一种应用于CAN收发器的宽输入范围的迟滞比较器设计

Design of a hysteresis comparator with wide input range for CAN transceiver

为了将CAN(Controller Area Network)总线上的-12~12 V的信号转化为0~5 V的串行数字信号,设计了一种应用于CAN收发器的宽输入范围的迟滞比较器。实现的方案是先使用电阻将电源和总线上的信号线性叠加得到5 V电压内的信号,再使用全差分放大器进行钳位,使用共模反馈稳定共模工作点,最后使用对尾电流进行温度补偿的内部正反馈的迟滞比较器比较得到数字信号。基于VIS 0.4μm BCD工艺,使用Hspice进行了仿真验证。仿真结果表明:电路能够将-12~12 V的电压比较得到正确的数字信号。在常温即25℃,TT工艺角下,迟滞门限为108.9 mV。在温度从-40℃~125℃变化时,迟滞门限电压变化小于9.16 mV,温度系数为0.0555 mV/℃。

A hysteresis comparator with wide input range for Controller Area Network(CAN)transceiver is designed to convert the-12~12 V signals on CAN bus into 0~5 V serial digital signals.The solution is to use resistance to linearly superimpose the signals on the power supply and bus to get the signals in the 5 V voltage,then use full differential amplifier to clamp,use common mode feedback to stabilize the common mode working point,and finally use the internal positive feedback hysteresis comparator that can compensate the temperature of the tail current to get the digital signal.Based on VIS 0.4μm BCD process,Hspice is used for simulation and verification.The simulation results show that the circuit can get the correct digital signal by comparing the voltage of-12~12 V.The hysteresis threshold was 108.9 mV at room temperature(25℃)and TT process corner.When the temperature changes from-40℃to 125℃,the change of hysteresis threshold voltage is smaller than 9.16 mV,the temperature coefficient is 0.0555 mV/℃.