一种差分式电容传感器读出电路及其前置放大器的设计  

Design of a Readout Circuit and Its Preamplifier for Differential Capacitive Sensors

作　　者：吕志军[1] 倪学文[1] 莫邦燹[1] 项斌[1] 

机构地区：[1]北京大学微电子研究所,北京100871

出　　处：《微电子学》2003年第3期232-236,共5页Microelectronics

摘　　要：　采用基于开关电容技术的CMOS电路,实现差分式电容微传感器的信号读出;阐述了这种电路结构的工作原理;分析了噪声特性,并提出了减小噪声的措施。分析了各晶体管尺寸对热噪声和1/f噪声的影响,并在设计时进行了折衷。采用3μmN阱CMOS工艺参数对前置放大器进行了HSPICE仿真:放大器具有68nV/Hz的输入噪声、84dB的开环增益、130dB的共模增益等优良的交、直流特性;电路还可以达到1fF的输入分辨率。Based on switchedcapacitor circuits, a CMOS readout circuit is desinged to support a variety of MEMS capacitive sensors Operational mechanism of the circuit is investigated Its noise characteristics are analyzed and methods for decreasing noise are presented Based on the effects of dimensions of different transistors on thermal noise and 1/f noise, tradeoffs are taken Using 3μm Nwell process parameters and HSPICE simulator, the preamplifier is simulated, which has an input referred noise of 68 nV/Hz, a DC gain of 84 dB, a CMRR of 130 dB and other excellent DC and AC characteristics And an input resolution of 1 fF is also achieved for the circuit

关 键 词：电容式微传感器 CMOS电路 过采样 前置放大器 差分式 读出电路 工作原理 噪声特性 

分 类 号：TP212.1[自动化与计算机技术—检测技术与自动化装置]