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？

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

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.

工艺偏差，噪声，面积，蒙特卡洛分析，等等。

THX VERY MUCH！

嗯~非常感谢~

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.