Based On Cmos Technology, High-performance Current-mode Instrumentation Amplifier Design

In many applications,Microsilicon acceleration sensor shows many advantages making it important to investigated its readout circuits. This paper aims at investigating and realizing an ASIC cell of high performance instrumentation amplifier based on the standard CMOS process, which is employed in the readout circuits of microsilicon sensor as a part of SOC.An instrumentation amplifier is a closed-loop gain block that has a differential input and an output that is single-ended with respect to a reference teminal. It must amplify the differential input acurately and suppress any unwanted common-mode signals. CMRR is the most important feature of instrumentation amplifier. The fact that most of these topologies need laser-trimming technique to improve the match precision to reach high CMRR is found after investigating several instrumentation amplifier topologies. In this paper, a new style instrumentation amplifier topology with current processing mode based on CCII and impedance amplifier is designed and realized. It does not need any matched components to reach high CMRR and its bandwidth is not gain-bandwidth product limited.In this paper, a high accuracy CCII and transimpedance amplifier are designed firstly because they have the main influence on the current mode instrumentation amplifier. The main research content about this two subcircuits are as follows:1. The precision and dynamic range of several typical current mirrors are discussed and an active input regulated-cascode output current mirror is adopted as the current duplicate circuits in CCII.2. The input stages of the CCII and the operational amplifier in transimpedance implifier are realized with folded cascode amplifier to reach high CMRR , large open loop gain and low offset.3. The output stage of transimpedance amplifier is realized with Rail-To-Rail topology to meet the requirement of output swing of the instrumentation amplifier.The simulation result shows that,the CMRR of current-mode instrumentation amplifier be able to reach 97dB, and the PSRR to 85dB.