A comparative study on low noise precision difet operational amplifier and low noise operational amplifier for potentiometric transduction circuit

摘要

This paper presents a comparative study on low noise precision difet operational amplifier, OPA111 and low noise operational amplifier, OP27 for potentiometric transduction circuit. Methods for integration of piezoresistive MEMS sensor with the potentiometric transduction circuit have reported successes. There was a need for a low noise operational amplifier for amplifying the output from the piezoresistive MEMS sensor since noise is the main problem in the circuit design. The purpose of this project is to reduce the noise effect by comparing two types of operational amplifier. The purpose of the design involved the piezoresistive MEMS sensing with the potentiometric transduction circuit. Since the sensor input range of 1.1 to 1.3 kilo ohms, the potentiometric transduction circuit designed enables the small changes in the resistivity. The circuit has been designed and test through theoretical, simulation and experimental studies. From the experiment, for the sensor input range, an output range of −0.108 to +0.1 volts is obtained. The percentages discrepancy within 4.278% for low noise precision difet operational amplifier, OPA111 and 8.308% low noise operational amplifier, OP27 is found between theoretical and hardware results, on the average. The null bridge condition is designed at 1.2 kilo ohms with the discrepancy of 5.71% is detected.