| Summary: | 碩士 === 中原大學 === 電子工程研究所 === 91 === The reliability, stability and linearity of the sensor signal readout are greatly improved by using the sensor array configuration. With the advantages of small size, reliability, rapid time response, compatible with standard CMOS technology and on-chip signal processing, ISFET based transducers become more important applications in physiological data acquisition and environment monitoring. Therefore, to develop an automatic data acquisition systems on multiple ISFETs become more valuable and important.
The objective of this paper presents the design and implementation of a multi-channel bridge-type floating source circuit with self-developed rail-to-rail op amp for H+ sensing applications. The design concerns were focused on self-developed ASICs, multi-channel bridge-type floating source readout circuit, and the automatic data acquisition system with virtual instrument LabVIEW. This architecture shows that all ISFETs are under operation, but only one reference electrode is used.
The proposed rail-to-rail op amplifier has been fabricated in UMC 0.5μm double-poly double-metal CMOS technology. Experimental results show with a 5V power supply, the rail-to rail operational amplifier presents a DC gain of 93dB, power dissipation of 7.45mW, offset voltage of 4.1mV and rail-to-rail common-mode input voltage range and voltage output swing.
Furthermore, the multi-channel bridge-type floating source configuration built by the proposed rail-to-rail amplifier can perform to collect and calibrate the signal by using LabVIEW, and the measured data are a statistical material in computer. The measured data including drift, sensitivity and hysteresis are satisfied with the sensor characteristics. In a word, the proposed system has the good capability in bio-chemical applications.
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