一种应用于锁相环频率合成器的自动选带电路

An Automatic Band-Selection Module for PLL Frequency Synthesizer

设计了一种适用于多带VCO锁相环频率合成器的自动选带结构。使用迟滞比较器对VCO控制电压进行电平信息采集,并将信息输入到控制电路。控制电路根据接收到的电平信息完成状态跳变,并输出相应的选带开关控制电平,完成自动选带。基于Chartered公司0.18μm RF CMOS工艺完成电路设计,并应用于锁相环小数频率合成器。仿真结果表明,自动选带电路可正常工作,频率合成器能够在30μs内实现快速锁定。

An automatic band-selection module was proposed for PLL frequency synthesizers with multi-band VCO.In this module,hysteresis comparator was used to sample the control voltage applied to VCO and transmit it to control circuit,which changed its state according to received information,and output control voltage to corresponding band-selection switches.The module was designed based on Chartered 0.18 μm RF CMOS process.Simulation results showed that the automatic band-selection module functioned properly,and the PLL frequency synthesizer was capable of fast locking in 30 μs.