A Signal Conditioning Circuit Design of a Differential Dynamic Displacement Sensor Chip
A signal conditioning circuit for a linear variable dynamic displacement sensor(LVDT)is designed,which is used to process the sub-border output signal of the LVDT and outputs a DC voltage of the iron core displacement.It is mainly composed of demodulation circuit,division circuit and amplifier.The LVDT secondary output is two complementary sine wave signals,which direct drives the signal conditioning circuit.The signal conditioning circuit uses a unique ratio architecture,which obtains the ratio of the difference and the sum of two voltage values,so it is not necessary for the LVDT primary excitation signal to make the voltage amplitude stable.At the same time,the phase shift of the LVDT primary and secondary coils and the interference voltage will not affect the function of the cir-cuit,effectively solving the problems of measurement precision and stability,and possessing better stability and performance advantages.The results of simulation verification and streaming tests show that the total error of the signal conditioning circuit is no bigger than 1.49%of FS,the linearity is no bigger than 0.05%,and the full range output voltage is no less than 10 V.All functional indicators meet the design requirements.
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