firsttimedesigning
Joined: 04 Jul 2007
Posts: 98
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 30 Oct 2007 7:13 slew rate |
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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...
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