This instrumentation amplifier is composed of three OA27P integrated operational amplifiers, OA27P features low noise, high speed, low input offset voltage and excellent common mode suppression ratio. The meter amplifier circuit is connected to a proportional arithmetic circuit, in which the first two op amps constitute the first stage, both are in the same phase input form, therefore has a high input resistance. Due to the structural symmetry of the circuit, their drift and disorders have a mutual offset. The latter op amp forms a differential amplifier and converts differential input into single-ended output. After calculation, the voltage amplification of the instrument amplifier in this design is au = R5 / R3 (1 + 2R1 / R2) = 100, and the results will be verified in the simulation. The structural characteristics of the instrument amplifier: make the instrument amplifier become a high input resistance, high co-model suppression ratio, with lower offset voltage, offset current, noise, and fluning amplifier. At the time of use, the four resistors of R4, R5, R6, and R7 are precisely and matched in FIG. Otherwise, otherwise the magnification will be paid to the zoomal multiple, and the common mode suppression ratio of the circuit will be reduced.
I. Instrumentation Amplifier Circuit Diagram This design uses the Prote199SE circuit simulation software, which can automatically generate a printed circuit board after drawing the electrical schematic. Circuit simulation can also be performed. Special attention to the packaging form of various components when drawing the electrical schematic. This is also one of the key to the successful automatic wiring. The packages of each component in this design are as follows: Resistance (AXIAL0.3), electrolytic capacitance (RB.2 / .4), porcelain capacitor (RAD0.1), integrated circuit (DIP-8), triple stable block (TO-220). The circuit diagram of the instrument amplifier is shown in Figure 1. R8 in the figure is added when the electrical examination is applied, and it is not installed when the actual production is active. Be
Second, the electrical material drawing is designed with the printed plate diagram. Enter the Prote199se SCH interface to draw the electrical schematic; Tool-ERC), it can generate a network table (Design-Great Netlist). 2, enter the Prote199se PCB interface, draw the printing plan. First determine the peripheral size: length 50mm, width 25mm. And require the outer frame to ground and cannot be closed as shown in Figure 2. Then load into the network table (Design-load Nets), reasonably fabricate all components to the printing board. Options-Rules). The most basic three points: line width, line spacing, and layers. This design uses a single panel. The parameter setting is complete. You can perform an automatic wiring command (Auto Routs-all). Design Result: Figure 2 is a printed plate diagram (ratio: 1: 1), Figure 3 is a component distribution map (ratio 2: 1). Be
Three Instrument Amplifier Circuit Principle Simulation 1. Simulation steps are as follows: (1) Add Simulation Library (2) Select the desired components from the simulation component library. Connect the schematic. Plus the excitation source, set the parameters. As shown 4. Note: 1R8, C1, C2, C3, C4, U4, U5 may not be connected; 2 Set the VCC to + 15V.vee set to -15V; 3VCC, VEE power supply to draw separately. (3) Execute the simulate-setup command to join the signal input1, input2, and output you need to analyze, and then execute the Simulate-Run command. You can see the set simulation waveform diagram. For example, Figure 5, Figure 6, Figure 7. 2, the simulation results analysis (1) Output voltage Voul = 100 (Vin1 + Vin2); (2) When the input signal frequency is about 50 kHz. The output signal begins distortion; (3) The low frequency response of this instrument is very good, when input When the signal frequency is 1 Hz, the output signal is still unhappy.
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