need help in the ring oscillator

[incol]

I am using a differential ring oscillator. The circuit and simulation result are as follows. the bias current is PATA current source, for I need a zero temperature coefficent. But I find my waveform has different amplitude, what is the reason? I can find the reason.
thanks!!

 

[incol]

Re: need help in my ring oscillator

the circuit

 

[Btrend]

could u reduce ur file size of attachment, cause we will lost points before answer ur question, that's a bad trade.

 

[incol]

could u reduce ur file size of attachment, cause we will lost points before answer ur question, that's a bad trade.

oh sorry, but i dont know how to reduce it.

 

[rogerliu]

use "Winrar" tool for compressing file

 

[lokeyh]

Are you taking the differential output for the ring oscillator?