环形振荡器全差分的结构，用两级可以吗？

lernerd

拉扎维书上说不行，要无穷大频率才能相移360. 不过看一些文章有出现2级的环形振荡器。请大牛来说说

rong00i8

我确实也见过。把电路的寄生极点搞大，应该是有可能的。不过可能有不起振的风险，而且设计不好，相噪也会很差。

wfcawy

It's OK to use 2-stage differential oscillator to generate IQ phase. 2 stage differential oscillator is actually have 4 Gm cells, so it is more than enough to have 360 phase shift.
However, you need to know the working principle for differential oscillator is somehow different to single end oscillator.
the most common 2 stage differential oscillator is for latch based fully CMOS INV structure.

nool

两级当然可以了
自身的反相180*2，两个极点90*2，total max phase shift 540

lwjee

三楼说的对。

amplifier_bias