SBIR Phase II: Delta-Sigma All-Digital Magnetometer

这个小企业创新研究（SBIR）第二阶段项目将基于数字磁传感器的创新方法开发和原型化单芯片磁强计。传统的方法是将具有模拟输出的物理传感器与电子模数转换器相结合。在这种传感器中，模数转换发生在传感器本身的物理机制中。采用这种方法，只需要廉价的数字电子电路来完成传感器系统，从而产生易于制造的坚固设计。利用了亚微米级磁阻传感器元件的独特性能。这些元件的小尺寸只允许两种磁状态，即磁状态代表一个二进制数字，它是外部磁场的函数。利用借鉴过采样delta-sigma模数转换器的概念，可以通过反复询问钻头的磁状态来测量磁场的模拟量级。利用δ - σ转换器的原理，包括噪声整形反馈和高过采样比，可以实现高分辨率和固有的线性响应。这种单芯片数字磁强计将是传感器技术的革命性进步，因为它是基于标准的晶圆级集成电路处理技术。因此，它将比现有的等效磁传感器系统更小，制造成本更低。该产品的高度集成特性，低功耗和数字输出将使其对远程和/或总线传感器应用极具吸引力。应用包括数字罗盘、地磁测量设备、交通控制车辆传感器、入侵检测、货币/文件验证和便携式生物医学检测设备。

This Small Business Innovation Research (SBIR) Phase II project will develop and prototype a single-chip magnetometer based on an innovative approach to digital magnetic sensors. The traditional approach combines a physical sensor having an analog output with an electronic analog-to-digital converter. In this sensor, the analog-to-digital conversion occurs in the physical mechanism of the sensor itself. With this approach only inexpensive digital electronic circuits are needed to complete the sensor system, resulting in a robust design that can easily be manufactured. The unique properties of sub-micron sized magneto-resistive sensor elements are used. The small size of these elements allows only two magnetic states, i.e. the magnetic state represents a binary digit that is a function of the external magnetic fields. Using concepts borrowed from over-sampling delta-sigma analog-to-digital converters, it is possible to measure the analog magnitude of a magnetic field by repeatedly interrogating the magnetic state of the bit. Using the principles of delta-sigma converters, including noise shaping feedback and high over-sampling ratios, high resolution and an inherently linear response can be achieved. This single-chip digital magnetometer would be a revolutionary advance in sensor technology since it is based on standard wafer-level integrated circuit processing techniques. It will thus be much smaller and cheaper to fabricate than existing equivalent magnetic sensor systems. The highly integrated nature of this product, low power consumption and the digital output will make it extremely attractive for remote and/or bussed sensor applications. Applications include digital compasses, geomagnetic surveying equipment, vehicle sensors for traffic control, intrusion detection, currency/document validation and portable biomedical assay devices.