求助 : VCO设计中如果用电阻代替电流源会有什么好处和坏处呢?

lion_cube

如题~想请教一下 VCO设计中如果用电阻代替电流源会有什么好处和坏处呢~

daxigua179

都很明显
避免1/f up conversion
amplitude 需要calibration 去锁

onepieceligen

TAIL Current-based LCVCO has a better PVT since its bias current is well-defined. For most of cases, even removing the tail is better than replacing it with a res.

Ham's design procedure for minimum phase noise:
1. set a Imax=Itail (power consideration)
2. find the Lmin that could start the VCO and provides a swing enough for next stage, i.e., divider or something capacitive.

sevtar

工艺偏差，噪声，面积，蒙特卡洛分析，等等。。。

lion_cube

回复 3# onepieceligen


   THX VERY MUCH!!!

lion_cube

回复 2# daxigua179


   嗯~非常感谢~

onepieceligen

回复 2# daxigua179


   1/f noise from tail is AM noise, so just being careful of the AM-TO-PM noise conversion by Varactors can almost eliminate it. I think tail is better than res, but a no-tail high-swing NPMOS 4T VCO is even better in low-voltage design.

sixye

   

daxigua179 发表于 2014-7-30 22:46
都很明显
避免1/f up conversion
amplitude 需要calibration 去锁

amplitude 需要calibration 去锁。请教一下，（1）原因是啥？尾电流的是怕尾电流管进入线性区，但电阻没这一说（2）有calibration文章推荐？感谢