| Summary: | 碩士 === 中原大學 === 電子工程學系 === 87 === A variable gain instrumentation amplifier (IA) has been designed in this thesis. Buffered two-stage operational amplifier and poly resistors construct the core of the instrumentation amplifier. In order to obtain good amplifier performance, the circuit configuration of the IA and its output stage, the offset and noise effects have been analyzed and investigated in this thesis. We also present key layout methods such as common-centroid structure, dummy device and guard-ring option for differential input transistor pair, compensated capacitor and poly resistors. Full custom design flow has been used in the instrumentation amplifier design. The circuit has been integrated in a 0.5mm double poly double metal n-well CMOS process.
In this research, several characterization methods have been developed to measure instrumentation amplifier. In order to assure the measurements, the commercial IA device has been also tested in this research. The test results show that the proposed IA has a variable gain of 0 dB to 40dB and a common-mode rejection ratio (CMRR) of more than 85dB. The minimum input offset voltage of less than 1mV has been measured. The amplifier has an acceptable die size of 810×400mm2 and its power consumption is 13mW at 5V operation.
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