对数域滤波器的设计与仿真研究

Design and Simulation Study of Log-Domain Filters

对数域滤波器可用以扩大有源滤波器的输入动态范围,减小输入输出信号间的相移。设计了一种对数域二阶低通滤波器,采用基于二阶低通LC滤波器的信号流图设计方法,并利用元件替代法获取二阶对数域低通滤波器的元件参数值,设计出晶体管级电路原理图。利用Pspice仿真工具对电路进行仿真分析,并分析和推导了三极管参数的非理想特性对对数域滤波器截止频率的影响。并按照3μm/40 V双极性工艺规则完成了版图设计,通过了DRC和LVS验证。仿真结果表明,该对数域二阶低通滤波器的输入动态范围、相移等技术指标明显优于常规有源滤波器。

The log-domain filters can be used to enlarge the dynamic range of active filter and to reduce the phase shift between input and output. A second-order low-pass log-domain filter was designed, which was based on the second-order LC passive filter. And then the signal flow graph （SFG） of the second-order low-pass log-domain filter was set up for calculating simulations. The calculation of parameters was completed by the way of the component substitution, followed by circuit principle diagram. The circuit was simulated with the Pspice simulation instrument to get the results. Besides, the influence of transistor＇s parameter on log-domain filter was analyzed and interpreted. Lastly, the designing of domain was completed by the ＂3 μm/40 V BJT rules＂, and has passed the DRC and LVS verification. The emulation domain filters show the evident advantages results show that the dynamic range and phase shift of the logcompared with common active filters.