【摘要】 针对AD变换器中的预放大器设计了两种全差分放大器电路,一种采用了传统的阻性共模反馈电路结构,另一种则对这个共模反馈电路上进行了改进,并给出了改进的理由、分析和仿真结果。利用SMIC 0.18μm COMS混合信号工艺,把这两种预放大器应用到一个Flash结构的AD变换器中进行了对比流片,预放大器满足AD变换器60 Mbit奈奎斯特采样带宽的要求。流片测试结果表明,采用改进结构预放大器的AD变换器与采用传统结构预放大器的AD变换器相比,信噪比SNR获得了改善,有效位数ENOB提高了大约0.6 bit,改进的预放大器达到了预期的设计要求。更多还原

【Abstract】 Two CMOS differential pre-amplifiers suitable for A/D converters are designed using SMIC 0.18 μm CMOS mixed technology.One adopts a classical resistive CMFB circuit,and another adopts improved CMFB circuit.The issues about reasons,analysis and results of simulation are given.At the same time,two Flash A/D converters introduced with two sorts of differential pre-amplifiers are tapeouted,which have a 60 Mbit Nyquist sample bandwidth.The measurement results show that the A/D converter with improved CMFB pre-amplifier has a better SNR than that one with classical CMFB pre-amplifier,and its ENOB increases of 0.6 bit.The improved pre-amplifier achieves purpose which is expected.更多还原