摘要
A complete closed-loop third order s-domain model is analyzed for a frequency synthesizer. Based on the model and root-locus technique, the procedure for parameters design is described, and the relationship between the process,voltage,and temperature variation of parameters and the loop stability is quantitatively analyzed. A variation margin is proposed for stability compensation. Furthermore,a simple adjustable current cell in the charge pump is proposed for additional stability compensation and a novel VCO with linear gain is adopted to limit the total variation. A fully integrated frequency synthesizer from 1 to 1.05GHz with 250kHz channel resolution is implemented to verify the methods.
通过分析频率综合器的完整三阶闭环s域模型，同时采用根轨迹分析技术，定量分析了工艺、电压和温度引起的环路参数变化对频率综合器稳定性的影响，并提出变化裕量的概念来进行稳定性分析和参数设计．为了获得更加稳定的系统，在电荷泵中设计了结构简单的电流单元用于补偿额外的参数变化，并采用线性压控增益的VCO来减小参数的变化．最后设计了一个分辨率为250kHz，频率范围为1～1．05GHz的集成频率综合器来验证上述的分析和设计方法．
基金
上海市科学技术委员会2003年度集成电路设计科技专项(批准号:037062019)
上海应用材料研究与发展基金(批准号:0425)资助项目~~
