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need help in wideswing casocode

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avlsi

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send me a design example of High Swing Cascode with both PMOS and NMOS devices.

Thanks in advance
 

eecs4ever

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The trick is to bias the gates of the cascode devices at the right level.

In the diagram, delta V refers to the vdsat of M3, M4, M5, M6.

See image 1 below.
If we bias the gate of M6 at Vgate_6 = Vdd - Vt - 2 delta V. then the
max output voltage that will still keep our transistors in saturation is

vout_max = Vgate_6 + Vt = Vdd - 2 delta V.

This is for a pmos.


For nmos, it is the same idea. You just have to bias the gate of M7, and M8 at Vt + 2Vdsat_8.

Then Vout_min = Vgate_8 - Vt = 2 Vdsat.
See diagram4 below.


The entire lecture slides is here:
https://bwrc.eecs.berkeley.edu/classes/ee140/Lectures/7_more_op_amps.pdf

Bob Brodersen explains those slides here:
watch the Mon, 10/11 lecture.
https://webcast.berkeley.edu/courses/archive.php?seriesid=1906978189

good luck.
 

avlsi

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Thanks a lot eecs4ever. I found ur info very useful.
 

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