Dear All,

 I am studying the lecture notes of ECE264 from USD by Prof.Song.

 In the slide talking about the Triple-Cascode Opamp (TCO), it is interesting to find the impedance of each node is pretty high, ½r_o(g_mr_o)² for the output node, and ½r_o(g_mr_o) for the node where parasitical pole locates.

 I am a little bit confusing that the parasitical pole location should be around 1/(½r_o(g_mr_o) C_p). But it is indicated in the slide the pole is locating at g_m/C_p.

 Could anyone explain it to me?

 Thanks a lot!

Feng

hi,
   i think the impedance's what you have shown in the slides are at the dc,but as soon as you cross dominant pole output load cap will start dominant and impedances at other nodes  are 1/gm, so pole's  are at gm/cp.This assumption holds good if cl/cp is very high, otherwise above approximation won't work ..

Thanks,
Rajasekhar.