Research And Design Of CMOS Operational Transconductance Amplifier And Its Application In Filter

Since integrated circuits came out half-century ago，they bring great influence onour daily life. The fully integrated continuous-time filter is discussed in this thesisand is a advanced and valuable field. The continuous-time filters have been adoptedin many fields such as communication, navigation, medical examination and signalprocessing. Analog filter is an essential block of analog integrated circuits．Thedesign approach for analog filters can be widely adopted in large-scale integratedcircuit, which is of significant application value. From architecture，it can be splitinto two categories: one is MOSFET-C filter; the other is OTA-C filter. It adoptsOTA (Operational Transconductance Amplifier) as its component，not traditionaloperational amplifier．It constructs current-control system，which has the advantagesof high-frequency and convenient tuning. The design principle, method andrealization circuit of the CMOS OTA and its application in OTA-C filter had beenstudied in this thesis. The main contents are as follows:A low power wide linear range OTA is presented based on comprehensivesummary on the circuit of OTA about application, it adopts cascode structure asinput stage, negative current feedback is used to enhance the linearity, them currentmirror is adopted as output stage, thus the proposed structure is of great linearity andlow power consumption. At last, the circuit is simulated by Cadence with0.18μmtechnology in order to verify the reliability.Having compared the design approaches of OTA-C filters such as the signal flowgraphics method and passive LC ladder type modeling method, the method that thecircuit of OTA about application is used as passive element is adopted to realize anOTA-C filter which has low power and good linearity. A third-order elliptic OTA-Cfilter has been realized and simulated by Cadence with0.18μm technology in orderto indicate that this filter is feasible.