| The operational amplifier (op amp) is a fundamental building block in analog integrated circuit design. For low power-supply voltages, the common-mode input voltage and the output voltage of op amps are always required to be able to swing from the negative power-supply rail to the positive power-supply rail, i.e., rail-to-rail. In this dissertation, op amps with rail-to-rail input and output capability are investigated. This dissertation mainly focuses on the rail-to-rail input stage design. Two different rail-to-rail input stages with a single differential pair and a common-mode adapter are presented. The common-mode adapter is used to shift the common-mode input voltage. Two new common-mode adapters for the input stage with a single differential pair are developed. The first common-mode adapter is based on a pseudo-differential pair, and the second one is based on current subtraction. Three bipolar and two CMOS op amps with rail-to-rail input and output capability are designed. The circuit simulation and chip test results are given in this dissertation. There are many aspects of performance for op amps. With different topologies, op amps may have different performance. One certain op amp may be good at some aspects but poor at others. The General System Performance Theory is a systematic method for system performance analysis. In order to get a single figure of merit, the General System Performance Theory is applied to compare the overall performance of the designed three different bipolar rail-to-rail op amps. |
