基于频率综合器应用的隐式双路径滤波器设计

Design of an Implicit Dual-Path Filter for Frequency Synthesizer

提出了一种隐式双路径环路滤波器结构。该结构克服了传统双路径滤波器需要两个电荷泵的缺点。通过对传统双路径滤波器的积分支路的改进,使积分支路的可适用频率范围展宽,而低频输出噪声减小。电路采用SMIC 0.18μm CMOS工艺实现;采用Hspice,对滤波器的传输函数和噪声特性进行仿真。仿真结果证明,文中提出的方法是十分有效的。

An implicit dual-path loop filter is proposed, which is driven by a single charge pump. The integration path can work in wider frequency range and the low frequency output noise is reduced by improving the conventional integration path. The circuit is implemented in SMIC＇s 0. 18 μm CMOS process. The transfer function and output noise of the filter are simulated using Hspice and results from simulation show that the proposed structure and improvement techniques are effective.