摘要
提出了一种新的环振式数字加速度传感器 ,它采用做在硅梁上的 MOS环形振荡器作为敏感元件 ,两个反方向变化的环振输出信号通过集成在片内的混频器实现频率相减 .该传感器具有准数字输出、灵敏度高、温度系数低以及制作工艺简单等特点 .分析了环形振荡器的频率特性 ,以及环形振荡器的谐振频率和加速度的关系 ,分析并设计了加速度传感器的环形振荡器电路、混频器电路、物理结构以及制作工艺 ,并制作了样品 ,其灵敏度为 6 .91k Hz/g.
A novel digital accelerometer using ring oscillators (RO) and mixer is presented.It is different from piezoresistive or capacitive accelerometers that the sensitive unit of this novel accelerometer is MOS ring oscillators located on silicon beams.There are two different ring oscillators in this accelerometer.The output signal is achieved by subtracting the syntonic frequency of one ring oscillator from that of another.The subtraction is realized by a mixer located on the bulk silicon.The accelerometer has many perfect characteristics such as high sensitivity,low temperature coefficient,and simple fabrication process.The best excellence is that digital signal can be achieved directly from the output signal of the RO accelerometer.The frequency characteristic of MOS ring oscillator and its relationship with acceleration are descriped.The circuits,physical structures and fabrication processes of RO accelerometer are designed.The sensitivity of fabricated device is 6.91kHz/g.
