应用于Sigma-Delta ADC中的高性能前置放大器

Design of a high performance pre-amplifier for Sigma-Delta ADC

设计了一种高性能的全差分型折叠式共源共栅放大器。一方面,电路中使用了斩波技术和AB类推挽技术,以提高放大器的精确度和动态性能;另一方面,放大器中的电流源采用自级联结构,可以进一步提高电路的电压裕度和鲁棒性。本电路基于华润上华CMOS 0.35μm工艺实现,版图面积为640μm×280μm,Spectre后仿真结果表明,在电源电压为5 V且斩波频率为156.25 kHz的情况下,等效输入噪声为1.11 n V/Hz^(1/2),失调电压为61.5μV,功耗为1.22 mW。

A high performance fully differential folded-cascode amplifier is designed. On the one hand, in order to improve the amplifier＇s precision and dynamic performance, the chopper and class-AB push-pull technique are applied in the circuit; on the other hand, to further improve the voltage margin and robustness in the circuit, the self-cascode current source is applied in the amplifier. The circuit is realized based on the CSMC 0.35 μm CMOS technique, and the layout area is about 640 μm×280 μm. The simulation results show： at a power supply of 5 V and the chopping frequency of 156.25 kHz, the equivalent input noise is 1.11 n V/Hz（1/2）, the offset voltage is 61.5 μV and the power consumption is 1.22 mW.