电流模式的CMOS三轴霍尔磁传感器集成技术研究

CMOS Hall sensors have been widely used in automotive, industrial control, intelligent instrumentation and consumer electronics and other fields. The low-offset and high-sensitivity three-axis magnetic sensor based on deep submicron (DSM) CMOS vertical Hall technology has become an important development and research direction. Aiming at solving the serious problems, such as low magnetic sensitivity and high offset in the DSM three-axis Hall sensors, in this project, a current-mode fully symmetric Hall device and a current-mode signal conditioning circuit are used to study the integrated realization of three-axis Hall sensors. Specific research contents include: based on DSM standard CMOS process, current mode vertical Hall device with the symmetrical structure will be studied to obtain the design principle and the realization method for offset reduction and magnetic sensitivity improvement. The four-phase spinning current modulation and demodulation technique for symmetric Hall devices will be studied to develop a feasible method of lowering residual offset. The low power current-mode signal conditioning circuit technique will be also studied to realize the linear amplification of weak Hall current signal and the elimination of all kinds of offset and noise. Finally, the effective integration methods and solutions will be explored out to implement CMOS monolithic integrated three-axis Hall sensor. The study of this project is of great significance to enrich the research connotation of CMOS vertical Hall device design and offset elimination technology and promote the application of low-offset and high-reliability CMOS three-axis Hall sensors.

CMOS霍尔传感器已广泛应用在汽车、工业控制、智能仪表、消费类电子等领域，基于深亚微米CMOS垂直霍尔技术实现低成本、高灵敏度三轴磁传感器已成为重要的发展和研究方向。本项目针对该三轴霍尔传感器磁场灵敏度低、失调严重的问题，拟采用电流模式的全对称霍尔器件和信号调理电路来研究三轴霍尔传感器的集成实现。具体研究内容包括：基于深亚微米标准CMOS工艺研究电流模式全对称结构垂直霍尔器件，获得减小霍尔失调和提高灵敏度的设计原理和实现方法；研究电流模式四相旋转电流调制和解调技术，发展降低三轴霍尔传感器残余失调的可行方法；研究低功耗电流模式信号调理电路技术，实现霍尔电流信号线性放大和各种失调、噪声消除方法；最终探索出有效的集成技术和解决方案，实现CMOS全集成三轴霍尔传感器。该项目研究对于丰富CMOS垂直霍尔器件设计及失调消除技术的研究内涵，推动低失调、高灵敏度CMOS三轴霍尔传感器的应用具有重要意义。

近几年来CMOS集成霍尔传感器已广泛应用于自动控制、汽车、医疗器械、智能仪器仪表和消费类电子，能同时检测空间三维磁场的三轴霍尔传感器是一个重要的发展和应用方向。然而深亚微米标准CMOS工艺下传统电压模式三轴霍尔传感器存在霍尔器件磁场灵敏度低、失调严重，电路失调消除技术不成熟，残余失调大等一系列问题。为了实现低成本、高灵敏度和低失调的三轴霍尔传感器，本项目基于深亚微米标准CMOS工艺研究了低失调、全对称结构的垂直型和水平型霍尔器件的设计方法，研究了电流模式的器件工作方式，获得了显著提高CMOS霍尔器件特别是垂直型霍尔器件电流灵敏度的有效方法；研究了适合全对称结构霍尔器件的四相旋转电流调制和解调技术，获得了降低残余失调的有效方法；研究了低功耗的电流模式信号调理电路技术，实现对微弱霍尔电流信号的线性放大和对各种失调、噪声的有效消除，获得了信号调理电路与CMOS霍尔器件全集成的方法；最终基于0.18 μm标准CMOS工艺实现一个低成本、低功耗、低失调和高灵敏度的全集成霍尔传感器芯片。测试结果表明，十字水平型霍尔器件在电流工作模式下的电流灵敏度大于6.5%/T，在2V偏压下初始失调小于1mV；通过器件结构优化，TCAD仿真得到的四阱三孔结构垂直型霍尔器件的电流模式灵敏度能提高到了3％/T以上。在3.3V电源下，霍尔传感器芯片最小探测磁场±2mT，残余失调电压小于72μT，输出霍尔电压的线性度大于99.9%，带宽大于30kHz，功耗小于15mW，完全能满足低成本CMOS集成霍尔传感器在精确位置定位、微小位移测量、旋转运动和角度测量等方面应用要求。本项目基于深亚微米标准CMOS工艺在不改变工艺条件前提下，探索出新的低失调、全对称结构的霍尔器件，研究出提高磁场灵敏度、消除失调的新技术和方法，实现了低成本、低功耗、高灵敏度和高可靠性的集成霍尔传感器，研究成果对于推动我国CMOS集成霍尔传感器芯片的自主开发和应用具有重大的研究意义。

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