Help me！ How to find the time constant of a current mirror.

Willy Sansen said: All time constants in that loop are of the same order of magnitude, they create a system with several poles.As a result, peaking can occur in the current transfer characteristic.

My questions are listed below.
1. How to find the time constants of a modified Wilison current mirror, left figure?
2. How to find the poles of this current mirror and explain why it results into a peaking of its current transfer characteristic.
Thanks you for your kindly help.You reply will be highly apprecialted.

may be you can draw the small signal by yourselves and then calculate the rcof each stage.

先求传输函数吧?

当有Iin注入M3是，M3栅和漏极的电压上升，随之M4源极电压上升，所以M2和M1的栅极电压上升，M1栅极的升高造成M1的漏极电压下降，所以M2的Vgs增大，在上点的瞬间形成了正反馈，所以有Peaking

我觉得造成尖峰的原因是两个极点靠得太近变成共轭极点，然后Q值引起的尖峰。
还请高手指正

同意这个观点，有了反馈自然会有出现complex poles的可能，如若Q值太大，就有peaking了