Design Of SiC Based CMOS Operational Amplifiers

Silicon carbide(Si C)has wide band gap and quite high thermal conductivity,and can work well at high temperature.Si C-based high-temperature operational amplifiers(op amp)can reduce the wiring complexity and enhance the anti-interference capability of the circuit system,and have important applications in the fields of petrole?m exploration and aerospace.However,the present Si C op amps usually show unsatisfactory open loop gain and gain-bandwidth product,and a maxim?m operation temperature not higher than 300 ?.Meanwhile,they are mostly fabricated by the bipolar process rather than the complementary-metal-oxide-semiconductor(CMOS)process.In view of this research status,this thesis proposes a design scheme of Si C CMOS op amp with high temperature tolerance.On the basis of the design of large open-loop gain and high frequency stability,the design mainly focuses on how to increase the work temperature of the Si C op amp.On the one hand,it is proposed to use MOSFETs with off-state-source-drain reverse saturation current matched to achieve neutralization of the mismatch current generated at high temperature,and reduce the output voltage drift of the op amp at high temperature.On the other hand,the zero temperature coefficient point(ZTCP)of the Si C op amp is sought based on the ZTCP theory,and the bias point of the op amp is stabilized at the ZTCP to enhance the stability of op amp at high temperature.The layout of the proposed Si C CMOS op amp structure is designed and the performance is simulated.The results show that the circuit design of the Si C op amp proposed in this thesis has alleviated the low output gain caused by low hole mobility to some degree.The expected performances are an open loop gain exceeding 65 d B,a gain bandwidth product reaching 500 k Hz,and a maxim?m temperature tolerance over350 ?.The feasibility of Si C as an integrated circuit material is preliminarily explored,that provides support for the development of the third generation wide band gap semiconductor materials.