described amplifying circuit is differential amplifier circuit, comprise three operational amplifier A 1, A2 and A3, operational amplifier A 1, A2 composition are with being in parallel differential operational amplifier, the signal output part of the in-phase input end connecting sensor of operational amplifier A 1, the input end grounding of operational amplifier A 2, with the output concatenation operation amplifier A3 of the differential operational amplifier that is in parallel, operational amplifier A 3 is as differential follower;

Described filter circuit is single order switch-capacitor filtering circuit, comprises two the interchangeable enhancement mode MOSFET T1 in drain-source the two poles of the earth, T2, two ground capacity C1, C2 and voltage follower A4 as switch; MOSFET T1, ground capacity C1, MOSFET T2, ground capacity C2, voltage follower A4 connect successively.