用于免疫微传感器的CMOS微弱电流读出电路

分析了传感器微电极产生信号的特点，阐述了读出电路的工作原理和设计要点，采用电流转换为时间的方法实现了弱信号的读出，最小可测量1pA的直流。电流，量程达5个数量级，相对误差小于0．1。并且系统自带10位数字信号输出，避免了使用AD转换器带来的功率和空间的消耗。系统采用Chartered 0．35um标准CMOS工艺流片。

CMOS Weak Current Readout Circuit for Amperometric Immunosensor

The characterist ics o f the signal f rom the sensor?? s microelect ro des are analyzed. A w eak cur rentreadout circuit is designed, w hich uses a method of t ransfer ring current signal into t ime one. Curr ent ran??g ing f rom 1 pA to 100 nA can be measured w ith a max imum relat iv e deviat ion of 0. 1. T he system also de??l iv ers a 10 bit dig ital o utput , w hich avoids use of an ex tr a analog??to??digital converter. T his w ay, pow erand space of the chip can be further reduced. The chip has been fabricated in the 0. 35 ??m Chartered CMOSpro cess. Ex perimental results are r eported, characterising the per formance of the system as an elect ro??chemical senso r.