How will the effect of slew rate be alleviated by adding clamp transistors?

[firsttimedesigning]

M11 and M12 can alleviate the effect of slew rate. (B.Razavi page 333)

First, please look at the file: folded-cascode.

if Iss > Ip then M3 will turn off and Vx will fall to a point, say point A(1V). Then Vx will rise back up because eventually M2 will turn on and every transistor will operate in saturation region.

pleaes look at the file: technique

I dont understand how will the the effect of slew rate be alleviated by adding the clamp transistors.

I think that Vx will drop to a certain point, say point B(1.5V), that will turn on M12. So, the current Ip - Iss will flow into M12. And so the circuit will return back to equilibrium, i.e transistor M3 will turn back on. Also, because point B has higher voltage than point A, Vx can return to equilibrium quicker.

I think that is how the clamp transistors can help alleviating the effect of slew rate but i am not sure...

 

[MikeR]

slew rate

technique.JPG scheme are work? You must have Vy-Vx> Vth for first and Vdd-Vx>Vth for second scheme, but it not realizable in practice schemes. I think this method not implemented for cascoding technique.