To improve the resolving limit of a micromachined gyroscope,a sensing interface model for the micromachined gyroscope fabricated by Silicon on Insulator(SOI) process was established,and a matching front-end was designed.Firstly,a RC lumped parameter model for the gyroscope was established based on the practical gyroscope structure,then a noise model for the sensing interface was built.The dominant noise source and methods to improve the resolving limit were analyzed.Finally,on the foundation of a TIA front-end,an improved T-network front-end was designed to match the sensing interface.Experimental results indicate that the T-network front-end improves the sensing interface equivalent input noise current from 1.18 pA/√Hz to 0.27 pA/√Hz,corresponding to a capacitive resolution of 0.62 aF/√Hz as compared to those of the transimpedance front-end.It suggests that the improved T-network front-end can reach a better resolution.%为了进一步提高微机械陀螺的极限分辨率,建立了基于SOI工艺的微机械陀螺的检测接口模型,并设计了与之相匹配的前置接口放大器.首先,根据陀螺表头的实际结构建立了微机械陀螺表头的RC集总参数模型和微机械陀螺检测接口的噪声模型,分析了检测接口主导噪声源及提高极限分辨率的措施.然后,在跨阻式前置放大器的基础上设计了改进的与检测接口匹配的T型前置放大器.实验结果表明:相比于跨阻式前置放大器,采用改进的T型前置放大器的等效噪声输入电流由1.18 pA/√Hz降低至0.27 pA/√Hz,对应的电容极限分辨率可达到0.62 aF/√Hz.结果显示,采用与检测接口匹配的T型前置放大器提高了微机械陀螺的极限分辨率.
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