The Integrated Operational Amplifier Parameter Measurement Instrument Based On Virtual Instrument

What is called virtual instrument, in fact it is automatic measurementsystem based on computer. The text has designed the modernized test meansof the intelligent parameter measurement system based on virtual instrument.The intelligent parameter measurement instrument based on Labview isdesigned in the paper. This system is composed by the integration operationalamplifier parameter measurement module, the sinusoidal wave signalgenerator, data gather module, embedded AVR control and virtual instrument.The parameter measurement circuit is made up of national standard circuit.The signal generator adopts the new direct digital frequency synthetictechnology (DDS) which has some advantages such as bandwidth is widerrelative, frequency conversion time is short, frequency resolution ratio is high,phase place change serially and the output waveform is flexible. The dataacquisition module with serial port is used in data acquisition part which maytransmit the data with the computer directly though serial port. EmbeddedAVR realize the DDS frequency transformation and the measurement circuitcontrol. Through the program that is designed by Labview software platformcan realize the functions of the DDS control, test board control, datacalculation, data waveform display, data acquisition and data print.The signal source adopts DDS integrated chip AD9831, through AVRone-chip computer controls time sequence, write the established frequencyvalue into the chip, can produce the necessary sinusoidal wave signal. Datagather module implement the examined signal do filter wave, amplify, A/Dchange and send conversion figure amount into the computer. Control moduleadopt the AVR series of Mega16 one-chip computer , it has many advantagessuch as fast speed,abundant slice resource, fine privacy, wide range ofworking voltage, low power dissipation etc, so it can complete test and controldata conveniently, and realize the communications between the computer andseries port.Labview is a development environment of integrated procedure based on"figure"way, it is used for measures and controls the instrument or thepackage of system, the whole man-machine interface should have a good testenvironment in a friendly way. The G language of the virtual instrument issimple and easy to study in programming, the procedure revises easily, mutualability is strong and has many functions such as abundant functions, numbervalue analysis, signal dealing and so on . Labview is the first choice to modernmeasurement system..The series port 2 is used for communicating between computer and AVRmodule , The series port 1 is used for sending data which gathered by the datagather module to computer. After the series port 2 passed test, the series port 1will be opened, the program enters the respond area of the button messages.After pushing exit button, the procedure will stop.Use Labview programming, can reduce the error and improve thestability of the data through the following means:(1)The software filter wave: Through the algorithm of middle filter wave,obtain 5 times measurement data, then get the average, which can raisestability degree of the data.(2)Utilize the strong floating-point operation function of the computer,the computer can realize calculated accurately the physical quantity, itsoperation is fast and accurate.(3) The Labview procedure can get unit of voltage examined, discern theswitch of unit of mV and V of the data gather module by the judging of testrange, further improve the accuracy of the data.The integrated operational amplifier parameter measurement instrumentuse Labview as the core control software, it constructs the system of datameasurement and control based on computer. The experimental resultsindicate the test precision and stability of the instrument are relatively highand the man-machine interface is friendly.